topic Re: LACP MAC Movement and Doubts in General Topics

LACP MAC Movement and Doubts

Ramakrishnan — Mon, 11 Dec 2023 10:09:57 GMT

Dear Folks,

First time I'm deploying PAs with LACP active/passive for HA solutions. I have some doubts couldn't get enough information from Internet source.

1. In the event, if one firewall goes down, PC on SW1 goes down, how this mac and arp movement happening?

Interestingly when I give show interface on PA's both FW1 & 2 sharing same AE MAC, so wondering how MAC[GARP] movement will kick in during FO event.

2. When I see lacp on PAFW1and2's what does mean system MAC and Partner MAC, in fact I couldn't see any ware in the switch. Where I get those details to study more about this?

Pre-negotiation: Enabled
Local: System Priority: 32768
System MAC: D:A:B:C:1a:01
Key: 66
Partner: System Priority: 65534
System MAC: A:B:C:D19:34:00
Key: 1

3. LACPDUs message are seeing [Sent and Recv counters are getting increase] on both fws. Why passive fw also doing LACPDUs sending and participating LACP election?

Re: LACP MAC Movement and Doubts

kiwi — Mon, 11 Dec 2023 10:57:44 GMT

Hi @Ramakrishnan ,

The switch will learn of the passive only if a failover happens, at which point the (formerly passive) firewall will send a gratuitous ARP which will tell the switch to forward packets on the new port even though the IP and MAC are the same.

https://live.paloaltonetworks.com/t5/Management-Articles/Gratuitous-ARP-in-HA-Failover/ta-p/62781

https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA14u000000sah9CAA&lang=en_US%E2%80%A9

https://live.paloaltonetworks.com/t5/general-topics/ha-active-passive-mac-address/td-p/227316

Passive Device:

—LACP or LLDP is not configured on the interface and the firewall does not participate in the protocol, but allows the peers on either side of the firewall to pre-negotiate LACP or LLDP, respectively:

https://docs.paloaltonetworks.com/pan-os/10-2/pan-os-admin/high-availability/ha-concepts/lacp-and-lldp-pre-negotiation-for-activepassive-ha

Kind regards,

-Kim.