[pcp] PANA and PCP port sharing (was Re: Comparison of PCP authentication)

> 
> Encapsulation/tunneling approach:
> - Pros: No impact on PANA specification
> - Cons: Encapsulation overhead
> 
> Demultiplexing/port-sharing approach:
> - Pros: No encapsulation overhead
> - Cons: Impact on PANA specification (an Update of RFC 5191 is needed
> on the use of "Reserved" field.)
> 

I prefer the latter approach as this seems to be most straightforward.

Yoshi and I exchanged some emails to figure out what needs to be done, and here's the finding:

We have 16 Reserved bits in PANA header.
Bits 5-6-7 will be used for demux'ing between PANA and PCP when the two are run over the PCP port.
PCP version 2 sets the values to 0-1-0 and future versions would be 0-1-1, 1-0-0, … 1-1-1 -- should be enough.

PCP-spec would state the following:
- When PANA is executed over the PCP port, sender shall set the Bits 5-6-7 to 0-0-0 and the receiver shall ignore them.
(Other reserved bits and Bits 5-6-7 when used over ports other than PCP port are still governed by RC 5191).

RFC 5191 will include an "Updated by RFC(PCP-spec)".

Alper

> Hope this helps,
> Yoshihiro Ohba
> 
> (2012/08/16 11:47), Zhangdacheng (Dacheng) wrote:
>> Have we got any conclusions on two approaches?  Or we can just support 
>> the two options in the draft for the moment and briefly compare their 
>> pros and cons, can we?
>> 
>> Cheers
>> 
>> Dcheng
>> 
>> *From:*pcp-bounces@ietf.org [mailto:pcp-bounces@ietf.org] *On Behalf 
>> Of *Margaret Wasserman
>> *Sent:* Friday, August 10, 2012 3:21 AM
>> *To:* Dan Wing
>> *Cc:* pcp@ietf.org
>> *Subject:* Re: [pcp] Comparison of PCP authentication
>> 
>> On Aug 9, 2012, at 2:32 PM, Dan Wing wrote:
>> 
>>        If I'm updating security policy on a firewall I want to be able to
>> 
>>        audit whether that actually happened.  That requires
>>        authentication.
>> 
>> 
>>    You are saying a PCP client would only want to update firewall
>>    policies
>>    if the PCP server supports authentication, otherwise it would tell the
>>    user that it cannot enable the webcam, Internet-connected NAS,
>>    Internet-connected printer, etc.?
>> 
>> I wont presume to guess what Sam is thinking...
>> 
>> However, I am thinking that there will be some clients  that are 
>> configured to perform authentication for every request.  For example, 
>> there is no reason for a PCP proxy, running in an environment where 
>> authentication is required to do a THIRD-PARTY request, to perform a 
>> useless round-trip for every THIRD-PARTY request it issues.
>> 
>> Margaret
>> 
>> 
>> 
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> 
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