PCoIP srr-queue

[JohnTylerPearce]

Hey, I have been having a hard timte understanding srr-queue. We have a PCoIP implementation and at a certain part in our network I have noticed a few thousand packet drops. This all appear sto be OutDiscards and I outbound packet drops. I would like to see up srr-queue on this port and all it to shape PCoIP traffic to a queue that gets 75% of the bandwidth.

I understand "srr-queue bandwidth shape x x x x"

I'm having a hard time understand those numbers.

I'm assuming Queue 1, 2, 3, 4. But if I were to do "srr-queue bandwidth shape 75 0 0 0" would that

configure Queue one for 75% of a 1gbps port shaped?

Sorry for the confusion, QoS is not my strong point.                  

[singhaam007 · Accepted solution]

Hi John,

srr-queue bandwidth shape means you reserving bandwidth for the queue and I will not share with other.

But srr-queue bandwidth share means bandwidth will be shared and queues can borrow if they need. Shape will reserve the bandwidth even if there is no traffic but no other queues will be able to use it.

please see this doc and hopefully it will explain you bit more.

please rate if this helps.

thanks

[JohnTylerPearce]

Thanks Singh I really enjoyed that article. I skimmed through it and read some. I'm going to read some more tonight.

In this topology, we have two switches connected to a switch which has a connect to the MetroE switch. IN our datacenter we have a MetroE switch which is connected to a specific 3750-x port. This specific port is showing a few thousand output drops per day. We our VoIP goes around this 3750-x so it will not affect that any. All switched involved will be L2 switches as well. I would like to configure all the ports going to hosts at a customer site to priority-queue out, since we don't have to worry about VoIP traffic. I'm assuming from reading this article on each end of the trust I would need to trust the COS value I assign to the port such as CoS 5 (unless priority-queue out does that by default). When it comes across the Metroc (If they allow QoS) they should still be marked as CoS 5, and then I could run 'srr-queue bandwidth shape x x x x' which would police it at a certain level.

I'm not asking for you to write out a full configuration (unless you want to lol) but just making sure I understand the article.

I plan on reading the whole thing tonight. Once again thanks for showing me that article and points will be awarded in the near future.

[singhaam007]

Hi John,

Packet drops are normal with Auto Qos because whole bandwidth gets divided it different queues. Less important traffic drops first.

You can check it with this command

#sh platform port-asic stats drop f0/2

Interface Fa0/2 TxQueue Drop Statistics

   Queue 0

     Weight 0 Frames 0

     Weight 1 Frames 0

     Weight 2 Frames 0

   Queue 1

     Weight 0 Frames 0

     Weight 1 Frames 0

     Weight 2 Frames 0

   Queue 2

     Weight 0 Frames 0

     Weight 1 Frames 0

     Weight 2 Frames 2112

   Queue 3

     Weight 0 Frames 0

     Weight 1 Frames 0

     Weight 2 Frames 0

You can see which queue is dropping packets and may be increase the buffer size for that queue. I will decrease the packet drops.

By default cos 5 gets translated to DSCP 46. So if you ISP sending you dscp traffic and switch automatically translate it to cos 5.

Hope this help.

Please rate if this helps.

thanks

[JohnTylerPearce]

I got the following.

Interface Gi1/0/11 TxQueue Drop Statistics

    Queue 0

      Weight 0 Frames 0

      Weight 1 Frames 0

      Weight 2 Frames 0

    Queue 1

      Weight 0 Frames 0

      Weight 1 Frames 0

      Weight 2 Frames 0

    Queue 2

      Weight 0 Frames 0

      Weight 1 Frames 0

      Weight 2 Frames 0

    Queue 3

      Weight 0 Frames 0

      Weight 1 Frames 0

      Weight 2 Frames 15370

    Queue 4

      Weight 0 Frames 0

      Weight 1 Frames 0

      Weight 2 Frames 0

    Queue 5

      Weight 0 Frames 0

      Weight 1 Frames 0

      Weight 2 Frames 0

    Queue 6

      Weight 0 Frames 0

      Weight 1 Frames 0

      Weight 2 Frames 0

    Queue 7

      Weight 0 Frames 0

      Weight 1 Frames 0

      Weight 2 Frames 0

I thought there were only 4 output queues.

[singhaam007]

You switch has 8q2t , 8 queues with 2 tail drop thresholds per queue. Where is my switch has 2q4t .

Check this link and hopefully it will help you.

http://www.cloudcentrics.com/?p=784

thanks

[JohnTylerPearce]

I'm a little confused by this.

Queue 3

Weight 0 Frames 0

Weight 1 Frames 0

Weight 2 Frames 15370

I'm assuming from this, that queue 3 is taildropping at taildrop 2?

[singhaam007]

Hi John,

queue 3 is acutaly queue 4. you need to count 0 as  queue 1st.

use this command to see which asic dropping packets

sh platform port-asic stats drop asic 1

thanks

[JohnTylerPearce]

Duh, that makes sense. So Queue 4 is Tail Dropping frames. I'm assuming this means

Queue 4 threshold 2 has dropped 15370 frames?

[singhaam007]

as far i think its true.

please rate if this helps

thanks

[JohnTylerPearce]

What does the following mean.

Weight 0 Frames 0

Weight 1 Frames 0

Weight 2 Frames 15370

I'm a little confused on what Weight 0, 1, and 2 are and how they relate to queue 4.

[singhaam007]

whats is your switch model?

thanks

[JohnTylerPearce]

3750-x

[JohnTylerPearce]

I think I fixed the problem. I increased the hold-queue inbound and I have seen dropped output packets stopped to a null.

So far so good. Your first word document gave me an idea of what might be happening. Thanks for much Amrinder.