H3c-technologies H3C MSR 50 Manuel d'utilisateur télécharger pdf (Page 8)

Configuring IPX

Overview

Internetwork packet exchange (IPX) is a network layer protocol of NetWare. Its position in NetWare is

similar to IP in TCP/IP. IPX implements such functions as address filling, routing, and packet forwarding.

IPX is a connectionless protocol. Though both data and the destination IPX address are included in an IPX

packet, IPX does not confirm whether the packet is forwarded successfully. Such functions as confirmation

of forwarding success and connection control are provided by the protocol at the layer above IPX. Any

IPX packet is considered an independent entity that is not related to any other IPX packets logically or

sequentially.

IPX address structure

The IPX address structure differs from IP. An IPX address consists of the network address and node address,

in the format: network.node.

The network address, with a length of 4 bytes and expressed by an 8-digit hexadecimal, identifies the

physical network where the site lies.

The node address identifies a node in the network, has the same structure as MAC address, and has a

length of 6 bytes. It is input as three parts of 2-byte digits separated by - and it cannot be a broadcast

or multicast address.

For example, in the IPX address bc.0-cb-47, the network address is bc (more accurately, it is 000000bc)

and the node address is 0-cb-47 (more accurately, it is 0000-00cb-0047). Therefore, an IPX address can

also be expressed in the form of N.H-H-H, in which N is the network address and H-H-H is the node

address.

IPX RIP

IPX employs routing information protocol (RIP) to maintain and advertise dynamic routing information.

Through RIP, an IPX router exchanges routing information with neighbors and maintains an inter-network

routing information database (usually called "routing table") according to network changes. When the

router receives a packet, it finds a next hop from the routing table to forward the packet.

IPX SAP

Service advertising protocol (SAP) is used to advertise the service types that servers provide and their

addresses. IPX advertises dynamic service information through SAP. When a server starts, it broadcasts

services it can provide through SAP. When being shut down, the server informs clients of the termination

of services through SAP.

Through SAP, an IPX router creates and maintains an inter-network service information database (usually

called "service information table"). A server on the same network periodically broadcasts its service

types and address. Clients not on the same network as the server cannot get such information directly,

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H3c-technologies H3C MSR 50 Manuel d'utilisateur Page 8