Thank you for your review, Elwyn. Do the authors have any thoughts on the 
issues that Elwyn raises here?

Jari

On Jul 6, 2013, at 3:01 PM, Elwyn Davies <[email protected]> wrote:

> I am the assigned Gen-ART reviewer for this draft. For background on
> Gen-ART, please see the FAQ at
> <http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
> 
> Please resolve these comments along with any other Last Call comments
> you may receive.
> 
> Document: draft-ietf-dhc-dhcpv6-failover-requirements-06.txt
> Reviewer: Elwyn Davies
> Review Date: 6 July 2013
> IETF LC End Date: 17 July 2013
> IESG Telechat date: (if known) -
> 
> Summary: Almost ready.  There are a few very minor issues and a fair
> number of editorial nits to fix but generally in good shape.
> 
> Major issues:
> None
> 
> Minor issues:
> s1, Introduction of Primary/Secondary terminology: The introduction
> talks about multiple servers (i.e., potentially > 2) but then in the
> last sentence of para 1 introduces primary and secondary servers.  The
> initial impression this gives is that the number of servers has now been
> reduced to <= 2.  Having read through the rest of the document I can see
> how I am supposed to interpret the last sentence of para 1, but things
> would be much clearer if an extra sentence or three describing the
> chosen model (and its intended extension) was added just before this
> last sentence.  Maybe something like:
>   The failover model, to which these requirements apply, will initially
>   be a pairwise "hot standby" model (see Section 4.1) with a primary 
>   server used in normal operation switching over to a backup secondary 
>   server in the event of failure.  Optionally, a secondary server may 
>   provide failover service for multiple primary servers.  However the 
>   requirements will not preclude a future load-balancing extension 
>   where there is a symmetric failover relationship. 
> 
> s7: Related to the previous comment, perhaps it should be made explicit
> that the resulting protocol is "load-balancing friendly" to avoid rework
> if at all possible.  Since both v4 and v6 load-balancing and v4 failover
> with load-balancing are in progress, it should be known how to avoid
> pitfalls by the time the v6 failover protocol is designed!
> 
> s7, item 4, last sentence: 
> "Long-lived connections must not be disturbed."
> I don't believe the DHCPv6 server or the failover protocol can either
> know that an address is in use for long lived connections or guarantee
> that they won't be disturbed beyond what is said earlier in this item.
> Presumably what is meant is something like: "Lease stability has the aim
> of avoiding disturbance to long-lived connections."
> 
> s7, item 6:  Maybe irrelevant thought: Presumably you could build a
> failover system using a shared, reliable database and a minimalistic
> version of the failover protocol instead of using lazy updates.  Should
> this be explicitly an option?
> 
> s7, last para: "Despite the lack of standardization of DHCPv4
> failover...": It appears that work is in progress on this
> (http://tools.ietf.org/html/draft-ietf-dhc-failover-12)... so what is
> meant here?
> 
> Nits/editorial comments:
> 
> Global: s/i.e./i.e.,/
> Global: s/e.g./e.g.,/
> 
> Abstract: s/any way/any way that/
> 
> s2: Expoand acronyms CPR, IA - even though IA is defined in RFC 3315, it
> would help readability to repeat the expansion.
> 
> s2, lease: Should this mention something about length of time for which
> the lease will be valid?
> 
> s3.1.1: Expand PXE acronym.
> 
> s3.1.1, para 1:
> OLD
>   Address and possibly other
>   configuration parameters are used during boot process and are
>   discarded afterwards. 
> NEW:
>   The address and possibly other
>   configuration parameters are used during the boot process and are
>   discarded thereafter. 
> 
> s3.1.1, para 2: s/distinct preference set/a distinct preference set/
> 
> s3.1.2, para 2:
> OLD:
>   There are several well documented approaches how such deployment
>   works. 
> NEW:
>   There are several well-documented approaches showing how such a deployment
>   could work.
> 
> s3.1.3, para 2:
> OLD:
>   It is also essential to use only databases that are really
>   distributed and do not have single point of failure themselves.
> NEW:
>   It is also essential to use only a database system that provides 
>   equivalent reliability and failover capability. 
> 
> s4: This paragraph implies that the document defines a protocol contrary
> to its expressed intention and reality.
> OLD:
>   These scenarios may be inside or
>   outside of scope for DHCPv6 failover protocol as defined by this
>   document.  They are enumerated here to provide a common basis for
>   discussion.
> NEW:
>   These scenarios may be in or
>   out of scope for the DHCPv6 failover model to which this 
>   document's requirements apply; they are enumerated here to provide a 
>   common basis for discussion.   
> 
> s5, para 2: s/General failover concept/The general failover concept/, 
> s/in case of the primary server/in case of a primary server/,
> s/In case of just/In the case of just/,
> s/Had there be more than two partners/Were there more than two partners/
> (subjunctive!)
> 
> s5, para 2:
> OLD:
>   there would be a third states in between (some
>   partners updated their state, but some didn't).
> NEW:
>   there would be intermediate, inconsistent states where some partners
>   had updated their state and some had not.
> 
> s4.1: s/Only one of partners/Only one of the partners/
> 
> s4.6, para 2: s/every time IPv6 address changes/every time an IPv6
> address changes/
> 
> s4.6, para 3: s/having stable address/having a stable address/
> 
> s5.1, last sentence:  This seems to imply that *this section* states
> whether the failure mode is in or out of scope for the protocol.  It
> doesn't - that is postponed to s7.  Either remove this sentence or
> redraft to refer to s7.
> 
> s5.1.2, para 2: s/is that partner also detected/is that the partner also
> detected/
> 
> s5.2: s/synchronization methods/synchronization method/,
> s/familiarity with distributed database/familiarity with distributed database 
> technology/
> 
> s5.2.1, para 1: s/response from partner/response from its partner/
> 
> s5.2.1, para 2: 'large' is an over-generalization. Maybe:
> s/a large performance penalty/typically a significant performance penalty/
> 
> s5.2.1, para 3:
> OLD:
> Due to advent of SSD disks or battery backed ram disks technology,
> NEW:
> Due to the advent of fast SSD (solid state disk) and battery-backed RAM 
> (random access memory) disk technology,
> 
> s5.2.2, para 2: s/if server crashes/if the server crashes/
> 
> s7, item 4: s/should pose/should have/
> 
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