Cabletron Systems 3T02-04 Manual Do Utilizador

Source routing bridging (SR) is an alternative to transparent or spanning 
tree bridging, and is widely used in Token Ring networks. The ATX 
supports source routing bridging on Token Ring LANs, and an 
enhancement to source routing called SRT on all LANs. 

With source routing bridging, all networked devices participate in the 
source routing protocol. Each packet that crosses a bridge specifies the 
originator's LAN segment, the particular bridge, and the destination LAN 
segment. It may also specify intermediate LAN segments and bridges.

In the example in Figure B-1, a data packet traveling from station C on 
LAN 43 through bridge B to station A on LAN 7 must specify the full 
route it is to take. The source station is responsible for specifying the 
route, hence the term “source routing.”

Bridges in a source routing network must be configured with the LAN 
numbers (normally 1 to 4095) to which it is connected and a bridge 
number (normally 1 to 15). The network administrator chooses the 
numbers; the LAN numbers must be unique in the source routed network 
and the bridge numbers must be unique between each pair of LANs. 

Ring

7

Ring

43

address

43

B

7

data

data packet

Station A

Station C

Bridge B