ForeRunner
ATM Switch Network Configuration Manual
5 - 5
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5.2 The Physical Network
In an ATM network, data is sent and received over virtual circuits, or circuits that only exist
when needed. This communication over these virtual circuits is made possible by signalling
that occurs between the switches in the network.
In a network of ForeRunner switches, any new addition to the topology is recognized immedi-
ately by all nodes (switches) having a direct connection to the new node. Then each switch
that has recognized the new switch sends a message to each of its direct connections, and so
on. Eventually, and within a very brief period of time, every switch in the network is aware of
the new addition and the links by which that new addition can be reached. This topology is
stored by each switch in its local topology database.
In a small, local area network (LAN), the topology is relatively simple, meaning that the
switches in the LAN have a relatively small topology database to maintain. As the LAN
grows, however, and more switches are added, that same database can grow to be very large
in a short period of time.
As this topology database grows, the amount of information a switch must look up when
searching for an address also grows. In the end, this can result in delayed connection set-up,
congestion in the network, and even lost data.
Figure 5.2 depicts a typical ATM network, containing 21 ForeRunner switches (
). The hierar-
chy of this network is flat, meaning that each switch must be aware of all the other switches in
the network, as well as all the possible routes to those switches. As more switches are added to
this network, the hierarchy will become more complex and the switches will have to contend
with larger topology databases.
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 ...