Hello
I am experiencing an issue with the default route not being installed in the routing table though it is present in the ospf database. The scenario is as below:
R1 --(area 249)-- R2----(area 0)--- R3 --- (area 0)--- R4
All routers in under OSPF process 20. R2,R3 and R4 are in area 0 whereas R1 is in area 249. R2 is the ABR and R4 is the ASBR.
R4 has a 'default-information originate always metric-type 1' command under its ospf 20 process.
The default route is getting propagates through the network and R1 has a default ospf external type 1 default route in its ospf database.
---R1 output---
#sh ip os database
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 10.248.0.2 190 0x80000087 0x00D3C0 20
#sh ip os da external -------- 'WHEN ROUTE IS NOT INSTALLED IN THE ROUTING TABLE'
OSPF Router with ID (10.249.0.2) (Process ID 20)
Type-5 AS External Link States
LS age: 225
Options: (No TOS-capability, DC, Upward)
LS Type: AS External Link
Link State ID: 0.0.0.0 (External Network Number )
Advertising Router: 10.248.0.2
LS Seq Number: 80000087
Checksum: 0xD3C0
Length: 36
Network Mask: /0
Metric Type: 1 (Comparable directly to link state metric)
MTID: 0
Metric: 1
Forward Address: 0.0.0.0
External Route Tag: 20
#sh ip os da external----- 'WHEN ROUTE IS INSTALLED IN THE ROUTING TABLE'
OSPF Router with ID (10.249.0.2) (Process ID 20)
Type-5 AS External Link States
Routing Bit Set on this LSA in topology Base with MTID 0
LS age: 287
Options: (No TOS-capability, DC, Upward)
LS Type: AS External Link
Link State ID: 0.0.0.0 (External Network Number )
Advertising Router: 10.248.0.2
LS Seq Number: 80000087
Checksum: 0xD3C0
Length: 36
Network Mask: /0
Metric Type: 1 (Comparable directly to link state metric)
MTID: 0
Metric: 1
Forward Address: 0.0.0.0
External Route Tag: 20
#sh ip ro--- 'WHEN ROUTE IS NOT INSTALLED IN THE ROUTING TABLE'
10.0.0.0/8 is variably subnetted, 14 subnets, 7 masks
O IA 10.0.6.0/24 [110/11] via 10.249.0.1, 00:34:43, GigabitEthernet0/0
O IA 10.248.0.0/16 [110/22] via 10.249.0.1, 00:00:49, GigabitEthernet0/0
C 10.249.0.0/30 is directly connected, GigabitEthernet0/0
#sh ip ro-- 'WHEN ROUTE IS INSTALLED IN THE ROUTING TABLE'
O*E1 0.0.0.0/0 [110/22] via 10.249.0.1, 00:00:52, GigabitEthernet0/0
10.0.0.0/8 is variably subnetted, 14 subnets, 7 masks
O IA 10.0.6.0/24 [110/11] via 10.249.0.1, 00:35:51, GigabitEthernet0/0
O IA 10.248.0.0/16 [110/21] via 10.249.0.1, 00:00:01, GigabitEthernet0/0
C 10.249.0.0/30 is directly connected, GigabitEthernet0/0
The issue I am facing is that R1 despite having the default route in its ospf database it installs the route in the routing table for one minute and then removes it from the routing table for one minute and then again installs for one min. The default route stays in the ospf database though, it does not get removed from the database.
The output in the red is when the route in installed in the routing table. the black output is when it is not installed in the routing.
Also I have other routes being propagated by R4 when reach R1 and they are installed in the routing table and they are NOT flapping like default route.
I have tried changing the metric-type to 2, restarting ospf process and restarting router but none of them worked
ios version is: c2900-universalk9-mz.SPA.154-2.T1.bin
Please if anyone could help regarding this, its urgent.
Best regard
Nitin sidhu
