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ForeRunner
ATM Switch Network Configuration Manual
ForeThought PNNI
5.1.4.1.2
Switch Summary Prefix
Each switch is configured with a switch mask (swmask) which gives the length of the switch
summary prefix within the switch prefix. The swmask gives the number of most significant bits
of the switch prefix that constitute the switch summary prefix. Since all end system addresses
attached to a switch have the same switch summary prefix, their reachability information can
be summarized by this prefix (i.e., by the switch summary prefix).
5.1.4.1.3
Peer Group ID
Each switch is configured with a peer group mask (pgmask) which gives the length of the peer
group ID within the switch summary prefix. The pgmask gives the number of most significant
bits of the switch summary prefix that constitute the peer group ID.
Each peer group has a peer group ID that uniquely identifies it from every other peer group.
Every node (switch or end system) in a particular peer group shares that same unique peer
group ID, thereby indicating membership to that peer group.
A simple example of summarizing by peer group ID can be seen in Figure 5.3, where every
switch (and end system, although not shown) in peer group A is identified starting with “A.”
5.1.4.2 Path Computation
Path computation is performed on demand whenever FT-PNNI signalling requests a path to a
given destination. The Bellman-Ford Shortest Path algorithm is used to compute the shortest
path tree of all nodes in the topology with the local node as the source. The administrative
weight metric in the loglinks is used as the minimizing criterion in computing the shortest
path route. In the case of finding multiple equal-cost paths to a given destination, available
cell rate is used to break ties.
Summary of Contents for forerunner series
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Page 16: ...TOC 10 ForeRunner ATM Switch Network Configuration Manual Table of Contents ...
Page 20: ...LOF 4 ForeRunner ATM Switch Network Configuration Manual List of Figures ...
Page 22: ...LOT 2 ForeRunner ATM Switch Network Configuration Manual List of Tables ...
Page 30: ...viii ForeRunner ATM Switch Network Configuration Manual Preface ...
Page 144: ...3 58 ForeRunner ATM Switch Network Configuration Manual Configuring an Emulated LAN ...
Page 180: ...6 12 ForeRunner ATM Switch Network Configuration Manual ATM Forum PNNI ...
Page 220: ...9 6 ForeRunner ATM Switch Network Configuration Manual Configuring Timing ...
Page 300: ...D 24 ForeRunner ATM Switch Network Configuration Manual Configuring FramePlus Modules ...
Page 308: ...Acronyms 8 ForeRunner ATM Switch Network Configuration Manual Acronyms ...
Page 346: ...Glossary 38 ForeRunner ATM Switch Network Configuration Manual Glossary ...
Page 352: ...Index 6 ForeRunner ATM Switch Network Configuration Manual Index ...