Re: [Gen-art] Gen-ART review of draft-ietf-dhc-dhcpv6-failover-protocol-04

[Christer Holmberg <[e-mail]>]

Hi,

INTRODUCTION:


>> Q2:        In the Introduction, before the first sentence, shouldn't
>> there be some background text, including some information about the 
>> problem that the document solves. I know there is something in the 
>> Abstract, but I think there should also be something in the 
>> Introduction, before jumping into the solution.
>>
>There's a whole RFC about it: RFC7031. It was intended as a gentle introduction to the DHCP failover problem: what is in and outside of scope, when failover is useful and >when it may not be the best tool. The DHC WG decided to split it into separate document, because there are lots of things to explain and the core document is already >obscenely large. This RFC is clearly linked at the end of Introduction section.
>Perhaps it would be more useful to move this reference to the front and add a sentence or two of explanation? How about this text added as a first paragraph?
>
>This document defines a DHCPv6 failover protocol, which is a mechanism for running two DHCPv6 servers with the capability for either server to take over clients' leases in >case of server failure or network partition. For a general overview of the DHCPv6 failover problems, use cases, benefits and shortcomings, see RFC7031."

Works for me.

>> Q3:        In the Introduction, I suggest adding a reference to the
>> first occurrences of "DHCP service" and "DHCP server".
>>
>DHCP service is not a formal term. It was intended as a general description of the DHCP server availability. How about we replace "or provide a DHCP service" with "to >provide service to DHCP clients"?

Works for me.

>> Q4:        In the Introduction, you switch between "This protocol" and
>> "The failover protocol". Please use consistent terminology. This 
>> applies to the document in general.
>>
> There are 8 instances of "this protocol" and 20 of "the failover protocol". We will go with the latter, ok?

I can live with both, but the latter would be my preference too.

SECTION 4:

>> Q5:        In the Abstract and Introduction it is said that DHCPv6
>> does not provide server redundancy. Then section 4 talks about 
>> failover concepts and mechanism.
>>
>> Are those concepts something used for DHCPv6 today, but for some 
>> reason do not fulfil the failover protocol requirements?
>>
>> OR, are these general concepts that will be supported by implementing 
>> the failover protocol?
>>
>> I think it would be good to have an introduction statement clarifying 
>> that.
>
> These are not being used by any non-failover DHCPv6 today. There is one implementation of this draft that uses them. Most of those mechanisms are required by any sane >failover design (e.g. any kind of failover-like solution has to use lazy updates or it would be undeployable due to performance), but some are specific to this particular >failover design (e.g. the allocation algorithms). Would the following text added at the beginning of Section 4 be sufficient?
>
>"The following section describes core concepts that are a foundation of this failover protocol. Allocation strategies described in Section 4.2 are specific to this particular >failover design, while the concept of Lazy updates (Section 4.3) and MCLT (Section 4.4) seem to be necessary for any failover design."

Works for me.

>Also, if you think it's useful, we can repeat a 7031 reference there, possibly to Section 5.2 that discusses lazy updates
>(update-after-response) and its alternative (update-before-response).

I think that would be useful.

Note that Kim had slightly different suggestions on how to address the issues. I am fine those, so I'll leave it up to you to decide which ones to adopt :)

Thanks!

Regards,

Christer