Purpose of ethernet address of a Switch's port

A DSL modem attached to a port on a catalyst 2924XL has, in its MAc address table, the ethernmet address assigned to the port on that switch.

eg: the ethernet address shown by:

SWITCH1>show interface fa0/23 FastEthernet0/23 is up, line protocol is up Hardware is Fast Ethernet, address is 0004.4dfd.1a97 (bia 0004.4dfd.1a97) Description: Modem1 WAN

However, if I telnet into the switch from different hosts, each host's ARP table show an ethernet address that is 1 below the first port's ethernet address. (eg: a central port-neutral MAC address).

So, under what circumstances will the switch emit packets to connected devices with those packets signed by the ethernert address associated to that port ?

Is this part of the spanning tree protocol where each port sends some broadcast signed by the port's address to see if the packet is returned to another port on the same switch ?

Are there more cases where a port will emit packets by itself ? Are there other uses for the ethernet address that is attached to each port ?

Reply to
JF Mezei
Loading thread data ...


Reply to
Walter Roberson

This is the MAC address associated with the management VLAN's SVI. It should be the same no matter where you telnet from.

If you do: switch#sh vlan 1 switch#sh int

You'll see that the management interface (VLAN 1's interface by default) has the lowest MAC-Address followed by fa0/1,...fa0/24, gig0/1, gig0/2

Reply to

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.