Re: NANOG Digest, Vol 90, Issue 1

["Roland Dobbins" <rdobbins () arbor net>]

On 8 Jul 2015, at 21:26, Ramy Hashish wrote:

> I am very happy because somebody is on the same page.

This is not what you were asking about in your original post on this 
topic - you were talking about BGP sessions inside GRE tunnels, which is 
not how most (any?) DDoS mitigation services operate, to my knowledge.

GRE is used over the Internet for many different applications, including 
post-DDoS-mitigation re-injection of legitimate traffic onwards to the 
server/services under protection.  Hardware-based GRE processing is 
required on both ends for anything other than trivial speeds; in 
general, the day of software-based Internet routers is long gone, and 
any organization still running software-based routers on their 
transit/peering edge is at risk.

DDoS mitigation providers using GRE for re-injection should set the MTU 
on their mitigation center diversion interfaces to 1476, and 
MSS-clamping on those same interfaces to 1436, as a matter of course.

This is not a new model; it has been extant for many years.  There are a 
variety of overlay and transit-focused DDoS mitigation service providers 
who utilize this model.  In your original post on this topic, you also 
made the assertion that these issues had not been addressed by DDoS 
mitigation service operators; that assertion is incorrect.

-----------------------------------
Roland Dobbins <rdobbins () arbor net>