OSPF: network mask for PtP links

Alexander V. Chernikov melifaro at ipfw.ru
Thu Feb 28 23:29:10 CET 2013

Hello list!

Currently bird uses '' network mask in OSPF hello messages for 
ptp links. This is (at least originally) done to catch possible 
misconfiguration at the other end.

RFC 2328 sec 10.5 tells us that this is perfectly OK and network mask 
should be ignored for p2p and virtual links.

However, Juniper interprets RFC more formally and their point is that 
Ethernet is not real point-to-point interface, so network mask is 
checked anyway. See 
http://kb.juniper.net/InfoCenter/index?page=content&id=KB23533 for more 
detailed explanation.

This check kills bird ability to establish p2p link with Juniper boxes.

Cisco and Huawei (at least some models) ignores netmask as they should, 
but sends real network mask in hello messages.

Maybe it will be useful to make bird behavior configurable:
patch adding 'real mask <switch>' interface option is attached.
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