Le 22/02/2012 04:27, Philip Prindeville a écrit :
> On 2/21/12 3:21 PM, Oliver wrote:
>> On Tuesday 21 Feb 2012 22:19:19 Etienne Champetier wrote:
>>> A plausible example:
>>> First default route: optical fiber (MTU 1500)
>>> Second default route: pppoe (MTU 1492) (failover link)
>>> If the optical fiber goes down, the traffic from the router will pass
>>> through the PPPoE link, but with a MSS set to 1500-40 instead of 1492-40
>>>
>> Presuming, for a moment that you are multihomed and actually have the same
>> IP usable on either interface (because, if you don't, your problem isn't
>> the MSS) the correct solution is for the router to drop the oversized
>> packet and send back an ICMP Fragmentation Needed/ICMPv6 Packet Too Big to
>> the original sender who will then reduce the transfer size and sliding
>> window accordingly.
>>
>> TCPMSS is ONLY ever needed for cases where someone criminally braindead is
>> filtering the ICMP mentioned above, as I believe the manpage states.
> There are also a lot of routers out there that *still* don't do PMTU correct
> ('still', because I worked on the standard more than 20 years ago).
>
> -Philip
As i understand it, if you're multihomed (packet load balancing), you need an
AS number, BGP ..., so maybe you have the skills to had the clamping you self,
and i'm not sure it's very common.
The multiwan package is for the case case that you have multiple wan with
multiple ip address, to do connexion load balancing
What i wanted to do is to put the MSS clamping in POSTROUTING because i see no
cons, only pros
Etienne Champetier
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