Subject: Problems in changing router's name

From: "[email-masked]" <[email-masked]>
Date: Wed, 16 Apr 2003 17:50:35 +0200

Hi all,
i wanted to refer to a potential problem in a network:
in a MPLS scenario using RSVP and OSPF protocols, 
could it happen this situation?

EXAMPLE: router R1 has interfaces
eth0 x.y.100.2
eth1 x.y.150.2
eth2 x.y.200.2
Suppose OSPF and ZEBRA running in all the net except R1.

When ZEBRA and OSPF daemons start in R1, after a certain period 
the net will know R1 with the name x.y.200.2 
(I think with ZEBRA it's so, isn't it?).

If R1 is a router Cisco, Juniper, ecc, is it possible
that interface eth2 disappears and eth0, eth1 continue their job? 
( for example system administrator could deactivate by operating system the eth2? ).

In Rfc2328 cap 5 is said that if the smallest interface (router ID; in ZEBRA i
saw that router ID was the HIGHEST interface! Is it possible or am i mistaking?)
goes down, router ID changes and OSPF software should be restarted before
new router ID takes effect. 

Again, in draft-katz-yeung-ospf-traffic-09.txt  2.4.1 is said that Router address TLV 
contains a "stable" IP address of the advertising router that is always reachable!
Stable means that IP address router doesn't change? But if i disable the interface
that names a Linux router, OSPF could update the topology or could
maintain the old router name even if that interface is down.

I think there will be this situation if eth2 becomes disabled: since R1 eth2 was the
highest R1 interface, after some seconds, router x.y.200.2 will disappear
and an new router will appear (x.y.150.2)!

Now the potential problem: what could it happen to LSPs not using eth2
on R1, but using eth0 or eth1? In their ERO (explicit route object)
there is the first R1 name: x.y.200.2; if these LSPs remain active, the ERO
will not change and after some seconds we have no more a x.y.200.2 router in the net!

RSVP will continue the refresh?
OSPF will change the routing tables to contain x.y.150.2, but the ERO of
each LPS for R1 will continue having x.y.200.2!

Thanks in advance for your kind answers and observations