Network +

Transmission Control Protocol (TCP) and User Datagram Protocol (UDP

TCP is a reliable service and UDP is not

Virtual Circuit

Virtual Circuit communication is called connection-oriented. TCP is a connection-oriented communication.

Introduction to Encapsulation

When a host transmits data across a network to another device, the data goes through encapsulation: It's wrapped with protocol information at each layer of the OSI model.

hybrid mesh

used in a restrained manner on WANs, including the Internet.

Open Systems Interconnection (OSI) reference model

was created by the International Organization for Standardization (ISO) to allow computers of different manufacturers to talk with one another..

Point-to-point link, in Star Topology

where you have not only the device in the center of the spoke acting as a hub, but also the one on the other ends acting as a hub.

The steps in the Connection-Oriented session—the three-way handshake

1of 3 -The first "connection agreement" segment is a request for synchronization. 2 of 3-The next segments acknowledge the request and establish connection parameters—the rules—between hosts. These segments request that the receiver's sequencing is synchronized here as well so that a bidirectional connection is formed. 3 of 3-The final segment is also an acknowledgment.

Networking Topologies, Connectors, and Wiring Standards

3.1 Categorize standard media types and associated properties. 3.2 Categorize standard connector types based on network media 3.8 Identify components of wiring distribution.

Backbones, and Segments

A networks iis divided nto different parts called backbones and segments.

Topology Selection, Backbones, and Segments

tips on selecting the right network topologies for your particular network

Several devices operate primarily at the Physical layer of the OSI model.

-Network Interface Cards (NICs) -Transceivers -Repeaters -Hubs

a service is considered connection-oriented if it has the following characteristics:

-A virtual circuit is set up (such as a three-way handshake). -It uses sequencing. -It uses acknowledgments. -It uses flow control.

The following are the topologies you're most likely to run in to these days

-Bus- Star -Ring -Mesh -Point-to-point -Point-to-multipoint -Hybrid

Physical Media

-Coaxial -Twisted-pair -Fiber optic

Some main components of the Transport Layer

-Connection-Oriented Communication -Flow Control -Windowing -Acknowledgements

3.1 Categorize standard media types and associated properties.

-Fiber:---Multimode---Singlemode---Copper:---UTP---STP---CAT3---CAT5---CAT5e---CAT6---CAT6a---Coaxial---Crossover---T1 Crossover---Straight-through-Plenum vs. non-plenum-Media converters:---Singlemode fiber to Ethernet---Multimode fiber to Ethernet---Fiber to Coaxial---Singlemode to multimode fiber -Distance limitations and speed limitations-Broadband over powerline

3.2 Categorize standard connector types based on network media

-Fiber:---ST---SC---LC---MTRJ -Copper:---RJ-45---RJ-11----BNC---F-connector---DB-9 (RS-232) ---Patch panel--- 110 block (T568A, T568B)

3.8 Identify components of wiring distribution.

-IDF-MDF-Demarc-Demarc extension-Smart jack-CSU/DSU

Benefits of Star topology over Bus

-New stations can be added easily and quickly. -A single cable failure won't bring down the entire network. -It is relatively easy to troubleshoot.

Here are some points about routers that you should definitely commit to memory:

-Routers, by default, won't forward any broadcast or multicast packets. -Routers use the logical address in a Network layer header to determine the next-hop router to forward the packet to. -Routers can use access lists, created by an administrator, to control security on the types of packets that are allowed to enter or exit an interface. -Routers can provide Layer 2 bridging functions if needed and can simultaneously route through the same interface. -Layer 3 devices (routers, in this case) provide connections between virtual LANs (VLANs). -Routers can provide quality of service (QoS) for specific types of network traffic.

OSI Reference Model Upper Layer

-The top three layers Application (Layer 7), Presentation (Layer 6), and Session (Layer 5) define how the applications within the end stations will communicate with each other and with users

Disadvantages of a star topology

-The total installation cost can be higher because of the larger number of cables (but prices are constantly becoming more competitive). -It has a single point of failure (the hub or other central device).

3 Common Network Components

-Workstations - Servers - Hosts

Servers

A powerful computers that runs specialized software for the network's maintenance and control known as the network operating system.

The Layered Approach

A reference model is a conceptual blueprint of how communications should take place.and divides these processes into logical groupings called layers. When a communication system is designed in this manner, it's known as layered architecture.

Address Resolution Protocol (ARP)

ARP is part of the TCP/IP protocol stack. It's used to translate TCP/IP addresses to MAC addresses using broadcasts. it will send an ARP broadcast that says,"Hey...exactly who is IP address xxx.xxx.xxx.xxx?"

Advantages of Reference Models

Advantages, but are not limited to, the following: -The OSI model divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting. -It allows multiple-vendor development through standardization of network components. - It encourages industry standardization by defining what functions occur at each layer of the model. -It allows various types of network hardware and software to communicate. -It prevents changes in one layer from affecting other layers, so it doesn't hamper development and makes application programming easier.

Client machine

Any device on the network that can ask for access to resources from a server or powerful workstation—that for instance, hosts a printer.

Network Segments End of Ch.1

Any small section of the network that may be connected to, but isn't actually a piece of, the backbone.

Selecting the Right Topology

Ask the right questions." -Cost -Ease of installation -Ease of maintenance -Fault-tolerance requirement

Note

Broadcast and collision domains are covered in detail in Chapter 5. For now, remember that routers break up broadcast domains and switches break up collision domains.

Coaxial Cable

Coaxial cable, referred to as coax, contains a center conductor made of copper that's surrounded by a plastic jacket with a braided shield over it. A plastic such as polyvinyl chloride (PVC) or fluoroethylenepropylene (FEP, commonly known as Teflon) covers this metal shield.

Flow Control

Data integrity is ensured at the Transport layer by maintaining flow control and by allowing users to request reliable data transport between systems.Reliable data transport employs a connection-oriented communications that is achieved by: -The segments delivered are acknowledged back to the sender upon their reception. -Any segments not acknowledged are retransmitted. -Segments are sequenced back into their proper order upon arrival at their destination. -A manageable data flow is maintained in order to avoid congestion, overloading, and data loss.

Two types of packets are used at the Network layer:

Data packets and Route-update packets

Media Access Control (MAC

Defines how packets are placed on the media. Contention media access is "first come/first served" access where everyone shares the same bandwidth—hence the name. Physical addressing is defined here as are logical topologies. What's a logical topology? It's the signal path through a physical topology

Ring Topology

Each computer is directly connected to other computers within the same network. has a lot in common with the bus topology because if you want to add to the network, you have no choice but to break the cable ring—something that is probably going to bring down the entire network.

The Network Layer process

First, when a packet is received on a router interface, the destination IP address is checked. If the packet isn't destined for that particular router, the router looksup the destination network address in the routing table. Once the router chooses an exit interface, the packet is sent to that interface to be framed and sent out on the local network. If the router can't find an entry for the packet's destination network in the routing table, the router drops the packet.

Host

HOST means any network device with an IP address. Usually this term comes up when people are talking about resources and jobs that have to do with Transmission Control Protocol/Internet Protocol

Exam Essentials Know the devices that operate at each layer of the OSI model.End of Ch.2

Hubs and repeaters see only bits, making them Layer 1 devices. Because all networking devices have physical connectivity to the network, they all operate at Layer 1, but hubs and repeaters operate only at this layer. Nevertheless, we generally consider that a device operates at the highest layer it supports; that layer's functionality is the main reason we implement the device on the network. For example, switches and bridges are considered Layer 2 devices because they understand and make decisions based on Layer 2 addresses. Routers are Layer 3 devices for a similar reason; they deal with Layer 3 addresses. Networking devices, such as workstations, that run applications, are said to operate at the Application layer (or you may hear that they operate at all layers) because they must include Application layer protocols that offer services to networked applications.

Note related to Windowing

If a receiving host fails to receive all the segments that it should acknowledge, the host can improve the communication session by decreasing the window size.

Point-to-Point Topology

In P-to-P you have a direct connection between two routers, giving you one communication path. The routers in a point-to-point topology can either be linked by a serial cable, making it a physical network, or be far apart and connected only by a circuit within a Frame Relay or MPLS network, making it a logical network.

Exam Essentials Know the sublayers of the Data Link layer End of Ch.2

In addition to the OSI layers, knowing the only layer that has sublayers and the functions of those sublayers is extremely important. The Data Link layer has two sublayers: LLC and MAC. The LLC sublayer is responsible primarily for the multiplexing of Network layer protocols. The MAC sublayer is responsible for physical addressing and determining the appropriate time to place data on the network.

Two examples of Routed Protocols

Internet Protocol (IP) and Internet Protocol version 6 (IPv6),

Three-Way Handshake

Is known as SYN, SYN/ACK, ACK, or synchronize, synchronize-acknowledgment, acknowledgement.

Initial Handshake, (during Connection-Oriented communications)

Is when two TCP processes agree on the amount of information that will be sent in either direction before the respective recipient's TCP sends back an acknowledgment

Physical Network Topologies

It defines the specific physical characteristics of a network, such as where all the workstations and other devices are located and the precise arrangement of all the physical media such as cables

Note

It's important for you to understand that routers, which work at the Network layer, don't care about where a particular host is located. They're only concerned about where networks are located and the best way to reach them—including remote ones

The Network Backbone

It's what all the networks segments and servers connect to. the backbone must use some kind of seriously fast, robust technology—often that's Gigabit Ethernet. And to optimize network performance (that is, speed and efficiency)you would want to connect all of the network's servers and segments directly to the network's backbone

MPLS

MPLS is a switching mechanism that imposes labels (numbers) to data and then uses those labels to forward data when the data arrives at the MPLS network

MultiProtocol Label Switching (MPLS)

MPLS is one of the most popular WAN protocols in use today. MPLS has become one of the most innovative and flexible networking technologies on the market and has several advantages compared to other WAN technologies: - Physical layout flexibility - Prioritizing of data - Redundancy in case of link failure - One-to-many connection

Plenum.

Many large multistory buildings are designed to circulate air through the spaces between the ceiling of one story and the floor of the next; this space between floors is referred to as the plenum.

The IEEE Ethernet Data Link layer has two sublayers:

Media Access Control (MAC) and Logical Link Control (LLC)

Mesh Topology

Most physical connections per device"! You won't find it used in LANs very often, if ever,, but you will find a modified version of it known as a hybrid mesh

Virtual Circuit setup

Overhead= After all of this required synchronization takes place, a connection is fully established and the data transfer begins

Point-to-Multipoint Topology

P-to-Mp consists of a succession of connections between an interface on one router and multiple destination routers—one point of connection to multiple points of connection. Each of the routers and every one of their interfaces involved in the point-to-multipoint connection are part of the same network

Plenum Note

Plenum rating applies to all types of cabling and is an approved replacement for all other compositions of cable sheathing and insulation like PVC-based assemblies.

(PDUs).

Protocol Data Units

Routing Protocols

Protocols that send route-update packets are called routing protocols Examples are:;Routing Information Protocol (RIP), RIPv2, Enhanced Interior Gateway Routing Protocol (EIGRP), and Open Shortest Path First (OSPF)

Windows ARP Table

Remember that the ARP table contains two kinds of entries: -Dynamic -Static

Connection-Oriented Communication

Requires the "Three Way Handshake" -Before a transmitting host starts to send segments down the model, the sender's TCP process contacts the destination's TCP process to establish a connection. What is created is known as a VIRTUAL CIRCUIT

Logical Link Control (LLC)

Responsible for identifying Network layer protocols and then encapsulating them. An LLC header tells the Data Link layer what to do with a packet once a frame is received.A host receives a frame and looks in the LLC header to find out where the packet is destined. LLC can also provide flow control and sequencing of control bits.

Project 802

Standard Topic 802.1 LAN/MAN Management (and Media Access Control Bridges) 802.2 Logical Link Control 802.3 CSMA/CD 802.4 Token Passing Bus 802.5 Token Passing Ring 802.6 Distributed Queue Dual Bus (DQDB) Metropolitan Area Network (MAN) 802.7 Broadband Local Area Networks 802.8 Fiber-Optic LANs and MANs 802.9 Isochronous LANs 802.10 LAN/MAN Security 802.11 Wireless LAN 802.12 Demand Priority Access Method 802.15 Wireless Personal Area Network 802.16 Wireless Metropolitan Area Network (also called WiMAX) 802.17 Resilient Packet Ring 802.18 LAN/MAN Standards Committee

The Application Layer

The Application layer is where users actually communicate with the computer (technically users communicate with the network stack through application processes interfaces or APIs that connect the application in use to the operating system of the computer).The Application layer comes into play only when it's apparent that access to the network will be needed soon

The Data Link Layer

The Data Link layer provides the physical transmission of the data and handles error notification, network topology, and flow control. The Data Link layer formats the message into pieces, each called a data frame, and adds a customized header containing the destination and source hardware address.

The Network Layer

The Network layer manages device addressing, tracks the location of devices on the network, and determines the best way to move data, which means that the Network layer must transport traffic between devices that aren't locally attached.Routers are (Layer 3 devices)

The Physical Layer

The Physical layer specifies the electrical, mechanical, procedural, and functional requirements for activating, maintaining, and deactivating a physical link between end systems. This layer is also where you identify the interface between the data terminal equipment (DTE) and the data communication equipment (DCE).

The Presentation Layer

The Presentation layer gets its name from its purpose: It presents data to the Application layer and is responsible for data translation and code formatting. This layer is essentially a translator and provides coding and conversion functions.Tasks like data compression, decompression, encryption, and decryption are associated with this layer

The Session Layer

The Session layer sets up and then tears down sessions between Presentation layer entities. It provides dialog control between devices, or nodes. It coordinates communication between systems and serves by offering three different modes of communication: simplex, half duplex, and full duplex. To sum up, the Session layer basically keeps applications' data separate from other applications' data.

Plenum-rated coating,

The Teflon-type covering is frequently referred to as a plenum-rated coating, and it's definitely expensive but often mandated by local or municipal fire code when cable is hidden in walls and ceilings.

The Transport Layer

The Transport layer segments and reassembles data into a data stream. The Transport layer is responsible for providing mechanisms for multiplexing upper-layer applications, establishing virtual connections, and then tearing down virtual circuits.Transmission Control Protocol (TCP) and User Datagram Protocol (UDP as well as other protocols reside on this layer. The Transport layer can be connectionless or connection-oriented.

Binding.

The communication processes that are related to each other are bound, or grouped together, at a particular layer

Devices Used in an Internetwork

The following network devices operate at all seven layers of the OSI model -Network management stations (NMSs) -Web and application servers -Gateways (not default gateways) -Network hosts

OSI Reference Model Bottom Layer

The four bottom layers: Transport (Layer 4), Network (Layer 3), Data Link (Layer 2), and Physical (Layer 1): define how data is transferred through switches, and routers. These bottom layers also determine how to rebuild a data stream from a transmitting host to a destination host's application.

Client-Server Networks

The polar opposite of peer-to-peer networks because in them, a single server uses a network operating system for managing the whole network.

Windowing

The quantity of data segments (measured in bytes) that the transmitting machine is allowed to send without receiving an acknowledgment is represented by what is called a window.

Reliable Networking

The term reliable networking can be used at the Transport layer. It means that acknowledgments, sequencing, and flow control will be used

Network Architecture: Peer-to-Peer or Client-Server

The two main network types you need to know

Network addresses

These are protocol-specific network addresses. A router must maintain a routing table for individual Routing Protocols because each routing protocol keeps track of a network with a different addressing scheme for example (IP and IPv6,).

Data packets

These are used to transport user data through the internetwork. Protocols used to support data traffic are called routed protocols

Route-update packets

These are used to update neighboring routers about the networks connected to all routers within the internetwork

Interface

This is the exit interface a packet will take when destined for a specific network

Metric

This value equals the distance to the remote network. Different routing protocols use different ways of computing this distance. For now, just know that some routing protocols (namely RIP) use something called a hop count—the number of routers a packet passes through en route to a remote network—whereas others use bandwidth, delay of the line, or something known as a tick count (1/18 of a second).

Protocol Data Units

To communicate and exchange information, each layer uses Protocol Data Units (PDUs).These hold the control information attached to the data at each layer of the model.

(CSU/DSU)

Usually a telephone line

Workstations

Workstations are often seriously powerful computers that run more than one central processing unit (CPU) and whose resources are available to other users on the network to access. Don't confuse workstations with client machines

Workgroup LANs

You must be physically connected to a workgroup's LAN to get the resources from it. - You can't get from one LAN to the other LAN and use its server data and printing resources remotely.

Hybrid Topology

a combination of two or more types of physical or logical network topologies working together within the same network.

Wide Area Network (WAN)

a list of some of the important ways that WANs are different from LANs: - WANs usually need a router port or ports. - WANs span larger geographic areas and/or can link disparate locations. - WANs are usually slower. - We can choose when and how long we connect to a WAN. A LAN is all or nothing our workstation is either connected permanently to it or not at all, although most of us have dedicated WAN links now. -WANs can utilize either private or public

Acknowledgments- Positive Acknowledgment with Retransmission

a technique that requires a receiving machine to communicate with the transmitting source by sending an acknowledgment message back to the sender when it receives data.

Star Topology

computers are connected to a central point with their own individual cables or wireless connections. You'll often find that central spot inhabited by a device like a hub, a switch, or an access point.

Bus Topology

consists of two distinct and terminated ends, with each of its computers connecting to one unbroken cable running its entire length.

Logical topologies

delineate exactly how data moves through the network

SONET

if you work at an ISP, you may find a physical ring topology in use for a technology called SONET

Thin Ethernet, Thinnet, or 10Base2

is Radio Grade 58, or just RG-58

Fault tolerance

is the capability of a computer or a network system to respond to a condition automatically, often resolving it, which reduces the impact on the system

Peer-to-Peer network

peer-to-peer network can be client machines or server machines.They work well if there's not a huge number of users on the network, user backs things up locally, and if your network doesn't require a lot of security

Peer-to-Peer Networks

peer-to-peer networks do not have any central, or special, authority—they're all peers, meaning that when it comes to authority, they're all equals. This means it's up to the computer that has the resource being requested to perform a security check for access rights to its resources.

One Star topology sophisticated implementations

point-to-point link,

local area network

restricted to spanning a particular geographic location such as an office building, a single department,, OR a home office.

Layered Reference Model Characteristics

software developers can a protocol for a certain layer, all they need to concern themselves with is that specific layer's functions, not those of any other layer