QoS in Tunnel Interface

[snarayanaraju]

Hi Experts,

I request you to share the concept Why

"Cisco IOS logical interfaces (Tunnel Interface) do not inherently support a state of congestion and do not support the direct application of a service policy that applies a queuing method"

I know that a child policy-map X has to be created and and must be applied as a service policy in another policy-map Y

I tried and not able to get why it is not supported.

Thanks in advance

RBK

[andrew.prince]

As the tunnel interfaces are virtual - normal QoS will not work.

You need to look at Shaping & Policing for tunnel QoS.

HTH>

[snarayanaraju]

Hi,

Thanks for your reply. I am aware that it is virtual interface and do not support QoS natively.

My doubt is why the child policy-map is been insisted to be used to make QoS work?

Thanks

sairam

[Joseph W. Doherty]

The child policy isn't needed unless you intend to support a CBWFQ policy. Then, since CBWFQ needs to "know" bandwidth, it uses a shaper, in a parent policy, to "define" the bandwidth, which the child policy then uses. (BTW, would need to double check, but the CBWFQ [HQF] starting with 12.4.20T, I recall, has some improved/changed support for tunnel QoS.)