Troubleshooting OSPF Neighbor Adjacency

Hello andrew,

why it required different subnet?.

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i labbed this but getting below error when i did with different subnet

*Oct 8 11:06:21.391: OSPF-10 ADJ Gi0/0: Rcv pkt from 192.168.12.2, area 0.0.0.0 : src not on the same network

Hello @lagapidis

on P2P network type, there is no DR/BDR election. Is it correct ?

Hello Sathish

One of the requirements for an OSPF adjacency to form is that the devices be directly connected. This means that by definition, the IP addresses on the connecting interfaces must be on the same subnet.

What Andrew is referring to here when he says “requires different subnets” is that each point-to-point link between any pair of OSPF routers requires a separate subnet. This is in contrast to the point to multipoint mode, where you can have a single subnet within which multiple OSPF adjacencies can occur. Does that make sense?

I hope this has been helpful!

Laz

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Thank you @lagapidis

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Hello Sathish

Yes, on a point-to-point network type, there is no DR/BDR election. Take a look at this NetworkLessons note that details these network types for more info.

I hope this has been helpful!

Laz