Cabletron Systems CSX400 - Manual (Page 22)

CSX Bridge View
3-2 Accessing the Bridge Traffic View Window
About Transparent Bridging
Individual Transparent bridges monitor packet trafÞc on attached network
segments to learn where end stations reside in relation to each segment by
mapping the Source Address of each received frame to the port (and segment) it
was detected on. This information gets stored in the bridgeÕs Filtering Database.
When in the Forwarding state, the bridge compares a packetÕs destination address
to the information in the Filtering Database to determine if the packet should be
forwarded to another network segment or Þltered (i.e., not forwarded). A bridge
Þlters a packet if it determines that the packetÕs destination address exists on the
same side of the bridge as the source address.
If two or more bridges are connected to the same Ethernet LAN segment Ñ
placed in parallel Ñ only a single bridge must be allowed to forward data frames
onto that segment. If two or more bridges were forwarding data frames onto the
same Ethernet segment, the network would soon be ßooded. With a data loop in
the topology, bridges would erroneously associate a single source address with
multiple bridge ports, and keep proliferating data by forwarding packets in
response to the ever-changing (but incorrect) information stored in their Filtering
Database.
To avoid such data storms, Transparent bridges communicate with one another
on the network by exchanging Bridge Protocol Data Units (BPDUs) to determine
the network topology and collectively implement a Spanning Tree Algorithm
(STA) that selects a controlling bridge for each LAN segment; this ensures that
only a single data route exists between any two end stations and that topology
information remains current.
Accessing the Bridge Traffic View Window
There are two ways to access the CSX Bridge View.
from the icon:
1. Click on the appropriate device icon to display the icon menu.
2. Drag down to Bridge-View and release.
from the command line (stand-alone mode):
1. From the appropriate directory type:
spmarun bridge