[637] in Info-AFS_Redistribution
udp_cksum on Sun
daemon@ATHENA.MIT.EDU (Dan_Hamel@transarc.com)
Fri Feb 28 19:33:29 1992
Date: Fri, 28 Feb 1992 17:15:59 -0500 (GMT)
From: Dan_Hamel@transarc.com
To: Info-AFS@transarc.com
While monitoring network traffic, I noticed that udp packets originating
from Sun platforms were not doing udp cksums. Further checking showed that
the default behavior for Sun machines is to have udp_cksum disabled.
AFS only does checksums on the RX packet header, not on the data in
the packet. This means that if either the AFS server or client machine
is a Sun, cksum's will be ignored during data transfers, possibly
resulting in file corruption. Other AFS-supported platforms have
udp_cksum enabled as a default.
Transarc recommends that udp_cksum be enabled on all Sun AFS servers and
clients to protect data integrity. To enable udp_cksum, you'll need to
modify both the memory and core image of the kernel using a debugger. The
following instructions will accomplish both tasks:
# adb -w -k /vmunix /dev/mem
udp_cksum/W 1
udp_cksum?W 1
^D
AFS 3.2 will include changes to client software to enable udp_cksum during
initialization. However, server machines that are not running the client
software will require the above change to the kernel to enable udp_cksum.
If you have any questions, please contact your Product Support representative
for more information.
Dan Hamel
Product Support Specialist
Transarc Corporation
