QoS

[djmlmco]

I posted this in Network Infrastructure but maybe this is a better forum for it...

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I have a rather interesting setup that I need to find a solution for. Basically I have chosen to use CBWFQ for QoS. I have two routers, let's say E0 are the transport interfaces between the two for now. Although these interfaces are Ethernet they are being dumped to slow modems - operating at worst 9.6kbps.

Now I have 3 policy maps installed on the router that will be handling the traffic (I only need QoS one direction). The policy map is supposedly giving 35% to TCP on port 5000, 35% to UDP on port 6000 and 5% for everything else. I set the E0 interface to "bandwidth 10" because I cannot set it to the exact bps unfortunately.

So now the policy maps are working fine. But they seemingly are giving far more bandwidth than "bandwidth" is set to. Do I have to specify bps instead of percentages on these interfaces? I would rather not do that but if it came down to it could resort that direction.

Also, is there a better way to do QoS on these fast interfaces when they are actually traversing a slow link? Traffic shaping? I'm asking because it doesn't seem like my policy map queues ever populate.

Any advice is much appreciated!

[mesuti]

hi djmlmco,

bandwith command provides MINIMUM guarantee for the traffic flows you attach it. So giving 35% for TCP, means that it will take that 35% and if other ( UDP 35% and other 5%) classes doesn't utilise their bandwidth, the bandwidth will be spread to TCP class. If you want to give them an exact bandwidth use shaping within TCP, UDP and other classes. By the way, be careful to match all traffic within these classes because there is also a default class named "class-defaul" which matches all traffic that didn't match classes that you created(TCP, UDP and other) and by default gives them 25% of the bandwith.

hope it helps

Best Regard

Mesut Abdurrahmani

[djmlmco]

Thank you for your reply Mesut.

Good point about the *minimum*. However, is there a way I can guarantee the 35% for my TCP port, 35% for my UDP port but have the 35% minimum be based on a different link speed than the actual physical link?

Is it possible to throw in GTS and have the class maps base traffic off of that available bandwidth?

I do have my class-default set so I think I am covered in that regard.

[rmv72]

You can use

class TCP

police 64000 8000 8000 conform-action transmit exceed-action drop

where 64000 - BW which you want to have exactly.

Look here-

http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_feature_guide09186a00801b23f8.html

[djmlmco]

Thank you for the link!

My main question now is can I do some type of rate limiting on the link (say down to 64kbps) AND split out that available bandwidth using a QoS mechanism - say CBWFQ?

[rmv72]

I think yes. Here part of my worked config-

....

policy-map REGIONS

class SIGNAL

bandwidth 8

class ISA->Eb

police 96000 16000 16000 conform-action transmit exceed-action drop

class Voice

priority 128

class E2K->Regions

police 64000 8000 8000 conform-action transmit exceed-action drop

class FileServer->Regions

police 64000 8000 8000 conform-action transmit exceed-action drop

!

....

[djmlmco]

Well, I have already done something along these lines and it isn't what I'm really looking for.

What I'd like is to, say, have GTS throttle based on an access list. Then split up that access list traffic with CBWFQ into possibly different classes. Is this possible?

[geoff.belknap]

Yes, you can accomplish this with Nested or Hierarchical Service Policies

Check out this:

http://www.cisco.com/en/US/products/sw/iosswrel/ps5014/products_feature_guide_chapter09186a008008813a.html#96509

[djmlmco]

Thank you!!! That is *exactly* what I was looking for!!!