interesting ospf

i recently was working on an ospf adjaceny issue and noticed something and wanted to get some feedback.

on the "head in/core" router had the network statement of

net 10.0.0.0 0.0.255.255 area 0

then another downstream router had

net 10.0.200.0 0.0.0.255 area 10.0.200.0

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Comments

EdTheLad

keenon wrote:

i recently was working on an ospf adjaceny issue and noticed something and wanted to get some feedback.

on the "head in/core" router had the network statement of

net 10.0.0.0 0.0.255.255 area 0

then another downstream router had

net 10.0.200.0 0.0.0.255 area 10.0.200.0

What do you wanna know?
A core area 0 router that attaches to the downstream router will need an interface configured in area 10.0.200.0

keenon

ed_the_lad wrote:

keenon wrote:

i recently was working on an ospf adjaceny issue and noticed something and wanted to get some feedback.

on the "head in/core" router had the network statement of

net 10.0.0.0 0.0.255.255 area 0

then another downstream router had

net 10.0.200.0 0.0.0.255 area 10.0.200.0

What do you wanna know?
A core area 0 router that attaches to the downstream router will need an interface configured in area 10.0.200.0

EdTheLad

i understand that the network command defines the interfaces that will run this routing protocol but from my understanding is that if the if the core has the entire /16 in case this network it will look at all of them area 0? its an odd config that i have not seen until now[/quote]

You're sure there was no passive-interface and neighbor statements?
The adjacency was up? The router was definitely directly connected?
Oh im thinking in that core router if there were more specific network statements they will be used.So even though you have the
network 10.0.0.0 0.0.255.255 area 0
if you include
network 10.0.5.1 0.0.0.0 area 5
this will take priority due to the longer mask.I think i remember reading this.

keenon

ed_the_lad wrote:

You're sure there was no passive-interface and neighbor statements?
The adjacency was up?

none, what so ever

but a section of the network is only up due to static routes the ospf adjaceny is constantly going through exstart and never goes past it. theres also a duplicate router id in the network as well. i have defined a router-id of the router that wouldn't talk to 1 of its downstream neighbors but it's direct upstream router its having the exstart issue with it

Core--U<-- D1<---D2
----<<Ex-- Ex-- Full

EdTheLad

keenon wrote:

ed_the_lad wrote:

You're sure there was no passive-interface and neighbor statements?
The adjacency was up?

none, what so ever

but a section of the network is only up due to static routes the ospf adjaceny is constantly going through exstart and never goes past it. theres also a duplicate router id in the network as well. i have defined a router-id of the router that wouldn't talk to 1 of its downstream neighbors but it's direct upstream router its having the exstart issue with it

Core--U<-- D1<---D2
----<<Ex-- Ex-- Full

Ok, i just checked on my router and a more specific mask will take priority.
So i have 3 interfaces with ip's 120.5.1.1,.5,.9
router ospf 1
network 120.0.0.0 0.255.255.255 area 0

The 3 interfaces will appear in the config like
network 120.5.1.1 0.0.0.0 area 0
network 120.5.1.5 0.0.0.0 area 0
network 120.5.1.9 0.0.0.0 area 0

So now if you change any of these statements to a new area you will still be left with the original
network 120.0.0.0 0.255.255.255 area 0

As to why your adjacency is going up and down? maybe mtu size? maybe timers need adjusting?

120.5.1.1 was placed into

keenon

i've used the ignore-mtu and this didn't change anything.

i saw something on the web that referred to a duplicated router-id in the network. after i set the D1 router-id the link to D2 came up. as to why the one between D1 and U issue i think it may also be on the U router now.