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Table of Contents
Cisco Interfaces In Use
Jan 2024
Introduction
A really useful task to perform when looking at remote systems is to see what interfaces on a Cisco Switch are in use (as in connected).
Interface Status
Lets look at how to see what interfaces we are using: sh interfaces status This has to be performed from the top level, same part of the Cisco menu you would do sh vlan br for instance.
sh interfaces status Port Name Status Vlan Duplex Speed Type Gi0/1 connected 2 a-full a-1000 10/100/1000BaseTX Gi0/2 notconnect 2 auto auto 10/100/1000BaseTX Gi0/3 notconnect 2 auto auto 10/100/1000BaseTX Gi0/4 notconnect 2 auto auto 10/100/1000BaseTX Gi0/5 connected 2 a-full a-1000 10/100/1000BaseTX Gi0/6 connected 2 a-full a-1000 10/100/1000BaseTX Gi0/7 connected 2 a-full a-1000 10/100/1000BaseTX Gi0/8 connected 2 a-full a-1000 10/100/1000BaseTX Gi0/9 notconnect 2 auto auto 10/100/1000BaseTX Gi0/10 notconnect 2 auto auto 10/100/1000BaseTX Gi0/11 notconnect 2 auto auto 10/100/1000BaseTX Gi0/12 notconnect 2 auto auto 10/100/1000BaseTX Gi0/13 notconnect 2 auto auto 10/100/1000BaseTX Gi0/14 notconnect 2 auto auto 10/100/1000BaseTX Gi0/15 notconnect 2 auto auto 10/100/1000BaseTX Gi0/16 notconnect 2 auto auto 10/100/1000BaseTX Gi0/17 notconnect 2 auto auto 10/100/1000BaseTX Gi0/18 notconnect 2 auto auto 10/100/1000BaseTX Gi0/19 notconnect 2 auto auto 10/100/1000BaseTX Gi0/20 notconnect 2 auto auto 10/100/1000BaseTX Gi0/21 notconnect 2 auto auto 10/100/1000BaseTX Gi0/22 notconnect 2 auto auto 10/100/1000BaseTX Gi0/23 notconnect 2 auto auto 10/100/1000BaseTX Gi0/24 notconnect 2 auto auto 10/100/1000BaseTX Gi0/25 notconnect 2 auto auto 10/100/1000BaseTX Gi0/26 notconnect 2 auto auto 10/100/1000BaseTX Gi0/27 notconnect 2 auto auto 10/100/1000BaseTX Gi0/28 notconnect 2 auto auto 10/100/1000BaseTX Gi0/29 notconnect 2 auto auto 10/100/1000BaseTX Gi0/30 notconnect 2 auto auto 10/100/1000BaseTX Gi0/31 notconnect 2 auto auto 10/100/1000BaseTX Gi0/32 notconnect 2 auto auto 10/100/1000BaseTX Gi0/33 connected 3 a-full a-1000 10/100/1000BaseTX Gi0/34 connected 3 a-full a-1000 10/100/1000BaseTX Gi0/35 notconnect 3 auto auto 10/100/1000BaseTX Gi0/36 notconnect 3 auto auto 10/100/1000BaseTX Gi0/37 notconnect 3 auto auto 10/100/1000BaseTX Gi0/38 notconnect 3 auto auto 10/100/1000BaseTX Gi0/39 notconnect 3 auto auto 10/100/1000BaseTX Gi0/40 notconnect 3 auto auto 10/100/1000BaseTX Gi0/41 notconnect 3 auto auto 10/100/1000BaseTX Gi0/42 notconnect 3 auto auto 10/100/1000BaseTX Gi0/43 notconnect 3 auto auto 10/100/1000BaseTX Gi0/44 notconnect 3 auto auto 10/100/1000BaseTX Gi0/45 connected 1 a-full a-1000 10/100/1000BaseTX Gi0/46 connected 1 a-full a-1000 10/100/1000BaseTX Gi0/47 notconnect 1 auto auto Not Present Gi0/48 notconnect 1 auto auto Not Present
In the above example above we can see that there are 9 interfaces in use, and we can see the following information for each interface:
Port Name Status Vlan Duplex Speed Type Gi0/1 connected 2 a-full a-1000 10/100/1000BaseTX
The following is what each field means:
Port - This is the interface number on the switch Name - This only shows if any names have been assigned, generally they are not. Status - Connected. VLAN - What VLAN the interfaces is currently in. DUPLEX - a-full (automatic-full) SPEED - a-1000 (auto 1000) TYPE - 10/100/1000BaseTX (this interface supports 10Mb/s / 100Mbs and 1GBs)
Show the Mac Address Table
We can use the following to show what MAC Addresses are present on each interface. If you have an interface that is connected to another switch then you will see all MAC addresses from that switch interface.
sh mac address-table Vlan Mac Address Type Ports ---- ----------- -------- ----- All 0100.0ccc.cccc STATIC CPU All 0100.0ccc.cccd STATIC CPU All 0180.c200.0000 STATIC CPU All 0180.c200.0001 STATIC CPU All 0180.c200.0002 STATIC CPU All 0180.c200.0003 STATIC CPU All 0180.c200.0004 STATIC CPU All 0180.c200.0005 STATIC CPU All 0180.c200.0006 STATIC CPU All 0180.c200.0007 STATIC CPU All 0180.c200.0008 STATIC CPU All 0180.c200.0009 STATIC CPU All 0180.c200.000a STATIC CPU All 0180.c200.000b STATIC CPU All 0180.c200.000c STATIC CPU All 0180.c200.000d STATIC CPU All 0180.c200.000e STATIC CPU All 0180.c200.000f STATIC CPU All 0180.c200.0010 STATIC CPU All ffff.ffff.ffff STATIC CPU 2 0025.b4bc.2901 DYNAMIC Gi0/1 2 74fe.4857.6d4a DYNAMIC Gi0/7 2 74fe.4857.72a5 DYNAMIC Gi0/8 2 a4bf.0169.b7af DYNAMIC Gi0/5 2 a4bf.016a.d0eb DYNAMIC Gi0/6 3 74fe.4857.6d4c DYNAMIC Gi0/33 3 74fe.4857.72a7 DYNAMIC Gi0/34 1 74fe.4828.799d DYNAMIC Gi0/45 1 74fe.4828.c136 DYNAMIC Gi0/45 1 9418.8266.b82c DYNAMIC Gi0/45 1 9418.8266.b82d DYNAMIC Gi0/45 1 a4bf.0169.b7ad DYNAMIC Gi0/45 1 a4bf.016a.d0e9 DYNAMIC Gi0/45
I want to look at this specific interface:
Vlan Mac Address Type Ports 2 a4bf.0169.b7af DYNAMIC Gi0/5