Cabletron Systems CSX100 series, Руководство пользователя, Страница: 108 / 153

ISDN Router 94
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NTT (Nippon Telegraph and Telephone)
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KDD (Kokusai Denshin Denwa Co., Ltd.)
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HSD64 (64Kb permanent connection)
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HSD128 (128Kb permanent connection)
Support for additional switches will be announced from time to time.
Bridging and Routing
Bridging
Bridging connects two or more LANs together so that all devices share the
same logical LAN segment and network number. The MAC layer header
contains source and destination addresses used to transfer frames. An address
table is dynamically built and updated with the location of devices when the
frames are received. Transparent bridging allows locally connected devices to
send frames to all devices as if they are local.
Bridging allows frames to be sent to all destinations regardless of the network
protocols used. It allows protocols that cannot be routed (such as NETBIOS)
to be forwarded and allows optimizing internetwork capacity by localizing
traffic on LAN segments. A bridge extends the physical reach of networks
beyond the limits of each LAN segment. Bridging can increase network
security with filtering.
Routing
Routing provides a way to transfer user data from source to destination over
different LAN and WAN links using one or more network protocol formats.
Routing relies on routing address tables to determine the best path for each
packet to take.
Routing tables can be seeded; i.e., addresses for remote destinations are
placed in the table along with network address masks and a metric for path
latency. Routing tables are also built dynamically; i.e., the location of remote
stations, hosts and networks are updated from broadcast packet information.
Routing helps to increase network capacity by localizing traffic on LAN
segments and reducing the amount of broadcasts that would result from
bridged traffic. It also provides security by isolating traffic on segmented