Subject: [homenet] a few drafts...

From: Ray Hunter <[email-masked]>
Date: Fri, 28 Oct 2011 22:12:25 +0200

This is certainly an interesting approach to the distributed prefix 
assignment problem and worth discussing further IMHO.

Since there are a lot of things to configure in Homenet I was advocating 
a specific topology discovery and configuration protocol.

Once you have a routing protocol up and configured it would certainly 
make all other configuration in Homenet much easier e.g. distributing an 
anycast address for a name server or DHCPv6 server to be used by end nodes.

I have a few dumb questions from a layman that are probably so obvious 
you won't think they're worth addressing in the draft.

After reading the drafts I'm unsure of the exact relationship between 
the 2 new TLV values and the AC LSA wrapper. 
draft-arkko-homenet-prefix-assignment-00 defines that they are always 
related on the wire, and "the information from all TLV instances is 
retained" but once they are unpacked in the local memory is maintaining 
the relationship necessary?

Do you need to remember from whom you learned a usable prefix TLV? I 
think you do, so you can age it out properly, but it isn't explicitly 
mentioned.

Do all AC LSA packets defined in 
http://tools.ietf.org/html/draft-acee-ospf-ospfv3-autoconfig-00 from a 
single source have to contain a complete set of TLV's associated with a 
particular Type every time they are sent out? So if one new interface 
comes up on a router whilst other have been up for a while, does the AC 
LSA update have to include TLV's for all assigned prefixes for all 
interfaces on the local router, and not just the  new assignments? I 
think that's true but it isn't explictly mentioned.

Is it not a potential DOS attack to flood in many usable prefixes into 
the OSPF AC, even if the router does wait 10 minutes before writing 
flash and retain at least the 5 most recent assignments? Worth warning 
about in security or trivial?

Is there a standard lifetime associated with the AC LSA?
Is it the standard MaxAge (1 hour)?
Is it the standard LSRefreshTime (30 mins)

Is there any guidance or timing constraints regarding advertising the 
newly assigned link prefixes learned via autoconfig into other OSPF LSAs 
or into RA? I can imagine you might want to wait a short interval to 
wait for any assignment conflicts to resolve to avoid disrupting routing 
or fresh host communications.

Is there any guidance about how prefixes learned via autoconfig 
could/should/should not interact with prefixes learned via other sources 
e.g. local hard configuration?

regards,
RayH
> Subject:
> [homenet] a few drafts...
> From:
> Jari Arkko <[email-masked]>
> Date:
> Tue, 25 Oct 2011 16:03:48 +0200
>
> To:
> "[email-masked]" <[email-masked]>
> CC:
> Acee Lindem <[email-masked]>
>
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>
> Here's a couple of drafts inspired by discussions from the interim 
> meeting:
>
> http://tools.ietf.org/html/draft-acee-ospf-ospfv3-autoconfig-00.txt
>
>    OSPFv3 is a candidate for deployments in environments where auto-
>    configuration is a requirement.  One such environment is the IPv6
>    home network where users expect to simply plug in a router and have
>    it automatically use OSPFv3 for intra-domain routing.  This document
>    describes the necessary mechanisms for OSPFv3 to be self-configuring.
>
> http://tools.ietf.org/html/draft-arkko-homenet-prefix-assignment-00.txt
>
>    This memo describes a prefix assignment mechanism for home networks.
>    It is expected that home gateway routers are assigned an IPv6 prefix
>    through DHCPv6 Prefix Delegation (PD).  This prefix needs to be
>    divided among the multiple subnets in a home network.  This memo
>    describes a mechanism for such division via OSPFv3.  This is an
>    alternative design to using DHCPv6 PD also for the prefix assignment.
>    The memo is input to the working group so that it can make a decision
>    on which type of design to pursue.  It is expected that a routing-
>    protocol based assignment uses a minimal amount of prefixes.
>
> Comments appreciated!
>
> Jari

---

From: Jari Arkko <[email-masked]>
Date: Fri, 28 Oct 2011 23:21:53 +0300

Ray,

These are certainly all good questions. I'm sure we need to fill in answers to all these. I don't have an immediate answer, but we will take this into account when preparing the next revision.

Jari