Forwarding And Filtering - 3Com MSR 50 Series Configuration Manual

408 C 21: B
HAPTER RIDGING
C
ONFIGURATION

Forwarding and filtering

The bridge makes data forwarding or filtering decisions based on the following
scenarios:
When Host A sends an Ethernet frame to Host C, the bridge searches its bridge
■
table and finds out that Host C is attached to bridge interface 2, and forwards
the Ethernet frame out of bridge interface 2, as shown in
Figure 109 Forwarding
MAC address : 00e0.fcaa .aaaa
Host A
Source address
00e0 .fcaa. aaaa
MAC address
00e0. fcaa. aaaa
00e0. fcbb. bbbb
00e0.fccc . cccc
00e0. fcdd. dddd
Source address Destination address
00e0 .fcaa .aaaa
Host C
MAC address : 00e0.fccc .cccc
When Host A sends an Ethernet frame to Host B, as Host B is on the same LAN
■
segment with Host A, the bridge filters the Ethernet frame instead of
forwarding it, as shown in
Figure 110 Filtering
MAC address : 00e0.fcaa .aaaa
Host A
Source address
00e0 .fcaa .aaaa
MAC address
00e 0.fcaa .aaaa
00e 0.fcbb . bbbb
00e 0.fccc . cccc
00e 0.fcdd .dddd
Host C
MAC address : 00e0.fccc .cccc
Destination address
00e0. fccc. cccc
Bridge table
Interface
Bridge interface 1
1
1
2
Bridge interface 2
2
00e0.fccc .cccc
Figure 110.
Destination address
00 e0. fcbb. bbbb
Bridge table
Interface
1
1
2
2
Figure
MAC address : 00e0. fcbb . bbbb
Host B
LAN segment 1
Bridge
LAN segment 2
Host D
MAC address : 00e 0. fcdd.dddd
MAC address : 00e0.fcbb . bbbb
Host B
LAN segment 1
Bridge interface 1
Bridge
Bridge interface 2
LAN segment 2
Host D
MAC address : 00e0.fcdd .dddd
109.