Date: Sat, 6 Sep 2003 18:39:12 +0100 From: "Colin Watson" <sb.mailinglist@lambdabroadband.com> To: <freebsd-net@freebsd.org> Subject: Packet loss problem Message-ID: <002201c3749d$c8cf4460$0b4e1151@blackbox>
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Hi, I've got a rather strange issue with UDP loss (at least I think it =
is) on my network, and frankly - I'm not sure it's me (think it might be =
the upstream providers stuff). Basically, the situation is this, FreeBSD =
4.8 box connects to the upstream provider, and another one at another =
location acts as a gateway for the customers. The gateway box has very =
high 'drops' on it's UDP sockets, making streaming stuff awful - and =
output of netstat -s (UDP,TCP & IP only) on the gateway box is shown at =
the end of this post. My particular concern is these lines in the UDP =
output "41738 datagrams received
/ 33104 broadcast/multicast datagrams dropped due to no socket " which =
seems an inordinatly high amount. There are no drops due to full socket =
buffers, although I have recompiled the kernel with nmbclusters=3D8192 =
and Maxusers=3D1024 (to increase number of available sockets - =
kern.ipc.maxsockets to 9391), still the loss occurs. Any suggestions, =
and could someone explicitly explain what "broadcast/multicast datagrams =
dropped due to no socket" means.
Many Thanks
Colin.
---> Output of netstat -s on Gateway Box ----->
tcp:
40102 packets sent
14837 data packets (1080215 bytes)
23 data packets (29468 bytes) retransmitted
0 resends initiated by MTU discovery
17949 ack-only packets (669 delayed)
0 URG only packets
0 window probe packets
6924 window update packets
370 control packets
46602 packets received
10485 acks (for 1080288 bytes)
227 duplicate acks
0 acks for unsent data
31029 packets (31656794 bytes) received in-sequence
132 completely duplicate packets (177030 bytes)
0 old duplicate packets
9 packets with some dup. data (3920 bytes duped)
7375 out-of-order packets (9107920 bytes)
0 packets (0 bytes) of data after window
0 window probes
11 window update packets
0 packets received after close
0 discarded for bad checksums
0 discarded for bad header offset fields
0 discarded because packet too short
182 connection requests
14 connection accepts
0 bad connection attempts
0 listen queue overflows
190 connections established (including accepts)
258 connections closed (including 1 drop)
19 connections updated cached RTT on close
19 connections updated cached RTT variance on close
9 connections updated cached ssthresh on close
5 embryonic connections dropped
9539 segments updated rtt (of 9546 attempts)
9 retransmit timeouts
0 connections dropped by rexmit timeout
0 persist timeouts
0 connections dropped by persist timeout
0 keepalive timeouts
0 keepalive probes sent
0 connections dropped by keepalive
1 correct ACK header prediction
27603 correct data packet header predictions
15 syncache entries added
1 retransmitted
0 dupsyn
0 dropped
14 completed
0 bucket overflow
0 cache overflow
1 reset
0 stale
0 aborted
0 badack
0 unreach
0 zone failures
0 cookies sent
0 cookies received
udp:
41738 datagrams received
0 with incomplete header
0 with bad data length field
0 with bad checksum
0 with no checksum
8443 dropped due to no socket =20
33104 broadcast/multicast datagrams dropped due to no socket =
<-- My Particular Concern
0 dropped due to full socket buffers
0 not for hashed pcb
191 delivered
254 datagrams output
ip:
28432403 total packets received
9 bad header checksums
0 with size smaller than minimum
211 with data size < data length
0 with ip length > max ip packet size
0 with header length < data size
0 with data length < header length
0 with bad options
0 with incorrect version number
2585861 fragments received
0 fragments dropped (dup or out of space)
57 fragments dropped after timeout
1292902 packets reassembled ok
9414002 packets for this host
2 packets for unknown/unsupported protocol
17696404 packets forwarded (0 packets fast forwarded)
16337 packets not forwardable
0 packets received for unknown multicast group
0 redirects sent
15047419 packets sent from this host
0 packets sent with fabricated ip header
0 output packets dropped due to no bufs, etc.
26 output packets discarded due to no route
97835 output datagrams fragmented
195670 fragments created
0 datagrams that can't be fragmented
0 tunneling packets that can't find gif
0 datagrams with bad address in header
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