Cogent BCP-38

Mike Hammett nanog at
Thu Aug 17 11:35:50 UTC 2017

Strict vs. loose. 

Mike Hammett 
Intelligent Computing Solutions 


----- Original Message -----

From: "Mikael Abrahamsson" <swmike at> 
To: "chris" <tknchris at> 
Cc: "NANOG list" <nanog at> 
Sent: Thursday, August 17, 2017 1:27:17 AM 
Subject: Re: Cogent BCP-38 

On Thu, 17 Aug 2017, chris wrote: 

> Time for someone to bake them a bcp38 cake .... 

I am all for people deploying BCP38, but from the original email this is 
definitely not a cause for celebration. BCP38 should be used against 
single homed customers only if you're doing it by using uRPF. Otherwise 
extreme care needs to be taken to make sure traffic isn't dropped because 
uRPF does the wrong thing (like it seems in this case). 

Mikael Abrahamsson email: swmike at 

More information about the NANOG mailing list