[AusNOG] PMTUD was -> RE: GRE Tunnel MTU suggestions

[Paul Gear]

On 07/02/2014 09:55 AM, Alex Samad - Yieldbroker wrote:
> ...
> {snip}
>> PMTUD is better to use, MSS adjusting is a TCP specific hack. Don't switch it
>> on unless you need to because PMTUD is broken.
>
> How broken is PMTUD now, I remember back in the day diagnosing a lot of DSL connection that failed because of this.

After my experiences earlier in the year [1], I came to the conclusion 
that PMTUD is always broken, and turned on TCP MSS clamping on all our 
edge routers.

Paul

[1] http://lists.ausnog.net/pipermail/ausnog/2014-February/022606.html