Monitoring flap in MPLS cloud

[leowchongwei]

Hi,

I'm having 2 MPLS links over 2 different service provider. BGP is configured. Sometimes we get disconnection for few mins in 2 or 3 days, it's not consistent. The logs did not show any flapping on the interface. What can i do now to help the situation? Or even gather some prove that the flap is within the MPLS cloud?

Thanks,

Steven

[mheusinger]

Hi,

what do you mean by disconnected? does that simply mean no connectivity, but still all routing info in place?

Then it sounds like a MPLS LSP problem in the provider backbone. MPLS VPN packets can only be delivered when a LSP exists. Routing packets however can be delivered through IP in the provider backbone without LSP. This is because VPN routing information is transported by BGP from PE to PE (loopbacks).

So a failed LSP disrupts your data plane (IP packets sent) but not the control plane (BGP).

Unfortunately for you, there is no way to detect that from a CE control plane perspective. So even the typical backup scenarios fail here like floating static, dialer watch and the like.

Hope this helps

Martin