HP 600 Series, Services And Applications

Page: 65 / 316

Figure 5. Architecture of the Source-Routing/Transparent (SRT) Bridge
Figure 5 shows an architectural model of the SRT bridge. When the SRT
bridge receives a frame, it examines the Routing Information Indicator (RII).
Frames with RII=1 are processed using source routing (SR) logic. Frames
with RII=0 are processed using transparent bridge (TB) logic. The RII is the
first bit transmitted of the source station address (MAC address). This bit
occupies the same position in the source address as does the
individual/group bit in the destination station address.
Source-Routing/Transparent Bridge Versus Source-Routing Bridge
A source-routing (only) bridge provides inter-ring communication only for
systems that support source routing. Systems that do not support source
routing can communicate only with systems on the same token ring. An SRT
bridge, in contrast, provides inter-ring communication for systems that
support source routing as well as those that do not support source routing.
Higher-Layer Entities
(Bridge Managment, etc.)
LLC Entity LLC Entity
SR LOGIC
TB LOGIC
RII = 1
MAC Entity
MAC Entity
Yes
No
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N
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2
Bridging Service
Token Ring Solutions
2-13