Messages in this thread | | | Date | Sat, 05 Jun 1999 00:06:53 +0930 | From | Glen Turner <> | Subject | Re: zero-copy TCP fileserving |
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"Richard B. Johnson" wrote: > I heard that at one time Sun didn't bother to checksum packets that > arrived via Ethernet. I don't know if it's true.
Traditional SunOS didn't generate checksums on UDP packets. This was a hack to make NFS faster.
What it also did was occassionally allow corrupt DNS responses not to be detected. And because the DNS requestor would cache the response, that corruption couldn't be recovered from until the DNS TTL (usually 1-10 days, 3 recommended) had expired.
This was a real problem in Australia, where we had a DNS forwarder on the Australia side of the AU--US link to reduce traffic on the link. Ditto most other non-US countries.
To give you idea of the scope of the problem, the NANOG mailing list cooperated in tracking down all the machines running DNS name servers with UDP checksumming disabled and e-mailed the NS contact.
Please don't take us back to those days. I suspect the problem would now be insoluble, because of the huge number of Internetworked machines, the increased amount of spam and the decreased clue of DNS administrators.
Cheers, glen
-- Glen Turner Network Specialist Tel: (08) 8303 3936 Information Technology Services Fax: (08) 8303 4400 The University of Adelaide 5005 Email: glen.turner@adelaide.edu.au South Australia
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