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Date:      Mon, 17 Nov 1997 01:50:00 +0900
From:      Jeong Seong Won <swjeong@woman.kitel.co.kr>
To:        dg@root.com
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: Network connection often stops. Why ?
Message-ID:  <346F2438.41C67EA6@woman.kitel.co.kr>
References:  <199711160800.AAA12641@implode.root.com>

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> 
> >In my company. About twenty of 686 FreeBSD 2.2.1 Machine is connected
> > via FastEthernet.(Intel EtherExpress)
> > Hub is SMC tigerstack.(not a switching)
> > Problem occurs in the same way when I used SMC 9332BDT.
> > Network options         MAXMEM=262144
> > Concurrent User is aboue 230 per machine.
> >
> > Problem is that suddenly telnet session stop.
> >                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > When this happens, all key stokes is not effective, and at last
> > conection is closed.
> >
> > vnode, file table, mbuf, somaxconn is sufficient.
> >
> > kernel configuration is
> >
> >....
> >
> >options         MAXMEM=262144
> >maxusers        250
> >options         NMBCLUSTERS=8192
> >options       
>   I just replied to your message in the NetBSD list as well. 
>   I think the problem is that you are running out of mbuf clusters
>   (even though you have the setting really high already). 
>   Can you monitor that with "netstat -m" and 
>   make sure that the second figure in the ratio of mbuf clusters 
>   in use is never more than 6000?

I make sure mbuf never more than 6000.
The problem often occurs when no one except root on console logined.
(when 'cd /;ls -lR')

Below is system status (netstat -s, netstat -m)
when it's load is relatively middle.(156 user)

Thank you.

----------------------------------------------------------------

$ netstat -m
1521 mbufs in use:
        99 mbufs allocated to data
        658 mbufs allocated to packet headers
        762 mbufs allocated to protocol control blocks
        2 mbufs allocated to socket names and addresses
40/1112 mbuf clusters in use
2414 Kbytes allocated to network (11% in use)
0 requests for memory denied
0 requests for memory delayed
0 calls to protocol drain routines
Here is system status. (netstat -m, netstat -s)

$ netstat -s (uptime 2 days, 17h)
ip:
        70806126 total packets received
        0 bad header checksums
        0 with size smaller than minimum
        0 with data size < data length
        0 with header length < data size
        0 with data length < header length
        0 with bad options
        0 with incorrect version number
        0 fragments received
        0 fragments dropped (dup or out of space)
        0 fragments dropped after timeout
        0 packets reassembled ok
        68037217 packets for this host
        2768909 packets for unknown/unsupported protocol
        0 packets forwarded
        0 packets not forwardable
        0 redirects sent
        62560291 packets sent from this host
        0 packets sent with fabricated ip header
        0 output packets dropped due to no bufs, etc.
        0 output packets discarded due to no route
        0 output datagrams fragmented
        0 fragments created
        0 datagrams that can't be fragmented
icmp:
        2769059 calls to icmp_error
        0 errors not generated 'cuz old message was icmp
        Output histogram:
                echo reply: 5
                destination unreachable: 2769059
        0 messages with bad code fields
        0 messages < minimum length
        0 bad checksums
        0 messages with bad length
        Input histogram:
                echo reply: 14
                destination unreachable: 2771433
                echo: 5
        5 message responses generated
igmp:
        0 messages received
        0 messages received with too few bytes
        0 messages received with bad checksum
        0 membership queries received
        0 membership queries received with invalid field(s)
        0 membership reports received
        0 membership reports received with invalid field(s)
        0 membership reports received for groups to which we belong
        0 membership reports sent
tcp:
        56960230 packets sent
                39981139 data packets (-1116894515 bytes)
                43014 data packets (20673340 bytes) retransmitted
                0 resends initiated by MTU discovery
                9784510 ack-only packets (6816381 delayed)
                6 URG only packets
                7847 window probe packets
                4767211 window update packets
                2378547 control packets
        65223827 packets received
                34333052 acks (for -1115532635 bytes)
                897408 duplicate acks
                0 acks for unsent data
                41680061 packets (-323558872 bytes) received in-sequence
                49030 completely duplicate packets (33264557 bytes)
                0 old duplicate packets
                414 packets with some dup. data (168205 bytes duped)
                1232106 out-of-order packets (507712999 bytes)

                2811 packets (4128 bytes) of data after window
                1387 window probes
                414935 window update packets
                7351 packets received after close
                16 discarded for bad checksums
                0 discarded for bad header offset fields
                0 discarded because packet too short
        1165552 connection requests
        68821 connection accepts
        323 bad connection attempts
        0 listen queue overflows
        1218177 connections established (including accepts)
        1233896 connections closed (including 3712 drops)
                61972 connections updated cached RTT on close
                61972 connections updated cached RTT variance on close
                43499 connections updated cached ssthresh on close
        12719 embryonic connections dropped
        30767651 segments updated rtt (of 30729917 attempts)
        40866 retransmit timeouts
                675 connections dropped by rexmit timeout
        7963 persist timeouts
                3 connections dropped by persist timeout
        3116 keepalive timeouts
                1332 keepalive probes sent
                163 connections dropped by keepalive
        14195968 correct ACK header predictions
        28492503 correct data packet header predictions
udp:
        2810847 datagrams received
        0 with incomplete header
        0 with bad data length field
        0 with bad checksum
        2769059 dropped due to no socket
        5124 broadcast/multicast datagrams dropped due to no socket
        0 dropped due to full socket buffers
        0 not for hashed pcb
        36664 delivered
        2805863 datagrams output
             
$ pstat -T
1932/8040 files
   3763 vnodes
16M/139M swap space



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