Re: Van J compression?

Andi Kleen (ak@muc.de)
03 Jan 1999 17:04:52 +0100


In article <19990103052709.B2843@tantalophile.demon.co.uk>,
lkd@tantalophile.demon.co.uk (Jamie Lokier) writes:

> But bear in mind that disabling VJ compression doesn't fix the problem
> in some cases. (Though it makes the problem rarer). At least one PPP
> link over a modem to an ISP gets consecutive TCPv4 checksum errors even
> with `novj'.

Sometimes hard discs screw up (that is why do backups and RAID if you care
about your data), sometimes network cable/gateways/systems corrupt packets.

Given the current state of cheap computer hardware and cables it is surprising
that it only happens with a few ISPs. In short: computer networks are
unreliable, bit errors are nothing uncommon even for end2end networks
that have other checksums and you have to accept that sometimes a packet
gets mangled. That is why TCP has a end2end checksum.

All standards say that packets with wrong checksum should be silently dropped,
2.2 will do that and turn off that debugging, I repeat, debugging message.

-Andi

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