Re: TCP Retransmission timers ?

[Neil Spring <[e-mail]>]

Hello,

On Wed, Sep 18, 2002 at 06:54:23PM +0200, sebastiano elia wrote:
> please, can someone tell me what kind of retransmit policy is used,
> in current
> implementations of TCP ?
> a)"First only"  with only one retrasmission timer for entire queue;
> b)"Batch" with only one retrasmission timer for entire queue;
> c)"Individual" with one timer for each segment in queue.

> Which of these is the standard ?

It seems to me that only one of these three makes sense,
given that basic TCP uses cumulative acknowledgements and
you'd like to avoid unnecessary retransmissions during times
of congestion (causes loss causes timeout).

see: http://lxr.linux.no/source/net/ipv4/tcp_timer.c#L316
hint: also look at the definition of tcp_retransmit_skb,
as called on line 377.

-neil