3Com Switch 8800 Advanced Software V5 Configuration Guide

7
MAC ADDRESS TABLE MANAGEMENT
CONFIGURATION
When configuring MAC table management, go to these sections for information
you are interested in:
■ “Introduction to MAC Address Table” on page 63
■ “Configuring MAC Address Table Management” on page 64
■ “Displaying MAC Address Table Management” on page 67
■ “MAC Address Table Management Configuration Example” on page 67
n
The term router and router icons mentioned in the following routing protocol
refer to the routers in a generic sense and the switches running routing protocols.
Introduction to MAC
Address Table
A device maintains a MAC address table for frame forwarding. Each entry in this
table indicates the MAC address of a connected device, to which interface this
device is connected and to which VLAN the interface belongs.
A MAC address table consists of two types of entries: static and dynamic. Static
entries are manually configured and never age out. Dynamic entries can be
manually configured or dynamically learned and may age out.
The following is how your device learns a MAC address after it receives a frame
from a port, Port 1 for example:
1 Check the frame for the source MAC address (MAC A for example).
2 Look up the MAC address table for an entry corresponding to the MAC address
and do the following:
■ If an entry is found for the MAC address, update the entry.
■ If no entry is found, add an entry for the MAC address and indicate from which
interface the frame is received.
When receiving a frame destined for MAC A, the device then looks up the MAC
address table and forwards it from port 1.
n
Dynamically learned MAC addresses cannot overwrite static MAC address entries,
but the latter can overwrite the former.