HP 200 Series Services And Applications page 78

Bridging Service
Source-Routing Bridging
Router C (in figure 13) is the last source-routing bridge to receive the ARE
frame. C updates B's last routing designator by changing bridge ID 0 to 1,
and then inserting the remainder of its routing designators (9–1, 2–0) in the
frame's MAC header. C then transmits the ARE frame to the destination node
H2.
H2 inspects the frame's MAC header to learn the route that this particular
frame traversed. The route is mapped out by the sequence of routing
designators (1–1, 7–1, 5–1, 8–1, 6–1, 9–1, 2–0) inserted by source-routing
bridges A, B, and C.
N o t e
Other route discovery protocols are available and extensively used. All
such protocols, however, exchange TSFs, ARE frames, and SRFs.
2-26