OSPF RID

Sa'ad

By default the highest IP address on a loopback interface is supposed to be the RID even if that loopback interface isn't OSPF enabled.

I'm not sure what I'm doing wrong, but I have 3 routers connected via frame-relay circuit with addresses 172.12.123.1 .2 and .3

and I have configured a loopback interface address on each

R1 lo = 1.1.1.1/24
R2 lo = 2.2.2.2/24
R3 lo = 3.3.3.3/24

But the routers are still using their physical interface ip's as the RID. Why is that.

By the way I have the loopback interface enabled as part of the ospf network.

I started the ospf process several times using the ( clear ip ospf process ) command, when the routers re-esablish their full adjacencies they're still using the 172 subnet addresses as their RIDs. Please someone help me understand this. Thanks

Sa'ad

OOPs wrong forum.

dtlokee

When you first enable ospf with the "router ospf" command or hen you use the "clear ip ospf process *" command the router will choose it's RID. The RID is chosen as follows:

1. If the router-id has been manually set using the "router-id" command in router configuration mode, use that ID
2. If the router ID hasn't been set manually, use the highest IP of the configured loopbacks (this requires the loopbacks are up)
3. If there are no loopback interfaces available, then use the highest configured IP of any available physical interface. (assumes they are up as well)

My first question is, are you using a simulator? if so they are very buggy. Second, are oyur loopbacks up when you clear the ospf process?

Sa'ad

Thanks for your quick response dtlokee. I'm using dynamips with a 3640 12.4.16 IOS.

Would you think that is the problem? I never really had issues with dynamips in the past but its still just an emulator not a real router.


The other weird thing about this is that, I go and change the loopback ip addresses from 1.1.1.1 to 11.11.11.11 and like 22.22 and 33.33 for the other two routers and once I do the ( clear ip ospf process ) they adopt the new loopback interface ip's for the RIDs. I've deleted my configs and configured the routers from fresh twice to see if I was missing something but I believe I'm doing everything right, yet the routers don't take the 1.1 2.2 3.3 as their RID regardless of what I do.

dtlokee

Make sure the loopbacks are up, and that you didn't somehow set the RID with the router ID command.

Sa'ad

Thanks for following up dtlokee.

I don't have the router-id 1.1.1.1 command configured. Here I'm gona post my router configs so you can see what I'm talking about here.




R1#
R1#sh ip int br
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES NVRAM administratively down down
Serial1/0 unassigned YES NVRAM up up
Serial1/0.1 172.12.123.1 YES NVRAM up up
Serial1/1 unassigned YES manual administratively down down
Serial1/2 unassigned YES NVRAM administratively down down
Serial1/3 unassigned YES NVRAM administratively down down
Loopback0 1.1.1.1 YES manual up up
R1#
R1#
R1#
R1#
R1#
R1#
R1#
R1#
R1#sh ip pro
Routing Protocol is "ospf 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 172.12.123.1
It is an area border router
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
1.1.1.0 0.0.0.255 area 1
172.12.123.0 0.0.0.255 area 0
Reference bandwidth unit is 100 mbps
Routing Information Sources:
Gateway Distance Last Update
172.12.123.3 110 00:00:32
172.12.123.2 110 00:00:32
Distance: (default is 110)

R1#
R1#
R1#
R1#
R1#
R1#sh run int lo0
Building configuration...

Current configuration : 61 bytes
!
interface Loopback0
ip address 1.1.1.1 255.255.255.0
end

R1#
R1#
R1#
R1#
R1#
R1#
R1#sh ip route ospf
2.0.0.0/32 is subnetted, 1 subnets
O IA 2.2.2.2 [110/65] via 172.12.123.2, 00:01:10, Serial1/0.1
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/65] via 172.12.123.3, 00:01:10, Serial1/0.1
R1#
R1#
R1#
R1#
R1#clear ip ospf process
Reset ALL OSPF processes? [no]: y
R1#
R1#
*Mar 1 03:14:13.859: %OSPF-5-ADJCHG: Process 1, Nbr 172.12.123.2 on Serial1/0.1 from 2WAY to DOWN, Neighbor Down: Interface down or detached
*Mar 1 03:14:13.867: %OSPF-5-ADJCHG: Process 1, Nbr 172.12.123.3 on Serial1/0.1 from 2WAY to DOWN, Neighbor Down: Interface down or detached
R1#
R1#
R1#
R1#
R1#
*Mar 1 03:16:14.523: %OSPF-5-ADJCHG: Process 1, Nbr 172.12.123.3 on Serial1/0.1 from LOADING to FULL, Loading Done
*Mar 1 03:16:14.539: %OSPF-5-ADJCHG: Process 1, Nbr 172.12.123.2 on Serial1/0.1 from LOADING to FULL, Loading Done
R1#
R1#
R1#sh ip pro
Routing Protocol is "ospf 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 172.12.123.1
It is an area border router
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
1.1.1.0 0.0.0.255 area 1
172.12.123.0 0.0.0.255 area 0
Reference bandwidth unit is 100 mbps
Routing Information Sources:
Gateway Distance Last Update
172.12.123.3 110 00:00:16
172.12.123.2 110 00:00:16
Distance: (default is 110)

R1#
R1#
R1#
R1#
R1#sh run
Building configuration...

Current configuration : 1312 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
!
!
ip cef
no ip domain lookup
!
!
!
!
!
!
interface Loopback0
ip address 1.1.1.1 255.255.255.0
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface Serial1/0
no ip address
encapsulation frame-relay
serial restart-delay 0
!
interface Serial1/0.1 multipoint
ip address 172.12.123.1 255.255.255.0
frame-relay map ip 172.12.123.2 102 broadcast
frame-relay map ip 172.12.123.3 103 broadcast
!
interface Serial1/1
no ip address
shutdown
serial restart-delay 0
!
interface Serial1/2
no ip address
shutdown
serial restart-delay 0
!
interface Serial1/3
no ip address
shutdown
serial restart-delay 0
!
router ospf 1
log-adjacency-changes
network 1.1.1.0 0.0.0.255 area 1
network 172.12.123.0 0.0.0.255 area 0
neighbor 172.12.123.2
neighbor 172.12.123.3
!
ip http server
no ip http secure-server
!
!
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
exec-timeout 0 0
logging synchronous
line aux 0
line vty 0 4
exec-timeout 0 0
logging synchronous
login
!
!
end

R1#

Sa'ad

I narrowed down the problem to the ( clear ip ospf process ) not working. Because initially I was adding the loopback interfaces after the ospf process was already configured...But this time I configured both the physical interfaces and the loopback interfaces at the same time then configured the ospf process then it selects the loopback 1.1.1.1 as it is RID ID. I'll have to try this on my real rack at home and see if it is a dynamips issue or a bug in the 12.4 IOS. And will post my findings.

dtlokee

I would say it's a dynamips issue, but I have never seen it do this. I use it all the time with OSPF over frame and never ran into an issue, but at the same time I don't see anything in your config that would cause it not to work.