Dave,

I've been working on a TCP session monitor.   It reports MB/Second +
changes to the TCP parameters, such as change in window size, buffer size
etc. all of which affect throughput.

I can let you have a copy of the program if you are interested.
[email protected]

it reports
//SYSPRINT
Using --PORT 22 --SLEEP 10 --COUNT 10 --TCPIP TCPIP

HH:MM:SS,remote         ,BytesI,BytesO,,SegsI ,
SegsO,,BI/Sec,BO/Sec,,ReXmtC,
08:33:23,10.1.0.2:41984 ,     0,     0,,     0,     0,,     0,     0,,
0,
08:33:23,10.1.0.2:55554 ,   676, 45832,,    54,    63,,    67,  4583,,
0,
08:33:33,10.1.0.2:41984 ,     0,     0,,     0,     0,,     0,     0,,
0,
08:33:33,10.1.0.2:55554 ,    52, 27452,,    15,    28,,     5,  2745,,
0,
08:33:43,10.1.0.2:55554 ,     0,     0,,     0,     0,,     0,     0,,
0,
Freeing entry 10.1.0.2:41984

08:33:53,10.1.0.2:37728 ,   156,  1164,,    14,    11,,    15,   116,,
0,
08:33:53,10.1.0.2:55554 ,     0,     0,,     0,     0,,     0,     0,,
0,
08:34:04,10.1.0.2:37728 ,   416, 71932,,    50,    77,,    37,  6539,,
0,
08:34:04,10.1.0.2:55554 ,     0,     0,,     0,     0,,     0,     0,,
0,
08:34:14,10.1.0.2:37728 ,     0,     0,,     0,     0,,     0,     0,,
0,
08:34:14,10.1.0.2:55554 ,     0,     0,,     0,     0,,     0,     0,,
0,
08:34:24,10.1.0.2:37728 ,     0,     0,,     0,     0,,     0,     0,,
0,
08:34:24,10.1.0.2:55554 ,     0,     0,,     0,     0,,     0,     0,,
0,
08:34:34,10.1.0.2:37728 ,     0,     0,,     0,     0,,     0,     0,,
0,
08:34:34,10.1.0.2:55554 ,     0,     0,,     0,     0,,     0,     0,,
0,

The first time the program sees a connection it dumps out
10.1.0.2:41984  JOBNAME SSHD4     Interface TAP0

10.1.0.2:41984       ResourceId:    45           InSegs:    37
 OutSegs:    31         SSThresh: 65535
10.1.0.2:41984      OutBuffered:     0       InBuffered:     0

10.1.0.2:41984       ReXmtCount:     0    CongestionWnd: 41760
 RoundTripTime:     4     RoundTripVar:    11
10.1.0.2:41984       SndBufSize: 65536           SndWnd: 64128
 MaxSndWnd: 64256          SendMSS:  1452
10.1.0.2:41984       RcvBufSize: 65536           RcvWnd:131020
 Lcl0WindowCount:     0  Rmt0WindowCount:     0
10.1.0.2:41984


If TCPIP parameters change, such as window size you get in //CHANGE

08:33:23 10.1.0.2:55554  NWMConnRoundTripTime n:2 - o:4 = -2

08:33:23 10.1.0.2:55554  NWMConnRoundTripVar n:2 - o:7 = -5

08:33:33 10.1.0.2:55554  NWMConnRoundTripTime n:3 - o:2 = 1

08:33:33 10.1.0.2:55554  NWMConnRoundTripVar n:3 - o:2 = 1

08:33:53 10.1.0.2:37728  NWMConnCongestionWnd n:36000 - o:20160 = 15840

08:33:53 10.1.0.2:37728  NWMConnRoundTripTime n:6 - o:10 = -4

08:33:53 10.1.0.2:37728  NWMConnRoundTripVar n:17 - o:29 = -12

08:33:53 10.1.0.2:37728  NWMConnRcvWnd n:131020 - o:130176 = 844


On Thu, 28 Mar 2024 at 12:31, Jousma, David <
[email protected]> wrote:

> All,
>
> Grasping at straws here, IBM support center is baffled too.
>
> To clone z/OS maintenance to various disconnected sysplex’s I do a DFDSS
> dump, and FTP it everywhere it needs to be.  Its roughly a 50Gb file
> transfer.  There is some environmental issue causing slow file transfers to
> some systems (40mb’s a sec) and fast file transfers (150Mb/sec) to other
> systems on the same CEC.    With IBM support help, we’ve narrowed down the
> problem to the specification of MODE B and EBCDIC on the transfer since it
> is a DSS dump.   Remove those, and the transfer is fast on the slow
> systems, and still fast on the fast systems.  Obviously that isn’t a
> solution though.
>
> So, we are a GDPS shop.   The oddity is that all the “fast” transfers are
> to the K systems(control systems), and all the “slow” transfers are to the
> traditional application systems.   TEST, DEV, PROD makes no difference, nor
> does LPAR busy or not busy.
>
> It seems there is something configured differently on the “slow” systems
> that is affecting mode b, ebcdic file transfers, but for the life of me, I
> cannot put my finger on what, nor can the support center, except that the
> issue is at the remote end, in that the OS cannot offload the data fast
> enough, so TCPIP/FTP is slowing the transfer pace.
>
> A virtual adult beverage of choice to the one that can point in a
> direction to look….
>
>
> Dave Jousma
> Vice President | Director, Technology Engineering
>
>
>
>
>
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  • Slo... Jousma, David
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