The IP over ATM Mailing List Archive by date

["Brian Carpenter CERN-CN" <brian@dxcoms.cern.ch>]

Pat,

It's a fundamental principle of the Internet that end systems
must not trust the network and must do their own accuracy,
confidentiality and authenticity checks. Whether it's TCP
or any other upper layer protocol, and whether it's ATM
or any other lower layer, the answer to your proposal
is the same: no, it is not safe.

See "End-To-End Arguments in System Design", J.H. Saltzer,
D.P.Reed, D.D.Clark, ACM TOCS, Vol 2, Number 4, November 1984, pp 277-288.

     Brian Carpenter

>--------- Text sent by Pat Medved follows:
> 
> 
> 
> The AAL5 specification calls for AAL5 to do a CRC for each cell.
> With this being done, and the fact that lines today
> are better than when TCP was first implemented, is there
> still a need to do a checksum in TCP when running over ATM?
> 
> I was wondering if most people think not doing the checksum
> would be safe.
> 
> I could see an option to TCP where as part of
> negotiation, we negotiate whether or not to do checksums.
> This would save on one of the biggest CPU users in
> TCP/IP processing.
> 
> Any comments or reasons why this should not be done?
> 
> 
> Pat Medved
> 
> medved@npr.legent.com
> 
> 
>