Tips for TCP/IP monitoring and tuning to make your network sing
Q: Which of the TCP protocol counters are worth watching? How can I
tell if there is a problem, and what should I tune?
--Fin_wait Freda
A: TCP/IP is simple in concept, but the reality of making it work reliably
in a wide range of conditions adds a lot more complexity. There are a
large number of protocol counters that can be viewed with netstat, but only a small number of them are of general interest.
-s
There is another set of values that can be obtained and set using the
ndd command.
The netstat -s command lists several protocols, but I just
show the TCP data that is reported by Solaris 2.5.1.
TCP tcpRtoAlgorithm = 4 tcpRtoMin = 200
tcpRtoMax = 60000 tcpMaxConn = -1
tcpActiveOpens = 3283 tcpPassiveOpens = 234
tcpAttemptFails = 0 tcpEstabResets = 100
tcpCurrEstab = 6 tcpOutSegs = 80370
tcpOutDataSegs = 57395 tcpOutDataBytes =9854298
tcpRetransSegs = 4826 tcpRetransBytes =644526
tcpOutAck = 23486 tcpOutAckDelayed = 5081
tcpOutUrg = 34 tcpOutWinUpdate = 3
tcpOutWinProbe = 5 tcpOutControl = 7066
tcpOutRsts = 132 tcpOutFastRetrans = 196
tcpInSegs = 96006
tcpInAckSegs = 52302 tcpInAckBytes =9856462
tcpInDupAck = 9887 tcpInAckUnsent = 0
tcpInInorderSegs = 63348 tcpInInorderBytes =20318851
tcpInUnorderSegs = 0 tcpInUnorderBytes = 0
tcpInDupSegs = 0 tcpInDupBytes = 0
tcpInPartDupSegs = 0 tcpInPartDupBytes = 0
tcpInPastWinSegs = 0 tcpInPastWinBytes = 0
tcpInWinProbe = 6 tcpInWinUpdate = 4
tcpInClosed = 15 tcpRttNoUpdate = 1286
tcpRttUpdate = 20744 tcpTimRetrans = 1514
tcpTimRetransDrop = 0 tcpTimKeepalive = 168
tcpTimKeepaliveProbe= 0 tcpTimKeepaliveDrop = 0
tcpListenDrop = 0
To make sense of this, and to pick out the data of interest, I'll
start with a simplified description of TCP, and relate this to the data
reported by netstat -s.
TCP is a reliable, connection-oriented protocol.
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