Cisco Catalyst - Show MAC address of all connected devices
Posted on 2013-05-16
I have a Cisco infrastructure setup with several switches connecting to a CORE infrastructure:
Cisco Catalyst 3750: Core
Cisco Catalyst 3560#1: PC Switch
Cisco Catalyst 3560#2: PC Switch
Cisco Catalyst 3560#3: PC Switch
Cisco Catalyst 3560#4: PC Switch
Cisco Catalyst 3560#5: PC Switch
Cisco Catalyst 3560#6: PC Switch
- Each switch is connected to the 3750 core via a (2) port port-channel group (port-channel group 1 going to switch 1, port-channel group 2 going to switch 2, etc...).
- The Core switch has 10 VLANs configured on it, and is setup in layer 3 mode.
- The Core switch is setup as VTP server.
- Every switch is setup as VTP client, so all VLAN's in the core are available to all switches.
- 90% of the environment is on a PC VLAN (VLAN 100).
- 10% of the environment (servers) is setup on a SERVER VLAN (VLAN 2)
- Each switch (other than the Core) has an IP address on the server VLAN for management (192.168.2.11 for switch 1, 192.168.2.12 for switch 2, etc...)
- The Core switch has an IP interface for each VLAN:
. VLAN 100 = 192.168.100.1/24
. VLAN 2 = 192.168.2.1/24
. Default route of the Core switch is to the firewall, 192.168.2.254
- Every VLAN interface that is servicing clients that need dynamic addressing has an "ip-helper" address setup on the IP interface pointing to the (2) DHCP servers serving the clients (192.168.2.100, 192.168.2.101)
- Most ports are setup as "Switchport access VLAN 100".
Everything is working fine as far as routing and DHCP addressing goes. Today, however, I was trying to track down what port a particular client is in and I was not able to track it down. Here's what I was trying to do:
1. From management station, ping NetBios name of PC to get IP address. Received 192.168.100.54.
2. Connected to CLI of Core Switch, did "show arp | include 192.168.100.54" and got the MAC address of 192.168.100.54.
3. From CLI of Core switch, did, "show mac address-table | include [mac address]" and got "100 [MAC address] DYNAMIC Po2" which tells me it's in VLAN100 (as expected), the MAC address (as expected), the type of address (DYNAMIC, as expected, as it was learned from a connected device) and the port that it was learned from (port-channel 2, which tells me this client should be connected to switch #2).
4. Connected to CLI of switch #2, did, "show mac address-table | inc [mac address]" and received the same message of "100 [MAC address] DYNAMIC Po2".
At each switch, we name the port-channel group the same as the port-channel group servicing the switch from the core so that it's easy to follow frontwards and backwards.
Why can I not track down the MAC address of the clients that are connected to my distribution switches? Is there a better way to be setup? Is it setup wrong? Or is there another command to list all of the MAC addresses of connected clients? I seem to remember viewing a CAM table long ago, but cannot find any references to a command doing this.
Help is appreciated, thanks!