GRE over MPLS

[aneesh.ts]

Hi,

My company has 2 locations and we have an MPLS connectivity between them. We are running a static route to the service provider's PE and MPLS starts from there. Now the issue we face is that if there is any backbone issues in provider's network, we won't be getting any logs on CE and hence calculating the downtime has become an issue.

I think implementing GRE tunnel between both the sites can be a good solution for this issue. Just a query I have is that whether backbone issues in Service Providers network would give me GRE Tunnel Up/Down logs in my CE.

c

[Danilo Dy · Accepted solution]

If you build a GRE Tunnel from point-A to point-B assuming there are three segments in between the two points, any of the segment break, the GRE Tunnel Interface wil log the events in the local router.

If MPLS segment in point-A is down, the physical interface of the local router in point-A will also log the event (same will happen if the MPLS segment in point-B is down). If the MPLS Backbone is down, you will only get the events for the GRE Tunnel interface, none for the physical interface.

[Joseph W. Doherty · Accepted solution]

Using a GRE tunnel might be one way to track a good path across the MPLS cloud (don't forget to activate tunnel keepalives). Another might be to use SLA probes. The latter could also record poor MPLS cloud performance (although you'll need to allow for clogged links between CE and PE).