[v6ops] Re: Dynamic addresses

[David Farmer <[e-mail]>]

On Fri, Aug 16, 2024 at 05:45 <[e-mail]> wrote:

> Hi,
>
> *Von:* Daryll Swer <contact=[e-mail]>
> *Gesendet:* Montag, 12. August 2024 06:07
> *An:* Brian Candler <[e-mail]>
> *Cc:* The Multach's <[e-mail]>; [e-mail]
> *Betreff:* [v6ops] Re: Dynamic addresses
>
> Getting a new IPv4/IPv6 allocation on session disconnect and reconnect
> is a matter of network design.  If the network design is that aggregate
> address pools are routed to BRASes, and the end user's address is
> allocated by the BRAS from its pool, then when you reconnect to a
> different BRAS you'll get a different address. So be it.
>
> > Yeah, they/we typically route an aggregate pool to the BRAS/BNG. But
> also,
>
> > they are configured in HA mode with VRRP etc and the pools do not
> change.
> > If they did change, we now have the problem with connectivity stability
> again,
>
> > and this brings up the old conversation about DHCPv6 HA (vendors solved
> it,
>
> > to my knowledge, using proprietary software).
>
> That’s what we are doing as well. We aggregate on the BNG and assign
> addresses
> (IPv4 and IPv6) from the address pools of the BNG. For residential users
> those addresses are dynamic.
>
>
>
> For business customers requiring a static address/prefix we backhaul them
> to a different set of BNGs providing static addresses. Those BNGs have
> their own pools for static assignments and allow to use the same, static
> address
> even in case users are moving within our network (e.g., from one city to
> another city).
>

On one level, this seems reasonable; static customers pay more for the
extra backhaul service to different BNGs with static pools. I understand
that, and it appears acceptable to me.

Regular customer addresses can change, and that's acceptable on one level.
But how often do they change, and what triggers these changes? Is it simply
due to rebooting and acquiring new addresses with each reboot? Or does it
occur during customer rebalancing events, where the BNGs for some customers
are changed, probably in an overnight change window? I'd like to know the
frequency.

While you can change their addresses, even regular customers deserve care
and stability. Their addresses shouldn’t be altered haphazardly, too
frequently, or unnecessarily.

With my ISP, when I reboot, I usually get the same address. However, my
address changes occasionally, I estimate once or twice a year. It is
primarily stable but changes infrequently, which seems reasonable to me.

There likely needs to be a service distinction between the statically
addressed business class and the dynamically addressed consumer class
customers. But there is a difference between a dynamic where addresses are
changed occasionally, like once a month or less, and a crazy dynamic where
addresses are changed haphazardly on every reboot or an overly frequent
basis, like every few hours or daily.

Thanks.