[dhcwg] Comments on draft-farrer-dhc-shared-address-lease

Qi Sun <sunqi.csnet.thu@gmail.com> Fri, 18 October 2013 09:31 UTC

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From: Qi Sun <sunqi.csnet.thu@gmail.com>
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Date: Fri, 18 Oct 2013 17:31:17 +0800
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Subject: [dhcwg] Comments on draft-farrer-dhc-shared-address-lease
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Dear authors,

I read this document and have some comments on it. Please see whether the comments are useful for the document.

Best Regards,


1. General comments:

1) The port set option is expected to be used by a various of mechanisms besides DHCPv4 over DHCPv6, like DHCPv4 over IPv6, DHCPv4 over Softwire, etc. If we define this option restricted to the context of DHCPv4 over DHCPv6, then in v4configuration draft DHCPv4 over IPv6 and DHCPv4 over Softwire are not supposed to support the port set allocation, which is not true.
2) Section 7 is discussing another topic. IMHO, it would be clearer to put it into another draft. 

2. Some detailed comments:
1) sec 3.1
The sentence of 'The following message flow is transported within the DHCPv6 OPTION_BOOTP_MSG message' indicates that the described message flow is within the context of DHCPv4 over DHCPv6. So IMHO, it would be not necessary to say again those DHCPv4 messages are within BOOTPREQUESTV6/BOOTREPLYV6 messages.

2) sec 3.1, bullet 1
The client MAY insert a non-zero value in the PSID-Len field
       within OPTION_PORTPARAMSV4 to indicate the preferred size of the
       restricted port range allocation to the unified server.
=> ... to indicate to the 4o6 Server the preferred size of the restricted port range allocation. 

3) sec 3.2
..., with the client's requested port set being included in the DHCPDISCOVER message.

4) sec 4
I think not all the functions are expected to be a DHCP client's. The client can configure a NAPT within a restricted port range. The rest should be done by the NAPT functionalities.

5) sec 6
"This is to maintain compatibility with existing implementations."
There are various implementation of the port set currently. This sentence is not necessary here, IMHO.

client MUST use apply this PSID to the interface... => ... MUST apply ... (remove use)

6) sec 7
   To provide this function, the DHCPV4oDHCPv6 client MAY implement
   OPTION_DHCPV4_O_DHCPV6_SADDR (defined below).  This option is
   included by the client within OPTION_BOOTP_MSG messages and is used
   alongside the DHCPv4 request process

OPTION_DHCPV4_O_DHCPV6_SADDR is a DHCPv6 option. This option should not be included in the OPTION_BOOTP_MSG option, which is used for encapsulating DHCPv4 messages. The two options are the same level, IMHO. 

3. Some nits:
1) Unified Server -> 4o6 Server
2) sec 3.1, bullet 1
transported within the DHCPv6 BOOTPRELAYV6 message => BOOTPREQUESTV6 message