3Com 2500 manual Sending Node’s Responsibility

6-6 CHAPTER 6: ROUTING WITH IPX

IPX Packet Delivery On a NetWare network, the successful delivery of a packet depends both on the proper addressing of the packet and on the internetwork configuration. Packet addressing is handled in the packet’s Media Access Control (MAC) protocol header and IPX header address fields.

To send a packet to another node, the sending node must know the complete internetwork address including the network, node, and socket of the destination node. Once the sending node has the destination node’s address, it can proceed with addressing the packet. However, the way the MAC header of that packet is addressed depends on whether the sending and destination nodes are separated by a router. See Figure 6-3.

Sending Node

Network =	000000AA
Node =	000000000001
Socket =	4003

Router

Node	Node
000000000020	000000000021

Destination Node

Network =	000000BB
Node =	000000000003
Socket =	0451

MAC Header
Destination Node =	000000000020
Source Node =	000000000001
IPX Header
Checksum =	FFFF
Packet Length =	011E
Tranport Control =	00
Packet Type =	11
Dest Network =	000000BB
Dest Node =	000000000003
Dest Socket =	0451
Source Network =	000000AA
Source Node =	000000000001
Source Socket =	4003
Data

Figure 6-3 IPX Packet Routing

MAC Header
Destination Node =	000000000003
Source Node =	000000000021
IPX Header
Checksum =	FFFF
Packet Length =	011E
Tranport Control =	01
Packet Type =	11
Dest Network =	000000BB
Dest Node =	000000000003
Dest Socket =	0451
Source Network =	000000AA
Source Node =	000000000001
Source Socket =	4003

Data

Sending Node’s Responsibility

When a node needs to send information to another node with the same network number, the sending node can simply address and send packets directly to the destination node. However, if the sending and receiving nodes have different network numbers, the sending node must find a router on its own network segment that can forward packets to the destination node’s network segment.