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Re: Low network throughput using DHCP
>
> Which stack are you using? OpenBSD or Freebsd? Did you use template
> net or new_net?
>
I tried both. Same results.
>
> So there are no retransmits or lost packets? www.tcptrace.org is a
> good tool for looking at TCP flows. Lost packets can have a big impact
> on performance so first make sure this is not happening.
>
> I suppose something else to check is the information returned from
> DHCP. Is the netmask, default router, etc correct?
>
> Andrew
>
The DHCP info is correct. About 20% packets are retransmitted for one
direction (from a Linux host to the target board), but only about 0.1%
packets are retransmitted for the other direction (from the target board
to the Linux host). If eCos is configured to use static IP, then there is no
retransmitted packet at all. How could this happen?
The output of tcptrace for the DHCP version is attached. Any helps is
highly appreciated. Thanks.
Regards,
Xavier
-----------------------------------------------------------------------------
1 arg remaining, starting with 'tcp_echo_dhcp.cap'
Ostermann's tcptrace -- version 6.2.0 -- Fri Jul 26, 2002
21369 packets seen, 21369 TCP packets traced
elapsed wallclock time: 0:00:21.832999, 978 pkts/sec analyzed
trace file elapsed time: 0:02:30.331473
TCP connection info:
2 TCP connections traced:
TCP connection 1:
host a: XAVIER:1040
host b: 172.20.15.6:9990
complete conn: no (SYNs: 2) (FINs: 1)
first packet: Fri Aug 9 04:50:34.726328 2002
last packet: Fri Aug 9 04:53:04.957365 2002
elapsed time: 0:02:30.231036
total packets: 11209
filename: tcp_echo_dhcp.cap
a->b: b->a:
total packets: 7280 total packets: 3929
ack pkts sent: 7279 ack pkts sent: 3929
pure acks sent: 2 pure acks sent: 3927
sack pkts sent: 0 sack pkts sent: 0
max sack blks/ack: 0 max sack blks/ack: 0
unique bytes sent: 8388620 unique bytes sent: 4
actual data pkts: 7277 actual data pkts: 1
actual data bytes: 10445904 actual data bytes: 4
rexmt data pkts: 1433 rexmt data pkts: 0
rexmt data bytes: 2057285 rexmt data bytes: 0
zwnd probe pkts: 0 zwnd probe pkts: 0
zwnd probe bytes: 0 zwnd probe bytes: 0
outoforder pkts: 0 outoforder pkts: 0
pushed data pkts: 6856 pushed data pkts: 1
SYN/FIN pkts sent: 1/2 SYN/FIN pkts sent: 1/0
req 1323 ws/ts: Y/Y req 1323 ws/ts: Y/Y
adv wind scale: 0 adv wind scale: 0
req sack: Y req sack: N
sacks sent: 0 sacks sent: 0
urgent data pkts: 0 pkts urgent data pkts: 0 pkts
urgent data bytes: 0 bytes urgent data bytes: 0 bytes
mss requested: 1460 bytes mss requested: 1448 bytes
max segm size: 1436 bytes max segm size: 4 bytes
min segm size: 12 bytes min segm size: 4 bytes
avg segm size: 1435 bytes avg segm size: 3 bytes
max win adv: 32120 bytes max win adv: 17376 bytes
min win adv: 32120 bytes min win adv: 956 bytes
zero win adv: 0 times zero win adv: 1 times
avg win adv: 32120 bytes avg win adv: 16145 bytes
max owin: 8617 bytes max owin: 5 bytes
min non-zero owin: 1 bytes min non-zero owin: 1 bytes
avg owin: 3125 bytes avg owin: 1 bytes
wavg owin: 4541 bytes wavg owin: 0 bytes
initial window: 12 bytes initial window: 4 bytes
initial window: 1 pkts initial window: 1 pkts
ttl stream length: 8388620 bytes ttl stream length: NA
missed data: 0 bytes missed data: NA
truncated data: 9878364 bytes truncated data: 0 bytes
truncated packets: 7276 pkts truncated packets: 0 pkts
data xmit time: 150.217 secs data xmit time: 0.000 secs
idletime max: 2639.4 ms idletime max: 2137.3 ms
throughput: 55838 Bps throughput: 0 Bps
RTT samples: 1500 RTT samples: 2
RTT min: 6.4 ms RTT min: 1.1 ms
RTT max: 638.3 ms RTT max: 3.6 ms
RTT avg: 21.2 ms RTT avg: 2.3 ms
RTT stdev: 21.2 ms RTT stdev: 0.0 ms
RTT from 3WHS: 3.6 ms RTT from 3WHS: 3.6 ms
RTT full_sz smpls: 1497 RTT full_sz smpls: 1
RTT full_sz min: 6.4 ms RTT full_sz min: 1.1 ms
RTT full_sz max: 638.3 ms RTT full_sz max: 1.1 ms
RTT full_sz avg: 21.1 ms RTT full_sz avg: 1.1 ms
RTT full_sz stdev: 21.0 ms RTT full_sz stdev: 0.0 ms
post-loss acks: 165 post-loss acks: 0
For the following 5 RTT statistics, only ACKs for
multiply-transmitted segments (ambiguous ACKs) were
considered. Times are taken from the last instance
of a segment.
ambiguous acks: 839 ambiguous acks: 0
RTT min (last): 1.5 ms RTT min (last): 0.0 ms
RTT max (last): 214.4 ms RTT max (last): 0.0 ms
RTT avg (last): 10.8 ms RTT avg (last): 0.0 ms
RTT sdv (last): 20.5 ms RTT sdv (last): 0.0 ms
segs cum acked: 3341 segs cum acked: 0
duplicate acks: 1425 duplicate acks: 7277
triple dupacks: 86 triple dupacks: 0
max # retrans: 3 max # retrans: 0
min retr time: 8.4 ms min retr time: 0.0 ms
max retr time: 1403.4 ms max retr time: 0.0 ms
avg retr time: 214.8 ms avg retr time: 0.0 ms
sdv retr time: 119.8 ms sdv retr time: 0.0 ms
================================
TCP connection 2:
host c: XAVIER:1039
host d: 172.20.15.6:9991
complete conn: no (SYNs: 2) (FINs: 1)
first packet: Fri Aug 9 04:50:34.726731 2002
last packet: Fri Aug 9 04:53:05.057802 2002
elapsed time: 0:02:30.331071
total packets: 10160
filename: tcp_echo_dhcp.cap
c->d: d->c:
total packets: 3400 total packets: 6760
ack pkts sent: 3399 ack pkts sent: 6760
pure acks sent: 3397 pure acks sent: 313
sack pkts sent: 0 sack pkts sent: 0
max sack blks/ack: 0 max sack blks/ack: 0
unique bytes sent: 4 unique bytes sent: 8388620
actual data pkts: 1 actual data pkts: 6446
actual data bytes: 4 actual data bytes: 8400204
rexmt data pkts: 0 rexmt data pkts: 8
rexmt data bytes: 0 rexmt data bytes: 11584
zwnd probe pkts: 0 zwnd probe pkts: 0
zwnd probe bytes: 0 zwnd probe bytes: 0
outoforder pkts: 0 outoforder pkts: 0
pushed data pkts: 1 pushed data pkts: 1172
SYN/FIN pkts sent: 1/1 SYN/FIN pkts sent: 1/0
req 1323 ws/ts: Y/Y req 1323 ws/ts: Y/Y
adv wind scale: 0 adv wind scale: 0
req sack: Y req sack: N
sacks sent: 0 sacks sent: 0
urgent data pkts: 0 pkts urgent data pkts: 0 pkts
urgent data bytes: 0 bytes urgent data bytes: 0 bytes
mss requested: 1460 bytes mss requested: 1448 bytes
max segm size: 4 bytes max segm size: 1448 bytes
min segm size: 4 bytes min segm size: 12 bytes
avg segm size: 3 bytes avg segm size: 1303 bytes
max win adv: 32120 bytes max win adv: 17376 bytes
min win adv: 22976 bytes min win adv: 17372 bytes
zero win adv: 0 times zero win adv: 0 times
avg win adv: 31488 bytes avg win adv: 17375 bytes
max owin: 5 bytes max owin: 4201 bytes
min non-zero owin: 1 bytes min non-zero owin: 1 bytes
avg owin: 1 bytes avg owin: 1985 bytes
wavg owin: 0 bytes wavg owin: 1436 bytes
initial window: 4 bytes initial window: 12 bytes
initial window: 1 pkts initial window: 1 pkts
ttl stream length: 4 bytes ttl stream length: NA
missed data: 0 bytes missed data: NA
truncated data: 0 bytes truncated data: 7897524 bytes
truncated packets: 0 pkts truncated packets: 6444 pkts
data xmit time: 0.000 secs data xmit time: 150.210 secs
idletime max: 2533.2 ms idletime max: 2533.1 ms
throughput: 0 Bps throughput: 55801 Bps
RTT samples: 3 RTT samples: 3388
RTT min: 3.6 ms RTT min: 0.1 ms
RTT max: 60.1 ms RTT max: 496.1 ms
RTT avg: 23.7 ms RTT avg: 6.2 ms
RTT stdev: 31.5 ms RTT stdev: 17.0 ms
RTT from 3WHS: 7.6 ms RTT from 3WHS: 0.2 ms
RTT full_sz smpls: 1 RTT full_sz smpls: 2719
RTT full_sz min: 3.6 ms RTT full_sz min: 0.1 ms
RTT full_sz max: 3.6 ms RTT full_sz max: 496.1 ms
RTT full_sz avg: 3.6 ms RTT full_sz avg: 3.8 ms
RTT full_sz stdev: 0.0 ms RTT full_sz stdev: 17.7 ms
post-loss acks: 0 post-loss acks: 2
For the following 5 RTT statistics, only ACKs for
multiply-transmitted segments (ambiguous ACKs) were
considered. Times are taken from the last instance
of a segment.
ambiguous acks: 0 ambiguous acks: 1
RTT min (last): 0.0 ms RTT min (last): 0.1 ms
RTT max (last): 0.0 ms RTT max (last): 0.1 ms
RTT avg (last): 0.0 ms RTT avg (last): 0.1 ms
RTT sdv (last): 0.0 ms RTT sdv (last): 0.0 ms
segs cum acked: 0 segs cum acked: 3048
duplicate acks: 6757 duplicate acks: 8
triple dupacks: 0 triple dupacks: 0
max # retrans: 0 max # retrans: 1
min retr time: 0.0 ms min retr time: 465.4 ms
max retr time: 0.0 ms max retr time: 465.4 ms
avg retr time: 0.0 ms avg retr time: 465.4 ms
sdv retr time: 0.0 ms sdv retr time: 0.0 ms
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