Re: [lwip-users] How to force dup ACK

[yueyue papa]

I add the different part to make duplicate ACK send, but still could
not find the proper  position.


I add  duplicate ACK here, but did not got expect result
static void
tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
{

....
  ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
      IP_PROTO_TCP);

/***
  if(  pcb->flags &TF_ACK_NOW == TF_ACK_NOW )
  {
  ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
      IP_PROTO_TCP);
  }
***/
}

Is there anyone could guild me where to set the DUP ACK?

I tried to make duplicate ACK to remote, so it becomes less possible
to lost ACK in GPRS. network.

Lee

On Thu, Apr 15, 2010 at 3:32 PM, yueyue papa <address@hidden> wrote:
> Hi All,
>
> I use lwIP in GPRS environment.  Wireshark is setup in the server.  I
> find these information:
>
> lwip  device  <--------------------> server (Wireshark running there)
>
> if  TSS = 512, the TCP stream is working very stable.
>
> if TSS = 1024, 1460, there is always TCP ACK lost in server. The
> resend is always happen.
>
> The resend cause the performance down.
>
> Is there a solution I could configure lwIP make duplicate ACK send, so
> as to decrease the ACK lost possibility?
>
> thanks
> Lee
>