OSPF Areas

Answered Question
May 27th, 2007
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Hello Everybody,


i know that question is asked for many times ,, i have attched my network design with OSPF Areas , R0 is connected to R1 & R2 with Point to point links and tunnels through internet. my question is

which design is fit to my requirements i need :

1- to put floating static route between R1 and R2 for backup reasons.

2- not to flood the area with many LSAs


so in case of multiple areas how can i overcome the problem of connecting R1 and R2 by floating Static route and connecting Area 1 to area 0 in case of failure without redistributing that route in OSPF..?


Regards //



Correct Answer by paolo bevilacqua about 10 years 1 day ago

Hi,


Yes you would need to change cost dramatically to make route throughout R0, as the direct connection is better by default. So good that you may want to use it all the time.


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paolo bevilacqua Sun, 05/27/2007 - 15:01
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Hi,


With today's fast cpu and memeory, the practical advice is that unless you have more than 500 routers / subnets or other special needs, don't bother setting up multiple areas.

Also I would advice against 'floating backup' that are easy to be forget about and can produce unexpected results. Alway rely on dynamic routing for as much as possible.

Good luck!


Hope this helps, please rate post if it does!


mahmoud.abotaleb7 Sun, 05/27/2007 - 15:31
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Hello bevilacqua;


can you advise how to set a backup link between R1 and R2 as i need when the conn. from R1 to R0 is lost , i can shift the traffic to R2 and the same i need same link to be on when link bet. R2 and R0 is lost. can you advise me a solution.


Regards //

paolo bevilacqua Sun, 05/27/2007 - 15:41
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Hi,

I'm not sure about the question, if there is no physical link between r1 and r1 evidently on loss of r0 or connecting links, these won't communicate, can you explain what do you have in mind ?

mahmoud.abotaleb7 Sun, 05/27/2007 - 15:46
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Hello bevilacqua ;


R0 is hub router and R1 , R2 are spokes, so i need when one of spoke routers loose the connectivity to hub , it will be able to communicate Hub through the other spoke.

i suggest the floating static route solution, but i will not redistribute it into the OSPF.


so what do you suggest .?


Regards //

paolo bevilacqua Sun, 05/27/2007 - 15:58
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Hello,


again referring to your diagram, there is no physical circuit between r1 and r2. If there is one, there would be no problem.


If I didn't understood the topology correctly, please explain what type of interface (leased line, frame-relay, ISDN or whatever) the routers have and to what are connected.

mahmoud.abotaleb7 Sun, 05/27/2007 - 16:14
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Hello;


the link between R1 and R2 will be Ethernet connection on VLAN for only that interfaces from R1 to R2.


so what is the suitable solution .. is to raise the OSPF cost ,, or what ..?


Thanks and Best Regards //

Correct Answer
paolo bevilacqua Sun, 05/27/2007 - 17:21
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Hi,


Yes you would need to change cost dramatically to make route throughout R0, as the direct connection is better by default. So good that you may want to use it all the time.


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