During a casual slide browsing Juniper JIR, its mentioned that,on Point to Point links ospf should not honor Subnet Mask, meaning you can have un-equal subnet masks and still form a neighbor on a point-to-point link.

Lets look this behavior in a Juniper Router

R1(ge-1/1/0.12) ———————-


We can clearly see, there arent any neighbors.  Before going into trace-options, lets see how a packet capture looks like, does the Hello-Packet


Subnet mask appears to be advertised, which is still fine as long as protocol knows to ignore it.

Lets see the what trace-options has to say , clearly its a mismatch which is causing this behavior ?


So,  is Juniper JUNOS not in accordance with RFC, well no, Junos in itself is a world-class operating system and how Juniper Interprets the RFC is quite correct? How is it ?

As per RFC its should not be honored on P2P links, when you configure interface-type p2p on an Ethernet interface, Juniper will ignore the interface-type parameter and will only consider True P2P links such Frame-Relay for this to work.

Lets see this configuration


and let see if OSPF is up


Below KB will explain the same




Rakesh M