[c-nsp] static into OSPF redistribution problem

[Blaine Kahle]

What causes a router to STOP redistributing a static route into OSPF if
it starts seeing that same external route from a neighbor? i.e. the
type-5 LSA is generated fine until another router starts sending a
similar LSA.

RTR1 and RTR2 are neighbors and DR/BDR on a FastEthernet link with the
following OSPF configuration on each:

router ospf 1
 log-adjacency-changes
 area 0 authentication
 redistribute connected metric-type 1 subnets
 redistribute static metric-type 1 subnets
 network 10.100.0.0 0.0.255.255 area 0
 network 10.101.0.0 0.0.255.255 area 0
 maximum-paths 2

RTR1#sh ip ospf int br
Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C
Fa0/1        1     0               10.101.0.4/28      1     DR    1/1
Lo0          1     0               10.100.0.129/32    1     LOOP  0/0

RTR2#sh ip ospf int br
Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C
Fa0/1        1     0               10.101.0.5/28      1     BDR   1/1
Lo0          1     0               10.100.0.130/32    1     LOOP  0/0


If my defined static routes are:

RTR1: ip route 0.0.0.0 0.0.0.0 a.b.c.d
RTR1: ip route 10.100.4.0 255.255.255.0 10.101.0.1

RTR2: nothing

Then RTR1 redistributes and advertises the static via OSPF fine:

RTR1#sh ip ro 10.100.4.0
Routing entry for 10.100.4.0/24
  Known via "static", distance 1, metric 0
  Redistributing via ospf 1
  Advertised by ospf 1 metric-type 1 subnets <------- See here
  Routing Descriptor Blocks:
  * 10.101.0.1
      Route metric is 0, traffic share count is 1



But if I add the same static router to RTR2, RTR1 stops
advertising:

RTR1#sh ip ro 10.100.4.0
Routing entry for 10.100.4.0/24
  Known via "static", distance 1, metric 0
  Redistributing via ospf 1                  <---- "Advertised" is gone
  Routing Descriptor Blocks:
  * 10.101.0.1
      Route metric is 0, traffic share count is 1

RTR2#sh ip ro 10.100.4.0
Routing entry for 10.100.4.0/24
  Known via "static", distance 1, metric 0
  Redistributing via ospf 1
  Advertised by ospf 1 metric-type 1 subnets <-----on RTR2, but not RTR1
  Routing Descriptor Blocks:
  * 10.101.0.1
      Route metric is 0, traffic share count is 1


I need both routers to advertise the static route so that I can do
load-balancing on a third router. What OSPF fundamental behavior am I
overlooking the TFM?

Both RTR1 and RTR2 are:

Cisco 2811 (revision 53.51) with 251904K/10240K bytes of memory.
Cisco IOS Software, 2800 Software (C2800NM-IPBASEK9-M), Version 12.4(5),
RELEASE SOFTWARE (fc3)
System image file is "flash:c2800nm-ipbasek9-mz.124-5.bin"



-- 
Blaine Kahle