[c-nsp] ospf nssa ibgp problem

[Jon Lewis]

I just tried setting up an NSSA area and had a strange issue with BGP 
routes.  The routers involved are a 7600 in area 0 and area 152, and a 
7206vxr in area 152.

On the 7600, I configured the NSSA area as:
  area 152 nssa no-redistribution no-summary

On the 7206, it's just:
  area 152 nssa

For some reason, iBGP (trying to send the 7206 full routes from a pair of 
7600's acting as route-reflectors) even with no synch on the 7206 isn't 
working properly.  The 7206 receives ~200K routes, loads them into the 
routing table (seen via show ip route sum), but then after less than a 
minute, it flushes the BGP routes from the routing table.  The BGP 
sessions remain up, and report ~200K routes received.  After a short 
time, the 7206 repopulates the routing table with the ~200K BGP routes, 
but then 30-40s later, it purges the table again.  The 7206 is running 
c7200-k91p-mz.122-18.S12.bin.

Making it a regular NSSA area by removing 'no-redistribution no-summary' 
from the 7600 makes no difference with this issue.  If I get rid of the 
NSSA area and put the 7206 into area 0, the routes load (and stay loaded) 
as expected.

Is this a BGP bug in 122-18.S12, or do NSSA and iBGP just not get along 
for some reason?

----------------------------------------------------------------------
  Jon Lewis                   |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
_________ http://www.lewis.org/~jlewis/pgp for PGP public key_________