HP 200 Series Services And Applications page 72

Bridging Service
Source-Routing Bridging
After adding a routing designator, each bridge forwards the frame
onto all ports except the port on which the frame was received. As a
consequence, multiple copies of the same ARE frame can appear on
a LAN, and the frame recipient can receive multiple copies of the
frame (one copy for each possible path through the extended net-
work). Each ARE frame received by the recipient contains a unique
sequenced list of routing designators tracing the frame's path
through the extended network.
Spanning tree explorer (STE),
Spanning tree broadcast (STB),
Single route explorer (SRE),
Single path explorer (SPE),
Single route broadcast (SRB),
Single path broadcast:
Generates a single frame that follows a loop-free (spanning-tree-
derived) path from source node to destination node. Such frames are
called single route explorer (SRE) or transparent spanning frames
(TSF), or one of the other names listed above. Upon receiving an
SRE, each bridge on the spanning tree forwards the frame onto all
active (non-blocked) ports except the port on which the frame was
received. With spanning tree broadcast routing, one copy of the SRE
appears on each LAN, and the frame recipient receives only a single
copy of the frame.
Some other terms referring to a looped topology are alternate routes,
parallel bridges, and redundant bridges.
Specific routing:
Generates a single frame that traverses a specific path designated by
the source node. Such a frame is called a specifically routed frame
(SRF). SRFs contain a list of routing designators that maps a unique
path through the extended network from source to destination node.
Upon receiving an SRF, each bridge examines the list of routing
designators. It forwards the SRF only if it is on the specified path,
otherwise it ignores the frame.
Null routing:
Indicates that the source node does not desire any routing services
from network bridges. As a result, null-routed frames are restricted
to the resident LAN of the originating node.
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