User`s guide

Introduction
1-19
where each bridge is likely to become congested.
Figure 1-4. Data Path Using Source Routing Bridging
In contrast to spanning tree bridging, all bridges and all links are
active with source routing bridging; the least-congested path is
chosen at discovery time. With products like the ATX, such
congestion avoidance is rarely necessary, since the bridge is
capable of handling nearly any traffic load without experiencing
congestion.
1.7.4 Source Routing Transparent Bridging
Source Routing Transparent (SRT) bridging is a method that
merges IBM-style source routing with transparent spanning tree
bridging. If a route is present in a packet, then the bridge uses it;
otherwise the bridge applies transparent learning rules. It
represents an attempt by the IEEE standards committee to
standardize source routing and correct some shortcomings in
source routing (notably multicast transmission). IEEE has defined
SRT bridging for Token Rings, and ANSI has incorporated it into
the FDDI standards. The ATX supports SRT bridging on these, as
well as on Ethernet (for Ethernet, there is no such standard; the
ATX provides this as a proprietary backbone service).
Congested
Alternative Route
Station A
Station C