[c-nsp] VOIP QOS
Matthew Crocker
mcrocker at crocker.com
Fri Nov 9 08:10:17 EST 2007
AutoQoS doesn't perform any voodoo to the config and the results are
pretty well documented in the IOS docs. Basically it sets the switch
ports to trust the DSCP or CoS values and then builds the appropriate
DSCP to queue table. Your VoIP packets need to be marked with the
proper DSCP values before the packet enters the autoQoS'ed router/
switch.
My Cisco & Linksys phones set the DSCP value for RTP streams to
'EF'. Make sure all of your switches along the way are set to trust
the DSCP values from the phones and not reset them to 0. Etherreal/
Wireshark comes in handy to track the packets and make sure they
remain marked through out your entire network
-Matt
On Nov 8, 2007, at 9:23 PM, Robert D. Holtz - Lists wrote:
> I have to admit that I've never actually used the AutoQoS feature so
> I'd be
> curious to find out how things go!
>
> Everything that I've read about it sound almost too good to be true.
>
> The network I'm currently on has all kinds of QoS requirements that
> exceed
> what the AutoQos feature is currently offering so we're still doing
> pretty
> heavy customizations.
>
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Paul Stewart
> Sent: Thursday, November 08, 2007 7:53 PM
> To: 'Holtz,Robert'; 'Fred Reimer'; 'Church, Charles';
> cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] VOIP QOS
>
> Thanks.. I"ll work from that idea for now and see where it
> goes...;) I'll
> give autoqos a try on a non production link - only seen it in action
> once
> before..
>
> Paul
>
>
> -----Original Message-----
> From: Holtz,Robert [mailto:Robert.Holtz at edwardjones.com]
> Sent: Thursday, November 08, 2007 3:18 PM
> To: Paul Stewart; Fred Reimer; Church, Charles; cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] VOIP QOS
>
> Have you considered using Cisco's AutoQoS feature?
>
> If you're only doing VoIP then this may be the best method.
>
> There's a lot of ways to slice this stuff up and here one quick and
> dirty example of traffic classifying:
>
> class-map match-all VOICE
> match ip rtp 16384 16383
>
> class-map match-all SIGNALING
> match ip dscp af31
>
> policy-map IPT-T1
> class VOICE
> priority 1024 2000
> class SIGNALING
> priority 128 1000
> class class-default
> fair-queue
>
> Then apply the policy map to an interface (service-policy command,
> in an
> outbound direction as below):
>
> interface Serial3/0/8:8
> bandwidth 1536
> ip address 10.254.254.1 255.255.255.252
> service-policy output IPT-T1
>
>
>
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> -----Original Message-----
>
>
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Paul Stewart
> Sent: Thursday, November 08, 2007 2:03 PM
> To: 'Fred Reimer'; 'Church, Charles'; cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] VOIP QOS
>
> Thanks... any config you can share on how to do this with a
> subinterface
> is involved on one side?
>
> appreciate it,
>
> Paul
>
>
> -----Original Message-----
> From: Fred Reimer [mailto:freimer at ctiusa.com]
> Sent: Thursday, November 08, 2007 2:53 PM
> To: Church, Charles; Paul Stewart; cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] VOIP QOS
>
> * PGP Signed by an unverified key: 11/08/07 at 14:52:49
>
> Yea, you don't want to shape VoIP traffic, you want to place it in a
> priority queue and police it to an absolute maximum. If there are any
> slow links in between, you probably want to configure LFI also.
>
> Fred Reimer, CISSP, CCNP, CQS-VPN, CQS-ISS Senior Network Engineer
> Coleman Technologies, Inc.
> 954-298-1697
>
>
>
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Church,
> Charles
> Sent: Thursday, November 08, 2007 12:26 PM
> To: Paul Stewart; cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] VOIP QOS
>
> I think you still want to priority queue the VoIP traffic, to cut down
> on jitter. You need to do that on the main interfaces though.
>
>
> Chuck
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Paul Stewart
> Sent: Thursday, November 08, 2007 10:33 AM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] VOIP QOS
>
> Hi there...
>
> I know this has been discussed several times and searched the
> archives...
> I'm being told by a client that this isn't working well.. my
> question is
> what is a better way to offer this?
>
> 5 Meg synchronous connection carrying VOIP (SIP/RTP) and general
> Internet traffic. Want to prioritize the VOIP and carve out "up to" 2
> meg of traffic when needed leaving "up to" 3 meg for general
> traffic...
> also want to be able to use 4 meg of general traffic when VOIP isn't
> using much etc....
>
> Cisco 2821 at customer premise with FE0/0 being the edge interface -
> Cisco 7206VXR on our side with customer connection coming off
> subinterface
> GigE0/0.101
>
> Between these devices is ethernet equipment that supports DSCP and is
> supposed to prioritize - below you'll see no congestion in place but
> on
> the VOIP side we're seeing dropped packets frequently that are not
> seen
> when we remove QOS from interfaces indicating something in this config
> is wrong....
>
> Any thoughts are appreciated...
>
> Both sides have the following applied outbound on the edge
> interface:
>
> class-map match-any VOIP
> match protocol rtp
> match protocol sip
> !
> !
> policy-map QOS-VOIP
> class VOIP
> set dscp ef
> shape average 2000000
> class class-default
> set dscp default
> shape average 3000000
>
>
> FastEthernet0/0
>
> Service-policy output: QOS-VOIP
>
> Class-map: VOIP (match-any)
> 4649311 packets, 996776732 bytes
> 5 minute offered rate 401000 bps, drop rate 0 bps
> Match: protocol rtp
> 4644189 packets, 993315456 bytes
> 5 minute rate 397000 bps
> Match: protocol sip
> 5121 packets, 3461062 bytes
> 5 minute rate 4000 bps
> QoS Set
> dscp ef
> Packets marked 4649311
> Traffic Shaping
> Target/Average Byte Sustain Excess Interval
> Increment
> Rate Limit bits/int bits/int (ms)
> (bytes)
> 2000000/2000000 12500 50000 50000 25
> 6250
>
> Adapt Queue Packets Bytes Packets Bytes
> Shaping
> Active Depth Delayed Delayed
> Active
> - 0 4649311 996776732 0 0
> no
>
> Class-map: class-default (match-any)
> 1687936 packets, 438092041 bytes
> 5 minute offered rate 120000 bps, drop rate 0 bps
> Match: any
> QoS Set
> dscp default
> Packets marked 1680145
> Traffic Shaping
> Target/Average Byte Sustain Excess Interval
> Increment
> Rate Limit bits/int bits/int (ms)
> (bytes)
> 3000000/3000000 18750 75000 75000 25
> 9375
>
> Adapt Queue Packets Bytes Packets Bytes
> Shaping
> Active Depth Delayed Delayed
> Active
> - 0 1687936 438092041 40206 48842063
> no
>
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> * Fred Reimer <freimer at ctiusa.com>
> * Issuer: The USERTRUST Network - Unverified
>
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