Cabletron Systems MMAC-Plus SFCS-1000, Configuration Manual

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F-1
APPENDIX F
ForeThought PNNI
PNNI (Private Network Node Interface or Private Network-to-Network
Interface) is a protocol defining interoperability between private ATM
switches. PNNI defines both the routing and signalling standards for inter-
switch interoperability.
This appendix provides a broad overview of Cabletron Systems’ version of
PNNI, ForeThought PNNI (FT-PNNI), and its use in a multiple-switch net-
work. FT-PNNI is a scalable routing and signalling protocol used in networks
containing multiple Cabletron switches. FT-PNNI simplifies large network
topologies by organizing the nodes (switches) in that network into smaller
groups.
It is this reorganization of the network topology that makes FT-PNNI’s sim-
plified routing possible. By segmenting a large network into smaller groups
of nodes, FT-PNNI reduces the amount of topology information that those
very nodes must maintain.
To understand FT-PNNI, it is important to first understand how a large net-
work topology can be simplified by grouping the nodes contained therein.
Once the organization of the physical network is determined, FT-PNNI’s
routing and signalling protocols can be better understood.
This appendix examines the routing and signalling that FT-PNNI utilizes. It
also looks at the physical network and how it can be simplified through the
use of peer groups.