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Sai_376190's avatar
Sai_376190
Icon for Nimbostratus rankNimbostratus
Nov 15, 2018

Identify to which core switch is my F5 connected

I am trying to identify to which interface (Cisco Core) is my F5 connected. 1. I used tracert to find the core (the last but one HOP should be my switch) 2. I tried to identify my interface by using the mac address of the F5 (show mac address-table | inc

 

Still could not identify is there any other way to identify my interface.

 

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  • Philip_Jonsson's avatar
    Philip_Jonsson
    Icon for MVP rankMVP
    Nov 15, 2018

    Not sure, but do you have access to the BIG-IP device? In that case you could use tcpdump to capture the MAC address of the switch. Use the following command:

    tcpdump -i [VLAN] -e

    Here is how my output looks:

    20:19:29.647839 00:0c:29:3f:a3:78 (oui Unknown) > 00:0c:29:ca:16:57 (oui Unknown), ethertype IPv4 (0x0800), length 61: 172.16.1.4 > 172.16.1.1: ICMP echo request, id 46973, seq 56340, length 20 out slot1/tmm1 lis=
20:19:29.650715 00:0c:29:ca:16:57 (oui Unknown) > 00:0c:29:3f:a3:78 (oui Unknown), ethertype IPv4 (0x0800), length 61: 172.16.1.1 > 172.16.1.4: ICMP echo reply, id 46973, seq 56340, length 20 in slot1/tmm1 lis=

    172.16.1.1 is my next hop from my F5 and the MAC address to reach it is 00:0c:29:ca:16:57. Once you have that you can check on the switch which interface that owns that MAC address.