Re: [dhcwg] Review of draft-ietf-dhc-topo-conf-01

[Sheng Jiang <[e-mail]>]

Additional to Simon's comments, here are my review from me.

In general, this is a mature document with clear structure and scope.

Section 3, it is helpful if there are some text to explain/emphases the diff between figure 1 and figure 2 when these figures first presented. In current version, it is not clearly understandable until section 5 and 6.

The footer of Figure 3 and Figure 4 have some errors. They are currently noted as "figure 2 and figure 3"

It may be worthy of adding some text regarding to Relay Agent Information Option (RFC 3046) and Relay-Supplied DHCP Options (RFC 6422), which may initiatively provide more helpful topology information by Relay Agent. This may particularly help in the scenarios of multiple subnets (in section 10). The relay agent may be dedicated to a certain subnet and identify this subnet in Reply-Supplied Option.

Sheng

>-----Original Message-----
>From: dhcwg [mailto:[e-mail]] On Behalf Of Simon Perreault
>Sent: Tuesday, March 25, 2014 11:24 PM
>To: <[e-mail]>
>Subject: [dhcwg] Review of draft-ietf-dhc-topo-conf-01
>
>Here's my review...
>
>Summary: Nicely written, very tutorial-like material. Nothing
>controversial here. I like.
>
>> 2. Terminology
>>
>>    an IP address with a scope of use wider than the local link.
>
>Is there something missing here? What is the term being defined?
>
>> 5. Relay agent running on a host
>>
>>    Relay agent is a DHCP software that may be run on any IP node.
>>    Although it is typically run on a a router, it doesn't have to be
>>    one.  Relay agent can be run on a host connected to two links.  That
>>    case is presented in Figure 2.  There is router B that is connected
>>    to links D and E. At the same time there is also a host that is
>>    connected to the same links.  The relay agent software is running on
>>    that host.  That is uncommon, but legal configuration.
>
>Is there supposed to be a visual difference in figure 2 between relay E
>and e.g. relay A? Is this text simply saying that router and relay are
>two separate logical functions that are often, but not necessarily,
>co-located? If so, maybe it would be useful to adjust figures 1 and 2
>such that all relays that are also routers are identified as
>"router+relay" or something like that.
>
>>    However, all modern commercial DHCP servers handle name resolution
>by
>>    querying the resolver each time a DHCP packet comes in.  This means
>>    that if DHCP servers and DNS servers are managed by different
>>    administrative entities, there is no need for the administrators of
>>    the DHCP servers and DNS servers to communicate when changes are
>>    made.  When changes are made to the DNS server, these changes are
>>    immediately and automatically adopted by the DHCP server.  Similarly,
>>    when DHCP server configurations change, DNS server administrators
>>    need not be aware of this.
>
>I would have liked further information on how DNS TTLs can/cannot be
>reflected in DHCP. What are the impacts? Does reconfigure play a role?
>Is the BCP to simply not care about TTL?
>
>In addition, a comparison with geographic DNS would be very useful.
>
>> 9. Relay Agent Configurations
>>
>>    It's worth mentioning that although we talk about relay agents and
>>    routers in this document mostly as if they are the same device, this
>>    is by no means required by the DHCP protocol.  The relay agent is
>>    simply a service that operates on a link, receiving link-local
>>    multicasts or broadcasts and relaying them, using IP routing, to a
>>    DHCP server.  As long as the relay has an IP address on the link, and
>>    a default route or more specific route through which it can reach a
>>    DHCP server, it need not be a router, or even have multiple
>>    interfaces.
>
>This section seems extremely redundant with section 5. Could they be
>merged into one?
>
>Simon
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