Subinterfaces with and without service-policy

[andrewharding]

I'm battling to find a definitive answer to this, so thought I'd post.

If a physical FastE interface has multiple subinterfaces configured and all except one of the subinterfaces have service-policy config on them, what will happen to the traffic on the subinterface which isn't configured with service-policy when a queue arises?

Many thanks

Andrew

[eofelt]

Hi Andrew,

A router begins to queue packets when the number of packets that needs to be transmitted out an interface exceeds the output rate of that interface.

Queuing configuration only takes effect during periods of interface congestion, when the hardware queue has overflowed.

HTH

[andrewharding]

Thanks Erik.

I apologise for putting my question incorrectly. I'm really trying to establish the effect on traffic over the unconfigured subint when QoS comes into force (i.e. at congestion).

Regards,

Andrew

[eofelt · Accepted solution]

If I understand your question correctly...

If QoS is not applied to

the sub interface, traffic will be best effort.

As you may already know, QoS is end to end. So, if traffic is not classfied or marked and it is priority(important) traffic, congestion and subsequent drops may occur...depending on the sub's traffic load.

HTH, if so please rate.

If I am wrong, someone please correct me.

[andrewharding]

Erik,

Exactly what I needed to know. Duly rated.

Regards,

Andrew