[cisco-voip] 7.1(2) voice quality issues, IP phone to IP phone

[Erick Bergquist]

I'm just getting involved in this issue, but they and
others have been focusing on the ATM side and carrier
for past 6 months. It is vbr-nrt right now but
discussion of moving to -rt. I'm trying to rule out
any issues on the whole network end-to-end and any
potential phoneload/CCM issues since it is IP phone to
IP phone and occurs now and then on the same LAN
locally. 

I don't believe SAA probes have been setup. 
I added QRT softkey yesterday when I got involved and
awaiting results. Will have a few monday to look at.

Theres no encryption set up on phones, or on the
network, and since it's IP phone to IP phone in same
CCM cluster that would be CAC/location setting. The
phones aren't rebooting, etc so signalling and
keepalives are good and not getting lost. They also do
have external call quality issues for calls coming
across same WAN to a PRI but I'm focusing on the
Internal call issues for now, because the issues
causing that are going to magnify issues on external
calls.

Locations is set to 200k, and the router llq policy
has 256k for priority. No drops there. It's set for
match-any ip rtp clause and dscp ef (was before I got
involved). I'm still investigating the end-to-end QoS
settings amongst all devices the calls travel through
to make sure nothing is resetting dscp/etc. 

I've done some 1000 packet size ping tests between the
CCM server and PCs at the remote site and its 40-45ms
response time. I know not a good test, but just
getting an idea.

--- "Dennis J. Hartmann" <dhartma5 at optonline.net>
wrote:

> 	What are the SAA (Service Assurance Agent) voice
> probes reporting
> during this time?  I'm assuming that SAA probes are
> being sent in the first
> place.  If they're not, this would be an easy way of
> completely ruling out
> the network.  
> 
> 	What are the call volumes during this time?  
> 
> 	What CAC mechanism are you using?  Locations does
> not account for
> IPSEC/SRTP and Layer 2 overhead.  H.323 CAC does not
> align with the priority
> queues.  
> 
> 	I think the most important parameter would be the
> delay incurred by
> the ATM provider.  Even though your not receiving
> lost packets, you may want
> to take a look at the jitter on the phone during
> this time.  Enable the QRT
> (Quality Reporting Tool) and train the users to
> click this soft key during
> bad calls so you have something to go from.
> 
> 	Also, enable CMR (call management records) that
> will tag your CDRs
> with QoS information so you can see what's going on
> in the network side.
> 
> 	Service providers have a very bad habit of maxing
> out memory in the
> TX and RX buffers so they delay ATM cells rather
> than drop them.  
> 
> Dennis Hartmann
> CCVP/CCIP/CCNP/CCSI/MCSE
> 
> -----Original Message-----
> From: cisco-voip-bounces at puck.nether.net
> [mailto:cisco-voip-bounces at puck.nether.net] On
> Behalf Of Erick Bergquist
> Sent: Saturday, October 01, 2005 1:40 AM
> To: cisco-voip at puck.nether.net
> Subject: [cisco-voip] 7.1(2) voice quality issues,
> IP phone to IP phone
> 
> Hi,
> 
> Just want to bounce this off list. Working on issue
> on a 4.1(2)sr1 system
> with 7960s on 7.1(2) currently.
> They have 3 remote sites, ATM between sites. QoS/LLQ
> is set and no drops but
> users reporting issues with IP phone to IP Phone
> calls, where the call will
> be fine for a few minutes then after a few minutes
> it starts to cut in and
> out and progressively gets worse. The call doesn't
> drop. No WAN/LAN
> interface errors along path calls travel. 
> 
> They have regions set, and are doing G729 between
> sites and have 200k
> bandwidth allocated under locations/CAC. No out of
> resources (checked the
> servers location performance counters). No drops on
> QoS policies and LAN
> appears to be ok with no visible issues.
> 
> They are also experincing echo on IP to IP phone
> calls now and then between
> sites, and between 2 IP Phones on same LAN in same
> device pool (G711 in this
> case).
> 
> I am aware of bug CSCeh01099 which may be playing a
> factor here maybe, but
> looking to see if anyone else has ran into this or
> not. I'm pushing for a
> phoneload update to 7.2(2) or 7.2(3) to start with
> and have set up QRT
> softkey on phone also. this bug id also mentions CCM
> version for fix so do
> also have to upgrade CCM to 4.1(3)sr1 to get
> complete fix?
> 
> 
> 		
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