Re: mac-address-table [Catalyst 4507R SUP4]

tmesbah · ‎02-11-2004

Hi,

When issue this command "sh mac-address-table int gX/X" on our Server FArm switch: Catalyst 4507R-SUP4-IOS 121-13.EW1] we got different results on some ports.

1)sh mac-address-table int g5/20

Unicast Entries

vlan mac address type protocols

-------+---------------+--------+------------

148 0050.8bbd.4ed1 dynamic ip

2)sh mac-address-table int g4/13

Unicast Entries

vlan mac address type protocols

-------+---------------+--------+-------------

16 0050.8bb4.7110 dynamic ip

Multicast Entries

vlan mac address type ports

-------+---------------+-------+-----------------

16 ffff.ffff.ffff system Gi4/1,Gi4/2,Gi4/3,

Gi4/4,Gi4/5,Gi4/6,

Gi4/8, Gi4/9,Gi4/11,

Gi4/12,Gi4/13,Gi4/14,

Gi4/15,Gi4/16,Gi4/17,

Gi7/24,Gi1/1

3) AC45M40-45#sh mac-address-table int g4/12

Unicast Entries

vlan mac address type protocols

-------+---------------+--------+-------------

16 0050.8bb8.dec3 dynamic ip

Multicast Entries

vlan mac address type ports

-------+---------------+-------+-----------------

16 0100.5e05.0607 igmp Gi4/2,Gi4/4,Gi4/6,

Gi4/12,Gi4/16,Gi1/1

16 ffff.ffff.ffff system Gi4/1,Gi4/2,Gi4/3,

Gi4/4,Gi4/5,Gi4/6,

Gi4/8,Gi4/9,Gi4/11,

Gi4/12,Gi4/13,Gi4/14,

Gi4/15,Gi4/16,Gi4/17,

Gi7/24,Gi1/1

Question:

========

a) Why we are having different results. All the port on the switch have same configuration

b) We are more conserned with number 3) showing igmp. What this mean ?

Thanks

smcquerry · ‎02-11-2004

The MAC address table is the Layer 2 switching, this output is caused by the devices connected to the ports as well as the configuration. Since the devices will have different MAC addresses and may be running multicast applications, the output will be different table. This command shows the MAC address of the devices that are "known" by the switch to be located out that port. Since this is a server farm, I assume that each port is connected directly to a different server. The output shows the VLAN and MAC addresses associated with each port.

For example port 5/20 is in vlan 148 and (assuming its connected to only 1 device) the server out that port has the MAC address of 0050.8bbd.4ed1.

The multicast entries show what multicast groups that a particular port is interested in seeing. The address 0100.5e05.0607 is a multicast group that the device connected to port g4/12 is requesting (using IGMP). So if there are multicast messages going to that layer 2 address, the switch will forward them to that port because the server is requesting them.

This output displayed is caused by the devices connected to the ports as well as the configuration. Since the devices will have different MAC addresses and may be running multicast applications, the output will be different.