3Com CoreBuilder 7000, Operation Manual

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PNNI Signaling Protocol 87
PNNI Signaling
Protocol
This section will cover PNNI signaling. Topics that will be covered include:
PNNI Signaling
Establishing a Channel in PNNI
Crankback and Alternate Routing
PNNI Signaling As stated earlier, PNNI is a signaling protocol used between networks, not
users. Figure 26 displays the signaling options that exist in a typical
network.
Figure 26 ATM Signaling Interfaces
PNNI signaling is used for call/connection establishment and clearing over
ATM interfaces. It is based on a subset of UNI 4.0 signaling specifications.
It makes use of the information that was gathered from the topology
database in the routing protocol (reachability, connectivity, resource
availability). It creates a Designated Transit List (DTL) as the mechanism
used to describe the path to the destination. In addition, when the path
cannot be established, crankback and alternate routing are the two
Public
Network
Public
Network
A T M U s e r
A T M U s e r
Private Network
or
S w i t c h
Private Network
or
Switch
Public UNI(PUNI)
Public UNI(PUNI)
P U N I P N N I
B-ICI