ospf config

Answered Question
Nov 20th, 2008
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Hi,


below is my ospf setting,


router ospf 100

network 192.168.1.0 0.0.0.255 area 0

network 172.16.1.5 0.0.0.3 area 1


what is different if I change to


"network 172.16.1.4 0.0.0.3 area 1"


which one is better?


network 172.16.1.5 0.0.0.3 area 1

or

network 172.16.1.4 0.0.0.3 area 1


rdgs



Correct Answer by Richard Burts about 8 years 4 months ago

Anita


It should be the same result.


I believe that you can type it in as:

network 172.16.1.5 0.0.0.3 area 1

but when you do show run I believe that you will find that IOS has translated and it will show up as:

network 172.16.1.4 0.0.0.3 area 1


This is because the address you want to input and the mask are inconsistent. The mask of 0.0.0.3 indicates a subnet address with mask of 255.255.255.252 and IOS will translate what you input to show the subnet address if you use the "subnet" nask.


HTH


Rick

Correct Answer by Jon Marshall about 8 years 4 months ago

Anita


Generally it would be either


network 172.16.1.5 0.0.0.0 area 1


OR


network 172.16.1.4 0.0.0.3 area 1


The mask just allows you to be very specific about which interfaces to run OSPF on.


As to which is better, well in this case it doesn't make a lot of difference because 172.16.1.4 0.0.0.3 only covers 172.16.1.4 -> 172.16.1.7.


Jon

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Correct Answer
Jon Marshall Thu, 11/20/2008 - 05:33
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Anita


Generally it would be either


network 172.16.1.5 0.0.0.0 area 1


OR


network 172.16.1.4 0.0.0.3 area 1


The mask just allows you to be very specific about which interfaces to run OSPF on.


As to which is better, well in this case it doesn't make a lot of difference because 172.16.1.4 0.0.0.3 only covers 172.16.1.4 -> 172.16.1.7.


Jon

anitachoi3 Fri, 11/21/2008 - 17:49
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Hi,


can I config as


network 172.16.1.5 0.0.0.3 area 1


Is it the same result?


rdgs

Correct Answer
Richard Burts Fri, 11/21/2008 - 18:23
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Anita


It should be the same result.


I believe that you can type it in as:

network 172.16.1.5 0.0.0.3 area 1

but when you do show run I believe that you will find that IOS has translated and it will show up as:

network 172.16.1.4 0.0.0.3 area 1


This is because the address you want to input and the mask are inconsistent. The mask of 0.0.0.3 indicates a subnet address with mask of 255.255.255.252 and IOS will translate what you input to show the subnet address if you use the "subnet" nask.


HTH


Rick

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