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Interface Hunting on a Nexus Switch


wildweaselmi
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So I have myself either a Mac-Address or Hardware Address that I need to find on a Cisco Nexus Switch (NX-OS) so how do I do it.

First I start at the core switch then depending if I know the mac-address or not... if not I first find out what it is

I ping the IP Address from the switch to make sure the address is in the ARP table

Then I look at the arp table for that IP Address to see what the mac-address is

sh ip arp 10.11.12.13

Now I have the mac-address and I can continue

sh mac address-table address 00:25:90:76:FB:6D

That may have told you what interface but in my case I have to keep digging because it said it belongs to Po201 (Port Channel 201), so let me figure out what switch that is by first finding out what intefaces belong to Po201

show interface po201

I get a bunch of info but looking mainly at

Members in this channel: Eth1/17, Eth1/19, Eth2/17, Eth2/19

Now I do a show cdp nei and it shows the same hostname for all the interfaces listed from the last command

txdfw1dcesrv01.zahsystems.com

Eth1/17 147 S I s N5K-C5596UP Eth1/1

Time to connect to that switch

(of course if you can't connect via FWDN, just ping the FQDN to find the ip and try with that instead)

Once connected, run your command again

sh mac address-table address 00:25:90:76:FB:6D

VLAN MAC Address Type age Secure NTFY Ports/SWID.SSID.LID

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

* 205 0025.9076.fb6d dynamic 10 F F Eth117/1/1

And there ya go

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