Network +

Bandwith Shaper

CH4 Components and Devices Common Network Devices Specialized Network Devices Bandwith Shaper

LAN: Local Area Network - single geografic location WAN: Wide Area Network - connect separate LANs, more than one geographic location referenced as MAN - Metropolitan Area Network WPAN - Wireless Personal Aera Network - connecting phones, tablets, etc. It's an ad-hoc network

CH 1 Intro to Networking Define: LAN, WAN, WPAN

VPN - Virtual Private Network Extends a LAN by creating a remote connection (using tunnelling) in a public network (Internet). Provides Point-to-Point dedicated link between two points. Because of the long distance, it is a form of WAN. Components: VPN Client, VPN Server, Access Method, VPN Protocols VLAN - Virtual Local Area Network Used for network segmentation, which increases performance, removes potential bottlenecks and can increase security. Each network acts as if they are in a separate network (logically). VLAN Membership: determines how devices are assigned to a VLAN. Protocol-based VLAN Port-based VLAN MAC address-based VLAN

CH 1 Intro to Networking Going Virtual VPN VLAN Define and Explain

Peer-to-Peer: decentralized network model, no more than 10 computers Client-Server: centralized network management incuding user management, security and backup procedures

CH 1 Intro to Networking Network Models

To request data from the server and present to the users.

CH 1 Intro to Networking Network Models What is the role of the client in the client-server model?

Physical and logical layout of the network. Bus - one backbone, cheap and easy Ring - no hub or switch needed, can be fault-tolerant (more than 1 ring), wired in star configuration Star - switch, single point of failure, easiest to expand, Mesh - each computer connects to every other, no hub or switch, redunduncy Wireless - 2 topologies: Infrastructure: connect to an AP (access point) Ad-hoc (unmanaged): devices connect directly between themselves Also: PtP (point to point): connects two remote locations PtMP (point to multipoint): links muliple wired networks Wireless Mesh Networks: extends the transmission distance by relaying the signal Hybrid topologiess: mix of wired/wired or wired/wireless

CH 1 Intro to Networking Network Topologies Define and list

Multi Protocol Label Switching: technology used to speed network traffic. Does not use routing tables, which packets travel from one router to the next with a forwarding decision at each point. MPLS uses short labels to direct packets through the network. MPLS uses paths instead of endpoints.

CH 1 Intro to Networking Network Topologies MPLS Define and Explain

Centralized, one computer provides both network processing power and storage place Distributed, newtork processing shared between client and server - most used

CH 1 Intro to Networking What is the difference of Centralized vs. Distributed Computing?

The DNS operates in the DNS namespace. This space has logical divisions hierarchically organized. Top level - domains (.com, .edu) subdomains - companies (Microsoft) FQDN (Fully Qualified Domain Name) = microsoft.com (domain + subdomain) Windows Network uses a system called WINS to enable Network basic Input/Output System (NetBIOS) names to resolve to IP adress.

CH2 OSI and TCP/IP Models and Network Protocols Domain Name Services (DNS) DNA Namespace Define

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CH3 Addressing and Routing IP Addressing IPv4 Default Gateway

It is a transmitter and receiver (transceiver) device used to create a LAN (WLAN). It is usually a separate network device with a built-in antenna, transmitter and adapter. It uses the infrastructure network to provide connection points. AP also has several ports that allows to expand the network. An AP can operate as a bridge, by connecting a wired network to wireless devices or as a router passing data transmission from one access point to another. APs can provide firewall and DHCP functions.

CH4 Components and Devices Common Network Devices Wireless Access Points

Resolves the hostnames to IP addressess in TCP/IP based networks. It is a platform independent protocol. Before the Internet, the network that was to become the Internet used a text file called HOSTS to perform name resolution. This is still supported by most platforms. Used to change a few hosts that will not change often or at all. DNS is a more dynamic and authomated method of doing it by using servers configured to act as name servers. Systems that ask DNS servers for a host name to IP adress are called DNS clients or resolvers. When client asks for the resolution, router turns to the DNS server for an IP address and after address is returned, client can establish a connection.

CH2 OSI and TCP/IP Models and Network Protocols Domain Name Services (DNS) Define

DHCP enables ranges of IP addressess, or scopes, to be defined on a system that runs DCHP server application. Server assigns an IP address from the scope to the client for a determined time, or a lease. DHCP supplies IP address, subnet mask and default gateway. When DHCP assigns a spefic address to a client, it is a reservation. DHCP is a protocol dependent service not platform.

CH2 OSI and TCP/IP Models and Network Protocols Dynamic Host Configuration Protocol (DHCP) Define and Explain

OSI - Open Systems Interconnect model 7 application: takes requests and data from users and pass them to the lower layers. File and print capabilities. 6 presentation: converts the data intented for or received from application layer into another format. 5 session: manage and controls synchronization of data apps on two devices. Establish, maintain and break sessions. 4 transport: transport data between network devices in 3 ways: error checking, service addressing, segmentation. Protocols TCP and UDP. Data flow control: Buffering - data is stored and waits for destination device to become available. Windowing: segments of data that require only one acknowlegement. 3 network: responsible for routing. Mechanism which data passess from one network system to another. Routers can be configured as static or dynamic = how routs are added to routing table. 2 data link: gets data to the physical layer. Error detection, error correction and hardware addressing. 2 sublayers: MAC (media access control) layer and LLC (logical link control) layer 1 physical: defines network physical characteristics. Hardware and topology

CH2 OSI and TCP/IP Models and Network Protocols OSI Model List and define each layer

Hub - Layer 1 (Physical) Bridge - Layer 2 (Data Link) Switch - Layer 3 (Nework) Router - Layer 3 (Nework) NIC - Layer 2 (Data Link) Access Point - Layer 2 (Data Link)

CH2 OSI and TCP/IP Models and Network Protocols OSI Model Map each device to the OSI Model Hub Bridge Switch Router NIC Access Point

Protocols: method or set of rules that establishes how system communicate. RFC (request for comment) are standards published by the IETF (Internet Engineering Task Force). Connection Oriented: Data delivery is guaranteed. Communication between sending and receiving devices continues until transmission has been verified. Uses TCP. Connectionless: Best effort but no verification if data has been delivered. Fire and forget. Uses UDP.

CH2 OSI and TCP/IP Models and Network Protocols OSI Model Protocols Connection Oriented vs. Connectionlesss Define

IP (Internet Protocol) Connectionless - moves data around the netowrk Layer 3 (Network) TCP (Transmission Control Protocol) Connection oriented - flow control, sequencing and retransmission Layer 4 (Transport) UDP (User Datagram Protocol) Connectionless - alternative to TCP Layer 4 (Transport) FTP (File Transfer Protocol) Uploads/download files from a remote host Layer 7 (Application) STPS (Secure File Transfer Protocol) Same as above but with SSH security. Layer 7 (Application) TFTP (Trivial File Transfer Protocol) File transfer with no security or error checking. Uses UDP.

CH2 OSI and TCP/IP Models and Network Protocols OSI Model Protocols List and Name, brief description, OSI Layer (1 of 4)

SMTP (Simple Mail Tranfer Prorocol) Sends and receives mail across the network Layer 7 (Application) HTTP (Hypertext Transfer Protocol) Retrieves files from a web server. Layer 7 (Application) HTTPS (Hypertext Transfer Protocol Secure) Retrieves files from a web server securely Layer 7 (Application) POPv3/IMAPv4 (Post Office Protocol) / Internet Message Access Protocol) Retrieves mail from a server in which it is stored Layer 7 (Application) Telnet (Telnet) Enables sessions to be established on a remote host Layer 7 (Application)

CH2 OSI and TCP/IP Models and Network Protocols OSI Model Protocols List and Name, brief description, OSI Layer (2 of 4)

SSH (Secure Shell) Enable secure sessions to be established on a remote host Layer 7 (Application) ICMP (Internet Control Message Protocol) In IP based networks - used for error reporting, flow control and route testing Layer 3 (Network) ARP (Address Resolution Protocol) Resolves IP address to MAC address to enable communication between devices Layer 2 (Data link layer) RARP (Reverse Address Resolution Protocol) Resolves MAC address to IP address Layer 2 (Data link layer) NTP (Network Time Protocol) Communicates time synchronization between devices in the network Layer 7 (Application) NNTP (Network News Transport Protocol) Facilitates access and downloading of messages from newsgroups Layer 7 (Application)

CH2 OSI and TCP/IP Models and Network Protocols OSI Model Protocols List and Name, brief description, OSI Layer (3 of 4)

SCP (Secure Copy Protocol) Enables files to be securely copied between two systems. Uses SSH. Layer 7 (Application) LDAP (Lightweight Directory Access Protocol) Access and queries directory services systems Layer 7 (Application) IGMP (Internet Group Management Protocol) Provides mechanism for systems within the same multicast group to register and communicate with each other Layer 3 (Network) TLS (Transport Layer Security) Provides privacy between client/server communication Layer 7 (Application) SIP (Session Initiation Protocol) Establish and maintain multimedia sessions such as internet phone calls Layer 7 (Application) RTP (Realtime Transport Protocol) Internet-standard protocol for transporting real-time data. Layer 7 (Application)

CH2 OSI and TCP/IP Models and Network Protocols OSI Model Protocols List and Name, brief description, OSI Layer (4 of 4)

Conceptual model that describes a network architecture that enables data to be passed between computer systems.

CH2 OSI and TCP/IP Models and Network Protocols OSI and TCP Models Define

OSI - Open Systems Interconnect model 7 application 6 presentation 5 session 4 transport 3 network 2 data link 1 physical TCP - Transmission Control Protocol 4 application 3 transport 2 Internet 1 network interface

CH2 OSI and TCP/IP Models and Network Protocols OSI and TCP Models Define acronym and list layers

SNMP enables network devices to communicate information about their state to a central system. Components: - Central system known as manager acts a cetral communication point for all the SNMP enabled devices. This system runs a software called Network Management System (NMS) - Software in the devices is called SNMP agent is set up and configured with manager's IP address. Messages between agent and manager is called traps. SNMP uses databases of information called MIB (Management Information Bases) which are created and controlled by ISO. SNMPv3 - supports authentication and encrytion.

CH2 OSI and TCP/IP Models and Network Protocols Simple Network Management Protocol (SNMP) Define and Explain

Introduced with Windows 98 and used in all versions afterwards. Its function is that a system can give itself an IP address if it is incapable of receiving one dynamically from the DHCP server. It assigns an address from the 169.254.0.0 range and configures subnet 255.255.0.0. It does not configure a default gateway address so as a result connection is limited to the local network. IMPORTANT: If a system that doesn't support APIPA cannot get an ip address from the DHCP server, it assigns itself an ip address of 0.0.0.0 It could cause issues if the DHCP server was operational and fails. Now different portions of the network have IP addresses from different ranges. APIPA is not used much in real world, it is more of a last resort.

CH3 Addressing and Routing IP Addressing APIPA (Automatic Private IP Addressing)

At a minimum, an IP Address and a Subnet Mask are required do connect to a TCP/IP Network. With this minimum configuration, connectivity is limited to the local segment and DNS resolution is not possible.

CH3 Addressing and Routing IP Addressing Assigning IP addresses Minimum elements to connect to a TCP/IP network

Static addressing: Manually assigning IP address to a system. Prone to mistakes and hard to change when there is a change in the network. Not used much. Dynamic addressing: Dynamic Host Configuration Protocol (DHCP) is the mechanism used to automatically assign IP addresses to systems. Central system that enables client systems with IP addresses. DHCP uses ranges of IP addresses, aka scopes, defined in a system running DHCP. Addresses are assigned for a predetermined amount of time, aka leases. A DHCP can be configured to do more than just assign IP addresses, it can also assign the subnet mask, the default gateway, and the Domain Name Service (DNS) information.

CH3 Addressing and Routing IP Addressing Assigning IP addresses Static vs Dynamic Explain

Developed so diskless workstations could obtain information needed to connect to a network (TCP/IP Address, subnet mask, and default gateway). A system broadcasts for a BOOTP server on the network, if the server exists, it compares the MAC address of the system issuing the request to the database of entries. Like DHCP, it is a broadcast system and by default routers aren't configured to forward broadcasts.

CH3 Addressing and Routing IP Addressing BOOTP (Boot Protocol) Define and Explain

Loopback Address - IPv4: 127.0.0.1 - IPv6: 0:0:0:0:0:0:0:1 (::1) Network-wide Addresses: - IPv4: IPv4 public addresses ranges - IPv6: Global Unicast IPv6 addresses Private Network Addresses: - IPv4: 10.0.0.0 / 172.16.0.0 / 192.168.0.0 - IPv6: Site-local address ranges (FEC0:: prefix) Autoconfigured Addresses: - IPv4: IPv4 automatic private IP addressing (169.254.0.0) - IPv6: link local address ranges (FE80:: prefix)

CH3 Addressing and Routing IP Addressing Comparing IPv4 and IPv6 address

- PoE (Power over Ethernet): enables electrical power to be transmitted over the twisted pair Ethernet cable. - STP (Spanning Tree Protocol): designed to prevent the switch of loops when there is more than one path available between devices in the network. Used for bridges and switches. It works at the layer 2 (data link), routers work at the layer 3 (network). Redundant paths and potential loops can be avoided within ports in several ways: Blocking: a blocked port accepts BPDU (protocol data units) but doesn't forward them. Disabled: the port if off Forwarding: part of the active spanning tree and forwards messages to other switches Learning: not part of the active STP but it can take over if another port fails. Listening: receives BDPU messages and monitors for changes to the topology - Trunking: use of multiple network cables or ports in parallel to increase the link speed beyond the limits of any cable or port. Aka link aggregation. (VLAN trunking) - Port Mirroring: monitors network traffic and how well a switch works. A copy of all inbound and outbound traffic is configured to go to a certain port so it can monitored by a protocol analyzer. - Port Authentication: authenticate users on a port by port basis. 802.1X standard, often associated with wireless security.

CH3 Addressing and Routing IP Addressing Configuring Routers and Switches

To communicate on a network using TPC/IP each system must be assigned a unique address. An IP address provides two pieces of information: the # of the network to which the device is attached and the # of the node in that network. Each device in a network segment must have the same network adress and different node addresses. A Subnet Mask defines which portion of the IP address refers to the network address and which refers to the note address.

CH3 Addressing and Routing IP Addressing How does it work?

It is a method to assign addresses outside of the Classes A, B, and C by specifying the number of bits in the Subnet Mask. Addresses are assigned using a value = / "slash" The value of the slash depends on how many bits of the subnet mask is used to express the network portion of the IP address. Example: 192.168.2.1/24 = means for the Subnet mask 8.8.8.0 8 = all 1s, which is 255.255.255.0 Whatever # after the slash, start taking out 8 at a time, then convert into binary to figure out the subnet number.

CH3 Addressing and Routing IP Addressing IPv4 Classless Interdomain Routing (CIDR) Define and Explain

IP address composed of 4 sets of 8 binary digits (octets) = 32 bits _ _ _ . _ _ _ . _ _ _ . _ _ _ 128+64+32+16+4+2+1 = 255 maximum value of each octet Each bit in an octet can be 0 or 1 128+64+32+16+4+2+1 1 0 0 0 0 0 1 = 129 0 0 1 0 1 0 1 = 37

CH3 Addressing and Routing IP Addressing IPv4 Explain how it works

Gruped 5 in logical divisions called classess (A - E) Only A- C assigns addresses to clients D - reserved for multicast addressing E - reserved for future development Class A uses the first octect Class B uses the first 2 octects Class C uses the first 3 octects

CH3 Addressing and Routing IP Addressing IPv4 IP Adress Classess Define

Address Class / Range / # networks / # hosts network / binary value of first octet A / 1 - 126 / 126 / 17mi + / 0xxxxxxx B / 128 - 191 / 16Mil + / 65Mil+ / 10xxxxxx C / 192 - 223 / 2mi+ / 254 / 110xxxxx D / 224 - 239 / NA / NA / 1110xxxx E / 240 - 255 / NA / NA / 1111xxxx 127.0.0.1 reserved for IPv4 local loopback - a function of the protocol suite used in troubleshooting process

CH3 Addressing and Routing IP Addressing IPv4 IP Adress Classess Identify Ranges, # Networks and Hosts per Network

Public - network that anyone can connect (i.e. the Internet). Private - access is restricted The addressing of devices in a Public Network must be carefully considered. The ISP provides IP addresses when connecting to the internet. Internet Assigned Number Authority (IANA) responsible for assigning IP addresses to Public Networks. It delegates this task to regional authorities.

CH3 Addressing and Routing IP Addressing IPv4 Public and Private Networks Define and Explain

Class / Address Range / Subnet Mask A / 10.0.0.0 to 10.255.255.255 / 255.0.0.0 B / 172.16.0.0 to 172.31.255.255 / 255.255.0.0 C / 192.168.0.0 to 192.168.255.255 / 255.255.255.0

CH3 Addressing and Routing IP Addressing IPv4 Public and Private Networks Table of Private IP Address Ranges

32 bits like IP address. Unlike an IP address, it performs only one function: defines which part of the IP address refers to the network address and which refer to the node address. Define Subnet Mask Associated with each class: Class / Subnet Mask A / 255.0.0.0 B / 255.255.0.0 C / 255.255.255.0

CH3 Addressing and Routing IP Addressing IPv4 Subnet Mask Assignment

The process by which the node portions of an IP address create more networks than if you used the default subnet mask. Reasons to do it: - More effective use of IP addresses - IP networking is more secure and manageable - reduces overall network traffic - create more broadcast domains

CH3 Addressing and Routing IP Addressing IPv4 Subnetting

- Unicast: point to point address link. A single address is specified. - Broadcast: an IP address that can be used to target all systems on a subnet or network instead of single hosts. - Multicast: Groups of network devices can send and receive data between the members of the group at one time.

CH3 Addressing and Routing IP Addressing IPv4 address types List and Define

Stateless refers to IP autoconfiguration. Stateful devices obtain address information from a server.

CH3 Addressing and Routing IP Addressing IPv6 addressing Statefull and Stateless configuration

IPv4 = 32 bit addressing scheme = over 4 bi addressess IPv6 = 128 bit addressing scheme Format: 16 bit boundaries, 4 digit hexadecimal number

CH3 Addressing and Routing IP Addressing IPv6 addressing difference from IPv4

- Unicast: single interface - from sending host to the destination host - Global Unicast Address: like IPv4 public addresses. Routable and travel through the network - Link-Local Addresses: to use on a single local network. Comparable to the 169 config in IPv4. Automatically configured. Prefix is fe80::/64 - Site-Local Addresses: Equivalent to the IPv4 10.0.0.0, 172.16.0.0 and 192.168.0.0. IPv6 uses site-local addresses that do not interfere with global addresses. Not automatically assigned. Prefix is FEC0::/10 - Multicast addresses: sends and receives data between a group of nodes - Anycast Addresses: delivers messages to any one node in the multicast group

CH3 Addressing and Routing IP Addressing IPv6 addressing types of addresses list and define

Aka the physical address of the NIC (network interface card). The IEEE (Institute of Electrical and Electronic Engineers) took over the assignment of MAC addresses. It delegated the task to each manufacturer. 6 byte hexadecimal address. 3 first bytes define the manufacturer and 3 last assigned by the manufacturer. OUI = organization unique identifier (first 3 bytes) Universal LAN MAC Address (last 3 bytes) Hexadecimal = only numbers 0 - 9 and A -F

CH3 Addressing and Routing IP Addressing Identifying MAC Addresses

- Windows 2003, 2008, XP, Vista, 7 ipconfig / all - Linux, some Unix ipconfig -a - Novell Netware config - Cisco router sh int interface name

CH3 Addressing and Routing IP Addressing Identifying MAC Addresses Commands

Routers are devices that directs data between networks by using two pieces of information, the gateway address and the routing tables. The Default Gateway: It's the router's IP address - the pathway to any and all networks. Routing Tables: Every computer on a TCP/IP network has a routing table stored locally. This is used to determine the best possible path for the data to reach its destination. Command: route print - to view the routing table on a client system. Information in the routing table includes the following: - Destination: the host IP address - Network mask: subnet mask value - Gateway: where the IP address is sent - Interface: the address of the interface - Metric: a measurement of the directness of a route A routing table must be up to date and complete. The router can get information for the routing table in two ways: through static routing or dynamic routing.

CH3 Addressing and Routing IP Addressing Managing TCP/IP routing

Many computers can hide behind a single IP address. Using NAT allows for only one registered IP address is needed on the system external interface, acting as a gateway between the internal and external networks. This is helpful because there aren't enough IPv4 addresses available. NAT is like a middleman, it funnels requests to one single IP address. To the remote host it looks like the request is coming from a single address. PAT enables nodes in the LAN to communicate to the internet without revealing their IP address.

CH3 Addressing and Routing IP Addressing NAT (Network Address Translation)

A variation of NAT. With PAT all computers in the network are translated to the same IP address, but with a different port port number assignment.

CH3 Addressing and Routing IP Addressing PAT (Port Address Translation)

Static routing: routes and route info are manually entered into the routing table. Time consuming and prone to errors. Only suited for the smallest environments with one or two routers. Command: to add info: route add (temporary until reboot) route add -p (permanent) Dynamic routing: routers use special routing protocols to communicate. They enable routers to pass information about themselves to other routers so other routers can build the routing tables. The two types of routing protocols are Older Distance-Vector and Newer Link-State protocols.

CH3 Addressing and Routing IP Addressing Static and Dynamic Routing

- Newer Link-State protocols: Different than distance-vector because it builds a map of the network and then holds it in the memory. Require more powerful hardware and more RAM. List of protocols: - OSPF (Open Shortest Path First): finds the least cost path. Layer 3, network layer more often used in a medium to large enterprise networks. - IS-IS (Intermediate System-to-Intermediate System): finds the least cost path. More often in large ISP networks because it can support more routers.

CH3 Addressing and Routing IP Addressing Static and Dynamic Routing Older Distance-Vector and Newer Link-State protocols Define and Explain. (2 of 2)

- Older Distance-Vector: Each router communicates all the routes it knows to the routers that it is directly attached. This communication is known as hops. Each router represents one hop. So a network with 6 routers has 5 hops between the first and last router. Command to see how many hops: tracert List of protocols: - RIP (Routing Information Protocol): limited to a max of 15 hops. - RIPv2: supports authentication. Changed from broadcast to multicast method. To maintain compatibility still max 15 hops. - BGP (Border Gateway Protocol): associated with the internet because it can be used between gateway hosts in the internet using TCP. - EIGRP (Enhanced Interior Gateway Routing Protocol): enables routers to exchanged info more efficiently than earlier versions. Routers can be configured to send a triggered update if a change in the network topology is detected. The process by which routers learn of a change in the network topology is called convergence.

CH3 Addressing and Routing IP Addressing Static and Dynamic Routing Older Distance-Vector and Newer Link-State protocols Define and Explain. (1 of 2)

- Hop Counts: number of hops necessary to reach a node. A hop count of infinity means that the route is unreachable. - MTU (maximum transmission unit): the size of the largest data unit that can be passed without fragmentation. - Bandwith: max package size allowed for internet transmission. - Costs: numbers associated with travelling from point A to point B - Latency: amount of time it takes for a packet to travel from one location to another.

CH3 Addressing and Routing IP Addressing Static and Dynamic Routing Routing Metrics

TCP Port / Port Assignment FTP (data port-rarely used) / 20 FTP (control port) / 21 SSH / 22 Telnet / 23 SMTP / 25 DNS / 53 HTTP / 80 POP3 / 110 NNTP / 119 NTP / 123 IMAP4 / 143 HTTP / 43 RDP / 3389

CH3 Addressing and Routing IP Addressing TCP/IP Port Assignments for Commonly Used Protocols TCP Ports

UDP Port / Port Assignment TFTP / 69 DNS / 53 DHCP (and BOOTP server) / 67 DHCP (and BOOTP client) 68 NTP / 123 SNMP / 161 RDP / 3389

CH3 Addressing and Routing IP Addressing TCP/IP Port Assignments for Commonly Used Protocols UDP Ports

Each TCP/IP or application has a port associated with it. When a communication is received, the target port number is checked to determine which protocol or service it is destined for. TCP/IP has 65,535 ports available. The term well-known ports identified the ports ranging from 0 to 1023

CH3 Addressing and Routing IP Addressing Understanding TCP/UDP port functions

Divides larger network into smaller sections by sitting between two physical network segments and managing the data flow between them based on the MAC address. Bridges can elect to forward or block data from crossing. They can learn MAC addresses, called learning bridges. Last 64 bits in the IPV6 address knows as EUI-64 (Extender Identifier) and are derived from the MAC address. Bridges can also be used to connect two physical LANs unto a larger logical LAN. STP (Spanning Tree Protocol): eliminates bridge loops that occur when there's more than one bridge in the network and bridges confuse each other by leading a device to think that a device is located in a segment and it is not. Types of Bridges: - Transparent: devices on network are unaware of its existence. - Source Route: token ring networks, entire packet route is embedded in the packet. - Translational: convert one network data format to another. A bridge work at a layer 2 (Data Link). Bridges are not used as much, Ethernet Switches can do the same function. They are also called multiport bridges.

CH4 Components and Devices Common Network Devices Bridges

When a DHCP server runs on a network, the workstation boots up and requests an IP address from the server. The server responds to the request and automatically assigns an IP address to the computer for a determined period of time, aka as lease. Manually assigning IP addresses leaves room for error and computers with duplicate IP addresses will be prevented from using all network services.

CH4 Components and Devices Common Network Devices DHCP Server

The presentation layer (layer 6) is responsible for encrypting/decrypting data sent across the network.

CH4 Components and Devices Common Network Devices Encryption devices

A network device, either hardware or software, that controls access to the organization network and typically placed at a network's entry/exit point (internal network and the Internet). It also controls access between specific network segments within a network. Routers and wireless access points have firewall functionality built in, in such a case, the router or AP might have a number of ports available to plug the system into.

CH4 Components and Devices Common Network Devices Firewalls

Hubs and switches can be connected to create larger networks, this can be achieved standard ports with a special cable or by using ports with a standard cable. HUB the ports are called MDI-X (Medium Dependent Interface Crossed). It uses straight through cable because the ports are crossed internally and one wire sending signal becomes the receiving signal on the other end. Regular port is a MDI. If those ports are not available, hubs and switches can be connected by using a cross-over cable. In a crossover cable, wires 1 and 3 and 2 and 6 are crossed.

CH4 Components and Devices Common Network Devices Hub and Switch cabling

Used in networks that use twisted-pair cabling. Simple devices that direct data packets to all devices connected to the hub, which is inefficient and can cause bottlenecks. Passive Hubs provide a pathway for the electrical signs to travel along. Active Hubs regenerates the signal and can provide data buffering before it forwards it data package. Hubs do not perform data any processing or error checking. Smaller hubs = workgroup hub Larger hubs = high density device Main function is to provide communication between devices. A hub work at Layer 1 (Physical layer).

CH4 Components and Devices Common Network Devices Hubs

Media converters enable companies to use current infrastructure while keeping pace with change in technologies. They are used to connect different types of cables within a network.

CH4 Components and Devices Common Network Devices Media Converters

Modem: Modulator/demodulator Converts digital signals generated by a computer to analog that can travel over phone lines. They can be an internal card or add on. NIC: Enables computer to connect to a network. Consider the following: - bus compatibility: PCI, PCI xpress - System resources: needs an IRQ (interrupt request) and memory I/O address. - Media compatibility: assumption is twisted pair cabling. If coaxial or fiber optic, it must be specified.

CH4 Components and Devices Common Network Devices Modem NIC (Network Interface Card)

Create larger networks by joining two network segments. It can be a dedicated device or a computer system with more than one NIC and appropriate routing device. All OS these days include routing functionality. Routers create, add, or divide network segments and they are IP based devices. It uses routing tables to determine whether it knows how to reach the destination, if it does, it sends the data packet to the next hop in the network. Routers work at layer 3 (Network).

CH4 Components and Devices Common Network Devices Routers

The difference between a hub and a switch is how they deal with the data they receive. A switch forwards data only to the port that connects to the destination device. It does this by learning the MAC address of the devices attached to it then matches the address to the data it receives. It can communicate in full duplex mode, meaning, data can be sent and received from the switch at the same time. The method of switching dictates how the switch deals with data received: - Cut through: packet is forwarded as soon as it is received. Fast and possibility of errors. - Store and forward: packet is is checked for error before forwarding, it takes longer but error free. - Fragment Free: skim through the packet so the switch can determine whether it has been involved in a collision. As soon as status is determine, the packet is forwarded. A switch can work at layer 2 (data link) or 3 (network).

CH4 Components and Devices Common Network Devices Switches