Is the pbf essential for automaticlly failover in dual ISP environment？

[qd_056]

hello guys,

Our FW is connecting to ISP lines, and we configured default route with different metric.

The metric of primary link is lower than the secondary link.

For such case, Can I have an automaticlly failover when the primary IPS line is down?

Do Ihave to create pbf and path montor? 

Thanks

[reaper · Accepted solution]

hi @qd_056 !

Using a lower metric will simply tell the system to not use the higher metric until the lower metric interface goes down. If there is a 'soft' breakage (upstream issue), the interface will not go down so the metric will remain and route the packets to a now broken pipe

Having PBF in place allows you to redirect certain (or all) sessions to one link while still using the secondary link 

 - this allows you to send non critical traffic over one link and ensure business critical applications run over your main link without getting drowned out

 - with a monitoring profile in place you can then dynamically fall back/over to the remaining link should one fail

[qd_056]

Hi @reaper

well noted, appreciate.

[pulukas]

In addition to the metrics for failover be sure to configure link monitoring.  Frequently upstream failures can occur that don't bring the physical link down so the better metric route will still be active even when the ISP is not working correctly.

Link monitoring probes ip addresses across the link to insure actual internet reachability not just link up/down.

https://live.paloaltonetworks.com/t5/Configuration-Articles/Link-Monitoring-and-Path-Monitoring-Beha...

[qd_056]

@pulukas, thanks you.

[khuynh]

If you are using 8.0, and for your case, you may also use the new feature 'Static Route Removal Based on Path Monitoring' instead, it's more simpler to configure than PBF.

https://www.paloaltonetworks.com/documentation/80/pan-os/pan-os/networking/static-routes/static-rout...

HTH