3Com 4007, Руководство по внедрению, Страница: 162 / 684

162 C
HAPTER
9: B
RIDGE
-W
IDE AND
B
RIDGE
P
ORT
P
ARAMETERS
Bridging Overview
Operating at the data link layer (Layer 2) of the OSI reference model, a
bridge interconnects two or more LANs and allows them to communicate
as if they were one LAN. Bridges examine incoming frames, make
forwarding decisions from comparing the address information in the
frame against the bridge’s own address table as well as considering other
factors such as VLANs.
Benefits Bridges provide the following benefits:
■
Bridges overcome cabling limitations and extend the effective length
of a LAN, allowing distant stations to communicate that would not
otherwise not.
■
Bridges can provide a level of separation that prevents some potential
damaging errors or undesirable frames from spreading or multiplying
on the network.
■
Because bridges only forward a percentage of total traffic received,
they diminish the traffic that devices on connected segments
experience and increase available bandwidth in each LAN.
■
Bridges allow a larger number of devices to communicate than a
single LAN can support.
■
Bridges can detect loops in the network topology and communicate
with each other to ensure that only one path exists between any two
points and thus minimize the probability of broadcast storms.
In this chapter, the term bridge refers to bridging operations on an
individual switching module.
The Switch 4007 software and management interfaces are built from
CoreBuilder 9000 switch technology. In releases 3.0.0 and 3.0.5, the
prompts and displays in all interfaces may indicate this heritage.