Subject: [AVT] Maximum rate with TFRC

From: Alejandro Cabrera Obed <[email-masked]>
Date: Fri, 12 Aug 2005 12:16:37 -0300

Dear people,

Suposse I have an application that transmit, let's say, at 1 Gbps.
Suppose I apply TFRC in order to control the congestion.

Can you explain to me how TFRC affects the maximum rate ??? Because if
I follow the formula, in absence of packet loss it's p = 0 and the
throughput will get high and high......(near infinite rate).

Or the maximum rate in absence of packet loss is always the throughput
of the application, in my example 1 Gbps ???

I need your help please........

Thanks and greetings !!!!

Alejandro

-- 
Alejandro Cabrera Obed
[email-masked]

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

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From: Ladan Gharai <[email-masked]>
Date: Fri, 12 Aug 2005 11:38:32 -0400

Alejandro:

The senders data rate is also limited by x_recv - and will not at any  
point be increased by more that 2*x_recv:

 From RFC 3448 (section 4.3):

    4) Update the sending rate as follows:

          If (p > 0)
              Calculate X_calc using the TCP throughput equation.
              X = max(min(X_calc, 2*X_recv), s/t_mbi);
          Else
              If (t_now - tld >= R)
                  X = max(min(2*X, 2*X_recv), s/R);
                  tld = t_now;

In absence of packet loss, a limited receiver and say your using a  
10G NIC then your limit would be the applications data rate, once  
your at steady state. I hope to test this scenario soon.

Ladan

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From: "kae" <[email-masked]>
Date: Mon, 15 Aug 2005 22:55:37 -0400

Hi,

 I wonder if anyone knows how much MTU reduction if I use AES algorithm in
SRTP. I need to run an encrypted video application in a reduced MTU
environment. I am concerned the performance impact due to the MTU reduction.

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From: Mark Baugher <[email-masked]>
Date: Mon, 15 Aug 2005 20:38:23 -0700

The incremental overhead of SRTP encapsulation is explained in RFC 
3711.  For an SRTP packet, there is a 4 byte or 10 byte authentication 
tag.  One may use a zero-length tag but this is not recommended.  For 
SRTCP, there is a 4 to 10 byte authentication tag plus the packet 
index.

Mark