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

[[e-mail]]

>>>> 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.
>
> Section 8.3.1 addresses the specific case of the packets address to the VRRP virtual address. I’ll make this clear. 

To me “forwarding responsibility for the virtual addresses” refers to forwarding of packets destined to
(i.e., IP header’s destination address contains) the virtual address.  To me, that phrase makes no sense.
Hence my comment about the Abstract and Introduction being confused.  One doesn't forward
traffic destined for the virtual addresses.  One forwards traffic that isn't destined for the virtual addresses.

One might forward traffic for the _MAC address_ of the virtual router, but not for the virtual IP address.

>>>> 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.

> The intent is to provide an example of VRRP load-balancing with different groups of 
> hosts using different primary and secondary default gateways. It is not to specify how this
> is provisioned using IPv6 RAs.  

In IPv6, the term “primary default gateway” doesn’t really exist as such.  That term
assumes that a host uses one default gateway for all packets as long as it’s up, and the
whole point of RFC 4311 is that that isn’t necessarily true.  A host selects a gateway for each
destination address, and so for each destination address one might have a primary gateway
and secondaries.  But the primary for one destination need not be the primary for another
destination.    As such, the wording for IPv6 needs to be changed to make sense, unless
to construct an example where it does make sense.

My 2 cents,
Dave