[Int-area] Comments on current MPvD draft.

[Ted Lemon <[e-mail]>]

I'd like to have a bit of discussion today on the architectural choices in the current draft, if possible.

There are two issues I want to discuss:
The assumption that each PvD will have its own router
The expected behavior of hosts that do not support MPvD in the presence of multiple routers

The first assumption is problematic in the sense that in most cases (I think), it will actually be the case that the multiple provisioning domains will both be on the other side of a leaf router from the host that is accessing them.   In this case, requiring multiple RAs with different link-local addresses is fairly heavyweight.

The second issue isn't, strictly speaking, an MPvD problem, but I think it implicates MPvD because I think the behavior in this case is undefined.   E.g., if both routers advertise a set of name servers, what does the host do?

We've been looking at this in Homenet, and this came up as a serious concern: if the host chooses one set of name servers, it may not be able to access services in the other PvD.  And yet if the host does support MPvD, we kind of want it to use different name servers per PvD.   So what we concluded is that we want to be able to give hosts that do not support MPvD a clear answer that is different than the answer we give out for each PvD.

This would not be possible with the current proposal.   It's not a hard problem to solve, but we need to consider whether or not, and how, to solve it.