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portoalegre's avatar
portoalegre
Icon for Nimbostratus rankNimbostratus
Jul 24, 2017

LTM Failover problem across OTV

I'm in a middle of a DC migration, IP addresses are remaining the same. Just a lift & shift exercise.

 

I've moved our Primary Active F5 LTM (Active/Standby setup) and when connected I forced DC B unit back into Standby as normal setup and Promoted shifted DC A F5. Upon doing this I could not telnet to any VIP/port or ping unless my workstation was in DC A, Pool servers I could access fine and telnet to relevant health check ports. I noticed the following.

 

The port channel on our OTV aggregation switches had the wrong mac address in DC B on the Port channel to OTV, was still DC F5 B floating mac rather than F5 DC A. I did a shut/no shut on the Port channel for our aggregation switches in DC B facing OTV and bingo I could see the correct F5 mac address from DC A. For some reason the F5 mac update is not travelling across OTV!

 

How does F5 failover work, do the F5's use Gratuitious ARP when offline? If so it doesn't seem to travel over OTV or updating! Really concerning, at the moment if DC A dies or a switch or F5 I have to manually shut/no shut Port channel so things work. HELP!

 

maybe this is a Cisco problem rather than an F5?

 

application delivery
BIG-IP
LTM

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  • Lee_Sutcliffe's avatar
    Lee_Sutcliffe
    Icon for Nacreous rankNacreous
    Jul 24, 2017

    I had a similar problem a while ago but wasn't using OTV, but still have vPC on an early Nexus version. Have you tried configuring MAC Masquerading? This means you are not reliant on gratuitous ARP. I'd also try doing a tcpdump to ascertain if F5 is sending the gratuitous ARP, but I'd put money on it being a Cisco loop avoidance quirk