[c-nsp] OSPF point-to-point vs dr/bdr

[sthaug at nethelp.no]

> > Funny, we look at it exactly the opposite way. We're a service provider,
> > and a large majority of the Ethernet links where we run an IGP are point
> > to point links. So we have the point to point configuration as part of
> > our standard config template, nothing extra to keep track of.
> 
> I agree that it makes a lot of sense, but what's the failure mode in the
> event that configuration is missing on one side, or that a network-type
> configured as point-to-point is multiaccess?

As far as I can see:

- Missing on one side: OSPF adjacency won't come up.
- Multiaccess: We use /30 on our point to point Ethernet links. A third
router on a multiaccess segment should lead to address conflicts, again
preventing OSPF adjacency.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no