[clug] MTU and webserving

Alex Satrapa grail at goldweb.com.au
Fri May 2 19:35:12 EST 2003

On Friday, May 2, 2003, at 02:28 , Andrew Donehue wrote:

> If I lowered the MTU settings on a webserver - would that in theory 
> allow users to view webpages on it okay (and retrieve DNS info from it)?

If the problem being experienced is due to "Must Fragment" ICMP messages 
being dropped, then yes, this will likely solve the problem.  An MTU as 
low as 1400 is likely to work too, and will provide a slightly higher 
data:overhead ratio.

Note that the problem might be caused by a network somewhere in the 
middle of nowhere - you'll have to experiment to find what setting makes 
life easiest for you and your clients.

>   -  (And would there be any real performance issues on the webserver, 
> I would set the MTU to 1300)

Yes and no - since you're limiting the maximum payload per packet, 
you're likely to see an increase (of about 1/15) in the CPU load 
required to process TCP connections, and a slight increase in overall 

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