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QoS and EIGRP on a 6509

Hi all,

I have put together a QoS implementation between 3 6509 on each of our sites.

From what I have read the classification happens ingress on a port/vlan.

This is fine for all user and server vlans behind the switches, but what happens for traffic generated on the switch, i.e routing. I can't see how I can mark my EIGRP traffic before it traverses the WAN which is a bit like shutting the barn door after the horse has bolted.

I'm probably missing something obvious here but would appreciate anyone putting me straight.


Re: QoS and EIGRP on a 6509

Cisco IOS assigns an IP precedence of 6 to routing protocol packets on the control plane like EIGRP & ospf hellos, Keepalives etc.

You can match these values and set priority for this traffic when it hits the WAN



Community Member

Re: QoS and EIGRP on a 6509

Thanks for this. I was hoping that would be the case. I forgot to mention one other thing though... I noticed in the link you posted it says this is the case if running IOS on both the Sup Engine and the MSFC, two of my switches are hybrid so the msfc is IOS and the chassis is CATOS. Do you know if the same rule applies??

Thanks again


Re: QoS and EIGRP on a 6509

Yup should be the same.

Its just the policies that would be needed to be defined on the MSFC.


Community Member

Re: QoS and EIGRP on a 6509

I'm thinking I should enable qos on the MSFC which should then mark the routing with IPPrec6. My guess is that the internal IP-Prec-COS mapping would allow the routing info to be placed in the priority queue at egress scheduling. I've defined the policies via CATOS as I read that if I configure my policies using the MSFC when using anything pre the Supervisor 720 and PFC3 (which I'm doing), then qos would only work in software.


Re: QoS and EIGRP on a 6509

Please note, the universal QoS map is "Internal DSCP" map. Meaning all values have to be converted into this value, before converting back and exiting the switch.

That means if you have a COS-marked packet, and it traverses your 6509, the COS-DSCP map will be used, and then DSCP-COS map.

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