QOS in the midle of the GRE tunnel

Unanswered Question
Jun 29th, 2009

Hi. Its possible to any router in the midle of a GRE tunnel to recognize the DSCP values and prioritize according with that values?

I have this problem too.
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Collin Clark Mon, 06/29/2009 - 08:48

You would have to tag the GRE packet since it encapsulates the IP packet. That could be fun to lab up. Figure out how to recognize the DSCP value, then encapsulate in GRE and then apply the original DSCP value in the GRE packet.

p.diaz Mon, 06/29/2009 - 11:13

ok. The IP packet comes marked with a DSCP value into the net. And I like to know if the GRE header inherit the DSCP value from the IP header. Whit that heritage we can manage the packets according with the DSPC field.

shivlu jain Tue, 06/30/2009 - 23:04

for dscp and wfq qos pre-classify is used in gre.

regards

shivlu jain

Laurent Aubert Wed, 07/01/2009 - 06:35

Hi Shivlu,

qos pre-classify is used if the classification on the physical egress interface (where GRE packets are sent) is still based on inner IP addresses and L4 ports.

If your traffic is already marked (IPP or DSCP) at the ingress (before encapsulation), you don't need this feature and can directly classify your traffic at the egress based on the ToS field.

HTH

Laurent.

swapnendum Wed, 08/12/2009 - 03:46

pre-classify feature is valid only on the head-end of the GRE tunnel.

the original question says that in between on a transit router so DSCP/IPP should be used.

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