11 network layer protocols chapter 5 ip ipx netbeui appletalk

11

NETWORK LAYER PROTOCOLS

Chapter 5

IPIPXNetBEUIAppleTalk

Chapter 5: NETWORK LAYER PROTOCOLS 2

EXAMPLES OF NETWORK LAYER PROTOCOLS The Transmission Control Protocol/Internet Protocol

(TCP/IP) suite Internet Protocol (IP)

Novell’s Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) suite Internetwork Packet Exchange (IPX)

Apple Computer’s AppleTalk suite Datagram Delivery Protocol (DDP)

Microsoft’s suite NetBIOS Extended User Interface (NetBEUI)


THE INTERNET PROTOCOL

IP, defined in Request for Comments (RFC) 791, is a connectionless network layer protocol that provides Datagram encapsulation

Logical addressing

Fragmentation and reassembly of datagrams

Routing


IP FUNCTIONS Encapsulation

IP forms a datagram by adding an IP header to information passed down from the transport layer protocol.

Addressing Each datagram includes logical source and

destination addresses. Fragmentation and reassembly

The source host or router divides packets into smaller datagrams that can be transmitted over the network.

The destination host reassembles fragments when it receives them.

Routing The selection of the most efficient path.


DATAGRAM ENCAPSULATION


FRAGMENTATION AND REASSEMBLY

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.

Fragmentation


IP HEADER AND FIELDS


Protocol Field Values (The most commonly used values)

0 IP

1 ICMP

3 Gateway-to-Gateway Protocol (GGP)

6 TCP (most expected)

8 Exterior Gateway Protocol (EGP)

17 UDP (most expected)


IP ADDRESSING

IP addresses are Logical network layer addresses used to

identify networks, subnetworks, and hosts

4 bytes (or 32 bits) in length and represented in dotted decimal notation The values within each byte range from 0 to

255.

Public or private


DECIMAL AND BINARY NUMBERING

The decimal numbering system uses 10 (base 10) values to represent numbers. Uses 0–9

The binary numbering system uses 2 (base 2) values to represent numbers. Uses 0 and 1


EXAMPLE OF 8-BIT CONVERSION


EXAMPLE OF 16-BIT CONVERSION


THREE IP ADDRESS CLASSES


THREE DEFAULT MASKS


IP ADDRESS CLASSES AND PARAMETERS


EXAMPLE OF A CLASS A ADDRESS


EXAMPLE OF A CLASS B ADDRESS


EXAMPLE OF A CLASS C ADDRESS


IP SUBNETTING

Each address class can be divided further to create subnets.

Subnet bits are borrowed from the available host bits. Class A: 24 host bits Class B: 16 host bits Class C: 8 host bits

Bits used to define subnets cannot be used to identify hosts.

Borrowed bits are added to the mask.


CLASS A, CLASS B, AND CLASS C SUBNETTING


CLASS C SUBNETTING EXAMPLE (CONT.)


PRIVATE IP ADDRESSES


INTERNET PROTOCOL VERSION 6 (IPV6) ADDRESSING

Addresses the depletion of Internet Protocol version 4 (IPv4) addresses

Increases the address space from 32 bits to 128 bits


INTERNET PROTOCOL VERSION 6 (IPV6) ADDRESSING (CONT.)

Uses six variable-length sections: Format Prefix

Registry ID

Provider ID

Subscriber ID

Subnet ID

Interface ID


EXAMPLE OF AN IPV6 ADDRESS


THE IPX PROTOCOL

Novell’s IPX protocol is a connectionless network layer protocol that provides Datagram encapsulation

Logical addressing


Routing


IPX ADDRESSING

IPX logical network layer addresses consist of three parts: Network

The network portion is four bytes long and is assigned by an administrator or dynamically during installation.

Node The node portion is the hardware address of

the interface attached to the network. Socket

The socket is a two-byte value specifying the application process.


IPX ADDRESSING


IPX ROUTING PROTOCOLS

There are two routing protocols in the Novell IPX/SPX suite: IPX Routing Information Protocol (RIP)

IPX RIP uses broadcasts to learn and advertise routes.

The entire route table is broadcast every 60 seconds.

The maximum number of network hops = 15 (16 is destination unreachable).

IPX RIP uses two metrics for best path selection: hops and ticks. (A tick is one-eighteenth of a second.)


IPX ROUTING PROTOCOLS (CONT.)

NetWare Link Services Protocol (NLSP) NLSP is a link state routing protocol.

NLSP does not broadcast; it sends route information only when there is a change in the network.

The maximum number of hops is 127.

The metric for the best path selection is based on link parameters, not hops.


THE APPLETALK DATAGRAM DELIVERY PROTOCOL

The DDP protocol is a connectionless network layer protocol in the AppleTalk suite that provides Datagram encapsulation

Logical addressing


Routing


NETBEUI

The NetBEUI protocol was developed by IBM and then adopted by Microsoft.

NetBEUI is a nonroutable protocol used for delivering NetBIOS data.

NetBEUI does not contain network layer addressing.

The NetBEUI frame format includes two components: A data-link layer Logical Link Control (LLC)

(802.2) Type II header with control fields A transport layer NetBIOS programming

interface


SUMMARY

Network layer protocols like IP, IPX, and DDP provide data encapsulation, logical addressing, fragmentation, and reassembly.

There are three classes of IP addresses: Class A, Class B, and Class C.

Subnet masks are used to further subdivide Class A, B, and C networks into subnets.

The NetBEUI protocol is the only network layer protocol that does not provide logical network layer addressing and is therefore not routable.

11 network layer protocols chapter 5 ip ipx netbeui appletalk

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