A client has reported that our Peplink Balance 380/Cisco ASA implementation did not fail over during testing. The Peplink is in drop in mode for ISP1 and proper NAT rules are configured for ISP2. I have looked through the firewall config and found an SLA configuration on a static route:
sla monitor 1
type echo protocol ipIcmpEcho 126.96.36.199 interface Outside_ISP1
sla monitor schedule 1 life forever start-time now
track 1 rtr 1 reachability
route Outside_ISP1 0.0.0.0 0.0.0.0 188.8.131.52.222 128 track 1
route Outside_ISP2 0.0.0.0 0.0.0.0 184.108.40.206 254
The interface on the ASA for ISP1 is plugged directly into the Peplink. There is nothing plugged into the ASA on the ISP2 interface.
220.127.116.11 is the default gateway for ISP1, which is a public, globally pingable IP address.
As I understand it, the Peplink is performing arp proxy to the ASA for the IP 18.104.22.168. This way the firewall will always send the traffic to the Peplink, no matter which link is up.
So, the second default route should never be used. The default gateway for ISP1 will always appear up even if traffic is routed through the ISP2 link.
I did notice something strange when performing a traceroute to this IP from the Peplink’s web interface:
Traceroute via ISP1 link:
traceroute to 22.214.171.124.222 (126.96.36.199), 30 hops max, 60 byte packets
1 188.8.131.52 (184.108.40.206) 19.556 ms 19.381 ms 19.294 ms
This is expected because 220.127.116.11 is the default gateway on ISP1. It should only be one hop.
Traceroute via ISP2 link:
traceroute to 18.104.22.168 (22.214.171.124), 30 hops max, 60 byte packets
1 126.96.36.199 (188.8.131.52) 32.624 ms 32.411 ms 33.682 ms
This is unexpected behavior. In order to get to the default route of ISP1 via ISP2 there should be many hops involved. The only thing I can think of is that the Peplink is tracerouting to itself because of the arp proxy used to trick the ASA into sending all the traffic to the Peplink. If that were true, however, the response times would be much less. Is the Peplink performing the traceroute correctly but displaying the results wrong?
Also, When does Arp proxy kick in? Is it used, while in drop in mode while traffic is routed out the main wan link (ISP1)? Or does the Peplink start proxying ISP1 gateway when traffic is failed over to the secondary WAN link?
Is there a way to view the arp table on the Peplink?