[SIPForum-discussion] TCP vs RTP

[McQuaid, Jim]

TCP simply does not work for real time data (audio streams = voip).  TCP
will start slowly, back off in the face of congestion, retransmit
packets not acknowledged by the receiver.  While these functions may
sound desirable, receiving a single sample of audio two seconds after
this sound needed to be played out to the listener is useless.  RTP must
run over UDP to get real time delivery.  It is exactly the lack of
overhead on UDP that is why it works (best) for real time audio.

 

Jim McQuaid

 

NetQoS

 

________________________________

From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of
alexzhang at gdnt.com.cn
Sent: Monday, April 23, 2007 5:04 AM
To: lokesh.agrawal at gmail.com; discussion at sipforum.org
Subject: Re: [SIPForum-discussion] TCP vs RTP

 

Hi Lokesh,

 

My question is: If RTP is based on the connectionless Oriented, can we
say this protocol is only applicable to the Audio and video
transporation? If we want to transfer data without any possible loss, is
it reliable to use RTP?

 

-- A l e x

 

 

________________________________

From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of lokesh agrawal
Sent: Monday, April 23, 2007 4:33 PM
To: discussion at sipforum.org
Subject: Re: [SIPForum-discussion] TCP vs RTP

Hi,

 

First of all let me tell you that TCP and RTP both are both different
purpose.

VoIP data packets live in RTP (Real-Time Transport Protocol) packets
which are inside UDP-IP packets

TCP is more making/terminating connections and RTP is for payloads and
data packets. 

 

VOIP data packets uses UDP, RTP and IP protocols for operation.

We can use TCP(Connection Oriented) in place of UDP(connectionless) but
VoIP doesn't use TCP because it is too heavy for real time applications
and for voice it will add delay in packets as it needs ACK for each and
every packet. 

 

 

Regards

Lokesh Agrawal

Persistent Systems Pvt. Ltd.

 

On 4/23/07, William Prusty <williamp at techmahindra.com> wrote: 

Whether TCP is capable to carry AUDIO , VIDEO data ?? if yes then why we
are using RTP in SIP to carry  AUDIO , VIDEO data

 

 

 

 

Plz answer .

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