[c-nsp] QoS for VoIP basics

Adam Greene maillist at webjogger.net
Fri Dec 1 11:40:55 EST 2006


Thanks to those who replied to my questions.

Setting the link to full duplex corrected the issue.

However, now voice quality is great no matter whether I enable or disable 
qos on the switches.

That's more a limitation of my test environment, though, than the qos 
itself, I think.

What I *really* need is
-    a good TCP / UDP traffic generator (right now I'm using TCPLoad which 
is so ancient I don't even know who made it). I'm considering MGEN 
(http://cs.itd.nrl.navy.mil/products/) but that's UDP only.
-    a better way to test VoIP quality. I'm simply subjectively gauging call 
quality by talking through (2) SIP phones which establish peer-to-peer 
communications after initial call setup via a SIP server. Some free software 
that provides MOS ratings based on latency, jitter, etc and allows 
simulation of multiple calls would be ideal. Perhaps I'm dreaming that there 
could be a free software available for this.

Adam



> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Adam Greene
> Sent: Tuesday, November 28, 2006 3:17 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] QoS for VoIP basics
>
> Hi,
>
> I am trying to master basic QoS concepts in a test lab before deploying
> general policies for our network:
>
>
>
>        3750            |both connections 10/half
>        |  |            |
> vlan700|  |vlan710     |
>        |  |            |
>        2950
>       ||  ||
>       ||  ||           |all connections 100/full
> PC A--- |  | --PC B     |
>        |  |            |
> VoIP A--    --VoIP B    |
>
>
> My aim is to make the VoIP traffic crystal clear no matter how much
> traffic I push between the two PC's.
>
> Here are my configs:
>
> ====
> 2950
> ====
>
> wrr-queue bandwidth 100 1 1 0
> wrr-queue cos-map 1 0 1 2 3 4 6 7
> wrr-queue cos-map 4 5
> !
> class-map match-all VoIP
>  match access-group 100
> !
> !
> policy-map All_Phone_Traffic_46
>  class VoIP
>    set ip dscp 46
> !
> access-list 100 permit ip any any
>
> PLUS the ports into which VoIP A and B plug are configured with
> "service-policy input All_Phone_Traffic_46"
>
>
>
> ====
> 3750
> ====
>
> (note that the following was generated via the "auto qos voip trust"
> interface command)
>
> mls qos map cos-dscp 0 8 16 26 32 46 48 56 mls qos srr-queue input
> bandwidth 90 10 mls qos srr-queue input threshold 1 8 16 mls qos
> srr-queue input threshold 2 34 66 mls qos srr-queue input buffers 67 33
> mls qos srr-queue input cos-map queue 1 threshold 2  1 mls qos srr-queue
> input cos-map queue 1 threshold 3  0 mls qos srr-queue input cos-map
> queue 2 threshold 1  2 mls qos srr-queue input cos-map queue 2 threshold
> 2  4 6 7 mls qos srr-queue input cos-map queue 2 threshold 3  3 5 mls
> qos srr-queue input dscp-map queue 1 threshold 2  9 10 11 12 13 14
> 15
> mls qos srr-queue input dscp-map queue 1 threshold 3  0 1 2 3 4 5 6 7
> mls qos srr-queue input dscp-map queue 1 threshold 3  32 mls qos
> srr-queue input dscp-map queue 2 threshold 1  16 17 18 19 20 21
> 22 23
> mls qos srr-queue input dscp-map queue 2 threshold 2  33 34 35 36 37 38
> 39 48
> mls qos srr-queue input dscp-map queue 2 threshold 2  49 50 51 52 53 54
> 55 56
> mls qos srr-queue input dscp-map queue 2 threshold 2  57 58 59 60 61 62
> 63
> mls qos srr-queue input dscp-map queue 2 threshold 3  24 25 26 27 28 29
> 30 31 mls qos srr-queue input dscp-map queue 2 threshold 3  40 41 42 43
> 44 45
> 46 47
> mls qos srr-queue output cos-map queue 1 threshold 3  5 mls qos
> srr-queue output cos-map queue 2 threshold 3  3 6 7 mls qos srr-queue
> output cos-map queue 3 threshold 3  2 4 mls qos srr-queue output cos-map
> queue 4 threshold 2  1 mls qos srr-queue output cos-map queue 4
> threshold 3  0 mls qos srr-queue output dscp-map queue 1 threshold 3  40
> 41 42 43 44 45
> 46 47
> mls qos srr-queue output dscp-map queue 2 threshold 3  24 25 26 27 28 29
> 30 31 mls qos srr-queue output dscp-map queue 2 threshold 3  48 49 50 51
> 52 53
> 54 55
> mls qos srr-queue output dscp-map queue 2 threshold 3  56 57 58 59 60 61
> 62 63
> mls qos srr-queue output dscp-map queue 3 threshold 3  16 17 18 19 20 21
> 22 23
> mls qos srr-queue output dscp-map queue 3 threshold 3  32 33 34 35 36 37
> 38 39
> mls qos srr-queue output dscp-map queue 4 threshold 1  8 mls qos
> srr-queue output dscp-map queue 4 threshold 2  9 10 11 12 13 14
> 15
> mls qos srr-queue output dscp-map queue 4 threshold 3  0 1 2 3 4 5 6 7
> mls qos queue-set output 1 threshold 1 138 138 92 138 mls qos queue-set
> output 1 threshold 2 138 138 92 400 mls qos queue-set output 1 threshold
> 3 36 77 100 318 mls qos queue-set output 1 threshold 4 20 50 67 400 mls
> qos queue-set output 2 threshold 1 149 149 100 149 mls qos queue-set
> output 2 threshold 2 118 118 100 235 mls qos queue-set output 2
> threshold 3 41 68 100 272 mls qos queue-set output 2 threshold 4 42 72
> 100 242 mls qos queue-set output 1 buffers 10 10 26 54 mls qos queue-set
> output 2 buffers 16 6 17 61 mls qos
>
> PLUS the two ports which connect to the 2950 are configured with:
>
> srr-queue bandwidth share 10 10 60 20
> srr-queue bandwidth shape  10  0  0  0
> mls qos trust dscp <-- (this was autoconfigured as trust cos, but I
> changed it to dscp) auto qos voip trust
>
>
>
> Unfortunately, when I pump 10Mbps (100 TCP streams) between PC A and B,
> the voice still chops up.
>
> Any hints? Maybe I'm missing something obvious.
>
> Thanks,
> Adam
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>
>
>
>
> 







More information about the cisco-nsp mailing list