Re: [dhcwg] Stephen Farrell's Discuss on draft-ietf-dhc-dynamic-shared-v4allocation-07: (with DISCUSS and COMMENT)

"Bernie Volz (volz)" <volz@cisco.com> Thu, 28 May 2015 11:33 UTC

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From: "Bernie Volz (volz)" <volz@cisco.com>
To: Stephen Farrell <stephen.farrell@cs.tcd.ie>
Thread-Topic: [dhcwg] Stephen Farrell's Discuss on draft-ietf-dhc-dynamic-shared-v4allocation-07: (with DISCUSS and COMMENT)
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Date: Thu, 28 May 2015 11:33:17 +0000
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Subject: Re: [dhcwg] Stephen Farrell's Discuss on draft-ietf-dhc-dynamic-shared-v4allocation-07: (with DISCUSS and COMMENT)
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There is no PSID at the start of client allocation request (DHCPDISCOVER) and client id is from the client to the server in DHCP. DHCP client identity is based on mac-address (already explained why not appropriate) or client id option. Why would we want to change this?

- Bernie

> On May 28, 2015, at 7:22 AM, Stephen Farrell <stephen.farrell@cs.tcd.ie> wrote:
> 
> 
> Hi Ted,
> 
>> On 27/05/15 20:16, Ted Lemon wrote:
>> On May 27, 2015, at 10:32 AM, Stephen Farrell
>> <stephen.farrell@cs.tcd.ie> wrote:
>>> I don't believe I saw an answer to the question above. What is the
>>> answer? (I think that is the key thing in figuring out how to
>>> handle the discuss btw.)
>> 
>> The base protocol specification uses either the client identifier
>> option or the client MAC address as an identifier.   This document is
>> requiring the use of the client identifier option, and excludes the
>> use of the MAC address, which potentially increases user privacy in
>> the event that the DHCP privacy profile is used.   If the
>> specification allowed the client to use its MAC address alone as an
>> identifier, this would not be possible.
>> 
>> However, I think the actual reason that the client identifier is
>> being required here is that the specific interface that is being
>> configured on the client is not a hardware interface--it's a virtual
>> point-to-point link, which has no hardware address, and thus the
>> client identifier is the only possible identifier to use.
> 
> But isn't the PSID here exactly the idenfier needed (plus the address
> where one's been allocated)?
> 
> S.
> 
>> 
>> The client identifier or MAC address is used as a database key by the
>> DHCP server to track resources allocated to the client: in this case
>> the A+P port set.   Without such a key, there would be no way to
>> renew the client's lease on that particular A+P port set, and so TCP
>> connections would be broken each time the client's lease expired.
>>