Subject: RFC6434bis open issue - RFC4191 text

From: Tim Chown <[email-masked]>
Date: Tue, 7 Nov 2017 11:48:03 +0000

Hi,

TimW and I would like to get some list feedback on some open issues in the draft in advance of the Singapore WG session.

The first topic is whether the text on RFC4191 is now acceptable, i.e.:

— snip —

5.9.  Default Router Preferences and More-Specific Routes - RFC 4191

   "Default Router Preferences and More-Specific Routes" [RFC4191]
   provides support for nodes attached to multiple (different) networks,
   each providing routers that advertise themselves as default routers
   via Router Advertisements.  In some scenarios, one router may provide
   connectivity to destinations the other router does not, and choosing
   the "wrong" default router can result in reachability failures.  In
   order to resolve this scenario IPv6 Nodes MUST implement [RFC4191]
   and SHOULD implement Type C host role.

— snip —

Any comments welcomed.  

(As a nit, I can see we should add "the" before "Type C”.)

Tim

---

From: Fernando Gont <[email-masked]>
Date: Tue, 7 Nov 2017 09:11:11 -0300

>    and SHOULD implement Type C host role.

Without looking at RFC4191... I assume this "Type C" thing is part of
FC4191, and hence s asubset of it?

Then I wonder if the text should read: MUST implement Type C host role,
and SHOULD implement RFC4191?  (You want the Type C functionality, and
implementing the rest of rfc4191 is desired, but not required?)

In any case: since RFC4191 has stuff for routers and for hosts, and
"Node" (as in "node requirements") encompasses both hosts and routers...
What kind of requirements we want for host and routers? The same level
of requirements for both? Or something else?

Cheers,

-- 
Fernando Gont
SI6 Networks
e-mail: [email-masked]
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492

---

From: Tim Chown <[email-masked]>
Date: Tue, 7 Nov 2017 12:15:14 +0000

Hi,

> On 7 Nov 2017, at 12:11, Fernando Gont <[email-masked]> wrote:
> 

It’s in Section 3.1 of RFC4191; the crux of it is:

  "Type A hosts ignore default router preferences and more-specific
   routes.  They use the conceptual data structures described in
   Neighbor Discovery [RFC2461].

   Type B hosts use a Default Router List augmented with preference
   values, but ignore all Route Information Options.  They use the
   Default Router Preference value in the Router Advertisement header.
   They ignore Route Information Options.

   Type C hosts use a Routing Table instead of a Default Router List.
   (The Routing Table may also subsume the Prefix List, but that is
   beyond the scope of this document.)  Entries in the Routing Table
   have a prefix, prefix length, preference value, lifetime, and next-
   hop router.  Type C hosts use both the Default Router Preference
   value in the Router Advertisement header and Route Information
   Options.”

> of requirements for both? Or something else?

Node Requirements is focused on hosts, but not exclusively.  Router-specific functionality is included in one section, see https://tools.ietf.org/html/draft-ietf-6man-rfc6434-bis-02#section-14.

There is also draft-ietf-v6ops-ipv6rtr-reqs-00 over in v6ops, but that’s not been updated since May as far as I can tell.  It would be interesting to know if the authors are still progressing this.  I’ll pop Russ a mail.

Tim

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From: Fernando Gont <[email-masked]>
Date: Tue, 7 Nov 2017 09:49:12 -0300

> It’s in Section 3.1 of RFC4191; the crux of it is:

May question would be: What you want is that all hosts iplement RFC4191,
and that by default they behave like Type C hosts?

If so, I'd say something like "MUST implement RFC4191 and SHOULD employ
the Type C host model"  ("*implement* Type C host model" was a bit
confusing to me). -- but ...well.. English as second language here, so...

> Node Requirements is focused on hosts, but not exclusively.  Router-specific functionality is included in one section, see https://tools.ietf.org/html/draft-ietf-6man-rfc6434-bis-02#section-14.

Me, I'd use "hosts" if you refer only to functionality expected in only
hosts, "routers" when it is only meant for routers, and "nodes" when
referring to both.

> There is also draft-ietf-v6ops-ipv6rtr-reqs-00 over in v6ops, but that’s not been updated since May as far as I can tell.  It would be interesting to know if the authors are still progressing this.…

Good grief!

Thanks!

Cheers,

---

From: Brian E Carpenter <[email-masked]>
Date: Wed, 8 Nov 2017 08:17:59 +1300

> (As a nit, I can see we should add "the" before "Type C”.)

I already mentioned this in my comments a couple of weeks ago,
and Tim W replied:

>> I suggest that the last phrase should clarify that "Type C" is defined
>> in RFC 4191, because as written that is not obvious.
>>
> We can clarify that in the next revision.

    Brian

---

From: Tim Chown <[email-masked]>
Date: Tue, 7 Nov 2017 19:25:45 +0000

> On 7 Nov 2017, at 19:17, Brian E Carpenter <[email-masked]> wrote:
> 

Agreed Brian, sorry we missed it last time round.

Tim