3550 QoS and Classes

[mcheatle]

I have been given the task of implementing QoS on a cat 3550, I have not done any QoS configurations before so I have purchased a number of Cisco books, I noticed on the Cat 3550 that there can only be 4 queues but we need six classes, so my question is do we need a separate queue for each class thus needing a Catalyst that will support 6 queues or more

Regards

Martyn

[spremkumar]

hi

if i assume you have the following applications being run in your network :

1.Voice

2.SAP

3.Oracle

4.Mail

5.FTP

6.Internet

i would suggest to have look on the mapping mentioned below to get some fair idea on how to go about in your scenario..

1.Voice - prority queue - 4

2.SAP - Queue - 3

3.Oracle - Queue - 3

4.Mail - Queue -2

5.FTP - Queue - 2

6.Internet - Queue 1

After finalising the queue allocations do configure the bandwidth accordingly for each queues.

Also would suggest to check this link on configuring queuing ..

http://www.cisco.com/en/US/products/hw/switches/ps646/products_configuration_guide_chapter09186a008014f36e.html#wp1023239

regds

[mcheatle]

Thanks for the reply, could you tell me what differentiates SAP and Oracle and also Mail and FTP which are in their respective queues but in different classes, this is what I do not understand does that mean that SAP and Oracle have the same priories; why not just have 4 queues

Martyn

[spremkumar]

hi

you can always use different kinda classifiers and markers to classify the traffic (i.e., to identify the traffic type whether it belongs to VOIP flow or MAIL)and the markers to mark and differentiate the high priority packets and the low priority ones.

marking can be done in many ways using DSCP values or IP Precedence values which 2 are more widely used,it was IP Precedence which was most widely deployed but at present its DSCP which is taken over in most of the production environment.It has numerous advantages over IP Prec coz in dscp u got the wisdom of having more marking options to choose.

u differntiate or segment the traffic pattern using the classifiers using ACLs or COS values,some of the NICs do have marking in built which can be very much useful as your IP PHONE does.

Classifcation configs comes under your class-map configurations.

Then u do your marking where u mark using dscp or ip prec .you can do this under your policy map configurations.

i would still refer the below link too if you havent checked out earlier so that you can get your things clarified with the CLIs mentioned on that and also to check out the process being carried out starting from classification till congestion management and avoidance.

http://www.cisco.com/en/US/partner/products/hw/switches/ps646/products_configuration_guide_chapter09186a00800c9fe9.html#xtocid21

And inline with your question about the queue limitations its the H/W limitation to have particular no of queues in the boxes but afaik in some of the boxes like 7600 u can manually tweak and increase the queue nos but not sure about 3550 :-)

regds