How ARP request initiated from Palo Alto sub interface

Roby_Sreejith — Tue, 05 Jun 2018 12:39:51 GMT

I am having some issues new ISP. I have assigned my sub interface with /29 range of IP given by my ISP.

I have added staic route towards gateway of ISP with exit interface( sub interface) specified in Palo Alto Virtual router.

Can some tell who will initaite ARP between these interface( its same subnet)

When I take the packet capture, only ISP sends the ARP request and Palo Alto interface reply back( arp reply). In Packet capture, I can not see any ARP request initaited from Palo Alto. Its just sending reply. ( i think i got answer this, in packet capture arp requests from PA wont be captured)

The problem is after 30 min of arp cacahe in Palo , ARP is not updated in Palo.

Why Sub interface of Palo Alto is not sedning ARP request.

ISP only send ARP request in the begnning, after that it does not send the ARP request to Palo Alto Interface IP again. However it sends to other IPs in the /29 Subnet.

Re: How ARP request initiated from Palo Alto sub interface

BPry — Mon, 04 Jun 2018 14:57:22 GMT

@Roby_Sreejith,

You probably want to open a support ticket with TAC for this so that they can actually look over your entire configuration; because there are some weird instances where NAT policies can actually interfere with this.

When the 30 minutes is up can you trigger a GARP on the subinterface and see if that gets things working again? It seems kind of odd that you would see things stop working after 30 minutes though, unless your ISP is refreshing your public IP space every 30 minutes which would be rather stupid you should have the same ARP entries and the table wouldn't even need to refresh.

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How ARP request initiated from Palo Alto sub interface

Re: How ARP request initiated from Palo Alto sub interface