ADSM-L

Why does ADSM use 536-byte data packets?

1995-11-20 04:38:39
Subject: Why does ADSM use 536-byte data packets?
From: Andy Raibeck <raibeck AT CONNIX DOT COM>
Date: Mon, 20 Nov 1995 14:38:39 +0500
Using a Sniffer, we've noticed that ADSM sends out packets, typically 598 or
604 bytes in size. When we look at the packet in greater detail, the actual
data portion is 536 bytes, with the remainder being protocol headers (LLC,
DLC, IP, SNAP, etc.). This strikes me as a major bottleneck; that if I could
send a smaller number of larger packets, I could improve performance by quite
a bit (potentially). Oh, BTW I'm using TCP/IP for connectivity to an ADSM/MVS
server.

I use TCPBUFFSIZE 32 and TCPWINDOWSIZE 24, which are the only tuning options
available in ADSM itself (for TCP/IP). IBM Level 2 tells me that the sizes
must be set somewhere in the network or network card.

Has anyone noticed this, and if so, can anything be done about it? I've seen
this for NetWare and AIX. I haven't sniffed my other client types yet, but
I believe I'd probably find something similar.

Any help would be appreciated.

Thanks,

Andy Raibeck
Connecticut Mutual
203-987-3521
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