QoS Configuration

Unanswered Question
Nov 24th, 2008

In the serial interface we have applied the following Qos:


Interface serial 0/0

random-detect dscp-based

service-policy output WAN-SERIAL


policy-map WAN-SERIAL

class class-default

shape average 487000

service-policy WAN-OUT


Policy-map WAN-OUT



class VOICE


class class-default


class ....



My questions is: Are random-detect dscp-based and service-policy output WAN-SERIAL Mutually exclusive or they can be together in the serial interface?


I have this problem too.
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Joseph W. Doherty Mon, 11/24/2008 - 04:38

WRED at the interface level might normally be exclusive with a service policy, unsure, because it might vary based on platform. The router should preclude you from doing so if unsupported on the platform.

Do keep in mind, you can often use WRED within a policy class, which is often a much better idea. For instance, in your post, it might not be a good idea to use WRED on your ROUTING or VOICE class, but perhaps good for class-default.



If you're thinking, with WRED you could adjust the DSCP weigths to treat ROUTING and VOICE different from other classes, certainly, and that's what you might need to do further downstream if just using WRED alone, by why subject all traffic to such QoS when there's no real benefit to do so (i.e. when you're using a service policy).

mtechnology Mon, 11/24/2008 - 22:28


I need to configure the QOS at my router to priortise the bandwidth 0f 256k to one o the destination citrix server.Provide me exact configuration to configure on my router.

As this is effectig my production,i need a fast response.

Thanks in Advance

durga_suji Mon, 11/24/2008 - 23:54

This should give you a basic idea on how to proceed...

1. Create a class map

a. Class Map match-all CITRIX (id 1)

b. Match protocol citrix

c. Match access-group name CITRIX-TRAFFIC (you can define a access list also for this connection to Citrix traffic, if needed)

2. Create a Policy map

a. Policy Map CITRIX

b.Class CITRIX

c. Strict Priority

d. Bandwidth 50 (%)(depends on what priority you want to give this traffic)

3. Apply the policy to interface

service-policy output CITRIX

IF you post the current QoS config, then accordingly I can check.


Joseph W. Doherty Tue, 11/25/2008 - 03:56

Srinath's post provides an outline of what needs to be done. Without knowing more information, unable to provide an exact configuration since QoS features vary on platform and IOS version.

Some additional notes to what Srinath posted: you may need to apply QoS in both directions; LLQ is normally used just for real-time traffic like VoIP, you could also place your Citrix traffic into a named class with the bandwidth required specified; later NBAR can match type of some Citrix traffix (e.g. screen scraping vs. printing); you might match to both Citrix protocol and to/from a host address, or either by itself. (Also if current queuing is FIFO, WFQ might alone be sufficient for your needs.)


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