Re: [Int-dir] Intdir telechat review of draft-ietf-rtgwg-vrrp-rfc5798bis-15

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> -----Original Message-----
> From: Acee Lindem <[e-mail]>
> Sent: Saturday, December 30, 2023 1:13 PM
> To: Dave Thaler <[e-mail]>
> Cc: [e-mail]; [e-mail]; Last Call
> <[e-mail]>; [e-mail]
> Subject: Re: Intdir telechat review of draft-ietf-rtgwg-vrrp-rfc5798bis-15
> 
> Hi Dave,
> 
> Thanks for the review.
> 
> > On Dec 27, 2023, at 6:30 PM, Dave Thaler via Datatracker <[e-mail]>
> wrote:
> >
> > Reviewer: Dave Thaler
> > Review result: Ready with Issues
> >
> > See https://1drv.ms/b/s!Aqj-Bj9PNivcn-MfckCWPYEAplaCJw?e=5TZtui for a
> > copy with my comments and editorial nits inline.
> >
> > Summary:
> > 1. I am confused by the discussion of "forwarding" packets addressed
> > to the Active Router's address.  The Abstract and Introduction seem to
> > talk about doing it but then section 8.3.1 says not to.
> 
> The primary purpose of VRRP is to assume “forwarding” responsibility for the
> virtual addresses.
> I don’t see any compelling reason to change this now. I could change “sent to
> these IPv4 and IPv6 addresses” to “routed to these IPv4 and IPv6 addresses”
> to avoid any confusion that this forwarding is tied to the packet header
> destination addresses. However, I don’t even see this as needed.

I was confused by the wording as noted in my comments, since it appears to
contradict text later in the document.
 
> > 2. Missing discussion of DHCPv4.
> > Section 1.3 seems to imply that static configuration of end hosts is
> > the primary mechanism for learning default routes, which is not the
> > case for clients or IoT devices as far as I know... DHCP is the
> > default.  I believe VRRP can still be used in a DHCP scenario and the
> document should say so.
> 
> Yes - but DHCP is really just another form of static route configuration. I’ll
> change this to “manual configuration” and include DHCPv4 [2131] and
> DHCPv6 [RFC8415] as well as static configuration. Any other suggested
> references?

That sounds sufficient to me at the moment.
 
> > 3. Section
> > 4.2's discussion of IPv6 is confusing to me (and I wrote one of the
> > relevant RFCs).  If there are two routers sending RA's on the same
> > LAN, then by default all hosts learn _both_ of them.  The text implies
> > half learned one and half "are using" the other one.  This text needs
> > to be clarified and then probably reference RFC 4191 and RFC 4311 for
> > more discussion.  Even better would be to update the text to
> > specifically discuss the interaction between VRRP and 4311 (which I
> > think would be straightforward), and if needed mention different cases
> > for the different host types in RFC 4191 section 3 (it's also possible
> > that the interaction with VRRP is the same for all the types and the
> > types need not be mentioned except to say that the interaction is the same
> for all the host types there).
> 
> For IPv6, I could change “learned” to “configured” since the purpose of
> section 4.2 Is to demonstrate load-sharing and not specify IPv6 Router-
> Advertisement behavior.

Is the intent of the example that half aren't paying attention to IPv6 RA
advertisements and are using manual configuration, or what?  I'm still
confused as to what the intent of the text is.

> Alternately, I could change “learned” to “preferred” with a reference to RFC
> 4311.
> 
> > 4. A couple places use "should" in cases where it's unclear whether it
> > means SHOULD or MUST (or even "MAY" when "may" occurs earlier in the
> text).
> > This could adversely affect interoperability if it meant MUST and
> > someone interprets it as optional.
> 
> I’ll look at all of these. As long as the statement is specific to VRRP, I will
> consider changing these to normative.
> 
> > 5. Section 8.3.2 says to log when multiple routers advertise priority
> > = 255, but doesn't say to log when multiple routers advertise the same
> > non-255 priority.  It says not to do that, so why wouldn't you want to
> > suggest logging any time the same priority is advertised by multiple
> > routers?  I.e., why is the logging recommendation limited to the 255
> > case?
> 
> The VRRP protocol handles this case with a tie-breaker of the VRRP router
> with the VRRP router with the greater primary IP address taking precedence.
> The reason for recommending that VRRP routers have different priorities is to
> minimize the churn do to them having the same advertisement skew time. It
> is not a protocol error.

My question is why not recommend logging when someone doesn't follow
the recommendation?  You mention there is churn, so why not at least log
as a MAY?

> > . Various grammatical nits.
> 
> I’ll incorporate these. Note that the pseudo-code wasn’t meant to be
> grammatically correct. However, the changes you have suggested may not
> obscure the logic and I’ll consider them.
> 
> Thanks
> Acee
> 
> 
> 
> >
> >