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Forum Discussion

Shahrzad_84598's avatar
Shahrzad_84598
Icon for Nimbostratus rankNimbostratus
Nov 04, 2015

LTM Floating IP`s mac address has gone mad!

Hi there! We have 2 BIG-IP LTM version 9.3.0, I know it s old :) These two have a floating ip between them(HA) and this ip is set on web servers as their default gateway, and it was working fine for...
application delivery
availability
floating ip
LTM
management
StephanManthey's avatar
StephanManthey
Icon for Nacreous rankNacreous
Dec 03, 2015

Hi,

did you check the MAC masquerading settings on your BIG-IPs?

In TMOS v9/v10 you will find it in the VLAN settings. (v11 has it in the traffic-group configuration.)

Perhaps somebody has entered the routers MAC address and you are facing a duplicated MAC address issue?

You can run a tcpdump including the layer 2 information to check for ARPs in you network: 

tcpdump -nnni  -e -c 100 'arp and host '

The sample above limits the output to 100 packets "

-c 100
" showing both ARP requests and responses related to your floating self IP and displays the ethernet header information "
-e
".

Now you can clear your servers ARP cache and force a new address resolution and watch what is happening.

Thanks, Stephan