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New Member

OSPF

Hi

I am preparing for CCNP, I ahve a question about AS is ospf. What determines if a particular router belongs to an AS, is its the OSPF process ID? I am not clear about this

thanks

6 REPLIES

Re: OSPF

Please check the following URL:

http://www.cisco.com/en/US/tech/tk365/tk480/technologies_design_guide09186a0080094e9e.shtml

The process ID has not the same significance for OSPF like it has for EIGRP. OSPF has no concept of AS. Instead, with OSPF, the area-id to which an interface belongs decides whether to exchange routing info or not. In fact there are a few more parameters that need to match (hello & dead time, etc) but these are generally equal in the whole network, so the area-id is the one that makes the final match.

Regards,

Leo

New Member

Re: OSPF

Hi

Thank you for sending you comments

One thing i am not clear with is, say I have to connect my AS with another AS and both run ospf. how is this handled.

Gold

Re: OSPF

The process number has no bearing on the AS a router is in for OSPF--it's not included in any OSPF prackets at all. An OSPF area boundary would be where two different processes talk on two different interfaces--the processes must exchange routes through redistribution. For instance, you could do this:

A--10.1.1.0/24--B--10.1.2.0/24--C

! router a

router ospf 100

network 10.1.1.0 0.0.0.25 area 0

! router b

router ospf 200

network 10.1.1.0 0.0.0.255 area 0

!

router ospf 100

network 10.1.2.0 0.0.0.255 area 0

! router c

router ospf 200

network 10.1.2.0 0.0.0.255 area 0

Router A's process 100 and router B's process 200 are in the same autonomous system, while router B's process 1 and router C's process 100 are in the same autonomous system.

I hope that helps....

:-)

Russ.W

Gold

Re: OSPF

dup..

Gold

Re: OSPF

dup..

New Member

Re: OSPF

Hi

Thank you for the reply

Also ignore my second question, that was so dumb to mix up exterior routing protocols with interior routing protocols

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