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New Member

how many routers can stay in one OSPF area?

i want to know whether there is a restriction for the number of routers in one area. especially in "area 0".

where can i find a documentation to explain the question?

thanks.

6 REPLIES
Silver

Re: how many routers can stay in one OSPF area?

this URL has what you are looking for

http://www.cisco.com/warp/public/104/3.html#17.2

New Member

Re: how many routers can stay in one OSPF area?

Thanks for your answer.

but my question is how many Routers can be designed in one OSPF area, the document you told me is describing how many neighbors can be designed for one DR router.

Is this a same question?

New Member

Re: how many routers can stay in one OSPF area?

50 is theoritical value , but recommended to keep the number of routers in an area less, as any change in the area would result in SPF being calculated by the routers in that area.

Gold

Re: how many routers can stay in one OSPF area?

There is no theoretical or hard limit on the number of routers in a single OSPF area at all. In fact, I have seen some large networks with hundreds of routers in a single area--200 is quite common, and I've seen many more. There's nothing in OSPF itself that would limit this number.

The primary limitation is going to be based on the amount of memory and processing power of the smallest router in the area. If you have a single 800 in the area, for instance, your entire area is going to be bound by the memory in that 800; if the 800 can only hold 2000 routes in memory, then you can only put enough routers in the area to generate 200 routes.

Note that things like incremental SPF:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_feature_guide09186a008012db76.html

will decrease the processing requirements, by reducing the amount of SPF that must be run, in the general case, although the extreme case would be the same as not running iSPF.

At any rate, all of these old "hard limits" came out of old design docs, and are based on routers like the MGS and AGS+. If you are deploying something newer than AGS+' in your network (and I hope you are), you should be fine with many more than 40 or 50 routers in a single area. Again, I've seen hundreds, with thousands of routes in a single area.

Russ.W

New Member

Re: how many routers can stay in one OSPF area?

Thanks for your answer.

but my question is how many Routers can be designed in one OSPF area, the document you told me is describing how many neighbors can be designed for one DR router.

Is this a same question?

Silver

Re: how many routers can stay in one OSPF area?

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