[c-nsp] Basic IP to Port finding question on Cisco 3850

Andrew Tutten atutten at digium.com
Wed Jul 26 12:19:12 EDT 2017


Can you do a

show mac-address-table | i <last 4 of mac>

and get the port?

Andrew Tutten
Digium, Inc. | Network and Security Administrator
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
direct: +1 256 428 6243 | mobile: +1 256 425 2860


On Wed, Jul 26, 2017 at 11:15 AM, Scott Granados <scott at granados-llc.net>
wrote:

> I think this is a basic question but Googling has not helped me much so
> I’m hopeful someone can shed the clue light on me a bit.
>
> I’m trying to find the specific port an IP address is attached to on a
> 3850 in L3 mode with SVI interfaces.  SO for example if I do a show arp
> a.b.c.d I’ll get the MAC and the SVI attached.  If I do a show VLAN ID X I
> see the port members but there are many, let’s say 10 or more per VLAN.  Is
> there an easy way to detect which port either the IP is received on or the
> MAC address that is displayed in the show arp?  Everything I’m doing seems
> to show the SVI that’s in play but not the specific gig port that the
> device is attached to and mapped to the VLAN as a member.  This seems like
> the sort of thing that would be easy to figure out but I’m stumped.  Any
> pointers would be most appreciated.
>
> Thanks and sorry for such a rudimentary question.
>
> Scott
>
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