A Network Advertise in Multiple OSPF Process

[Ravi_916]

On R1 i have advertise 1.1.1.1 (Loopback1) in OSPF 100 and OSPF 200, and Even 1.1.1.1 is only advertised in OSPF 200.and On R2 i have advertise 4.4.4.4 (Loopback1) in OSPF 100 and OSPF 200, and where 4.4.4.4 has advertised in only OSPF 100.

My question is: I have advertise a network in multiple OSPF Process at the same time then why the network is advertising in only one OSPF, and how ospf is choosing which OSPF Process?

[paul driver]

Hello
OSPF PID's are local significant so they dont have to be the same on any neighboring routers although it is recommended, and having multiple opsf process on the same router does create multiple databases so this inst recommended unless its required.

These networks are being advertised into the same area so it isn't the process id that is having any influence here its the path cost deciding the route preference via what looks like an additional router between Rtr1-4 

[Cristian Matei · Accepted solution]

Hi,

   For an unknown but probably good reason, Cisco decided that an interface can only be owned/part of a single OSPF process. So in case you match on the same interface via network statements on multiple OSPF process, the first configured process or on a reload the lowest process id number will win the battle for owning the interface.

Regards,

Cristian Matei.