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New Member

default-information originate in OSPF

Hi,

if I configure in the router OSPF the command "default-information originate always" I see that the IOS set a TAG at the route 0.0.0.0 with the value equal at the OSPF process-id.

Is there some one that know why of this tag number?

Thanks

Giovanni

4 REPLIES

Re: default-information originate in OSPF

Please check the following. I beleive it contains the answer to your question:

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00801ec9f0.shtml

Regards,

Leo

Re: default-information originate in OSPF

Hello,

the route tag can be used for filtering purposes. This might get handy when applying filters when redistributing to avoid routing loops.

You can also configure a TAG with a different value with the help of a route-map.

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: default-information originate in OSPF

Hi,

the question is not about the use of the TAG. If you crate a routing OSPF and you need to advertise the default route you can configure the "default-information originate", and this is OK. I don't know becouse the default route is generate with a TAG number equal at the processor Id of the ospf.I don't want the TAG. I know that it is possible with a route-map to set the TAG =0. This question is only for my curiosity. What I should know is this one,why does the IOS set this TAG?

Regards

Giovanni

Purple

Re: default-information originate in OSPF

Hi Giovanni,

That default tag is there simply for convenience. That way, if you have multiple default routes being injected by different OSPF processes, you can easily filter them. Apart from that, there is no real reason for it. There is nothing in RFC2328 that says that it should be done this way - it's just the way Cisco has implemented it.

Hope that helps - pls rate the post if it does.

Paresh

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