OSPF summary problem

[study_voip]

I only have one OSPF area 0

diagram like

R1---area 0----R2

R2 has huge connected routes, just like loop10,11,12........ totally around 2000 connected routes.

this 2000 connected routes were redistributed to area 0

the problem is, because the 2000 routes always changes, like every second has more than 200 routes up/down

so the area 0 is not stable, is there any way to do some configuration to make it more stable?

"don't tell me create another area, it is impossible"

Thanks for any input

[pkhatri]

Can you easily summarise the 2000 routes ? If so, set up your network statements so that OSPF does not run over those loopbacks. Then, do a 'red connected subnets' together with a 'summary-address' command that covers the entire range of connected routes. That way, you will only have one route advertised.

HTH,

Paresh.

[Harold Ritter]

Are all the connected routes generated from loopback interfaces? I suppose not. If they were they wouldn't be going up and down. Can you tell us a bit more about what you are trying to achieve.

Thanks,

[study_voip]

Hi Hritter,

happy to get your input again.

of course, it is not loopback, just like loopback, the problem is, if every second, there are about 500 routes up/down, how the OSPF's performance?

otherwise, by experience, what is the max OSPF routes Cisco router support with good performance? 5000? 7000? I guess no more than 4000, or 3000

[Harold Ritter]

Continuous route flaps are usually not a good sign. However as someone suggested in a previous post, you could use summarization (summary-address) if these routes are redistributed in OSPF.

As for your second question, a lot of different parameters have to be taken in consideration to determine the maximum number of routes such as performance of the routers used througout the networks, amount of memory available, stability of the links, single vs multi area, etc,etc.

Hope this helps,

[study_voip]

Thanks for your reply.

R1----area0----R2, totally, there are about 3000 OSPF routes, and about 2500 routes were redistributed into the OSPF area0 by "redistribute connected subnet", because only one Area0, so I can not do summary and I can not build more OSPF areas.

the 500 flapping routes are randomly from the 3000 routes, so I am thinking to try to get a better solution for this one, but not.

second question regarding the OSPF performance

all routers are 650x and 751x with 256M DRAM, FastEthernet link, and only one area0, but as you know, the SPF caculation is huge based around 500 flapping routes, how about the OSPF performance for this situation?

thanks again