[afnog] A heads up on a nasty IPv6 bug

[Andrew Alston]

On the static stuff, it depends how you do it.

If you are automatically allocating usernames for PPPoE authentication its relatively simple to tie that username provisioning to static assignments.

As an example, if your username ends in a numeric on your auto provisioning system its relatively simple to use some basic maths and hex conversion to produce a static subnet that’s tied.

With regards to the subnet issue on the RA, I’ll respond to that later, though perhaps Jan would also like to make some comments on this, since his understanding of it is admittedly better than mine until I do more testing and labbing

Andrew


From: "Mukom Akong T." <mukom.tamon at gmail.com>
Date: Sunday, 14 August 2016 at 5:32 PM
To: Andrew Alston <Andrew.Alston at liquidtelecom.com>
Cc: Mark Tinka <mark.tinka at seacom.mu>, "afnog at afnog.org" <afnog at afnog.org>
Subject: Re: [afnog] A heads up on a nasty IPv6 bug


On 14 August 2016 at 12:54, Andrew Alston <Andrew.Alston at liquidtelecom.com<mailto:Andrew.Alston at liquidtelecom.com>> wrote:
Particularly if you are doing a DHCPv6-PD and then grabbing a segment of the PD to assign to the LAN interface which in turn does RA.  Because if the client reconnects and gets a new DHCPv6-PD segment, and the RA then changes towards the client, the client ends up with two v6 subnets and two gateways until the RA expires,


I can understand why it gets a new address. Unsure why it will get a second gateway considering that both RAs came from the same router thus same link local address that's a default gateway candidate. Can you shed more light on what the two different default gateways?



The general consensus that I’m seeing elsewhere is that when doing v6 to the mass market, static is better and full of far less problems, and that’s what we’re switching to now with a provisioning system, so v6 prefix to every client will be static.


do you mean in lieu of DHCPv6-PD?

With static prefix, then all CPE provision on the client network will also need to be manually done (or scripted somehow) which limits scalability right







--

Mukom Akong T.

LinkedIn:Mukom<https://www.linkedin.com/in/mukom>  |  twitter: @perfexcellent
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