[v6ops] Re: Dynamic addresses

[[e-mail]]

Hi,

In our case new addresses are re-assigned (changed) in case the CPE disconnects from the network.
This can be either caused by reboot, link failures, within a maintenance window, you name it… In addition
some of the CPEs offer the option to change IP addresses regularly (e.g., once a day) for privacy reasons.
Besides that, the addresses are stable. If there is no reconnect and/or privacy feature active they
will change once or twice a year.

regards

Nic

Von: David Farmer <[e-mail]>
Gesendet: Freitag, 16. August 2024 16:46
An: Leymann, Nicolai <[e-mail]>
Cc: contact=[e-mail]; [e-mail]; [e-mail]; [e-mail]
Betreff: Re: [v6ops] Re: Dynamic addresses


On Fri, Aug 16, 2024 at 05:45 <[e-mail]<mailto:[e-mail]>> wrote:
Hi,
Von: Daryll Swer <contact=[e-mail]<mailto:[e-mail]>>
Gesendet: Montag, 12. August 2024 06:07
An: Brian Candler <[e-mail]<mailto:[e-mail]>>
Cc: The Multach's <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[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.