LARTC - Feb 2002 - TCP MSS clampage

Hey,

My internet is provided via ADSL using PPPoE. When I take a look at 
ifconfig''s output, I see that eth0 has an MTU of 1500, and ppp0 has an
MTU
of 1492. I don''t _think_ that rp-pppoe (my pppoe util) is clamping the
MSS.
I am noticing some latency when there''s a lot of bandwidth in use (but
not
 >90%). What should I clamp, eth0/ppp0? How much? And what with, rp-pppoe, 
or tc/iproute2/etc ?  I guess I don''t really understand clamping MSS,
can
someone explain it in laymans terms? I have read the lartc-FAQ, and the only 
time I see clamping-MSS mentioned is section 15.7, which doesn''t really
explain why you''d do it.

Apologies if M$ makes this email look squonky in any way.

Thanks,

Tim Carr

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On Thu, Feb 28, 2002 at 04:02:54PM +0000, Tim Carr
wrote:
> Hey,
> 
> My internet is provided via ADSL using PPPoE. When I take a look at 
> ifconfig''s output, I see that eth0 has an MTU of 1500, and ppp0
has an MTU
> of 1492. I don''t _think_ that rp-pppoe (my pppoe util) is clamping
the MSS.
> I am noticing some latency when there''s a lot of bandwidth in use
(but not
Don''t think, meassure :-)
>  >90%). What should I clamp, eth0/ppp0? How much? And what with,
rp-pppoe,
> or tc/iproute2/etc ?  I guess I don''t really understand clamping
MSS, can
> someone explain it in laymans terms? I have read the lartc-FAQ, and the
only
> time I see clamping-MSS mentioned is section 15.7, which doesn''t
really
> explain why you''d do it.
If you don''t experience any problems then by all means do not tcp
clamp.
rp-pppoe comes with wonderful documentation, I suggest you read it :-)

Regards,

bert

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