Cisco – How to find out which physical port the ethersvi MAC address corresponds to on a Cisco switch

ciscocisco-catalystmac addressnetworkingswitch

I'm doing a layer2 network map (my first) and this is the first virtual mac I've encountered.

From the mac address table of switch1, I have

VLAN 1 6416.8d98.52c0 DYNAMIC Te0/1

and on the other, which I'll call switch0, when I am looking for that mac address, this is what I find:

Vlan1 is up, line protocol is up
Hardware is EtherSVI, address is 6416.8d98.52c0 (bia 6416.8d98.52c0)
Internet address is 192.168.101.252/24

How do I find out the physical port that corresponds to?

When I do a show vlanon switch0, I get:

VLAN Name Status Ports

1 default active Gi0/1, Gi0/2, Gi0/11, Gi0/12, Gi0/13, Gi0/14, Gi0/15, Gi0/16, Gi0/17, Gi0/18, Gi0/19, Gi0/20, Gi0/21, Gi0/22, Gi0/23, Gi0/24

2 VLAN0002 active Gi0/7, Gi0/8

3 VLAN0003 active Gi0/9, Gi0/10

4 VLAN0004 active Gi0/3, Gi0/4

5 VLAN0005 active Gi0/5, Gi0/6

What command should I use?

Edit: Mike's command worked (thanks mike!), but now that I have had time to pay a little more attention to my mac address table, I am re-confused. My ignorance will shine bright, so try not to be blinded by it:

How come several ports belong to many VLANs at once? here is a sample of the output on one of the switches:

VLAN

1    0014.4f97.bb1f    DYNAMIC     Gi0/11 <-- ??? similar to MACs on a solaris box
1    edgertr  Fa0/0    DYNAMIC     Gi0/1
1    sw00     Te0/1    DYNAMIC     Te0/1
1    6416.8d98.52c0    DYNAMIC     Te0/1  <--virtual MAC from before
2    box2     nxge2    DYNAMIC     Te0/1
2    box1   e1000g2    DYNAMIC     Gi0/7
2    box0   e1000g2    DYNAMIC     Te0/1
2    sw00     Te0/1    DYNAMIC     Te0/1
3    box2     nxge3    DYNAMIC     Te0/1
3    box1   e1000g3    DYNAMIC     Gi0/9
3    box0   e1000g3    DYNAMIC     Te0/1
3    sw00     Te0/1    DYNAMIC     Te0/1
4    box2     nxge0    DYNAMIC     Te0/1
4    box0   e1000g0    DYNAMIC     Gi0/3
4    edgertr  Fa0/0    DYNAMIC     Gi0/1
4    boxx      bge0    DYNAMIC     Gi0/2
4    box0   e1000g0    DYNAMIC     Te0/1
4    sw00     Te0/1    DYNAMIC     Te0/1
5    sw00     Te0/1    DYNAMIC     Te0/1

And here is my current attempt at a layer2 diagram for good measure (incomplete, haven't started on the other switch). Anything I should leave out or add?

enter image description here

Best Answer

Usually, the best way to map a Cisco network is with CDP (as long as it is enabled on switch0 and switch1). Do a show cdp nei Te0/1 on switch1; this will tell you what Cisco device/port number is connected on the other side.

Vlan1 is up, line protocol is up Hardware is EtherSVI, address is 6416.8d98.52c0 (bia 6416.8d98.52c0) Internet address is 192.168.101.252/24

How do I find out the physical port that corresponds to?

Strictly speaking an SVI doesn't correlate a virtual mac-addresses to a single physical port; that is the point of an SVI. An SVI's virtual mac-address is available on any port that belongs to that SVINote 1. You can find what physical port in a given SVI connects to another by using the switch's CAM, LLDP, or CDP tables.

BTW, your switches are using an SVI on Vlan1; best practices dictate that you don't use Vlan1 for data traffic, but that's getting outside the scope of this question.

Note 1: As long as that port isn't blocked by spanning-tree

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