OSPF and IP secondary

[jsoletti]

I have some troubles when an interface have an ip address secondary that overlaps with primary ip address, eg:

primary 10.10.0.1 /16

secondary 10.10.10.1 /24

The router running OSPF only advertises the network configured in secondary ip address (network /24 in example above). If I swap the IP address, then OSPF advertises the network /16 (now configured like ip secondary).

This issue doesn't happen if networks don't overlap, like:

10.10.10.1 /24 primary and 10.10.20.1 /24 secondary then OSPF advertises both networks.

Someone has an ideia to solve this issue???

Thanks.

[mark-obrien]

Please show your interface and OSPF configurations.

Mark

[jsoletti]

My configuration is:

int f0/0

ip address 10.30.0.1 255.255.240.0

int f0/1

ip address 10.13.0.1 255.255.240.0

ip address 10.13.15.1 255.255.255.0

router ospf 10

network 10.13.0.0 0.0.255.255 area 0

network 10.30.0.0 0.0.255.255 area 0

In another router running OSPF connected in network 10.30 /20, the network 10.13/20 doesn't appear. This router only learn the network 10.30.15 /24

[mark-obrien]

I have seen OSPF act unpredictably (i.e. it made no sense to me) when there were overlapping addresses. You may need to get rid of you overlapping addresses.

HTH

Mark

[kbodie]

Can you send a copy of your complete config and routing table

[jsoletti]

Configuration #Router A#

=====================

interface FastEthernet0/0

ip address 10.30.0.45 255.255.240.0

duplex auto

speed auto

!

interface Serial0/0

no ip address

shutdown

!

interface FastEthernet0/1

ip address 10.13.15.1 255.255.255.0 secondary

ip address 10.13.0.1 255.255.240.0

duplex auto

speed auto

!

router ospf 10

log-adjacency-changes

network 10.13.0.0 0.0.15.255 area 0

network 10.30.0.0 0.0.15.255 area 0

## sh ip route in RouterB

RouterB#sh ip route 10.13.0.0

% Subnet not in table

RouterB#sh ip route 10.13.15.0

Routing entry for 10.13.15.0/24

Known via "ospf 10", distance 110, metric 2, type intra area

Last update from 10.30.0.45 on FastEthernet0/0, 00:15:48 ago

Routing Descriptor Blocks:

* 10.30.0.45, from 10.30.0.45, 00:15:48 ago, via FastEthernet0/0

Route metric is 2, traffic share count is 1

[ruwhite]

I don't see this in my lab, on version 12.2(16.9)S. What version of code are you on? I'd open a TAC case, and see if you can track down any defect in the code revision you're running that would cause this.

Take a look at the commands I've issued below, and see if they look similar to what you are seeing (replacing the ip addresses as needed), or if they look completely different.

interface Loopback0

ip address 144.1.1.1 255.255.255.0 secondary

ip address 144.1.2.1 255.255.240.0

ip ospf network point-to-point

!

router ospf 100

log-adjacency-changes

network 144.1.0.0 0.0.255.255 area 0

network 208.0.7.0 0.0.0.255 area 0

!

7206F#sho ip ospf data router 144.1.1.1

....

Link connected to: a Stub Network

(Link ID) Network/subnet number: 144.1.0.0

(Link Data) Network Mask: 255.255.240.0

Number of TOS metrics: 0

TOS 0 Metrics: 1

Link connected to: a Stub Network

(Link ID) Network/subnet number: 144.1.1.0

(Link Data) Network Mask: 255.255.255.0

Number of TOS metrics: 0

TOS 0 Metrics: 1

On the other router:

2651A#sho ip route

....

144.1.0.0/16 is variably subnetted, 2 subnets, 2 masks

O 144.1.1.0/24 [110/65] via 208.0.7.4, 00:03:23, Serial0/0

O 144.1.0.0/20 [110/65] via 208.0.7.4, 00:03:23, Serial0/0

Russ.W

[jsoletti]

The router that advertise routes is running 12.1(17).

All routers don't learn routes. For example:

IOS (tm) 4500 Software (C4500-J-M), Version 11.1(10)