Cabletron Systems 3T02-04 - Manual (Page 47)

Source Routing Bridging
Token Ring Switch Module User Guide Page B-3
B.3 SOURCE ROUTING BRIDGING
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.
Figure B-1 Source Routing Example
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