[nsp] TTCP doubt

From: Cybelle Suemi Oda Oyama (cybelle@rnp.br)
Date: Thu Apr 18 2002 - 09:40:24 EDT


Hi,

I am trying to discover if I´m having packet loss between 2 sites. At one
site(A) I have GSR12000 and at other site (B) I have a 7507, connected through
an ATM cloud. Using ping command from (B)->(A) I get 10% packet loss, but from
(A)->(B) it doesn´t happen. Since ping is not such reliable, I´m using ttcp
command in order to generate a 512 kb data traffic. But I got some doubts:
which ttcp parameters to choose (I used the defaults value) and what is the
correct output interpretation. I mean, I just have to look at ttcp-t and
ttcp-r values? I´m copying the outputs that I got below. Thanks for
any help.

        Cybelle

c12000#ttcp
transmit or receive [receive]: transmit
Target IP address: x.x.x.x
perform tcp half close [n]:
send buflen [8192]:
send nbuf [2048]: 8
bufalign [16384]:
bufoffset [0]:
port [5001]:
sinkmode [y]:
buffering on writes [y]:
show tcp information at end [n]: y

ttcp-t: buflen=8192, nbuf=8, align=16384/0, port=5001 tcp -> y.y.y.y
ttcp-t: connect (mss 536, sndwnd 4128, rcvwnd 4288)
ttcp-t: 65536 bytes in 3480 ms (3.480 real seconds) (~17 kB/s) +++
^^^^^^^
ttcp-t: 8 I/O calls
ttcp-t: 0 sleeps (0 ms total) (0 ms average)
Connection state is ESTAB, I/O status: 1, unread input bytes: 0

Enqueued packets for retransmit: 7, input: 0 mis-ordered: 0 (0 bytes)

Event Timers (current time is 0x1192BE388):
Timer Starts Wakeups Next
Retrans 106 0 0x1192BE50F
TimeWait 0 0 0x0
AckHold 0 0 0x0
SendWnd 0 0 0x0
KeepAlive 0 0 0x0
GiveUp 0 0 0x0
PmtuAger 0 0 0x0
DeadWait 0 0 0x0

iss: 2397725955 snduna: 2397788124 sndnxt: 2397791492 sndwnd: 4128
irs: 3113508542 rcvnxt: 3113508543 rcvwnd: 4288 delrcvwnd: 0

SRTT: 300 ms, RTTO: 607 ms, RTV: 3 ms, KRTT: 0 ms
minRTT: 152 ms, maxRTT: 300 ms, ACK hold: 200 ms
Flags: higher precedence, retransmission timeout

Datagrams (max data segment is 536 bytes):
Rcvd: 115 (out of order: 0), with data: 0, total data bytes: 0
^^^^
Sent: 130 (retransmit: 0), with data: 128, total data bytes: 65536
^^^^

c7507#ttcp
transmit or receive [receive]:
perform tcp half close [n]:
receive buflen [8192]:
bufalign [16384]:
bufoffset [0]:
port [5001]:
sinkmode [y]:
rcvwndsize [4128]:
delayed ACK [y]:
show tcp information at end [n]: y

ttcp-r: buflen=8192, align=16384/0, port=5001
rcvwndsize=4128, delayedack=yes tcp
ttcp-r: accept from x.x.x.x (mss 536, sndwnd 4288, rcvwnd 4128)
ttcp-r: 65536 bytes in 3524 ms (3.524 real seconds) (~17 kB/s) +++
^^^^^^
ttcp-r: 115 I/O calls
ttcp-r: 0 sleeps (0 ms total) (0 ms average)
Connection state is CLOSEWAIT, I/O status: 7, unread input bytes: 0

Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)

Event Timers (current time is 0xEAD322C0):
Timer Starts Wakeups Next
Retrans 1 0 0x0
TimeWait 0 0 0x0
AckHold 111 0 0x0
SendWnd 0 0 0x0
KeepAlive 0 0 0x0
GiveUp 0 0 0x0
PmtuAger 0 0 0x0
DeadWait 0 0 0x0

iss: 3113508542 snduna: 3113508543 sndnxt: 3113508543 sndwnd: 4288
irs: 2397725955 rcvnxt: 2397791493 rcvwnd: 3976 delrcvwnd: 152

SRTT: 37 ms, RTTO: 1837 ms, RTV: 1800 ms, KRTT: 0 ms
minRTT: 188 ms, maxRTT: 300 ms, ACK hold: 200 ms
Flags: passive open, retransmission timeout, nagle, gen tcbs

Datagrams (max data segment is 536 bytes):
Rcvd: 131 (out of order: 0), with data: 128, total data bytes: 65536
^^^^
Sent: 122 (retransmit: 0, fastretransmit: 0), with data: 0, total data bytes: 0
^^^^

--------------------------------------------------------------
Cybelle Suemi Oda Oyama cybelle@rnp.br
Centro de Engenharia e Operacoes Fone: +55 19 3787-3300
Rede Nacional de Pesquisa Fax : +55 19 3787-3301
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