3com 3031 Instruccion De Instalación

Given that Workstation A sends an Ethernet frame to Workstation B, the bridge 
will filter this frame rather than forwarding it, for Workstation B and Workstation 
A are located on the same physical network segment.

Figure 88   Filter (not forward)

Suppose that Workstation A sends an Ethernet frame to Workstation C, and the 
bridge does not find the correlation between the MAC address of Workstation C 
and the port in the bridging address table, what will the bridge do? The bridge will 
forward this frame destined to an unknown MAC address to all ports except the 
one on which it is received. In this case, the bridge actually plays the role of a hub 
to make sure the continuous information transmission, as shown in Figure 89.

Figure 89   No matched MAC address is found in the bridging table

As shown in Figure 90, both bridge X and bridge Y are connected with Ethernet 
segment 1. Once detecting a broadcasting frame, both bridges will send it to all 

No forwarding

Bridge

Ethernet segment 1

Bridge port 1

Bridge port 2

Ethernet segment 2

00e0.fcaa.aaaa 00e0.fcbb.bbbb

Source address Destination address

Bridging table

MAC address

00e0.fcbb. bbbb
00e0.fccc . cccc

00e0.fcdd.dddd

00e0.fcaa.aaaa

Port

1
1
2
2

Workstation A

Workstation B

Workstation C

Workstation D

00e0.fcaa.aaaa

00e0.fcbb.bbbb

00e0.fcdd.dddd

Bridge

Ethernet segment 1

Bridge port 1

Bridge port 2

00e0.fccc.cccc

00e0.fcdd.dddd

Ethernet segment 2

00e0.fcaa.aaaa

00e0.fcbb.bbbb

00e0.fcaa.aaaa 00e0.fccc.cccc

Source address Destination address

Bridging table

MAC address

00e0.fcaa.aaaa

Port

1

1

00e0.fcbb.bbbb