INTRODUCTION
according to the specific needs of a network manager. The network manager's ability to set up parameters within Remote LANVIEW ensures optimal performance for each bridge, and hence, each network. For example, a network manager can manage and monitor: the flow of traffic through a bridge, the status of a database, the bridge protocol and port parameters, and the bridge setup.
Both bridges also incorporate Cabletron Systems' LANVIEW Status Monitoring and Diagnostics Systems. Should a problem arise, LANVIEW's LEDs will help you to diagnose problems, such as power failures or cable faults. Individual or separate LEDs advise you that: the bridge is on line and operational, the bridge is receiving or transmitting data packets, or the bridge is detecting a collision signal from an individual segment.
The NB20E or NB25E Bridge interconnects networks consisting of Ethernet Version 1, Version 2, and/or IEEE 802.3 equipment. The bridge has two AUI ports so it can be connected directly to any of Cabletron’s many Ethernet transceivers for data transmission over various media including twisted pair, fiber optic, and/or thick or thin Ethernet coaxial cable.
1.4THE BRIDGE FILTERING METHOD
The Cabletron Systems NB20E and NB25E prevent unnecessary network traffic from passing through the bridge, by implementing a filtering process. This process begins with the creation of a list of local node addresses in a table referred to as the Source Address Table.
When the NB20E or NB25E first goes on line, the bridge initially forwards all packets through the bridge. As the bridge receives a packet, it learns the address of the sending node from the packet and stores that address in its Source Address Table, indicating the segment on which the address resides. In this manner, the bridge learns the address of each node on each side of the bridge and is able to use the addresses stored in the table to compare the destination address of each subsequent packet that travels to the bridge. If the destination address of a packet is located on the same segment (local segment) as the sending node, the packet is not forwarded across the bridge.
Figure
