Re: [Contiki-developers] "HTTP request sent, awaiting response... Read error (Connection reset by peer) in headers" error using wget

[David K. <da...@em...>]

That’s the one
/* Allocate remaining RAM as desired */
/* 30 bytes per TCP connection */
/* 6LoWPAN does not do well with concurrent TCP streams, as new browser GETs 
collide with packets coming */
/* from previous GETs, causing decreased throughput, retransmissions, and 
timeouts. Increase to study this. */
/* ACKs to other ports become interleaved with computation-intensive GETs, 
so ACKs are particularly missed. */
/* Increasing the number of packet receive buffers in RAM helps to keep ACKs 
from being lost */
#define UIP_CONF_MAX_CONNECTIONS  4
/* 2 bytes per TCP listening port */
#define UIP_CONF_MAX_LISTENPORTS  4

/core/net/uipopt.h for the other
/**
* How long a connection should stay in the TIME_WAIT state.
*
* This can be reduced for faster entry into power saving modes.
*/
#ifndef UIP_CONF_WAIT_TIMEOUT
#define UIP_TIME_WAIT_TIMEOUT 120
#else
#define UIP_TIME_WAIT_TIMEOUT UIP_CONF_WAIT_TIMEOUT
#endif


There are  web pages showing tcpip connections and their status, you can 
just dump that out the serial port e.g when you get a SYN.
E.g. /apps/webserver/httpd-cgi.c

static unsigned short
make_tcp_stats(void *arg)
{
  struct uip_conn *conn;
  struct httpd_state *s = (struct httpd_state *)arg;
  conn = &uip_conns[s->u.count];

#if UIP_CONF_IPV6
  char buf[48];
  httpd_sprint_ip6(conn->ripaddr, buf);
  return snprintf((char *)uip_appdata, uip_mss(),
         "<tr 
align=\"center\"><td>%d</td><td>%s:%u</td><td>%s</td><td>%u</td><td>%u</td><td>%c 
%c</td></tr>\r\n",
         uip_htons(conn->lport),
         buf,
         uip_htons(conn->rport),
         states[conn->tcpstateflags & UIP_TS_MASK],
         conn->nrtx,
         conn->timer,
         (uip_outstanding(conn))? '*':' ',
         (uip_stopped(conn))? '!':' ');
#else
  return snprintf((char *)uip_appdata, uip_mss(),
         "<tr 
align=\"center\"><td>%d</td><td>%u.%u.%u.%u:%u</td><td>%s</td><td>%u</td><td>%u</td><td>%c 
%c</td></tr>\r\n",
         uip_htons(conn->lport),
         conn->ripaddr.u8[0],
         conn->ripaddr.u8[1],
         conn->ripaddr.u8[2],
         conn->ripaddr.u8[3],
         uip_htons(conn->rport),
         states[conn->tcpstateflags & UIP_TS_MASK],
         conn->nrtx,
         conn->timer,
        (uip_outstanding(conn))? '*':' ',
        (uip_stopped(conn))? '!':' ');
#endif /* UIP_CONF_IPV6 */
}
-----Original Message----- 
From: Ivo Leitao
Sent: Friday, June 22, 2012 1:13 PM
To: Contiki developer mailing list
Subject: Re: [Contiki-developers] "HTTP request sent, awaiting response... 
Read error (Connection reset by peer) in headers" error using wget

Thank you for your reply.

Which parameter are you referring to? This one?  #define 
UIP_CONF_MAX_CONNECTIONS 4

Where do I change the timeout value? Is it this one defined in 
httpd-simple.c in rpl-border router?

timer_set(&s->timer, CLOCK_SECOND * 10);


I think I'm using standard CSMA: #define NETSTACK_CONF_MAC     csma_driver

Thank you for the help,

Ivo Leitão




On 22 June 2012 17:30, David Kopf <da...@em...> wrote:
How many active tcpip connections are allowed? Once full the webserver will 
send RST to incoming SYNs until one of the connections
times out.
A shorter timeout might help; I think it is 20 seconds by default.

Are you using CSMA burst mode that sets the pending bit on fragmented 
packets?


-----Original Message-----
From: Ivo Leitao
Sent: Friday, June 22, 2012 12:09 PM
To: Contiki developer mailing list
Subject: [Contiki-developers] "HTTP request sent, awaiting response... Read 
error (Connection reset by peer) in headers" error using
wget

Hello all,

I've been using small modified versions of the RPL-Border Router and
Sky-Websense examples to simulate in Cooja a multi-hop network with
two opposite rows of 3 sky-websense nodes each with a Border router in
the center.

The idea is to evaluate the performance of http requests to get the
sensing data stored in each sky-websense webpage. In order to automate
the simulations I wrote a small bash script which used wget a given
number of times to fetch the pages. One thing I noticed is, when using
wget all the errors I've got were "HTTP request sent, awaiting
response... Read error (Connection reset by peer) in headers", which
were followed by a RST,ACK tcp message that can be seen in wireshark.

What is causing this errors? I noticed that I never had more than 4
tries to fetch a page (3 errors followed by a successful data
transfer).

The parameters changed in both contiki-conf for the sky platform and
project-conf are:

#define QUEUEBUF_CONF_NUM          15
#define UIP_CONF_BUFFER_SIZE    300
#define UIP_CONF_RECEIVE_WINDOW  60

#define SICSLOWPAN_CONF_COMPRESSION             SICSLOWPAN_COMPRESSION_IPV6

#define UIP_CONF_DS6_NBR_NBU     2 (to force multihop)
#define UIP_CONF_DS6_ROUTE_NBU   10 (enough route entries for this network)




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