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Re: [eng/rtg][vendor specific] changing loopbacks
- From: Warren Kumari
- Date: Thu Sep 29 16:08:19 2005
So, on vendor C boxes you might be able to get away from having to do
a full reboot to change your OSPF ID by doing a "clear ip ospf process".
If you don't do this, even though you change the loopback address,
your router will still keep the old address as the OSPF router ID[1].
You won't actually end up with a route to the old loopback, but it
will still be in the OSPF database.
While this is less than optimal, it will still work (note, I don't
recommend running your network like this!). It is somewhat
disconcerting if you don't know that changing loopback address
doesn't automatically change OSPF ID[2] and look in your OSPF
database and see addresses that you shouldn't / you retired, etc,
especially because most people only page through their OSPF database
when they suspect something is odd...
Warren Kumari
[1] As with most things, I am sure that the exact behavior depends
upon hardware and software version, phase of moon, flavor of
doughnut, etc.
[2] Sure it seem obvious when you thin about it, but most people
don't seem to think.
On Sep 29, 2005, at 12:20 PM, Neil J. McRae wrote:
this is my fear. which is why i asked. pushing out new
configs (the canonic config is on disk, not the router [0])
and setting a reload of a bunch of routers at time t0 does
not give me warm fuzzies about what the world will be like at
time tn (n > 0).
but i may have to take that path. i am hoping folk will give
me a magic pill. after all, any group with such a deep
understanding of how to deal with the world's social ills
must know a bit of router magic <smirk>.
I think with OSPF this will be very difficult to
do without rebooting (or as long an outage as rebooting).
We migrated from OSPF to IS-IS and changed some loopbacks a
while ago, the IS-IS change was totally transparent - no issue,
but on the change of loopback caused a lot of BGP churn.
It was easier to change it and reboot and do
it over a period of time in small network triangles.
I always thought that the billing system was the database
of record ;-)
Neil.
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