Time to add 2002::/16 to bogon filters?

Gary McArtor gmcartor at cymru.com
Fri Jul 6 14:43:29 UTC 2018

Hi Youssef,

My original reply wasn't sent to the Nanog list.

Team Cymru considers 2002::/16  and  to be legitimate
prefixes at this time, and will be not be adding them to our bogon
filters.  Our interpretation of the 6to4 anycast rfc is that while these
are encouraged to be made obsolete, in practice they may still be in
use, excluding them from being universally defined as a bogon in our feed.

The RFC in question:

The rule, as it always should be, is to know your network, and know what
is best for it.  As noted in the RFC you are encouraged to review any
current deployments and any existing filtering and adjust based on your
own discretion.


Gary McArtor
Team Cymru

On 6/28/18 2:32 PM, Rabbi Rob Thomas wrote:
> FYI, the question has been raised.  I'm not sure if this is wise or not.
>  Gary, what are your thoughts?
> -------- Forwarded Message --------
> Subject: Re: Time to add 2002::/16 to bogon filters?
> Date: Thu, 28 Jun 2018 21:11:22 +0200
> From: Youssef Bengelloun-Zahr <bengelly at gmail.com>
> To: Job Snijders <job at ntt.net>
> CC: NANOG [nanog at nanog.org] <nanog at nanog.org>
> Hello Job,
> Thank you for this feedback. I guess that NTT adopting this as a best
> practice will ring some bells around.
> Do you know if Team Cymru has updated their filters accordingly ?
> Best regards.
>> Le 28 juin 2018 à 20:58, Job Snijders <job at ntt.net> a écrit :
>> Dear alll,
>> Thank you all for your input. Just a heads-up - we deployed a few days ago.
>> NTT / AS 2914 now considers “2002::/16 le 128” and “ le 32”
>> to be bogon prefixes, and no longer accepts announcements for these
>> destinations from any EBGP neighbor.
>> Kind regards,
>> Job

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