[cisco-voip] Weird Conference Voice Quality
Wes Sisk
wsisk at cisco.com
Thu Jul 22 17:52:03 EDT 2004
Vandy,
This looks mostly correct - just a cpl questions-
Can we see the rest of the config for the route-map on the FastE
"ip policy route-map SET-IP-QOS" This may be re-marking your VOIP traffic
so it does not match your outbound QOS policy, which identifies VOIP bearer
traffic based on:
ip access-list extended VOIP-Classify-Voice
permit ip any any precedence critical
permit ip any any dscp ef
Also, your QOS-POLICY appears to allocate 650kbps, this ususally should only
be 75% of available bw, so do your links offer 650/0.75= 866kbps at least?
This is discussed in the QOS srnd at http://www.cisco.com/go/srnd if you'd
like to read more.
/Wes
> -----Original Message-----
> From: Vandy Hamidi [mailto:vandy.hamidi at markettools.com]
> Sent: Thursday, July 22, 2004 5:27 PM
> To: Wes Sisk; cisco-voip at puck.nether.net
> Subject: RE: [cisco-voip] Weird Conference Voice Quality
>
>
> Thanks Wes, that explains a lot and confirms a hunch I had. It looks
> like the 6608 waiting for a jittery stream will cause choppiness for all
> participants. That's a real great design...
>
> Because conference voice quality is always GOOD when data isn't
> competing, the QOS classifying and policing must not be setup right. We
> had outside consultants install our base system and I've been using
> their QOS to stamp out other remote sites.
> Something must be misconfigured.
>
> Can anyone just give it a once over. I cut and paste just the pertinent
> parts of my 2651XM config below.
>
> If anyone could email me their QOS setup, I would be extremely grateful.
> This problem is high priority and high visibility and I've be very
> thankful.
> Thank you in advanced,
>
> -=Vandy-=
>
> class-map match-all VOIP-VOICE_CONTROL
> match access-group name VOIP-Classify-Control
> class-map match-all VOIP-VOICE
> match access-group name VOIP-Classify-Voice
> !
> !
> policy-map QOS-POLICY
> class VOIP-VOICE
> priority 600
> class VOIP-VOICE_CONTROL
> bandwidth 50
> class class-default
> fair-queue
> !
> interface Multilink1
> description Market Tools PL431562
> ip address 172.16.16.70 255.255.255.252
> service-policy output QOS-POLICY
> load-interval 30
> no peer neighbor-route
> no cdp enable
> ppp multilink
> ppp multilink fragment delay 20
> ppp multilink interleave
> ppp multilink group 1
> !
> interface FastEthernet0/0
> description User/Server VLAN
> encapsulation dot1Q 1 native
> ip address 10.21.0.1 255.255.255.0
> ip policy route-map SET-IP-QOS
> !
> interface FastEthernet0/1
> description VOIP Phone VLAN
> encapsulation dot1Q 4
> ip address 10.21.4.1 255.255.252.0
> ip policy route-map SET-IP-QOS
> !
> ip access-list extended VOIP-Classify-Control
> permit ip any any precedence flash
> permit ip any any dscp af31
> ip access-list extended VOIP-Classify-Voice
> permit ip any any precedence critical
> permit ip any any dscp ef
> ip access-list extended VOIP-Control
> permit tcp any any range 2000 2002
> permit tcp any any eq 1720
> permit tcp any any range 11000 11999
> permit udp any any eq 2427
> ip access-list extended VOIP-Routine
> permit ip any any
> ip access-list extended VOIP-Voice
> permit udp any any range 16384 32767
>
>
> -----Original Message-----
> From: Wes Sisk [mailto:wsisk at cisco.com]
> Sent: Thursday, July 22, 2004 6:07 AM
> To: Vandy Hamidi; cisco-voip at puck.nether.net
> Subject: RE: [cisco-voip] Weird Conference Voice Quality
>
> Vandy,
>
> If audio coming from the source device to the conference device has
> large,
> irregular jitter, then everyone listening to the conference will be
> affected.
>
> Simple way to test this out:
> setup conference with remote users and 1 central user.
> have all remote users go on "mute" (no RTP stream generated on mute)
> have central user speak.
> How is voice quality?
>
> Now, have everyone except 1 remote user go on mute.
> How is voice quality?
>
> We need to make sure those streams coming from the remote sites are
> "good"
> with very low jitter as the 6608 uses a static dejitter buffer in
> contrast
> with most ipphones and gateways which use dynamic jitter buffers. This
> makes fragmentation critical on the WAN links.
>
> CSCdx78486 6608 configured as CFB has a static jitter buffer, needs
> adaptive
> Problem Description: Voice quality suffers with choppiness when
> conference
> particants are located across low speed links and the device providing
> for
> conferencing is the 6608.
>
> Workaround: None
>
> /Wes
>
> > -----Original Message-----
> > From: cisco-voip-bounces at puck.nether.net
> > [mailto:cisco-voip-bounces at puck.nether.net]On Behalf Of Vandy Hamidi
> > Sent: Wednesday, July 21, 2004 11:30 PM
> > To: cisco-voip at puck.nether.net
> > Subject: [cisco-voip] Weird Conference Voice Quality
> >
> >
> > Hey guys,
> > I'm having a weird problem that isn't making sense
> >
> > I have a 6608-T1 blade in my main office performing conferencing for
> > most of the remote offices in the company. I know, not recommended,
> but
> > read on.
> >
> > All the offices are connected Hub/Spoke to the main office and I have
> > QOS setup (supposedly correctly) on my wan links and call quality is
> > great. I've tested the QOS by maxing out the line during voice calls.
> >
> > We've been receiving user complaints of voice quality problems.
> Cutting
> > out, delays, overall chopping communication. All these complaints are
> > when they are on conference calls.
> >
> > We've performed testing and during high wan usage the conference call
> > quality becomes horrible to/from the remote sites and sometimes for
> all
> > users for example I'll have a hard time understanding a conference
> > attendee in my own office.
> > We're able to reproduce with windows copies during conference calls.
> >
> > 1) Why is the voice quality ok with phone to phone calls, but become
> > horrible during a conference call.
> > 2) Does the 6608-T1 blade change/alter the QOS/TOS bits on the
> packets?
> > 3) Why would this issue affect local attendee conference quality when
> > everyone is connected to the same switch where the 6608 blade is.
> >
> > TIA,
> >
> > -=Vandy=-
> >
> >
> > _______________________________________________
> > cisco-voip mailing list
> > cisco-voip at puck.nether.net
> > https://puck.nether.net/mailman/listinfo/cisco-voip
>
>
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