CompTIA A+ 220-1001 Lesson 5

IEEE 802.11

(Wi-FI) used to implement Wireless Local Area Netwoks (WLAN)

PATCH PANELS AND STRUCTURED CABLING

- A Gigabit Ethernet link using twisted pair cabling can be up to 100 m (328 feet) long. - Solid cabling uses a single thick wire for each conductor for "permanent" links aka cable through walls. also called drop cable This cable links the RJ-45 port on a wall plate with a patch panel. Rather than using modular RJ-45 connectors, solid cable terminates in Insulation Displacement Connectors (IDC) at the back of the wall plate and patch panel - The other side of the patch panel has pre-wired RJ-45 ports. A patch cord connects a port on the patch panel to a port on the switch. A patch cord is made using stranded cable = lots of thin wires twisted to make a single conductor. cable = flexible but less efficient. - A patch cord is no longer than 5 m. - A second patch cord is used between the computer's network adapter and the wall port. This use of patch cords, permanent links, and patch panels is referred to as a structured cabling system. Note: It is vital to use an effective labeling system when installing this type of network so that you know which patch panel port is connected to which wall port.

Ethernet NIC Features

- All onboard cards support copper-based Ethernet with RJ-45 ports. - add-in card =supports other Ethernet types, (fiber optic). Some cards support more than one type of connector. You can also purchase cards with multiple ports of the same type The multiple ports can be bonded to create a higher speed link. Four Gigabit Ethernet ports could be bonded to give a nominal link speed of 4 Gbps.

TCP AND UDP PORTS

- At the link/physical layer, Ethernet allows nodes to send one another frames of data using MAC addresses. frames would be transporting IP packets. -At the network layer, IP provides addressing and routing functionality for a internetwork - Protocols at the transport layer, one up from the network layer, are concerned with effective delivery. - One of the critical functions of the transport layer is to identify each type of network application. It does this by assigning each application a port number between 0 and 65535. - data addressed to the HTTP web browsing application = port 80 data requesting an email application service = port 143. At the transport layer, on the sending host, data from the upper layers is packaged as a series of segments and each segment is tagged with the apps port number. The segment is then passed to the network layer for deliver Note: In fact, each host assigns two port numbers. On the client, the destination port number is mapped to the service that the client is requesting (HTTP on port 80, for instance). The client also assigns a random source port number (47747, for instance). The server uses this client-assigned port number (47747) as the destination port number for its replies and its application port number (80 for HTTP) as its source port. This allows the hosts to track multiple "conversations" for the same application protocol. At the network and data link layers, the port number is not significant

BINARY AND HEXADECIMAL NOTATION

- Binary values are converted to decimal for IPv4 addresses but as IPv6 addresses are h longer, hexadecimal notation is used. - Hexadecimal has 16 characters (0...9 plus A, B, C, D, E, F). it only takes 1 hexadecimal character to represent 4 binary characters.

Coaxial Cabling and Connectors

- Coaxial, or coax cable type of copper cabling carrying electrical signals. - twisted pair uses balancing to cancel out interference, - coax uses two conductors that share the same axis. The core signal conductor is enclosed by plastic insulation (dielectric) then a second wire mesh conductor serves both as shielding from EMI and as a ground. Radio Grade (RG) "standard."- classifies Coax cables The Radio Grade (or Radio Guide) classifications were developed by the US military but are no longer active. they do not categorize by the coax cable quality but by the thickness of the core conductor and the cable's characteristic impedance. •RG-6 cable •RG-59 Coax cabling is also available with tri- or quad-shielding for better resistance to EMI and eavesdropping. In most cases, BNC (alternately Bayonet-Neill-Concelman, British Naval Connector, or Barrel Nut Connector) connectors are crimped to the ends of the cable. The impedance of the connector must match the cable type (50 or 75 ohm). - Coax installations also use screw-down F-connectors. A broadband cable service, is likely to use the F-connector for drop cables. - Ethernet LAN media product (10BASE-5/Thicknet and 10BASE-2/Thinnet), coax could support 10 Mbps with cable lengths of up to 500 m and 185 m, respectively. - Coax is not used for LAN applications - still used for CCTV networks and as drop cables for cable TV (CATV) and Internet access it can support higher bandwidths but at reduced range. - Hybrid Fiber Coax (HFC) network, coax cable links the fiber optic trunk serving the whole street to the cable "modem" installed in the customer's premises. Coax suffers less from attenuation than twisted pair but is generally bulkier and more difficult to install.

DIAL-UP INTERNET ACCESS

- Dial-up is simply a telephone conversation between two computers. . - A dial-up link is very low bandwidth. - A dial-up connection is facilitated by analog modems on each end of the line. - A dial-up modem converts digital signals to an analog carrier signal (modulation) and transmits it over the telephone cable, The modem at the other end converts the analog signal back to digital (demodulation) and processes the data. - disadvantages=low data transfer rates,, and error prone links. - fastest modems can only usually work at 33.6 Kbps (V.34+) - V.90 or V.92 digital signaling protocol, a downlink speed of up to 56 Kbps is possible in theory, -compression can also improve the data transfer throughput, though as many of the files are likely to be compressed already (image files, for instance), the improvement will be variable.

Fully Qualified Domain Name (FQDN).

- FQDN=The full name of any host FQDNs reflect the hierarchy, from most specific (the host) to least specific (the top level domain followed by the root). For example: www.widget.com. - The domain name identifies a company, organization, or even individual. The name is unique/officially registered . Host names and local domains are specified within the organization (for example, to identify a server located in the sales department of a company). The www host name is a common alias to indicate that the resource is a web server. Parts of two FQDNs with 1) Top level domain; 2) Subdomain; 3) Host name.

Secure Sockets Layer (SSL)

- HTTP=unsecure bc no encryption . Secure Sockets Layer (SSL) was developed by Netscape to address these problems. SSL proved very popular with the industry and is still in widespread use. Transport Layer Security (TLS) was developed TLS can also be used with UDP applications, referred to as Datagram Transport Layer Security (DTLS). Some VPN solutions depend on the use of DTLS. Note: HTTPS operates over port 443 by default.

DHCP AND DNS SERVERS

- Hosts must also receive a suitable network config to communicate on the network. DHCP and DNS are two of the services that facilitate this: •Dynamic Host Configuration Protocol (DHCP) assign IP address info to host automatically when they connect to the network. •Domain Name System (DNS) allow users to access resources using host names and Fully Qualified Domain Names (FQDN) by resolving those names to IP addresses.

Default Gateway

- IP address of a router to which packets destined for a remote network should be sent by default. failure to enter a gateway would limit to communication on the local network only.

IPv4 ADDRESS AND SUBNET MASK

- IPv4 address and subnet mask can be set manually (static address). - IP address is entered as four decimal numbers separated by periods (e.g., 172.30.15.12). -The IP address identifies the network to which the interface is attached and also its unique identity on that network. An interface must be configured with an IP address. The subnet mask is used in conjunction with the IP address to determine whether another interface is located on a local or remote network. An interface must be configured with a subnet mask.

IPV4 Address format

- IPv4 address is 32 bits long and is used within an IPv4 packet to define the source and destination of the packet. In its raw form it appears as: 11000110001010010001000000001001 The 32 bits are subdivided into four groups of 8 bits (1 byte) known as octets. The above IP address could therefore be rearranged as: 11000110 00101001 00010000 00001001 . To make IP addresses easier to use, they are usually displayed in dotted decimal notation. This notation requires each octet to be converted to a decimal value. The decimal numbers are separated using a period. Converting the previous number to this notation gives: 198 . 41 . 16 . 9

IPv6 ADDRESSING SCHEMES

- IPv6 address is divided into two main parts: the first 64 bits are used as a network ID while the second 64 bits designate a specific interface. -The interface identifier is always the last 64 bits; the first 64 bits are used for network addressing. As the network and host portions are fixed size, there is no need for a subnet mask. -addresses are written using prefix notation, where /nn is the length of the routing prefix in bits. Within the 64-bit network ID, the length of any given network prefix is used to determine whether two addresses belong to the same IP network.

Link-Local Addressing

- IPv6 for network housekeeping traffic. -Link-local addresses span a single subnet (they are not forwarded by routers). Nodes on the same link are referred to as neighbors. -In hex notation, link-local addresses start with fe80:: The equivalent in IPv4 is Automatic Private IP Addressing (APIPA) and its 169.254.0.0 addresses. -unlike IPv4, IPv6 host always configured with link-local addresses , even if it also has a globally unique address.

GLOBALLY UNIQUE UNICAST ADDRESSING

- In IPv4 a unicast address identifies a single network interface. The main types =global and link-local. - global address is one that is unique on the Internet Global unicast addresses have the following format: • first 3 bits indicate that the address is within the global scope. In hex notation, a address will start with either "2" or "3." •The next 45 bits are allocated in a hierarchical manner to regional registries and from them to ISPs and end users. •The next 16 bits identity site-specific subnet addresses. • final 64 bits are the interface ID = generated from the adapter's MAC address (padded with extra bits to make it 64 bits in length) or is randomly generated. - address blocks are automatically assigned hierarchically by routers. Top-level routers have top-level address blocks, which are automatically divided and assigned as routers and segments are added. This divides the address space as a logical hierarchy, compared to the ad-hoc address-space management procedures that were developed for IPv4, making it easier to manage.

LIGHTWEIGHT DIRECTORY ACCESS PROTOCOL (LDAP)

- Network resources are recorded within a directory. - In order for products from different vendors to be interoperable, directories are based on the same standard. - main directory standard= X.500 series of standards, developed by the International Telecommunications Union (ITU) The problem with X.500 is that the full set of standards specified the use of a complex protocol stack as a means of network access, at a time when most organizations were opting to use TCP/IP. - a means for clients to connect to an X.500 server over TCP/IP and this was standardized by the IETF as the Lightweight Directory Access Protocol (LDAP). LDAP is a protocol used to query and update an X. 500 directory, or any type of directory that can present itself as an X.500 directory. It is widely supported in current directory products—Windows Active Directory, Apple OpenDirectory, or the open source OpenLDAP, for instance. LDAP uses TCP and UDP port 389 by default.

Basic Rate Interface (BRI)

- Provides two 64 Kbps "B" channels for data and one 16 Kbps "D" channel for link management control signals. sometimes called 2B+D. - One option = one B channel for data and the other for voice or fax; another I= provide a 128 Kbps link by concatenating the two B channels. This form of ISDN is 4 SOHO use.

WIRING STANDARDS FOR TWISTED PAIR

- RJ-45 connectors. - RJ-45 (8P8), (8-position/8-contact) Each conductor in 4-pair color-coded. Each pair is assigned a color (Blue, Orange, Green, or Brown). The first conductor in each pair has a white insulator with stripes of the color; the second conductor has an insulator with the solid color. - The ANSI/TIA/EIA 568 standard=two methods for RJ-45 connectors: T568A and T568B. The wiring for In T568B, pin 1 is wired to Orange/White, pin 2 is wired to Orange, pin 3 is wired to Green/White, and pin 6 is wired to Green or, put another way, the orange and green pairs are swapped over. - A normal—or straight through—Ethernet cable is wired with the same type of termination at both ends. Using T568A at one end and T568B at the other creates a crossover cable. - Crossover cables were once used to connect computers directly, but Gigabit Ethernet interfaces can perform this automatically, even w/ standard cables - try to avoid using a mixture of the two standards. T568A is mandated for US government premises and by the residential cabling standard (TIA 570).

SOHO Network

- SOHO (Small Office Home Office) LAN is a business-oriented network possibly using a centralized server in addition to client devices and printers, but often using a single Internet for connectivity. - Home and residential networks may also be classed as SOHO. These Internet appliances provide the following functions: •Access point—allows clients with wireless radio adapters to connect to the network. •Ethernet switch—connects wired client devices and printers with RJ-45 cables. •Internet modem—interfaces with the physical link to the ISP's routers (DSL or cable, for instance). •Internet router—forwards communications to and from the Internet Service Provider (ISP) routers to provide Internet access.

SATELLITE INTERNET ACCESS

- Satellite systems =bigger areas of coverages. -A Very Small Aperture Terminal (VSAT) microwave antenna is aligned to an orbital satellite that can either relay signals between sites directly or via another satellite. -Satellites use frequency bands in the Super High Frequency range (3-30 GHz). - Satellite services for business are expanding, -. The transfer rates available vary between providers and access packages, but 2 or 6 Mbps up and 15-20 Mbps down. quite restrictive usage limits. - disadvantage = severe latency problems because bigger range + a delay -if accessing a site over DSL involves a 15-50 ms delay on the link, accessing the same site over a satellite link = 1000 ms delay. issue for real-time applications, video-conferencing, VoIP, and multi-player gaming. - satellite connection created by the installation of a satellite dish (antenna) (by the ISP) aligned with the orbital satellite. -the satellites are in geostationary orbit above the equator, so in the northern hemisphere the dish will be pointing south. no need for any realignment. -The antenna is connected via coaxial cabling to a DVB-S (Digital Video Broadcast Satellite) modem. This can be installed as an adapter card or as an external box connected via a USB or Ethernet port.

(TIA 570).

- T568A is mandated for US government premises and by the residential cabling standar

CAT STANDARDS

- The #r of twists is one factor in the speed and transmission limitations of the cable. - Twisted pair cable is rated for different Ethernet applications according to "Cat" specifications, defined in the TIA/EIA-568-C Commercial Building Telecommunications Cabling Standards. Note: Vendors sometimes label Cat 6A cable as "Cat 6e" because Cat 5e followed Cat 5. The "A" stands for "augmented." - Cat 5 cable is no longer available. - Cat 5e is tested at 100 MHz—as Cat 5 was—the cable is rated to handle Gigabit Ethernet throughput. - Cat 5e a good choice for network links for workstations. - Cat 6 can support 10 Gbps, but over shorter distances. - Cat 6A is an improved specification cable with the ability to support 10 Gbps over 100 m. mostly used in data centers or as backbone cabling between servers and network appliances. Note: Cabling is not the only part of the wiring system that must be rated to the appropriate category. For faster network applications (Gigabit Ethernet and better), the performance of connectors becomes increasingly critical. For example, if you are installing Cat 6A wiring, you must also install Cat 6A patch panels, wall plates, and connectors.

Cable Testing Tools

- The best time to verify wiring installation and termination is just after you have made all the connections since you should have access to the cable runs. Identifying and correcting errors at this point is much easier than when trying to set up end user devices. When troubleshooting a cabled network link, you may need to consider: •The patch cord between the PC and the wall port. •The wall port and the cabling in the wall. •The port on the patch panel and the patch cord to the switch port. Test patch cords by substitution. If the patch cord is fine = no configuration errors. then start testing the structured links. There are a number of network cabling and infrastructure troubleshooting devices help.. - A multimeter is a basic cable testing tool. a multimeter tests electrical circuits, but you can use one to test for the continuity of any sort of copper wire, the existence of a short, and the integrity of a terminator. - advanced cable testers provide details on the physical/electrical properties of the cable. they test and report on cable conditions, crosstalk, attenuation, noise, resistance, and other characteristics of a cable run. - Devices classed as certifiers test and certify cable installations to a certain performance category (for example, that a network is TIA/EIA 568-C Category 6 compliant). - They use defined transport performance specifications to ensure an installation exceeds the required performance characteristics for parameters such as attenuation and crosstalk.

SHIELDED TWISTED PAIR (STP)

- When twisted pair cabling was first used in networks it was shielded to make it less susceptible to interference and crosstalk. Each pair was surrounded by a braided shield. - STP is bulky and difficult to install, so when protection from interference is required, STP installations use screened cables, meaning a shield positioned around all pairs. - Most Cat 5e/ 6/6A cable is available in shielded variants, notably F/UTP and U/FTP: •F/UTP—with a foil screen around all pairs, often also designated ScTP. •U/FTP—with foil shielding for each pair. - Legacy STP are more complex to install as bonding each element to ground manually is required - modern screened and shielded solutions reduce this by incorporating grounding within the design

AUTHENTICATION SERVER

- access control system to prevent unauthorized users (and devices) from connecting. In a Windows=simple password. - enterprise networks configure user accounts and authenticate the subjects trying to use those accounts. - On a Windows domain, the user database and authentication service is provided by Active Directory, - An Authentication, Authorization, and Accounting (AAA) server is one that consolidates authentication services across multiple access devices, such as switches, routers, and access points. - Remote Authentication Dial-in User Service (RADIUS) is an example of an AAA protocol.

UNIFORM RESOURCE LOCATOR

- addressing scheme used to access resources on the internet - A URL contains all the information necessary to identify and access an item. For example, a URL for an HTTP resource contains •The protocol describes the access method or service type being used. •The host location is usually represented by a Fully Qualified Domain Name (FQDN). The FQDN is not case sensitive. The host location can also be an IP address; an IPv6 address must be enclosed in square brackets. •The file path specifies the directory and file name location of the resource (if required). The file path may or may not be case-sensitive, depending on how the server is configured. URL with 1) Protocol; 2) FQDN; 3) File path

Intrusion Protection System (IPS)

- adds some sort of real-time blocking functionality on top of IDS. - may drop packets, reset connections, or run a script to trigger a response on another server or network device (firewall, switch, or router).

Access Point

- allows clients with wireless radio adapters to connect to the network -In 802.11 this is referred to as a Basic Service Set (BSS). The MAC address of the AP is used as the Basic Service Set Identifier (BSSID). More than one BSS can be grouped together in an Extended Service Set (ESS). - The access point works as a bridge, forwarding communications between the wireless stations and the wired network, aka a Distribution System (DS). -the access point will be joined to the network via a wall port and cabling to an Ethernet switch.

Metropolitan Area Network (MAN)

- an area equivalent to a city or other municipality. - a company with multiple connected networks within the same metropolitan area - larger than a LAN but smaller than a WAN.

Server Message Block (SMB)

- application protocol underpinning file and printer sharing on Windows networks. version 2 of the protocol is used (SMB2), - TCP on port 445 but can also run as part of NetBIOS over TCP/IP, over UDP and TCP in the port range 137-139. - Samba software implements the protocol for Linux, enabling them to share/access resources on a Windows-based network. SMB is also sometimes referred to as the Common Internet File System (CIFS).

Dynamic Host Configuration Protocol (DHCP)

- avoids problems when an interface is configured manually with a static address - Server allocate an IP address and subnet mask (plus other settings) dynamically. - The computer contacts the DHCP server as it starts up and is allocated a lease for an IP address. Settings such as default gateway and DNS server addresses may be passed to the computer at the same time.clients will update themselves automatically when they seek a new lease (or a new lease can be requested manually). Note: The DHCP client communicates with the server using broadcast communications so there is no need to configure a DHCP server address.

Network Interface Card (NIC)

- communications are transported over ethernet cables by electrical signaling in the case of twisted pair, or light signaling in the case of fiber optic. - The physical connection to the network media is made using a port in the computer's network adapter or Network Interface Card (NIC). - NIC transmits/receives signals and processes them as digital data, they must be divided into regular units with a consistent format. There must also be a means for each node on the local network to address communications to another node. Ethernet provides a data link protocol to perform these framing and addressing functions. - The signaling device uses methods to represent the 1s and 0s of computer data as electrical or light pulses. The transceiver in the NIC is responsible for transmitting and receiving these pulses in the agreed frame format.

Wireless Internet Service Provider (WISP)

- companies specializing in LoS networks Wireless Internet Service Provider (WISP). A WISP might use Wi-Fi type networking or proprietary equipment. -an operate over a range of frequencies. -The use of certain frequencies may be impacted by the deployment of 5G cellular services

Virtual Private Network (VPN)

- connects components/resources of two (private) networks over another (public) network. - The Internet = cost effective way of connecting both users to networks and networks to networks. -Rather than a user direct-dialing your server, which is private but expensive, the user connects to an ISP, which is cheap, but public. - A VPN is a "tunnel" through the Internet. - Once the connection has been established, to all intents and purposes, the remote computer becomes part of the local network

Private Addressing

- defined by RFC 1918 and are sometimes referred to as RFC 1918 addresses. Hosts with IP addresses from these ranges are not allowed to route traffic over the Internet. Use of the addresses is confined to private LANs. There are three private address ranges, each associated with one of the default subnet masks: •10.0.0.0 to 10.255.255.255 (Class A private address range). •172.16.0.0 to 172.31.255.255 (Class B private address range). •192.168.0.0 to 192.168.255.255 (Class C private address range). •169.254.0.0 to 169.254.255.255 (APIPA/link-local autoconfiguration). Internet access can be facilitated for hosts using the private addressing scheme in two ways: •Through a router configured with a single or block of valid public addresses; the router translates between the private and public addresses using Network Address Translation (NAT). •Through a proxy server that fulfills requests for Internet resources on behalf of clients.

ANSI/TIA/EIA 568 standard

- defines two methods for terminating RJ-44 Cables - T568A and T568B. T568B, pin 1 is wired to Orange/White, pin 2 is wired to Orange, pin 3 is wired to Green/White, and pin 6 is wired to Green or, put another way, the orange and green pairs are swapped over. - A normal—or straight through—Ethernet cable is wired with the same type of termination at both ends. Using T568A at one end and T568B at the other creates a crossover cable. - Crossover cables were once used to connect computers directly, but Gigabit Ethernet interfaces can perform this automatically, even w/ standard cables

Wire Stripper (cutter)

- designed for cutting copper wire and stripping insulation and cable jackets. there are tools that have replaceable blades for different data cable types. - Cable cutting blades should be rounded to preserve the wire geometry. - Stripping tools should have the correct diameter to score a cable jacket without damaging the insulation around each wire.

Network Basic Input/Output System (NetBIOS)/ NetBIOS over TCP/IP (NetBT)

- earliest Windows networks used this -allowed computers to address one another by names/and establish sessions. - NetBIOS was re-engineered to work over the TCP and UDP protocols, referred to as NetBIOS over TCP/IP (NetBT): •Name service (UDP port 137). •Datagram transmission service (UDP port 138). •Session service (TCP port 139). . NetBT should be disabled on most networks. It is only required if the network has to support pre-Windows 2000 legacy systems

UNIFIED THREAT MANAGEMENT (UTM)

- enforces a variety of security-related measures, combining the work of a firewall, malware scanner, and intrusion detection/prevention. - centralizes the threat management service, providing simpler configuration and reporting -There are two basic ways of implementing network connectivity for IDS and IPS or UTM server services and appliances: Install the appliance inline with the network—all network traffic passes through the server so suspect traffic can be blocked easily. - drawback is that a single appliance would represent a critical point of failure. If the forwarding function of the appliance were to fail, no traffic would be able through the network. Install the appliance as a sensor—the appliance has a tap or mirror that enables it to view the traffic passing over a network link or switch. - prevention=slower and more complex as the appliance must trigger a script for the preventive action to be enacted by another device If the device is overwhelmed by the traffic volume, it will not be inspecting all of that traffic and could be allowing malicious traffic to pass undetected

Terminal Adapter (TA)

- facilitated ISDN connection -TA may be an external appliance or a plug-in card for a PC or compatible router. - TA is connected to the ISDN via an NT1 device (Network Terminator). The ISDN-enabled router may be connected to a switch or support direct ISDN

Automatic Private IP Addressing (APIPA)

- fallback mechanism 4 when a computer cannot contact a DHCP Iit is connected to. In this scenario, the computer selects an address at random from the range 169.254.1.0 to 169.254.254.255. -Microsoft calls this (APIPA). -Whenusing an APIPA address, it can communicate with other hosts on the same network that are using APIPA, but cannot reach other networks or communicate with hosts that have managed to obtain a valid DHCP lease.

Multi-mode (MMF)

- fiber optic cable - larger core (62.5 or 50 microns) designed to carry a shorter wavelength light (850 nm or 1300 nm) transmitted in multiple waves of varying length. - MMF uses less expensive optics and consequently is less expensive to deploy than SMF. - does not support high signaling speeds or long distances so is more suitable for LANs than WANs..

Single-Mode Fiber (SMF)

- fiber optic cable -small core (8-10 microns) and is designed to carry a long wavelength, near infrared (1310 or 1550 nm) light signal, generated by a laser. - Single-mode cables support data rates up to 10 Gbps or better and cable runs of many kilometers, depending on the quality of the cable and optics.

Domain Name System (DNS)

- hierarchical system for resolving names to IP addresses. - uses a distributed database that contains info on domains/hosts within those domains - loss of one DNS server does not prevent name resolution from being performed. - At the top of the DNS hierarchy is the root,=often represented by a period (.). - 13 root level servers (A to M). Immediately below the root lie the Top Level Domains (TLDs). several types of top level domain, but the most prevalent are (.com, .org, .net, .info, .biz), sponsored (.gov, .edu), and country code (.uk, .ca, .de). The domain name system is operated by ICANN (icann.org), who also manage the generic top level domains. Each domain name has to be registered with a Domain Name Registry for the right TLDt Information about a domain is found by tracing records from the root down through the hierarchy. -The root servers have complete information about the top level domain servers.

Enterprise LAN

- hundreds or thousands of servers and clients. Such networks would - require multiple enterprise-class switch, access point, and router appliances to maintain performance - The term Campus Area Network (CAN) is sometimes used for a LAN that spans multiple nearby buildings. -. Client devices are located in work areas, which are connected to the network by cabling running through wall conduit and patch panel or by wireless access points. Workgroup switches connect these devices to core/distribution switches and routers, which provide access to network servers, printers, and Internet services. - Internet services run in protected Demilitarized Zones (DMZ) to provide Internet access for employees, email and communications, remote access via Virtual Private Networks (VPNs), and web services for external clients and customers.

Endpoint Management Server

- identifies computing devices running on the network and ensuring that they are securely configured. This might mean applying OS and antivirus updates automatically, cataloging software applications installed on each device, applying security policies, retrieving and analyzing log files, and monitoring performance and other status alerts. Microsoft has the System Center and Configuration Manager (SCCM) for Windows

Negative Acknowledgement (NACK)

- if the data is damaged or doesn't send, NACK forces retransmission

Hybrid Fiber Coax (HFC)

- internet cable used for CATV (Cable Access TV) -These networks combine a fiber optic core network with coax links to customer equipment, also called "broadband cable" or just as "cable." The cable modem is interfaced through an Ethernet adapter and coax. More coax then links all the premises in a street with a Cable Modem Termination System (CMTS), which routes data traffic via the fiber backbone to the ISP's Point of Presence (PoP) and from there to the Internet.

IPv6

- it is feared IPv4 addresses will run out, IP Version 6, has been developed. - 128-bit number (contrast with the 32-bit number used in v4). - also includes new efficiency features, simplified address headers, hierarchical addressing, support for time-sensitive network traffic, and a new structure for unicast addressing.

repeater

- legacy networking device - device used to overcome network cabling distance limits It receives a transmission arriving over one cable segment and then regenerates and retransmits it at the original strength over another cable segment. Note: Standalone repeater devices are still widely used. On fiber optic networks it is often necessary to use repeaters on long-distance communications cabling.

Bridges

- legacy networking device -device that divides a local network into 2+ segments. -helps hosts on dif segments communicate -Contention arises in hub-based Ethernet bc all communications are received by all comps connected to the hub. The hub repeats all transmissions across all ports. A lot of the communications are unneeded so many "collide." collision=all nodes have to stop & resend frames, slowing the network down. The network segment in which these collisions occur is called a collision domain. Any nodes attached to a hub are in a single collision domain. -bridge used to divide an overloaded network into separate collision domains. -bridge keeps track of the MAC addresses attached to each segment. Then passes signals from one segment to another if needed, reducing traffic loads Bridge operation—the bridge tracks MAC addresses associated with each port and only forwards communications out of the port associated with the destination MAC address.

Hub

- legacy networking device -device which implements the Ethernet cabling design (aka star topology). contains a number of ports(4-48) to provide connections for network devices. A hub ensures that all devices receive signals put on the network, working as a multiport repeater. - Node A transmits a signal, which is received by the hub and forwarded out of each other port for reception by all the other nodes.

ad-hoc mode

- older network standard used to configure direct connections between stations. -. Such peer-to-peer connections are now more likely to be implemented as Wi-Fi Direct, which has the advantage of automatically configuring a secure link between the stations.

Unmanaged Switch

- performs the microsegmentation without configuration. - power it on, connect some hosts, and it will work. -unmanaged switches with four-eight ports used in small networks. -unmanaged switch embedded in most of the Internet router/modems supplied by ISPs

MICROSEGMENTATION

- point-to-point link (virtual circuit) between any 2 network nodes established by the switch in switch port collision domains 1.Computer A transmits a frame intended for Computer B. 2.The switch receives the frame into a port buffer and reads the destination MAC address from the Ethernet frame. 3. The switch uses its MAC address table to find the port connected to the destination MAC address. 4.The switch uses its high speed backplane to send the frame out on port 3 for computer B to receive. 5.None of the other connected devices, such as host c, observe any activity on the network during this process. so other devices can transmit/receive at the same time. - Because each port is in a separate collision domain, collisions can occur if port is in half-duplex mode. This would only occur if a legacy network card/hub is attached to it. collisions only affect the segment between the port and that adapter—they do not slow down the whole network. other devices are able to send communications at the same time using the full bandwidth of the network media. Note: Half duplex means that a port can either send or receive but cannot do both at the same time. Ports supporting Gigabit Ethernet can send and receive at the same time (full duplex). Note: You are very unlikely to come across hub or bridge appliances. The vast majority of Ethernet networks are implemented using switches. Gigabit Ethernet can only run using switches. Note that the function of a bridge is still an important one, though. For example, a PC might use a software bridge between network adapters (for network connectivity when the host is running virtualization software, for instance).

Transmission Control Protocol/Internet Protocol (TCP/IP)

- protocol suite for LAN and WAN communications - developed by the US Department of Defense but is now an open standard - Developments are implemented through the Internet Engineering Task Force (IETF), -Standards are published as Request For Comments (RFCs). -TCP/IP protocols are packet-based. This means a data package t is split into small packets. - Smaller packets have a better chance of being delivered successfully

Switches

- replaced hubs and bridges - Like hubs, switches connect nodes together in a single network, repeating/regenerating signals over many ports. - Like bridges, switches are used to reduce the effect of contention.

defense in depth

- security principle in an endpoint management server which ensures policies cannot be compromised

Local Area Networks (LANs)

- self-contained network that spans a small area, such as a s building, floor, or room. - all the nodes or hosts participating in the network are directly connected with cables or short-range wireless media. - typically a single site or possibly several sites in close proximity connected by high-speed backbones. The term campus area network (CAN) is sometimes used for a LAN that spans multiple nearby buildings. Any network where the nodes are within about 1 or 2 km (or about 1 mile) of one another can be thought of as "local."

Wide Area Network (WAN)

- spans multiple geographic locations. WANs typically connect multiple LANs using long-range transmission media. - rely on some intermediate network, ex) Internet or phone system, to connect geographically diverse LANs. - A network where remote users "dial-in" is also a type of WAN.

IEEE 802.11n

- substantially more bandwidth than the legacy standards. -multiplexes the signals from 2-4 separate antennas in a process called Multiple-Input-Multiple-Output (MIMO). -The configuration of 802.11n devices is identified by AxB:C notation, where A is the number of transmit antennas, B is the number of receive antennas, and C is the number of simultaneous transmit and receive streams. The maximum possible is 4x4:4 but common configurations are 2x2:2, 3x3:2, or 3x3:3. Both the transmitter and receiver must support the same number of streams. -can deliver ore bandwidth with the option to use two adjacent 20 MHz channels as a single 40 MHz channel (channel bonding). - can use channels in the 2.4 GHz band or the 5 GHz band. The 5 GHz band is preferred -Channel bonding is only a practical option in the 5 GHz band. -data rates for 802.11n are 288.8 Mbps for a single channel and 600 Mbps for bonded channels. Note: Cheaper adapters may only support the 2.4 GHz band. Many smartphone models only support 2.4 GHz. An access point or adapter that can support both is referred to as dual band. A dual band access point can support both 2.4 GHz and 5 GHz bands simultaneously. This allows legacy clients to be allocated to the 2.4 GHz band.

syslog

- system in UNIX and Linux is usually syslog. designed to follow a client-server model and so allows for centralized collection of events from multiple sources. - provides an open format for event logging messages and as such, has become a de facto standard for logging events from distributed systems. For example, syslog messages can be generated by Cisco routers and switches, as well as servers and workstations, and collected in a central database for viewing and analysis.

CLIENT-SIDE DNS

- the IP address of one or more Domain Name System (DNS) servers - essential for locating resources on the Internet. - Most local networks also use DNS for name resolution. Typically, the DNS server would be the gateway address, -Often two DNS server addresses (preferred and alternate) are specified for redundancy.

RG-6 coax cable

- thicker core conductor - better signal quality - drop/patch cable for modern Cable Access TV (CATV) and broadband cable modems.

RG-59 coax cable

- thinner core conductor - used as a drop cable for older CATV/cable modem installs and is also used for CCTV cabling.

Network

- two or more computer systems linked together by some form of transmission medium that enables them to share info - The network technology is what connects the computers, but the purpose of the network is to provide services or resources to its users. - Historically, these services have included access to shared files, folders, and printers plus email and database applications. -Modern networks are evolving to provide more diverse services, including web applications, social networking, Voice over IP, multimedia conferencing, and Internet of Things connectivity for household devices and appliances.

Authoritative name server

- type of DNS server holds domain records and can respond authoritatively to requests for hosts info in the domain(s) it manages. On a private network, such as an Active Directory (AD) domain, a name server must be running to host the AD DNS records. - t, public information about a domain, such as the location of its web and email servers, will be published to a name server.

Unshielded Twisted Pair (UTP)

- type of cabling most used for computer networking. - the cable contains four copper conductor "pairs." - Each conductor has an insulating sheath. - Each pair of conductors is twisted, which reduces interference between the wires (crosstalk) and interference from other electromagnetic sources, referred to as Electromagnetic Interference (EMI). -Each pair is twisted at a different rate to further reduce interference. - The signals sent over each pair are balanced. each wire carries an equal but opposite signal to its pair. This helps to identify the signal better against any source of interference. - The four pairs are covered by a protective outer jacket. - insulation sheaths and jacket are usually made of (PVC). UTP works well where there are no powerful interference sources, - but the electrical signaling method has limited range. - The signal loses power quickly over long ranges (above 100 m).

Transport Control Protocol (TCP)

- used at the transport layer to ensure reliable data delivery. achieved by TCP using acknowledgement messages to inform the sender the data was successfully received.. - TCP is connection-oriented, because it ensures reliability/sequencing of messages. - Sometimes it is more important that communications be faster than they are reliable. = UDP

Public Switched Telephone Network (PSTN)

- used by SOHO, - national/international telecommunications network

Managed Switches

- used by larger workgroups/corporate networks designed for larger LANs -will work as an unmanaged switch out-of-the-box, but an administrator can configure security settings, and change advanced functions. -benefit=enterprise networks can link switches together to provide 1000s of access ports= performance and security issues, so ports are divided into separate Virtual LANs (VLANs). -Config can be done over a web interface or a command line.

Subnet Mask

- used to distinguish these two components within a single IP address(network ID and Host ID). It is used to "mask" the host ID portion of the IP address and thereby reveal the network ID portion. -Where there is a binary 1 in the mask, the corresponding binary digit in the IP address is part of the network ID. The sizes of the network and host portions determines the number of networks and hosts per network a addressing scheme can support. -Many subnetting schemes use o default masks. These are masks comprising whole octets only. Each default mask is known by a particular "class." - The mask can be expressed in dotted decimal format or as a network prefix. The network prefix is simply the number of ones that appear in the mask. Note: The 1s in the mask are always contiguous. For example, a mask 11111111 11110000 00000000 00000000 is valid but 11111111 00000000 11110000 00000000 is not.

loopback plug

- used to test a port. - It involves connecting pin 1 to pin 3 and pin 2 to pin 6 by rewiring the jack or twisting the relevant pairs together on a cable stub. - Alternatively, you can purchase a prefabricated loopback plug. - When you connect a loopback plug to a port, you should see a solid connection LED. You can also use the plug in conjunction with diagnostic software.

Tone Generator and Probe

- used to trace a cable from one end to the other. - useful when cables are bundled/not labeled - This device is also known as a "Fox and Hound" or "toner and probe." - The tone generator is used to apply a signal on the cable. - The probe is used to detect the signal and follow the cable and identify it -To locate a cable in a group of cables, connect the tone generator to the copper ends of the wires, then move the tone locator over the group of cables. A soft beeping tone indicates that you are close to the correct wire set; when the beeping is loudest, you have found the cable. Note: Do not connect a tone generator to a cable that is connected to a NIC. The signal sent by the tone generator can destroy network equipment.

Intrusion Detection System (IDS)

- uses a sensor plus/analysis engine that scans network traffic for signs of threats or other violations of security policy. - similar to an antivirus - IDS can use behavioral or heuristic techniques to identify potential threats. In contrast to a basic packet-filtering firewall, which can be configured with rules about IP addresses and application protocol ports, a network-based IDS examines the contents of the application - When IDS detects an intrusion event, it creates a log entry and sends an alert to an administrator, - drawbacks of IDS is the detection of too many innocuous events (false positives). There are many vendors supplying IDS software and appliances. The underlying detection engine for most of these products is based either on Snort or on Suricata. Each IDS solution adds its own connectivity (options for sensor placement), configuration, and reporting tools

NETWORK ADDRESS TRANSLATION (NAT)

- where the router converts a private IP into a public one so that the internet can be accessed A NAT address pool supports multiple connections but is still limited by the #of available public IP addresses. -referred to as Port Address Translation (PAT) or as NAT overloading. - NAPT converts a private id into a public address NAPT works by allocating each new connection a high level TCP or UDP port. say 2 hosts (10.0.0.101 and 10.0.0.103) initiate a web connection, requesting responses on the client port 1024. -NAPT service creates 2 new client port mappings for these requests (10.0.0.101:60101 and 10.0.0 .103:60103). It then substitutes the private source IPs for a single public source IP (217.45.253.5) and forwards the requests to the public Internet.

Very High Frequency (VHF)

-(30-300 MHz). - FM radio and television signals

File Transfer Protocol (FTP)

-1 of the earliest protocols used on TCP/IP networks/Internet. - allows a client to upload and download files from a remote server. -widely used to upload files to websites.. Files made available through FTP can be in any format, -TCP port 21 to establish a connection and either TCP port 20 to transfer data in "active" mode or a server-assigned port in "passive" mode. The FTP client may take a number of forms: •Most installations of TCP/IP include a command-line client interface. The commands put and get are used to upload and download files, respectively. •Dedicated GUI clients allow you to connect to servers, browse directories, and upload and download files. •internet browsers allow you to connect to an FTP service and download files. You use another type of URL to connect to an FTP server; for example, ftp:// ftp.microsoft.com/. - plain FTP is unencrypted and poses a high security risk

IEEE 802.11 - 2.4GHz band

-2.4 GHz =longer wavelength, - longer range(30-45m, 100-150ft) - better at propagating through solid surfaces. - does not support a high number of individual channels and is often congested. - increased risk of interference - maximum achievable data rates are lower -The 2. band is subdivided into up to 14 channels, spaced at 5 MHz intervals from 2412 MHz up to 2484 MHz. - Wi-Fi requires bandwidth of approximately 20 MHz, not 5 MHz. Consequently, a site designer needs to choose the channels that do not overlap. On a WLAN where only the first 11 channels are available, channels 1, 6, and 11 can be selected as non-overlapping. Note: In the Americas, regulations permit the use of channels 1-11 only, while in Europe, channels 1-13 are permitted. In Japan, all 14 channels are permitted.

Evolved High Speed Packet Access (HSPA+)

-3G standard developed via several iterations from the Universal Mobile Telecommunications System (UMTS) used on GSM networks. HSPA+ supports download speeds up to 168 Mbps and upload speeds up to 34 Mbps. H SPA+-based services are marketed as 4G if the nominal data rate is better than about 20 Mbps.

Long Term Evolution (LTE)

-4G standard supported by all network providers. -Any device using a 4G connection needs a SIM card. LTE has a max=downlink of 150 Mbps in theory, but no provider networks can deliver that. -.Around 20 Mbps is more typical

Personal are network (PAN)

-A PAN refers to using wireless connectivity to connect to devices within a few meters—printers, smartphones, headsets, speakers, etc.

CELLULAR RADIO (GSM/TDMA AND CDMA)

-A cellular radio makes a connection using the nearest available transmitter (cell or base station). Each base station has a range of up to 5 miles (8 km). The transmitter connects the phone to the mobile and landline telephone networks. -Cellular radio works in the 850 and 1900 MHz frequency bands (mostly in the Americas) and the 900 and 1800 MHz bands (rest of the world). -Cellular digital communications standards are described as belonging to a particular generation. For 2G, there were two competing formats, established in different markets: Global System for Mobile Communication (GSM) TIA/EIA IS-95 (cdmaOne)-based handsets. With Code Division Multiple Access (CDMA) In both cases, the network built to support voice calls, so 2G data access was provided on top, using Circuit Switched Data (CSD). CSD similar to a dial-up modem, no analog transmissions . --requires a data connection to be established to the base station (incurring call charges) and is only capable of around 14.4 Kbps at best.

Wireless Distribution System (WDS)

-Access Points can also be configured to forward frames between one another, functioning in a Wireless Distribution System (WDS) to extend the network without cables -A WDS can be configured in bridge mode, where the access points only forward communications between one another, and repeater mode, where they also communicate with stations. - A WDS=hard to set up and suffer from compatibility problems when devices from dif vendors are used. -For residential users, a range extender is a simpler device for regenerating a signal from an access point to a more remote location Another option is a range extender that works with a powerline adapter to communicate with the access point over the electrical wiring.

Data Over Cable Service Interface Specification (DOCSIS

-HFC cable specification -supports downlink speeds of up to 38 Mbps (North America) or 50 Mbps (Europe) and uplinks of up to 27 Mbps. DOCSIS version 3 allows the use of multiplexed channels to achieve higher bandwidth.

802.3at (PoE+)

-IEEE Power over Ethernet Standard - powered devices can draw up to about 25 W. PoE+ allows for a broader range of devices to be powered such as cameras with pan/tilt/zoom capabilities, door controllers, and thin client computers.

802.3af

-IEEE Power over Ethernet Standard -devices can draw up to about 13 W over the link. -Power supplied as 350mA@48V and limited to 15.4 W - voltage drop over max 100 feet of cable = power around 13 W

Ethernet Standards

-Most cabled LANs are based on the Ethernet networking product, developed by the DIX consortium . - Ethernet standards are now maintained by the Institute of Electrical and Electronics Engineers (IEEE). -Ethernet is known by the series of standards produced by the IEEE 802.3 working group. There are four broad "types" of Ethernet: --10 Mbps (10BASE-) --Fast Ethernet (100BASE-) --Gigabit Ethernet (1000BASE-) --10G Ethernet (10GBASE-) =The IEEE 802.11 series of standards (Wi-Fi) are used to implement Wireless Local Area Networks (WLAN) so the technologies complement one another. -Ethernet can support a wide range of different types and sizes of LAN. While a - LAN is self-contained, that does not mean that it has to be small. LANs can range from networks with three or four nodes to networks with thousands of nodes. two particular classes of LAN: SOHO and enterprise.

ETHERNET OVER POWER

-SOHO networks don't use cabling -A network may need 2 connect to smart devices. The main challenge linking the equipment location with the internet. -As an alternative to new data cabling, Ethernet over Powerline products can make use of building power circuits. - Power delivered as a 50-60 Hz AC, between 100-240 volts, varying from country to country. -Powerline =higher frequency carrier signal -network connection is established via a Powerline adapter plugged directly into an electrical outlet. strip sockets =not supported. - The adapter provides 1-2 Ethernet RJ-45 ports to connect network equipment. - The adapters automatically detect/communicate=no configuration needed, - a security key can be enabled to encrypt transmissions. -pass-through adapter features an electrical outlet, allowing use of the socket. Standards for Ethernet over Powerline =IEEE 1901 -products managed by the HomePlug Powerline Alliance. Most products conform to the HomePlug AV or AV2 standards, which are interoperable (older HomePlug 1.0 devices are not compatible). Note: Most Powerline installations will not achieve more than half the theoretical bandwidth.

DHCP reservation

-Servers, routers, printers, and other network infrastructure can be easier to manage if their IP addresses are known. - configure the DHCP server to reserve a particular IP address for that device. The DHCP server is configured with a list of the MAC addresses of hosts that should receive the same IP address. When it is contacted by a host with one of the listed MAC addresses, it issues a lease for the reserved IP address. Note: The main drawback of this method is that if the DHCP server fails, then critical network devices might fail to obtain IP addresses.

MASKING AN IP ADDRESS (ANDing)

-The network ID portion of an IP address is revealed by "ANDing" the subnet mask to the IP address. When two 1s are ANDed together, the result is a 1. Any other combination produces a 0. 1 AND 1 = 1 1 AND 0 = 0 0 AND 1 = 0 0 AND 0 = 0 -to determine the network ID of the IP address 172.30.15.12 with a subnet mask of 255.255.0.0, the dotted decimal notation of the IP address and subnet mask must first be converted to binary notation. The next step is to AND the two binary numbers. The result can be converted back to dotted decimal notation to provide the network ID (172.30.0.0). 172. 30. 15. 12 10101100 00011110 00001111 00001100 255.255. 0. 0 11111111 11111111 00000000 00000000 172. 30. 0. 0 10101100 00011110 00000000 00000000 Instead of quoting the mask each time, you could express that network ID with a prefix instead: 172.30.0.0/16.

FIBER TO THE CURB (FTTC)

-The projects to update this wiring to use fiber optic links are referred to by the umbrella term "Fiber to the X" (FTTx). The most expensive solution is Fiber to the Premises (FTTP) or its domestic variant Fiber to the Home (FTTH). The essential point is that the fiber link is terminated on customer equipment. not often used - Fiber to the Node (FTTN) or Fiber to the Curb/Cabinet (FTTC). extend the fiber link to a communications cabinet in the street servicing multiple subscribers. T similar model to HFC, but instead of the coax segment, each subscriber is linked to the fiber service by running Very High Bitrate DSL (VDSL)

Wireless Mesh Network (WMN)

-Unlike an ad-hoc network, nodes in a WMN (called Mesh Stations) are capable of discovering one another and peering, forming a Mesh Basic Service Set (MBSS). -The mesh stations can perform path discovery and forwarding between peers, using a routing protocol, such as the Hybrid Wireless Mesh Protocol (HWMP).

Internet eXchange Points (IXPs)

-Within the data center supporting any given IXP, Internet Service Providers (ISPs) establish high-speed links between their networks, using transit and peering arrangements to carry traffic to and from parts of the Internet they do not physically own. - the internet backbone connects these IXPs

Global System for Mobile Communication (GSM)

-based phones. GSM allows subscribers to use a Subscriber Identity Module (SIM) card to use an unlocked handset with their chosen network provider. GSM is adopted internationally and by AT&T and T-Mobile in the US.

User Datagram Protocol (UDP)

-connectionless, non-guaranteed method of communication no sequencing or flow control. - suitable for applications that do not require acknowledgement of receipt and can tolerate missing/out-of-order packets. - used for applications that transfer time-sensitive data but do not require complete reliability, such as voice or video. - reduced overhead means that delivery is faster. I - the application layer can be used to control delivery reliability.

802.11ac

-continues the development of 802.11n technologies. -802.11ac works only in the 5 GHz band. -2.4 GHz band used 4 legacy standards (802.11b/g/n) in mixed mode. -aim for 802.11ac is to get throughput similar to Gigabit Ethernet -supports more channel bonding (up to 80 or 160 MHz channels), up to 8 spatial streams rather than 4, and denser modulation (at close ranges). -only high-end equipment can make use of up to 8 streams. -no devices actually support more than 4x4:4 streams. -maximum theoretical data rate with 8 streams and 160 MHz channel bonding is about 6.93 Gbps. -Cisco's Aironet 1850e 4x4:4 access points support up to 1.7 Gbps with 80 MHz channels.

Integrated Services Digital Network (ISDN)

-digital circuit-switched technology for voice, video, and data -ISDN makes use of existing copper telephone wiring, - Unlike dial-up, it uses the line to transmit digital signatures for both voice and data. =higher speeds -Although it is a dial-up technology, it enables a circuit connection in less than 1 second The most common uses of ISDN are for interconnection of LANs and remote users (teleworkers) to businesses. There are two classes of ISDN: Basic Rate Interface (BRI) and Primary Rate Interface (PRI) -superseded by DSL and cable. -good solution outside metropolitan areas where services = not available. -ISDN connection facilitated through a Terminal Adapter (TA).

IEEE 802.11 Wireless LAN standards (WLAN) aka Wifi

-five main versions of the standard -2.4GHz and 5GHz most common bands

Simple Network Management Protocol (SNMP)

-framework for management/monitoring network devices. -consists of a management system and agents. The agent is a process running on a switch, router, server, or other SNMP-compatible network device. - This agent maintains a database called a Management Information Base (MIB) that holds statistics relating to the activity of the device. - The agent is also capable of initiating a trap operation where it informs the management system of a notable event (port failure, for instance). The management system monitors all agents by polling them at regular intervals for info from their MIBs. It also displays any trap operations as alerts for the network administrator to assess and act upon as necessary. -SNMP device queries take place over UDP port 161; traps are communicated over UDP port 162.

Very High Bitrate DSL (VDSL)

-higher bit rates at the expense of range. It -allows for both symmetric and asymmetric modes. Over 300 m (1000 feet), -an asymmetric link supports 52 Mbps downstream and 6 Mbps upstream -symmetric link supports 26 Mbps in both directions. -VDSL2 also specifies a very short range (100 m/300 feet) rate of 100 Mbps (bi-directional).

Frames

-identified by a preamble sequence, which tells the NIC to expect a new frame. - formatted with control information (header fields), of fixed sized in fixed order. - most important fields=destination and source addresses of the adapter to which the frame is being directed/sent - -Other infor = frame length and network layer protocol id -after comes the payload= the data that is being transported over the network. which consists of a network packet(Internet Protocol (IP) packet), with its own headers/payload. - encapsulation=putting layers of packets within one another -The frame finishes with a checksum. The receiving computer can calculate its own checksum and compare it to this value. If they do not match, the receiving host rejects the frame as damaged.

LTE Advanced (LTE-A)

-intended to provide a 300 Mbps downlink, - typical performance for LTE-A is around 40 Mbps.

IEEE 802.11 - 5GHz band

-less effective at penetrating solid surfaces -shorter maximum ranges (up to 30m) - supports more individual channels - suffers less from congestion and interference = higher data rates - subdivided into 23 non-overlapping channels each ~20 MHz-wide. - co-channel interference is less of a problem Note: Initially there were 11 channels in the 5 GHz band, but the subsequent 802.11h standard added another 12. 802.11h also adds the Dynamic Frequency Selection (DFS) method to prevent access points working in the 5 GHz band from interfering with radar and satellite signals. The exact use of channels can be subject to different regulations in different countries.

CDMA2000/Evolution Data Optimized (EV-DO)

-main 3G standards deployed by CDMA network providers. - EV-DO can support a 3.1 Mbps downlink and 1.8 Mbps uplink.

Power over Ethernet (PoE)

-means of supplying electrical power from a switch port over Cat 5 or better data cabling to a connected powered device, PoE is defined in two IEEE standards (now both rolled into 802.3-2012): 802.3af— 802.3at (PoE+)— -PoE-enabled switches= Power Sourcing Equipment (PSE). If an existing switch does not support PoE, a power injector can be used. - When a device is connected to a port on a PoE switch, the switch determines whether the device is PoE-enabled. - If not, it does not supply power via port and If so, it determines the device's power consumption and sets the supply voltage level appropriately. -Powering these devices through a switch is more efficient than using a wall-socket AC adapter for each appliance. It also allows network management software to control the devices and apply power schemes, such as making unused devices go into sleep states and power capping.

SME (Small and Medium Sized Enterprise)

-network supporting tens of users. -use structured cabling and multiple switches, access points, and routers to provide connectivity.

broadcast radio frequencies (RF)

-range= 3 KHz to 300 GHz

Routers

-responsible for moving data around a network of networks -a switch forwards frames using hardware (MAC) addresses a router forwards packets around an internetwork using logical network and host IDs. a router tends to perform one of the following two tasks: •LAN router—divide a single physical network into multiple logical networks. useful for security/performance reasons. •WAN or edge/border router—join a network using one type of media with a network using different media. A typical example is to join a LAN to a WAN, such as the Internet. Selection of the path or route to the destination network is determined dynamically or statically. The packet moves, hop by hop, through the internetwork to the target network. Once it has reached the destination network, the hardware address can be used to move the packet to the target node. This process requires each logically separate network to have a unique network address.

closed network

-the elements of the network are all known to the system vendor and there is no connectivity to wider computer data networks. Where embedded systems need to interact within a computer data network, there are special considerations to make in terms of the network design, especially as regards security.

Distinguished Name

-unique id for any given resource within the directory. -made up of attribute-value pairs, separated by commas. Examples of attributes include Common Name (CN), Organizational Unit (OU), and Domain Component (DC). - The most specific attribute is listed first a - This most specific attribute is also referred to as the Relative Distinguished Name, as it uniquely identifies the object within the context of successive (parent) attribute values.

Media Access Control (MAC)

-unique physical hardware/physical address in ethernet network adaptor ports - MAC addresses provide the value used in a frame's source and destination address fields. - consists of 48 binary digits (6 bytes). typically represented as 12 digits of hexadecimal with colon or hyphen separators or no separators at all—for example, 00:60:8c:12:3a:bc or 00608c123abc.

Point of Presence (PoP)

-used for customers to connect to an ISP's network - isps use a backhaul link to connect each POP to their core network and 1+ IXPs

Point-to-Point Protocol (PPP)

-used to encapsulate the network protocol, which will be TCP/IP, over the link to the ISP. -PPP also provides a mechanism to authenticate the user and manage the connection between the local computer or network and the ISP's router.

Line of Sight (LoS)

-wireless connection method using ground-based microwave antennas aligned. Endpoints transmit signals to one another as long as they are unobstructed. The antennas affixed on top of tall buildings to reduce this interference. -cover great distances that typical wireless signals cannot, & the service provider doesn't need to install cabling infrastructure. - often low latency, lower latency than satellite. - disadvantage= unobstructed sight line difficult to maintain, - LoS services are usually more expensive s. A company specializing in LoS networks = Wireless Internet Service Provider (WISP).

Internet Control Message Protocol (ICMP),

-works at the network layer. -ICMP delivers status and error messages and is used by diagnostic utilities such as ping and tracert.

Modem

-works at the same level as a switch, making a physical network link with the ISP's network. The modem must be matched to the type of link (dial-up, DSL, cable, and so on). A router makes decisions about forwarding between the two logical networks. -For SOHO networks, this is usually a simple choice between the local network and the Internet. On a SOHO network, the modem and the router are typically bundled in the same appliance.

ADDRESS RESOLUTION PROTOCOL (ARP)

. Address Resolution Protocol (ARP) finds the MAC (network adapter) address associated with an IP address. with a physical data link (ethernet/wifi), this is the mechanism that delivers messages at the network layer to computers at the link layer.

Proxy Server

.- takes a whole HTTP request from a client, checks it, then forwards it to the destination computer on the Internet. When the reply comes back, it checks it, and then shuttles it back to the LAN computer - can operate either as a transparent service, in which case the client requires no special configuration, or as non-transparent. For a non-transparent proxy, the client must be configured with the IP address and service port (often 8080 by convention) of the proxy server

Top Level Domains (TLDs)

.com, .org, .net

10G Ethernet (10GBASE-)

10 Gbps links for LANs and WANs, mostly using fiber optic media. 10G Ethernet is widely used in data centers.

Gigabit Ethernet (1000BASE-)

1000 Mbps LANs. This has replaced Fast Ethernet as the "standard" for a typical LAN.

General Packet Radio Services/Enhanced Data Rates for GSM Evolution (GPRS/ EDGE)

3G technology - precursor to 3G (2.5G) with GPRS up to 48 Kbps and EDGE about 3-4 times that. - Unlike CSD, GPRS and EDGE allow "always on" data connections, with usage billed by bandwidth consumption rather than connection time.

5G

4G service was supposed to deliver 1 Gbps for stationary or slow-moving users - 100 Mbps for a fast-moving vehicle. Those - data rates are now the minimum hoped-for standards for 5G. -5G is currently only available in trial areas. -Speeds of up to 70 Gbps have been achieved under test conditions,

RJ-45

8P8C, (8-position/8-contact) Each conductor in 4-pair Ethernet cable is color-coded. Each pair is assigned a color (Blue, Orange, Green, or Brown). The first conductor in each pair has a white insulator with stripes of the color; the second conductor has an insulator with the solid color.

Straight Tip (ST)

A bayonet-style connector that uses a push-and-twist locking mechanism; used mostly for multi-mode networks. - used for fiber optic cables

multimeter

A multimeter is a basic cable testing tool. a multimeter tests electrical circuits, but you can use one to test for the continuity of any sort of copper wire, the existence of a short, and the integrity of a terminator. - To perform useful tests, you need to know the readings that are expected - For example, if the resistance measured across UTP Ethernet cable is found to be 100 ohms, then the cable is OK, but if the resistance between the two ends of a cable is infinity, then the cable has a break. - Many multimeters designed for ICT use incorporate the function of a wire map tester. These are also available as dedicated devices. - Wire map testers can identify wiring problems that a simple continuity test will not detect, such as transpositions and reversed pairs.

Plenum Cable

A plenum space is a void in a building designed to carry Heating, Ventilation, and Air Conditioning (HVAC) systems. -Plenum space is typically a false ceiling, or a raised floor. - As it makes installation simpler, this space has also been used for communications wiring in some building designs. - Plenum space is an effective conduit for fire, as there is plenty of airflow and no fire breaks, such as walls and doors. If the plenum space is used for heating, there may also be higher temperatures. Therefore, building regulations require the use of fire-retardant plenum cable in such spaces. - Plenum cable must not emit large amounts of smoke when burned, be self-extinguishing, and meet other strict fire safety standards. - General purpose (non-plenum) cabling uses PVC (polyvinyl chloride) jackets and insulation. - Plenum-rated cable uses treated PVC or Fluorinated Ethylene Polymer (FEP). This can make the cable less flexible but there's no effect on bandwidth. - Data cable rated for plenum use under the US National Electrical Code (NEC) is marked CMP/MMP. -General purpose cables are marked CMG/MMG or CM/MP.

Lucent or Local Connector (LC)

A small form factor connector with a tabbed push/pull design. LC is similar to SC but the smaller size allows for higher port density. - used for fiber optic cabling

IP address

An IP address provides two pieces of information encoded within the same value: •The network number (network ID)—this number is common to all hosts on the same IP network. •The host number (host ID)—this unique number identifies a host on a particular IP network.

WELL-KNOWN PORTS

Any application or process that uses TCP or UDP for its transport, s assigned a unique ID number called a port. - For example, a client may contact an HTTP server at IP address 77.72.206.10 on port 80 (77.72.206.10:80). Server port numbers are assigned by the Internet Assigned Numbers Authority (IANA). - IANA defines the ephemeral port range as 49152 to 65535, - Enabling/disabling ports I=important part of configuring a firewall, to ensure that only valid application protocols are allowed. Some of the principal protocols amongst these are discussed in the following sections. Port # TCP/UDP Process Description 20 TCP ftp-data File Transfer Protocol - Data 21 TCP ftp File Transfer Protocol - Control 22 TCP ssh Secure Shell 23 TCP telnet Telnet 25 TCP smtp Simple Mail Transfer Protocol 53 TCP/UDP domain Domain Name System 67 UDP bootps BOOTP/DHCP Server 68 UDP bootpc BOOTP/DHCP Client 80 TCP http HTTP 110 TCP pop3 Post Office Protocol 123 UDP ntp Network Time Protocol 137-139 UDP/TCP netbt NetBIOS over TCP/IP 143 TCP imap4 Internet Mail Access Protocol 161 UDP snmp Simple Network Management Protocol 162 UDP snmp-trap Simple Network Management Protocol Trap 389 TCP ldap Lightweight Directory Access Protocol 427 TCP slp Service Location Protocol 443 TCP https HTTP Secure 445 TCP smb Server Message Block/Common Internet File System 548 TCP afp Apple Filing Protocol 3389 TCP rdp Remote Desktop Protocol

Subscriber Connector (SC)

Connector with a push/pull design that allows for simpler insertion and removal than FC. There are simplex and duplex versions, though the duplex version is just two connectors clipped together. It can be used for single- or multi-mode. - used for fiber optic cabling

FIBER OPTIC CABLING AND CONNECTORS

Copper wire carries electrical signals, which are subject to interference.. Light signals are not susceptible to interference, cannot easily be intercepted (eavesdropped), and suffer less from attenuation. fiber optic cabling can support much higher bandwidth, measured in multiple gigabits or terabits per second, and longer cable runs, measured in miles rather than feet. - An optical fiber consists of an ultra-fine core of glass to carry the light signals surrounded by glass or plastic cladding, which guides the light pulses along the core, and a protective coating called the buffer. - The fiber optic cable is contained in a protective jacket and terminated by a connector. Fiber optic cables fall into two broad categories: single-mode and multi-mode: Single-Mode Fiber (SMF) Multi-mode (MMF) A number of connectors have been designed for use with fiber optic cabling. Some types are more popular for multi-mode and some for single-mode. Connectors for MMF are usually color-coded beige while those for SMF are blue. The core of each connector is a ceramic or plastic ferrule that ensures continuous reception of the light signals. Straight Tip (ST) Subscriber Connector (SC) Lucent or Local Connector (LC) - Patch cords for fiber optic can come with the same connector on each end (ST-ST, for instance) or a mix of connectors (ST-SC, for instance). - Fiber optic connectors are quite easy to damage and should not be repeatedly plugged in and unplugged. Note: To protect your eyesight, do not look directly into a fiber optic port.

DNS SERVERS

Different types of DNS servers are used by private organizations: Authoritative name server Recursive resolver Note: On a private network, the same DNS server is likely to be identified for both functions. For example, an AD DNS server might both host the DNS records and provide name resolution for other Internet domain requests. the network might use client-facing forwarding-only servers whose only purpose is to select the best DNS server . - UDP port 53.

Mail Servers

Email is a messaging system that can be used to transmit text messages and binary file attachments encoded using Multipurpose Internet Mail Extensions (MIME). 1.The email client software on the sender's computer ([email protected]) sends the message to the Exchange email server using Microsoft's Message Application Programming Interface (MAPI) protocol. The mail server puts the message in a queue, waiting for the next Simple Mail Transfer Protocol (SMTP) session to be started. SMTP uses TCP port 25 by default. 2.When the Exchange SMTP server starts it first contacts a DNS server to resolve the recipient's address (for example, [email protected]) to an IP address for the othercompany.com email server, listed as a Mail Exchanger (MX) record in DNS. 3.It then uses SMTP to deliver the message to this email server. The delivery usually requires several "hops"; f The hops taken by a message as it is delivered over the Internet are recorded in the message header. 4.The message is put in the message store on the recipient's mail server. To retrieve it, the recipient uses his or her mail client software to connect with the mailbox on the server, using the Post Office Protocol (POP3) on TCP port 110 or Internet Message Access Protocol (IMAP) on TCP port 143. POP3 is more widely implemented, but IMAP provides extra features, such as support for mail folders other than inbox on the server and calendar functionality. Note: Email communications between a client and server would normally be protected with SSL/TLS security. The default port numbers for these are 587 (SMTPS), 993 (IMAPS), and 995 (POP3S). Configuring an email account. The incoming server is either POP3 or IMAP while the outgoing server is SMTP.

HTTP AND HTML

HyperText Transfer Protocol (HTTP) = basis of the World Wide Web. HTTP enables clients to request resources from an HTTP server. - client connects to the HTTP server using TCP port 80 and submits a request for a resource, using a Uniform Resource Locator (URL). The server acknowledges the request and returns the data. - Larger organizations with their own Internet Point-of-Presence may - Private networks use intranets (if they permit only local access) or extranets (if they permit remote access). HTTP is usually used to serve HyperText Markup Language (HTML) web pages, . A web browser can interpret the tags and display the text and other resources associated with the page.Another powerful feature is its ability to provide hyperlinks to other related documents. HTTP also features forms mechanisms (GET and POST) whereby a user can submit data from the client to the server.

campus area network (CAN)

LAN that spans multiple nearby buildings

TCP/IP protocols

Link or Network Interface layer—responsible for putting frames onto the physical network. This layer does not contain TCP/IP protocols. networking products such as Ethernet or Wi-Fi can be used Communications take place only on a local network segment and not between different networks. Data at the link layer is packaged in a unit called a frame and nodes are identified by a MAC address Internet Protocol (IP)—provides packet addressing and routing at the network layer. IP provides best effort delivery of an unreliable and connectionless nature. A packet might be lost, delivered out of sequence, duplicated, or delayed. Transmission Control Protocol (TCP)—guarantees orderly transmission of packets at the transport layer. TCP can identify/ recover from lost or out-of-order packets. used by most TCP/IP application protocols as failing to receive a packet can cause serious data errors. User Datagram Protocol (UDP)—unreliable, non-guaranteed transfer of packets. comes with less of a transmission overhead because it does not need to send extra info to establish reliable connections. It is used in time-sensitive applications, here a few missing packets can be tolerated. Rather than causing the application to crash, they would just manifest as a glitch. Application protocols—there are numerous protocols used for network configuration, management, and services. Application protocols use a TCP or UDP port to connect the client and server.

4G

Long Term Evolution (LTE) LTE Advanced (LTE-A)

Message Application Programming Interface (MAPI)

Microsoft client software which sends an email

Extended Service Set (ESS).

Multiple Basic Service Set Identifiers (BSSID) grouped together

Enterprise Network Architecture

Networks supporting larger businesses or academic institutions use the same switch, access point, router, and modem functions as are present in SOHO but they support more clients with a greater degree of reliability, 2 categories: SME (Small and Medium Sized Enterprise) Enterprise LAN

Power Sourcing Equipment (PSE

PoE enabled switches

IPV4 Packet structure

Source IP address: Identifies the sender of the datagram by IP address. Destination IP address: Identifies the destination of the datagram by IP address. Protocol Indicates whether the data should be passed to UDP or TCP at the destination host. Checksum Verifies the packet's integrity upon arrival at the destination. Time to Live: number of hops a datagram is allowed to stay on the network before being discarded.. A router will decrease the TTL by at least one when it handles the packet.

IEEE 1901

Standards for Ethernet over Power

IEEE 802.3-2012

Standards for Power over Ethernet (PoE)

Simple Mail Transfer Protocol (SMTP)

TCP port 25 by default. - sends email messages after they're put in a queue

Code Division Multiple Access (CDMA)

TIA/EIA IS-95 (cdmaOne)-based handsets. With Code Division Multiple Access (CDMA), the handset is managed by the provider, not the SIM. CDMA adoption is largely restricted to the telecom providers Sprint® and Verizon.

Internet Connections

The major infrastructure of the Internet, also referred to as the Internet backbone, consists of very high bandwidth trunks connecting Internet eXchange Points (IXPs).

DSL Access Multiplier (DSLAM

The phone line makes the connection to a bank of DSL -channels voice and data traffic to the appropriate network. Depending on the equipment used by the ISP, the data link protocol used for DSL may be PPP over ATM (PPPoA) or PPP over Ethernet (PPPoE).

VIRTUAL LAN (VLAN)

The switches on an enterprise network can provide thousands of ports which are divided into groups using a feature of managed switches called Virtual LAN (VLAN). - each VLAN is associated with a different logical subnetwork address. -Communications between different VLANs go through a router. As - improved security since traffic can be easily filtered/monitored

3G

The transition from 2G to 3G saw various packet-switched technologies deployed to mobiles: •General Packet Radio Services/Enhanced Data Rates for GSM Evolution (GPRS/ EDGE) •Evolved High Speed Packet Access (HSPA+) •CDMA2000/Evolution Data Optimized (EV-DO)

structured cabling system

The use of patch cords, permanent links, and patch panels

Crimpers

These tools fix a jack to a cable. As with an IDC, the wires are laid in the appropriate terminals in the jack and the crimper tool then closes and seals the jack. The tools are specific to a particular type of connector and cable, though some may have modular dies to support a range of RJ-type jacks Note: It is best to use prefabricated patch cords where possible. These are far less likely to create problems.

Punch-Down Tool

These tools fix conductors into an IDC. - The wire pairs are untwisted and laid in the terminals in the IDC in the appropriate termination order (T568A or T568B). - It is important not to untwist the pairs too much, however. T - he punch-down tool then presses the wire into the terminal, cutting through the insulation to make an electrical contact. There are different IDC formats (66, 110, and Krone) and these require different blades. Many punch-down tools have replaceable blades.

IPv6 ADDRESS NOTATION

To express a 128-bit IPv6 address in hexadecimal notation, the binary address is divided into eight double-byte (16-bit) values delimited by colons. For example: 2001:0db8:0000:0000:0abc:0000:def0:1234 Even this is quite cumbersome, so where a double-byte contains leading zeros, they can be ignored. In addition, one contiguous series of zeroes can be replaced by a double colon place marker. Thus, the address above would become: 2001:db8::abc:0:def0:1234

Industrial, Scientific, and Medical (ISM)

Unregulated frequency band, does not require license - 2.4GHz and 5GHz bands

Basic Service Set (BSS)

What the Access Point is referred to in 802.11

Routing Decision

When two hosts attempt to communicate via IPv4, the protocol compares the source and destination address in each packet against a subnet mask. If the masked portions of the source and destination IP addresses match, then the destination interface is assumed to be on the same IP network. For example: 172. 30. 15. 12 10101100 00011110 00001111 00001100 255.255. 0. 0 11111111 11111111 00000000 00000000 172. 30. 16.101 10101100 00011110 00010000 01100101 In the example, IP concludes the destination IPv4 address is on the same IP network and would try to deliver the packet locally. If the masked portion does not match, IP assumes the packet must be routed to another IP network. For example: 172. 30. 15. 12 10101100 00011110 00001111 00001100 255.255. 0. 0 11111111 11111111 00000000 00000000 172. 31. 16.101 10101100 00011111 00010000 01100101 In this case, IP concludes the destination IPv4 address is on a different IP network and would forward the packet to a router rather than trying to deliver it locally. Note: This describes unicast addressing, where a single host is addressed. An address where the host bits are all "1"s is the broadcast address for a network. A message sent to a broadcast address is received by all hosts on the network. The broadcast address of the previous example would be 172.16.255.255.

Hybrid Fiber Coax (HFC) network

coax cable links the fiber optic trunk serving the whole street to the cable "modem" installed in the customer's premises. Coax suffers less from attenuation than twisted pair but is generally bulkier and more difficult to install.

Post Office Protocol (pop3)

connects recipient with mailbox on the server uses TCP port 110

Ethernet Switch

connects wired client devices and printers with RJ-45 cables.

Fast Ethernet (100BASE-)

copper wire and fiber optic implementations of 100 Mbps LANs.

10BASE-5/Thicknet and 10BASE-2/Thinnet) Coax cable

could support 10 Mbps with cable lengths of up to 500 m and 185 m - ethernet LAN media produt

Broadband

covers a range of connection technologies. -The main characteristics are that they are "always-on" and data transfer rates are (a lot) higher than analog dial-up.

802.11s

defines a wireless mesh network(WMN)

embedded system

designed to perform a specific, dedicated function. These systems can be as small and simple as a microcontroller in an intravenous drip-rate meter or as large and complex as an industrial control system managing a water treatment plant - designed to operate in a closed network

Transport Layer Security (TLS)

developed from SSL and ratified as a standard by IETF. - 1.2 as the latest version. SSL/TLS is typically used with the HTTP application (referred to as HTTPS or HTTP Over SSL or HTTP Secure) but can also be used to secure other TCP/IP application protocols. The basic function of TLS is: 1.A server is assigned a digital certificate by some trusted Certificate Authority. 2.The certificate proves the identity of the server (assuming that the client trusts the Certificate Authority). 3.The server uses the digital certificate and the SSL/TLS protocol to encrypt communications between it and the client.

DIX consortium (Digital Equipment Corporation [DEC], Intel, and Xerox)

developed the ethernet standards

infrastructure mode

each client device (or station) is configured to connect to the network via an Access Point (AP)

Multipurpose Internet Mail Extensions (MIME)

encodes and transmits binary file email attachments

Homeplug AV AV2 standards

ethernet over power products, rated according to max theoretical bandwidth from AV200 (200Mbps) - AV1200

Internet Router

forwards communications to and from the Internet Service Provider (ISP) routers to provide Internet access.

Network Address Port Translation (NAPT)

hen clients on the local network connect via a router, the router converts the client's private IP address into a valid public address using Network Address Translation (NAT).

Legacy Networking Devices

hubs, repeaters, bridges

Internet Modem

interfaces with the physical link to the ISP's routers (DSL or cable, for instance).

International Telecommunications Union (ITU)

international standards for the radio spectrum

Asymmetrical DSL (ADSL)

is a "consumer" version -provides a fast downlink but a slow uplink. -(ADSL2+) offering downlink rates up to about 24 Mbps and uplink rates up to 1.4 Mbps, or 3.3 Mbps upstream if the provider supports Annex M/ADSL2+ M. - The max range of an ADSL modem is about 10,000 feet (2 miles or 3 km), -Symmetric versions offer the same uplink/downlink speeds. -These are of more use to businesses and for branch office links, where more data is transferred upstream than with normal Internet use.

IEEE 802.11a/b/g

legacy standards - 802.11nb and g worked at 2.4 GHz, - 802.11g provided an upgrade path for 802.11b WLANs. - in the 5 GHz band, 802.11a is incompatible with the other two and was not as widely adopted.

Electrical and Electronics Engineers (IEEE).

maintain ethernet standards

Unicast addressing

one single host is addressed

Static Addresses

only assigned to systems with a dedicated functionality, such as router interfaces, network-attached printers, or servers that host applications on a network.

Apple Filing Protocol (AFP)

performs a similar file sharing function to SMB but for Apple networks running Mac OS. AFP is associated with the use of two ports: •UDP or TCP port 427—this is a port running the Service Location Protocol, used to advertise the availability of file shares. It is not required by later versions of OS X (10.2 and up). •TCP port 548—this is the main port used by AFP. Note: Apple is phasing out support for AFP in favor of its own version of SMB2 (SMBX).

RFC 1918 addresses

private LAN addresses

Protocols

procedures or rules used by networked hosts to communicate. For communication to take place, the two hosts must have a protocol in common

Primary Rate Interface (PRI)

provides 23 or 30 "B" channels (or between about 1.5 and 2 Mbps), and one 64 Kbps D channel. - This form of ISDN is intended for larger companies. used to provide a link between two company locations.

web server

provides client access using the HyperText Transfer Protocol (HTTP) or its secure version (HTTPS).

Cable Modem Termination System (CMTS)

routes data traffic via the fiber backbone to the ISP's Point of Presence (PoP) and from there to the Internet.

Protocol Suite

several protocols used for networking are designed to work together.

Basic Service Set Identifier (BSSID)

the mac address of the Access Point

10 Mbps (10BASE-) Ethernet

this is the original standard, specifying cabling and connectors for copper wire and fiber optic products.

power injector

used when switch does not support PoE

Digital Subscriber Line (DSL)

uses the higher frequencies available in a copper telephone lin - The use of a filter prevents the DSL signals from contaminating voice traffic. - advanced modulation and echo cancelling techniques enable high bandwidth, full duplex transmissions. - there is also DSLAM, Asymmetrical DSL (ADSL), and Very High Bitrate DSL (VDSL)

Plain Old Telephone Service (POTS),

voice-grade copper wire used in PTSN networks

Recursive resolver

when a client application wants to resolve a name or FQDN, it uses a recursive resolver to perform the query. - The resolver contacts name servers in the DNS hierarchy until it either locates the requested record or times out. When you configure a DNS server on a client, it is usually the address of a resolver that you are entering.

F/UTP

with a foil screen around all pairs, often also designated ScTP. - type of STP

U/FTP

with foil shielding for each pair - type of STP

NIC LED STATUS DIODES

•link light = indicates if there is a network signal. If the link light is not lit = cable/connection problem •activity light=flickers when packets are received/sent. light flickers constantly=network overused or device is generating network noise. • multi-speed adapter=speed light to show whether the adapter is operating at 10 Mbps (Ethernet), 100 Mbps (Fast Ethernet), or 1000 Mbps (Gigabit Ethernet). •Some types of equipment combine the functions of more than one light into dual-color LEDs. For example, a green flickering light might indicate normal activity, whereas an orange flickering light indicates network traffic collisions.