[cisco-voip] MGCP Audio Cut Through Delay

[Wes Sisk]

at the end the router reports call statistics:
P: PS=978, OS=156480, PR=980, OR=156800, PL=0, JI=0, LA=0
PS = packets sent
PR = packets received
978 is close enough to 980. this means all RTP packets made it through 
the network between the endpoints.
980 packets * 20msec/packet = 19,600msec of audio.

Time from sendrecv to recvonly = 03:51:40.645 - 03:52:00.227 = 19.6 
seconds (approximately).
19.6 seconds connected and 19.6 seconds of RTP traffic.  Thus audio was 
successfully established and packets were sent and received successfully 
for the duration of the connection.

Router responded correctly and offered its ip address to receive RTP 
stream.  the mgcp call agent (cm?) sent instruction to establish 
bidirectional audio full 15 seconds later.  *Need to see what took the 
call agent(cm?) so long to obtain the media ip/port from the other 
endpoint.*

debugs with comments:
//create connection to setup new call
Jul 10 03:51:25.534 CST: MGCP Packet received from 10.1.1.10:2427--->
CRCX 89768

//router provides ip & port for RTP stream:
Jul 10 03:51:25.550 CST: MGCP Packet sent to 10.1.1.10:2427--->
200 89768 OK
I: 6

// router receives instruction to change audio mode to sendrecv. this is 
usually 2 way audio
Jul 10 03:51:40.645 CST: MGCP Packet received from 10.1.1.10:2427--->
MDCX 89773 AALN/S0/SU1/3 at MC003776.mcenery.local MGCP 0.1
C: A00000000200d51c000000F5
I: 6
X: 0
L: p:20, a:PCMU, s:off, t:b8
M: sendrecv
R: L/hu, D/[0-9ABCD*#]
S:
Q: process,loop

v=0
o=- 6 0 IN EPN AALN/S0/SU1/3 at MC003776.mcenery.local
s=Cisco SDP 0
t=0 0
m=audio 18840 RTP/AVP 0
c=IN IP4 172.20.113.10
<---

//router receives instruction to stop transmitting audio
Jul 10 03:52:00.227 CST: MGCP Packet received from 10.1.1.10:2427--->
MDCX 89775 AALN/S0/SU1/3 at MC003776.mcenery.local MGCP 0.1
C: A00000000200d51c000000F5
I: 6
X: 0
M: recvonly

// router reports call statistics:
Jul 10 03:52:00.287 CST: MGCP Packet sent to 10.1.1.10:2427--->
250 89776 OK
P: PS=978, OS=156480, PR=980, OR=156800, PL=0, JI=0, LA=0






v=0
c=IN IP4 172.20.115.254
m=audio 17344 RTP/AVP 0 100



/Wes


Jonathan Charles wrote:
> Here you go... no obvious errors...
>
>
>
> Jonathan
>
> On Wed, Jul 9, 2008 at 2:42 PM, Wes Sisk <wsisk at cisco.com> wrote:
>   
>> yep
>>
>> Jonathan Charles wrote:
>>     
>>> The MGCP packet debug?
>>>
>>>
>>> J
>>>
>>> On Wed, Jul 9, 2008 at 1:02 PM, Wes Sisk <wsisk at cisco.com> wrote:
>>>
>>>       
>>>> can you share the debug (blank out the actual phone numbers) with debug
>>>> datetime msec?
>>>>
>>>> /wes
>>>>
>>>> Jonathan Charles wrote:
>>>>
>>>>         
>>>>> We have a remote site via a VPN tunnel (over MPLS), and we are seeing
>>>>> significant audio cut through delays.
>>>>>
>>>>> We did a debug mgcp packet and saw no retries.
>>>>>
>>>>> We can also see the problem when PSTN callers are placed on hold and
>>>>> retrieved.
>>>>>
>>>>> Delay lasts between 3 to 4 seconds...
>>>>>
>>>>> Any ideas?
>>>>>
>>>>> MGCP config is the default (no special packages enabled/disabled)...
>>>>>
>>>>>
>>>>>
>>>>> Jonathan
>>>>> _______________________________________________
>>>>> cisco-voip mailing list
>>>>> cisco-voip at puck.nether.net
>>>>> https://puck.nether.net/mailman/listinfo/cisco-voip
>>>>>
>>>>>
>>>>>           
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