QoS in MPLS with TE

networknoobs · ‎11-29-2008

Hi, I've tried to established tunnels between PE and wondering how should I apply the QoS. The physical connection for example goes like this:

PE -> P -> P -> PE

The tunnels was from between the both PE, so would it be feasible to check in qos on the PE -> P physical interface instead of the tunnels? If for example, I have allow 10Mbps for 1 application and check it as a "service-policy output" in the PE-P interface, since there's tunnels formed between PE-PE, can I still apply policer at the P ingress interface facing the PE? QoS will be checked between it get routed to the tunnels?

If says from the PE, the PE-P physical interface has qos applied and policed accordingly, but once the traffics get inspected it get routed into the tunnels between PEs, can the P routers still see the EXP and DSCP bit and police the traffic accordingly?

I just think that the P router might not able to police the traffics as it get routed into the tunnels...

Hope to get some opinions here

Giuseppe Larosa · ‎11-30-2008

Hello Creed,

>> I just think that the P router might not able to police the traffics as it get routed into the tunnels...

With both LDP LSPs and MPLS TE LSPs traffic is forwarded inside MPLS frames and so EXP field of the topmost label is accessible to P routers to provide diffserv QoS treatments.

Usually P routers implement only outgoing scheduling (queueing) combined with congestion avoidance (WRED).

The service policies are applied outbound the physical interfaces.

Rate control of what traffic enters the MPLS cloud both LDP LSPs and MPLS TE LSPs is made on PE at the edge before traffic enters the MPLS space.

DSCP bits should not be accessible inside the MPLS cloud once the ip packet travel inside an MPLS label stack.

Actually some inside inspections can be performed for flow based load-balancing purposes.

So policing on the P routers is not used in general.

Hope to help

Giuseppe