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Forum Discussion

cjunior_138458's avatar
cjunior_138458
Icon for Altostratus rankAltostratus
Oct 02, 2015

ARP for NAT - Active/Active cluster

Hi folks,   I'm facing a NAT issue in Active/Active cluster in BIG-IP v11.4.1 HF4.   Could you tell me if the BIG-IP should send GARP to report the new MAC for the NAT address when the cur...
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IheartF5_45022's avatar
IheartF5_45022
Icon for Nacreous rankNacreous
Oct 02, 2015

It should send a GARP for all floating addresses (inc NAT/SNAT). Have you tried running a tcpdump to see the GARP?

 

Could it be that the receiving device is not updating it's arp table or the GARP is getting lost?

 

I prefer not to rely on hosts updating their arp tables when failover occurs as it often gores wrong, instead I use Mac masquerade. That way the MAC address doesn't change during failover so exetrnal hosts don't have to update anything. A GARP is still sent, but only for the purpose of getting the switch to update it's MAC address table which happens at a lower layer than ARP so is a simpler operation.

 

  • cjunior's avatar
    cjunior
    Icon for Nacreous rankNacreous
    Oct 03, 2015
    First, I thank you for the reply. Yes, I made some analysis and now I can see the GARP, but the requests arrives on active box and the standby box is sending the reply, thus is not working yet. I've tried the MAC masquerade but I had no luck.