[c-nsp] "perform tcp half close" option in IOS ttcp implementation

Martin T m4rtntns at gmail.com
Fri Dec 12 11:45:05 EST 2014


in Cisco IOS ttcp(Test TCP) utility implementation there is a "perform
tcp half close" option both in case utility works in transmit mode or
receive mode. If "perform tcp half close" is enabled in receive mode,
it will enable following options in ttcp interactive user-interface
besides the ones which are shown if "perform tcp half close" is

send buflen [8192]:
send nbuf [2048]:
buffering on writes [y]:

If "perform tcp half close" is enabled in transmit mode, then options
below are added to usual ones:

receive buflen [8192]:
rcvwndsize [4128]:
delayed ACK [y]:

As far as I know, TCP half-close is a state where one of the hosts
sends an ACK to FIN packet received, but doesn't send the FIN itself
and thus keeps the TCP connection half-closed. How to understand this
"tcp half close" in IOS ttcp? Is it some sort of bidirectional test?
If yes, then what is the association with TCP half-closed connection?


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