Cabletron Systems CSX100 series User Manual - Bridging and Routing

ISDN Router

94

· 

NTT (Nippon Telegraph and Telephone)

· 

KDD (Kokusai Denshin Denwa Co., Ltd.)

· 

HSD64 (64Kb permanent connection)

· 

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