MAC address on 2950

mo shea · ‎04-08-2005

Hi...

Whenever I telnet to the switch that my PC is connected to and type sho arp I get all the IP addresses of PCs connected to the switch while the hardware address is the same for all of them.

How can I get the mac addresses of the PCs connected to the ports?

Thanks

scottmac · ‎04-09-2005

You should be getting the correct hardware address if the PCs are directly connected to the switch.

If you are connecting a group of PCs that pass through a router, then the single MAC that you are seeing is the MAC of the router interface connecting to the 2950.

To get the real MACs of the PCs, you'd need to look at the ARP table of the router.

Here's a sh arp from my switch:

Smack_2950#sho arp

Protocol Address Age (min) Hardware Addr Type Interface

Internet 172.16.1.254 190 000a.4144.d4bd ARPA Vlan1

Internet 172.16.1.198 3 0004.75db.07b9 ARPA Vlan1

Internet 172.16.1.57 74 00d0.5836.f441 ARPA Vlan1

Internet 172.16.1.29 - 0009.b74a.9580 ARPA Vlan1

Internet 172.16.1.127 81 0013.6042.8a8d ARPA Vlan1

Internet 172.16.1.77 0 0002.b349.c8c8 ARPA Vlan1

Smack_2950#

You might also try a sh mac-address-table, it'll give you MAC and switch-port that the MAC is connected to.

Here's an example:

Smack_2950#show mac-address-table

Mac Address Table

-------------------------------------------

Vlan Mac Address Type Ports

---- ----------- -------- -----

All 0009.b74a.9580 STATIC CPU

All 0100.0ccc.cccc STATIC CPU

All 0100.0ccc.cccd STATIC CPU

All 0100.0cdd.dddd STATIC CPU

1 0002.b349.c8c8 DYNAMIC Fa0/24

1 0002.b349.c965 DYNAMIC Gi0/1

1 0004.75db.07b9 DYNAMIC Fa0/23

1 000a.4144.d4bd DYNAMIC Fa0/18

1 000d.613b.28e5 DYNAMIC Gi0/1

1 000e.a62d.abf1 DYNAMIC Gi0/1

1 000f.f73a.bc4d DYNAMIC Fa0/19

1 0010.7be7.a772 DYNAMIC Fa0/21

1 0011.240d.960f DYNAMIC Fa0/19

1 0013.6042.8a8d DYNAMIC Fa0/20

1 0030.4821.e689 DYNAMIC Fa0/24

1 00d0.5836.f441 DYNAMIC Fa0/22

56 0001.5c22.9982 DYNAMIC Fa0/12

56 000a.4144.d4bc DYNAMIC Fa0/13

100 0000.0c4a.5eca DYNAMIC Fa0/1

100 00c0.7b4c.9325 DYNAMIC Fa0/2

200 0000.0c5d.b3ee DYNAMIC Fa0/3

400 0010.7b80.2ecd DYNAMIC Fa0/8

300 0000.0c5c.f28c DYNAMIC Fa0/7

Total Mac Addresses for this criterion: 23

Smack_2950#

Check it out and let us know what you find.

FWIW

Scott

mo shea · ‎04-09-2005

Thanks for the feedback.

The second command, show mac-address-table worked like a charm. The first one, sho arp only gave two mac-address.

Anyway I am now using Solar-winds toolset and it pretty much does the job.

Thanks again