07-19-2008 05:19 PM - edited 03-03-2019 10:48 PM
My perimeter router is connected with my branch over a leased circuit and remote branch network appears in routing table as OE2, my floating static route on perimeter is installed and pointing towards ISDN interface with the AD of 200 and redistributed into OSPF, whenever leased circuit goes down this static route will install in routing table and redistributed into ospf, but if leased circuit comes up the the remote branch subnet will not appear in routing table through OSPF, coz the perimiter router dont trust that E2 route coz it have the static route to same destination which its redistributing into ospf, so it dont install that already redistributed route which it received from another ASBR, if i stop redistributing the static on perimeter then it will install that E2 route received by other ASBR.
How can i prevent this perimeter to keep install that static route over O E2 even primary circuit restores
07-19-2008 07:43 PM
Increase the metric on the redistribute command for the static.
For instance,
router ospf 1
redistribute static metric 50 subnets
The router coming from your neighbor router would have a metric of 20 (default metric on E2). Metric of 20 will be preferred over metric of 50 when comparing both routers in the RIB.
HTH,
__
Edison.
07-19-2008 11:36 PM
I already try this but no success, metric is not the cause of problem, router recieved network from another ASBR with type E2 but also have static route for same subnet and feel better to redistribute its own static route into ospf rather then other learned ASBR route
07-20-2008 07:21 AM
Please post the show ip os data from your router and tell us which route is the one in question.
__
Edison.
07-20-2008 02:07 PM
R2#sh ip ospf database
OSPF Router with ID (192.168.5.2) (Process ID 1293)
Router Link States (Area 971)
Link ID ADV Router Age Seq# Checksum Link count
192.168.1.1 192.168.1.1 303 0x80000004 0x007591 3
192.168.4.3 192.168.4.3 177 0x80000002 0x001C58 2
192.168.5.2 192.168.5.2 75 0x80000007 0x002865 4
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
192.168.4.0 192.168.4.3 50 0x80000001 0x00CFF2 0
192.168.6.0 192.168.5.2 46 0x80000001 0x00C744 0
Subnet is 192.168.6.0 above output is taken when leased circuit is down and ISDN is up
Below output is taken when leased circuit is up
R2#sh ip ospf database
OSPF Router with ID (192.168.5.2) (Process ID 1293)
Router Link States (Area 971)
Link ID ADV Router Age Seq# Checksum Link count
192.168.1.1 192.168.1.1 525 0x80000004 0x007591 3
192.168.4.3 192.168.4.3 400 0x80000002 0x001C58 2
192.168.5.2 192.168.5.2 297 0x80000007 0x002865 4
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
192.168.4.0 192.168.4.3 272 0x80000001 0x00CFF2 0
192.168.6.0 192.168.4.3 17 0x80000001 0x00B907 0
4.3 is neighbour ASBR which is injecting route as E2, 5.2 is R2 itself
R2 will not switch back to E2 route even it come back again the only way to do so is to convert that E2 into type 2 or 3 but how?
I did an exercise in lab in which i remove the command redistribute static in R2 and problem is resolved and R2 will switch back to E2 when link is up coz after removing this command R2 will no longer ASBR and then it trust same routes of another ASBR.
I also removed the redistribution from R3 (4.3) this will resolve the issue coz then it forward the route as type2 and R2 will trust on that route rather then its own redistributed, but in live network both solutions are not aplicable
07-20-2008 02:41 PM
I'm unable to duplicate your problem. Again, I'm altering the metric on the redistribute static on the router connected to the ISDN.
I'm tagging the route from both routers, the one doing the original redistribution and the one doing the redistribution with static.
I have the following setup
R1 <----> R2 <---> R3
R3 is doing the original redistribution, on this example, I'm redistributing connected (just loopback0)
Rack1R3#sh run | sec router os
router ospf 1
log-adjacency-changes
redistribute connected subnets tag 3
network 192.168.23.3 0.0.0.0 area 0
!
!
Rack1R3#sh ip route connected
C 192.168.23.0/24 is directly connected, Serial1/1
150.1.0.0/32 is subnetted, 1 subnets
C 150.1.3.3 is directly connected, Loopback0
___
R2 is receiving the route as E2 with metric of 20. It also has a redistribute static with metric of 50.
Rack1R2#sh run | sec router os
router ospf 1
log-adjacency-changes
redistribute static metric 50 subnets tag 2
network 192.168.12.2 0.0.0.0 area 0
network 192.168.23.2 0.0.0.0 area 0
!
!
Rack1R2#sh ip route
C 192.168.12.0/24 is directly connected, Serial1/0
C 192.168.23.0/24 is directly connected, Serial1/1
150.1.0.0/32 is subnetted, 1 subnets
O E2 150.1.3.3 [110/20] via 192.168.23.3, 00:04:05, Serial1/1
Rack1R2(config-if)#do show run | i ip route
ip route 150.1.3.3 255.255.255.255 192.168.12.1 200
Rack1R2(config-if)#
___
R1 is the router where the changes are observed when the link goes down. Currently, it's getting its E2 from R3 (tagged as 3) and metric is 20.
Rack1R1#sh ip route 150.1.3.3
Routing entry for 150.1.3.3/32
Known via "ospf 1", distance 110, metric 20
Tag 3, type extern 2, forward metric 128
Last update from 192.168.12.2 on Serial1/0, 00:05:29 ago
Routing Descriptor Blocks:
* 192.168.12.2, from 150.1.3.3, 00:05:29 ago, via Serial1/0
Route metric is 20, traffic share count is 1
Route tag 3
____
If I bring the link down between R2 and R3, the redistribute static on R2 will kick in with metric of 50 and tag of 2.
___
Rack1R1#sh ip route 150.1.3.3
Routing entry for 150.1.3.3/32
Known via "ospf 1", distance 110, metric 50
Tag 2, type extern 2, forward metric 64
Last update from 192.168.12.2 on Serial1/0, 00:00:31 ago
Routing Descriptor Blocks:
* 192.168.12.2, from 192.168.23.2, 00:00:31 ago, via Serial1/0
Route metric is 50, traffic share count is 1
Route tag 2
____
If I bring the link up, it returns to R3's route as expected.
Rack1R1#sh ip route 150.1.3.3
Routing entry for 150.1.3.3/32
Known via "ospf 1", distance 110, metric 20
Tag 3, type extern 2, forward metric 128
Last update from 192.168.12.2 on Serial1/0, 00:00:00 ago
Routing Descriptor Blocks:
* 192.168.12.2, from 150.1.3.3, 00:00:00 ago, via Serial1/0
Route metric is 20, traffic share count is 1
Route tag 3
____
In order to help you further, we are going to need to see some configs from your routers.
HTH,
__
Edison.
Please rate helpful posts
07-20-2008 03:12 PM
07-20-2008 04:34 PM
You forgot to mention the route is being brought from RIP on R3.
When the link is brought back up, R3 will prefer the route from R2 since it has an administrative distance of 110 over the RIP administrative distance of 120.
In order to correct the problem, you need to change the administrative distance in RIP between R3 and R4 so RIPs routes are preferred over OSPF.
Example,
router rip
distance 109
HTH,
__
Edison.
Please rate helpful posts
07-21-2008 12:30 AM
In actual scenario R3 is PE and redistributing another OSPF process in our OSPF process, the distance command will help to resolve the issue but PE is under control of SP and we will request to change the Distance but not sure they will accept or not, i think distance is locally significant and we can't do any thing related to this am i correct?
07-21-2008 05:07 AM
i think distance is locally significant and we can't do any thing related to this am i correct?
Correct. The PE Router (R3) must have the RIP route on its routing table. When R3 converges with R2 after a service restoration, R2 has a better route for that network with OSPF and R3 will never return to the original RIP route coming from R4.
__
Edison.
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