1 Chapter Overview IP IPX NetBEUI AppleTalk. 2 Network Layer Protocols Responsible for end-to-end...

1

Chapter Overview

IP IPX NetBEUI AppleTalk

2

Network Layer Protocols

Responsible for end-to-end communications on an internetwork

Contrast with data-link layer protocols, which provide communications on the same local area network (LAN)

3

IP Encapsulation

4

IP Functions

Encapsulation Addressing Routing Fragmentation Protocol identification

5

The IP Datagram Format

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IP Addresses Internet Protocol (IP) is the only network layer

protocol with its own addressing system. IP addresses are 32 bits long. IP addresses have two parts: a network identifier

and a host identifier. IP addresses are assigned to network interface

adapters, not to computers. The Source IP Address field in the IP header

always identifies the computer that generated the packet.

The Destination IP Address field in the IP header always identifies the packet’s final destination.

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End Systems and Intermediate Systems

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Fragmentation Routers connect networks that support different-

sized packets. The largest packet size supported by a network is

called its maximum transmission unit (MTU). When a packet is too large to be forwarded to a

particular network, the router splits it into fragments.

Each fragment is encapsulated with a header and is transmitted as a separate packet.

Fragments are not reassembled until they reach their final destination.

Fragments can themselves be fragmented.

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Fragmentation (Cont.)

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Protocol Field Values

0 IP

1 ICMP

3 Gateway-to-Gateway Protocol (GGP)

6 TCP

8 Exterior Gateway Protocol (EGP)

17 UDP

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The IPX Standard

Developed by Novell for use with NetWare

Proprietary; never published as a public standard

Reverse engineered by Microsoft to create NWLink

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IPX Functions

Routing Addressing Protocol identification

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The IPX Header Format

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IPX Addressing

Internet Packet Exchange (IPX) uses Separate node and network addresses Network interface adapter hardware

addresses for node addresses Network addresses

Are assigned by administrators Do not need to be registered

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NetBEUI Characteristics

Original Microsoft Windows default networking protocol

Designed for small local area networks (LANs)

Does not support Internet communications Does not need configuration Can be used to troubleshoot Transmission

Control Protocol/Internet Protocol (TCP/IP) configuration protocols

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NetBIOS Names

Assigned to computers during Windows installation

Sixteen characters long; the sixteenth character is a resource identifier

Can identify computers, domain controllers, users, groups, and other resources

Have no network identifier (which is why NetBEUI is nonroutable)

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The NBF Protocol Format

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Protocols Using NBF

Name Management Protocol (NMP) Session Management Protocol (SMP) User Datagram Protocol (UDP) Diagnostic and Monitoring Protocol

(DMP)

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AppleTalk Data-Link Layer Options

LocalTalk EtherTalk Fast EtherTalk TokenTalk FDDITalk

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Datagram Delivery Protocol

AppleTalk’s network layer protocol Provides packet addressing, routing,

and protocol identification Has short-format and long-format

packet headers

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AppleTalk Addressing AppleTalk computers have a unique 8-bit

node ID that is self-assigned. AppleTalk networks can have no more

than 254 nodes. AppleTalk uses 16-bit network numbers

for routing. Computers obtain network numbers using

the Zone Information Protocol (ZIP). Computer processes are identified by 8-

bit socket numbers.

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AppleTalk Addressing (Cont.)

Network numbers, node IDs, and socket numbers are expressed as three decimal numbers, separated by periods.

AppleTalk computers resolve node IDs into hardware addresses, using the AppleTalk Address Resolution Protocol (AARP).

AppleTalk computers also have friendly names and groups of computers called zones.

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Chapter Summary Network layer protocols are responsible for end-

to-end communications across the network. IP is a connectionless protocol that encapsulates

transport layer data into datagrams. IPX is a proprietary standard that performs

routing, addressing, and protocol identification. NetBIOS Extended User Interface (NetBEUI) is

used by small Windows networks for LAN networking.

AppleTalk provides basic networking to small networks.