HP 200 Series Services And Applications page 85

Track 3. A Specifically Routed Frame From Node 1 to Node 2
This section tracks specifically routed frames (SRFs) from H1 to H2. HP's
source routing algorithm works the same as when H2 routes a specifically
routed frame to H1. To follow this case, refer to the sample network illustra-
tion in figure 22.
If there is only a single bridge ID (for an HP router) in the RIF, then the
bridge simply transmits the frame to the outgoing circuit group without
making any modification. This is only true when the frame only has to
traverse a single bridge between the source and destination end nodes. This
case is not described in any further detail here.
On the other hand, if there are multiple bridge IDs (for an HP router) in the
RIF, the RIF is manipulated differently by the bridges in the first, middle, and
last positions—A, B, and C, respectively, for this case.
1
router A
H1
Internal LAN ID = 100
Group LAN ID = FFF
Bridge ID = A
Figure 22. Tracking a Specifically Routed Frame from Node 1 to Node 2
First of several bridges receiving the SRF:
receive the frame from ring 1 and does the following to the RIF before
transmitting the frame toward ring 2. (Figure 23 illustrates the RIF in the
frame.)
Changes the destination node's station address at the beginning of
the frame to an HP group address. This address appears as
C000A2FFFFFx, where x is the bridge ID of the next bridge specified
by the RIF.
Removes its own internal LAN ID.
Inserts the group LAN ID before the last Incoming LAN ID /bridge ID
listed in the RIF. (See figure 23.) Eventually, the group LAN ID will
be replaced with the internal LAN ID of the last bridge along the
frame's path.
Copies the destination node's station address into the data portion of
the frame.
2 3
router B
Internal LAN ID = 101 Internal LAN ID = 102
Group LAN ID = FFF Group LAN ID = FFF
Bridge ID = A Bridge ID = A
Bridging Service
Source-Routing Bridging
4
router C
H2
Bridge A is the first to
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