topic Re: External ping to public ip of secondary ISP interface. in General Topics

External ping to public ip of secondary ISP interface.

Dyardley — Tue, 23 Nov 2021 15:24:35 GMT

I am having issues allowing pings on my secondary ISP interface. I have a dual ISP set up with my main connection a 10gbit connection with ISP1 and a backup 1gbit with ISP2. I am currently using path monitoring for internet failover and I also have a few PBF rules for some traffic to leave through ISP2. I was asked by ISP2 to allow ICMP for their subnet so they can monitor the connection. So I set up a second management profile that only allowed ping from their subnet and applied it to that interface. They still can seem to get a response when they ping it. Is there something else that I am missing?

Re: External ping to public ip of secondary ISP interface.

SutareMayur — Tue, 23 Nov 2021 17:15:54 GMT

Hi @Dyardley ,

If other end is still not able to ping the palo alto interface, did you checked the traffic logs? Traffic logs should give you clarity on what's actually happening.

Re: External ping to public ip of secondary ISP interface.

johnwalshaw — Thu, 25 Nov 2021 22:42:03 GMT

I literally just configured this. I have the default virtual router and then a separate virtual router for each ISP (hub and spoke). With this method, you can prevent the dedicated ISP virtual routers having a zero route to the other ISP. Therefore path monitoring will have the desired effect to flush the zero route for that specific ISP. You need to create a loopback on each virtual router. Then create static routes (hub and spoke) to each ISP router (requires loopback). You can then configure eBGP on those links, along with redistribute. The method I used was local pref on the internal (default) virtual router to designate primary and secondary ISP. The failover is tuned to 3 seconds and then hold time of 2 minutes for fail back. PDF with screenshot can be found here, although this is not a how-to guide, it will give you some of the main concepts.

https://www.linkedin.com/feed/update/urn:li:activity:6869729830720688128/