Solved: OSPF Area 0 IP addressing

branfarm1 · ‎02-06-2009

Hi all,

I'm getting ready to split my single area OSPF network into a multi-area deployment. Right now all the links between my core devices are either /30 or /29 in the 10.5.0.0/24 address space. My concern is that after splitting the areas there will still be some of those address spaces outside of Area 0. Should I change the address space I use in Area 0, and if so, what would you recommend?

Thanks

paolo bevilacqua · ‎02-06-2009

Yes. A reasonable amount of prefixes to start thinking area segmentation is perhaps around 1000, with frequent flapping and intensive SPF recalc.

Instead you have a small network, try to keep it the simple as possible.

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paolo bevilacqua · ‎02-06-2009

Sorry, how may prefixes you have, any issue running area 0 only ?

The idea is exactly to avoid the issues you're going toward, and you didn't even began using it.

branfarm1 · ‎02-06-2009

Well, we don't have any issues running area 0 only right now. Just that any reconvergence anywhere in the WAN causes the whole thing to reconverge. I know that's the point, but I wanted to do multi-area OSPF so that our future expansion can isolate individual sites from problems in the WAN.

Right now we have 3 sites, using LAN addresses 10.20.0.0 /16, 10.100.0.0 /16, and 10.70.0.0 /16, respectively. All of the WAN interfaces at all sites are subnets of 10.50.0.0/24.

I guess my overall goal was to add multiarea ospf so each site only had to advertise one summary route. Am I wasting my time?

paolo bevilacqua · ‎02-06-2009

Yes. A reasonable amount of prefixes to start thinking area segmentation is perhaps around 1000, with frequent flapping and intensive SPF recalc.

Instead you have a small network, try to keep it the simple as possible.

branfarm1 · ‎02-06-2009

Thanks for the help. I'll be back when I hit 1000 :)

paolo bevilacqua · ‎02-06-2009

In the meanwhile you can get few cheap routers for a lab and experiment what if ...

Thanks for the nice rating and good luck!