Redistribution between different or same routing protocols can become a nasty thing when there are 2 or more redistribution points.

In this quiz, I present you the following scenario with redistribution between 2 different OSPF processes on 2 routers (R1 and R2) - see below diagram and configuration:



quiz-2_ospf


Although, at first glance, everything looks ok, this scenario poses some problems. Try to think of the problems from the perspective of Net A (33.33.33.1/24).
Then reveal the hints below to understand when the problem will come to the surface:

Show me the first hint !

At some moment in time you'll notice that R1 is reaching Net A via the bottom OSPF Area: 

R1#trace 33.33.33.1

Type escape sequence to abort.
Tracing the route to 33.33.33.1

  1 172.16.1.2 20 msec 44 msec 16 msec
  2 192.168.1.3 40 msec 56 msec 20 msec

Why does R1 prefers R2 to reach Net A (lo1 on R3)?

Show me the second hint !

The cable connected to Fa0/0 on R3 gets unplugged. At this moment there is a routing loop in your network: 

R4#traceroute 33.33.33.1

Type escape sequence to abort.
Tracing the route to 33.33.33.1

  1 172.16.1.2 68 msec 20 msec 20 msec
  2 192.168.1.1 36 msec 48 msec 32 msec
  3 172.16.1.2 52 msec 32 msec 20 msec
  4 192.168.1.1 20 msec 56 msec 52 msec
  5 172.16.1.2 40 msec 60 msec 52 msec
  6 192.168.1.1 108 msec 44 msec 68 msec
  7 172.16.1.2 68 msec 96 msec 68 msec  ...and so on...

How would you solve this problem?

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