[ixpmanager] Migration to another IPv4 range

[Nick Hilliard (INEX)]

aleksandr at speed-ix.net wrote on 29/10/2021 15:37:
> The biggest problem from our point of view is the migration of members. 
> As soon as the first member will change their setting to use new IPs 
> (RouteServers, Collectors, etc) they will not be able to exchange 
> traffic with other members and the traffic of this member will be gone 
> from IXP till the rest will do changes. Otherwise, they must keep 
> sessions with old RouteServers till all members will migrate to the new IPs.

yeah, this is the way it is. There are two potential work-arounds.  One 
is to keep the cut-over window as short as possible.  The less good 
option for some participants is to have 2x config on their routers. 
Honestly, this is a nuisance and causes a lot of unnecessary 
complication, so we don't really recommend it.

We had a cut-over window of 5d, but in retrospect this was probably too 
long for the 90 members at the time. Incidentally, once the cut-over 
window was completed, we implemented hardware filters on all edge ports 
to block BGP sessions on the old IP addresses, and then manually engaged 
with the handful of remaining ports that were still using the old 
addresses to get them to update their configs.  It was a lot of work 
over the couple of days, but short and sharp was good overall.

Nick