[e2e] IP options inserted in transit

Angelo Dell'Aera buffer at antifork.org
Sat Aug 9 09:23:39 PDT 2003

Hash: SHA1

On Sat, 9 Aug 2003 11:34:03 -0400
RJ Atkinson <rja at extremenetworks.com> wrote:

>On Friday, Aug 8, 2003, at 19:40 America/Montreal, Angelo Dell'Aera 
>> I don't agree. Letting intermediate routers adding/deleting IP options
>> on-the-fly means  just losing   performance. If a  router is  asked to
>> modify every IP header (whose size could be variable), it will waste a
>> lot of time searching where it's  possible to add one or more bytes or
>> which bytes to remove.
>This is untrue, particularly for well-designed routers.
>So far, I don't see any reason to add such an IP option on the fly,
>but it is not hard to do in a well-designed ASIC-based router.
>One does have to have very good Verilog designers, of course.

I agree that it's possible to design routers in such a way as to do it
but if the router is called to parse every packet searching for 
on-the-fly added IP options (and this means it is called to parse what 
is beyond the IP header searching for "something useful"), this will 
cause a loss of performance. Maybe, it will be a little loss but you 
should agree with me that the router will need more time for the single 
packet processing. 

Moreover, I completely agree with you when you say you find no reason
for doing it. 


- --

Angelo Dell'Aera 'buffer' 
Antifork Research, Inc.	  	http://buffer.antifork.org

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