-----Original Message-----
From: Sambasiva Rao Manchili
[mailto:[email protected]] 
Sent: Monday, March 21, 2011 11:37 AM
To: Uttam Sarkar (usarkar); Sambasiva Rao MANCHILI;
[email protected]
Cc: Antonio Gambin
Subject: RE: [Sip-implementors] SIP UDP packet loss?

Hi
What ever we received from GEI driver is being sent to  user and no
where lost in between after receiving from GEI dribver by ETHER and then
to  IP stack and then to  SIP subscriber.

What we observed is the number of packets sent to  GEI driver on Side-A
is not equal to number or packets received on Side-B from GEI Driver.
This means it is lost inbetween GEI driver on one side to GEI Driver on
other side.  Can this happen ?  Did you come across such behaviour ?
We use gei825xxVxbEnd driver.
[US] If the packets are sent faster rate than the consuming rate then
this problem could happen. You try to find out what UDP packet rate you
observe this problem.

Thanks for your time.
Samba.

-----Original Message-----
From: Uttam Sarkar (usarkar) [mailto:[email protected]]
Sent: Monday, 21. March, 2011 16:24
To: Sambasiva Rao MANCHILI; [email protected]
Cc: Sambasiva Rao Manchili
Subject: RE: [Sip-implementors] SIP UDP packet loss?

There could be bottle neck in your application. Maybe it's unable to
read all the UDP packets from the network.
You need to find out what is the capacity of your application.

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
Sambasiva Rao MANCHILI
Sent: Sunday, March 20, 2011 2:31 PM
To: [email protected]
Cc: [email protected]
Subject: [Sip-implementors] SIP UDP packet loss?

Hallo  Sip Implementors,
I am not a SIP expert of application layer. I am part of Test System
Development where we simulate the SIP traffic over different transport
types like UDP,TCP and SCTP.
When we are simulating just SIP signalling messages between our two test
systems at the rate of  greater than 500  UDP packets per second, we
observed some of Subscribers fail Signalling.After further
investigations it is found that UDP packets are lost  consequently
Signalling is failing for some subscribers intermittently.

To overcome this we then increased the udp.recvspace and udp.sendspace
and socketbuffer size in our Networking stack.
This helped the packet loss to reduce by 10%.  Before increasing buffers
we have Faults rate of ~8 to 10%  on Signalling after increasing buffers
we have fault rate of 0.9% over Signalling.
*Qeury 1*:- Is increasing buffer space is a solution or workaround for
our Network stack  to overcome packet loss ?

Default values of our Network stack  were 40K for udp.recvspace and 9K
for udp.sendspace and socketbuffers are 256K.
We changed these values in our Network stack  to 256K  for
udp.recvspace, 256K for udp.sendspace and socketbuffers to 1024K.
This change has reduced packet loss but can could not make 0% packet
loss.
 I understand UDP is not reliable transport, but I am looking for
solution which can reduce Packet loss to less than 1%.  When I enabled
speech path codec G.729/ G.711 I see still more packet loss of 15%.

Query2:- Can you please suggest us what should be the right values for
such buffer space if this is right approach ?

We have yet to enable the voice transmission as a next immediate step,
then again SIP RTP UDP packets will further increase based on the codec
chosen and this will cause even more packet loss.

Query3:-  What is the ultimate  solution for eliminating packet loss
both on Signalling and on speech path ?

Thank you in advance for your time.
Samba.
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