Beta Draft Confidential
Configuring PNNI Routing
PNNI Routing Protocol Overview
ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000 1/19/0521-11
The PGL node aggregates all of the topology information from its peer group and
propagates (distributes) a summarized version of that information to the LGN
higher-level peer group. In turn, the PGL receives summarized routing information
from its LGN and distributes that information to the other nodes in its peer group.
This automated collection and propagation process eliminates the need for manual
configuration and maintenance of routing information about network nodes. In effect,
PNNI allows network nodes to automatically learn the topology of the network, and
use the topological knowledge they acquire to route data to its correct destination.
Figure 21-3 illustrates the flow of PNNI topology information within peer groups and
between peer groups. The neighboring nodes in each peer group exchange topology
information to synchronize each other’s topology databases. The LGNs also propagate
information about how to reach their child groups to other LGNs.
Figure 21-3. Flow of PNNI Topology Information
Note – Each PGL exchanges aggregated topology information with its own LGN
vertically within the hierarchy. Peer group leaders do not exchange topology
information with other peer group leaders.
N
N
N
LGN LGN
Legend
N = Lowest-level Node
LGN = Logical Group Node
PG = Peer Group
PG1
PG3
N
N
N
PG2
Flow of topology
information between
PG1 and PG2.
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