service-policy input purpose?

[Kypamop]

Hi, guys!

Can someone explain me for which purpose i need ingress queuing by subj. command.

AFAIK, queuing is only make sense in "egress side": if output interface rate much slower then current ingress data streams. I just can't understand how router would handle packets, which are arriving in random order from various other interfaces...

As i see here http://www.cisco.com/en/US/tech/tk543/tk757/technologies_tech_note09186a0080160fc1.shtml there are no place for queuing for "in" direction.

Plz, help me understand! :)

Thx, in advance.

[mmellet]

Attaching a Traffic Policy to an Interface

To attach a traffic policy to an interface and to specify the direction in which the traffic policy should be applied (on either packets coming into the interface or packets leaving the interface), use the following commands in interface configuration mode, as needed:

Command Purpose

Router(config-if)# service-policy output policy-map-name Specifies the name of the traffic policy to be attached where it can be applied to all packetes leaving the interface.

Router(config-if)# service-policy input policy-map-name Specifies the name of the traffic policy to be attached where it can be appliced to all packets entering the interface

[jsayer · Accepted solution]

You are correct that queuing only makes sense for packets leaving the router. However, remember that with the modular QoS commandset you can also specify traffic policing or rate-limiting, which is often done at the input side of the interface. A requirement might be to queue and traffic-shape at the remote side of a WAN interface, and then police or rate-limit at the input side of your router.

Hope this helps,

John