[HECnet] Need help with DECnet routing

[Paul Koning]

"Brett" == Brett Bump <bbump at rsts.org> writes:

Brett> Marc you might also double check your cabling (in fact even
Brett> change them).   As I recall, DECnet (like IPX) is not an error
Brett> correcting protocol.   I've worked on networks where TCP will
Brett> error correct for poor cabling while the Novell connections
Brett> fell flat on their faces.   This could explain why your IP
Brett> connection seems to work fine, but you have no DECnet
Brett> connectivity.

That seems strange.

DECnet (NSP) is just like TCP in that it handles lost packets.   Bad
cables will produce lost packets but they will not produce corrupted
packets.   Corrupted packets are caused by defective switches or
routers.   Bad cables only cause CRC errors.   (Well, except for the
EXTREMELY low probability of a random error getting past the Ethernet
CRC.) 

You're right that TCP detects corrupted packets (some of them, anyway
-- TCP checksum is pretty weak) while NSP does not.   But if you see
TCP checksum errors, the way to fix them is not to change the cabling,
but the defective switches/routers.

      paul