[homenet] HCNP: my points this morning

[Juliusz Chroboczek <[e-mail]>]

Hi,

During this morning's session, I mentioned how much I like the HCNP
protocol, and that I'm looking into abandoning AHCP for a hacked-up
HCNP.  I made the following points this morning:

0. As far as I'm concerned, this is not "The Homenet Configuration
Protocol", this is a configuration protocol for unmanaged routers that
happens to have been designed by the Homenet group.  Please keep this
in mind when you read the following.

1. The draft seems overspecified at times.  Do we really mandate
Trickle, or do we want just an abstract description of flooding
requirements?  (Knowledgeable people commented that Trickle is fine.)

2. Related to the previous point, is everything MUST, or should some
parts be made optional?  I'd personally like the DNS proxy stuff to be
made optional.

3. There would appear to be no way to specify "please carve this
prefix into /64 or shorter" as opposed to "please feel free to grab
a /128 in this prefix".

4. Do we want the ability to mark an option as mandatory, as in
"Please don't configure unless you understand the following TLV, and
intend to act upon it".  One the one hand, this makes is easier to
design compatible extensions to the protocol (by sending two
configuration blocks, one with a mandatory incompatible option, one
without the option, and having old routers ignore the block with the
incompatible option).  On the other hand, it adds another failure mode.

5. I don't think the routing protocol should be negotiated by the
config protocol, since that implies that the routing daemon is started
by the config daemon.  The routing daemon(s) should be started at
boot, and notice when the config daemon adds IP addresses to
interfaces.  Knowledgeable people appeared to disagree.

(It seems to me that the config protocol should be routing-protocol
agnostic, and merely say "this protocol assumes that a routing
protocol satisfying the following conditions is available".  Homenet
should specify what the protocol is, and mandate implementation of The
One Homenet Routing Protocol (OHRP).)

I'd like RIP to be the OHRP, but I don't have strong opinions on the
subject.

I also don't care whether Homenet says that routers MUST implement
OHRP, or whether they MUST implement OHRP and MAY implement other
routing protocols.  In either case,

  - commercial Homenet router vendors will implement the OHRP and
    ignore the MAY protocols;
  - the OpenWRT routing overlay will probably install the OHRP by
    default, but provide its usual set of optional routing daemons.

In short, there will be no difference in practice whether Homenet
allows non-Homenet routing protocols or not.

-- Juliusz