Eric,

As Alper mentioned, your previous assessment on PANA+DHCP call flow is
for the worst case.

Here is my assessment.  I am showing IPv4-only cases to focus on
"number of messages" discussion, but I can also show IPv6-only and
dual-stack cases if people would like to see how PANA works with IPv6.


Abbreviation
------------

RT: Round-Trip
PRPA: Pre-PANA Address
POPA: Post-PANA Address (=Service IP address)

Assumption
----------

- A 1RT EAP method is used
- Piggybacking EAP is turned off in PANA
- AAA RTs are not shown

Use Cases
---------

Use Case 1: Link Local PRPA (4.5RT)

  PaC-initiated PANA (2.5RT) 
  DHCP for POPA (2RT) 

  Note: Use Case 1 requires multicast PAA discovery mechanism
  which needs to be defined.

Use Case 2: DHCP-provided PRPA, PRPA==POPA (5RT)

  DHCP for PRPA with short lease (2RT) 
  PAA-initiated PANA (2RT)
  DHCP for extending lease (1RT)

Use Case 3: DHCP-provided PRPA, PRPA!=POPA (6RT)

  DHCP for PRPA (2RT) 
  PAA-initiated PANA (2RT) 
  DHCP for POPA (2RT)

Regards,
Yoshihiro Ohba



On Thu, Dec 06, 2007 at 08:34:12AM -0500, Eric Voit (evoit) wrote:
> Alper,
> 
> >From my point of view, it is simple:
> 
> Show me a PANA+DHCP call flow that meets DSLF requirements.  If it has
> an equivalent number of messages and error states, I will support it.  I
> will even help implement it.
> 
> Until then, I will believe my analysis earlier in these threads is
> accurate.
> 
> Eric
> 
> 
> > From: Alper Yegin, December 06, 2007 5:42 AM
> > 
> > Eric, Ric,
> > 
> > Answering you at once... as your messages have the same 
> > symptom: Repeating the same problem claims and ignoring the 
> > answers already provided..... This is not the way to take 
> > this community to the right technical answers.
> >  
> > > PANA might be good for some things, but based on my 
> > interpretation, it 
> > > is very inefficient for the DSLF requirements.  E.g., see:
> > > http://www1.ietf.org/mail-archive/web/dhcwg/current/msg07834.html
> > 
> > Already answered:
> > http://www1.ietf.org/mail-archive/web/dhcwg/current/msg07780.h
> > tml but didn't hear from you.
> > 
> > 
> > > These extra messages lead to additional error states which 
> > will be a 
> > > pain for the uneducated subscriber to debug.  Without DHCP 
> > Auth, don't 
> > > be surprised to see IEEE 802.1af eventually grow to fill 
> > the Broadband 
> > > Authentication space.
> > 
> > Anyone should be less concerned about 1X doing its job than 
> > DH-Configuration-P growing into DH-Configuration-and-Authentication-P.
> > 
> > > Disclaimer: If someone can provide an integrated PANA+DHCP 
> > flow which 
> > > explicitly matches the DSLF requirements, and which doesn't 
> > need all 
> > > the extra messages, then I reserve my right to change my 
> > opinion!  But 
> > > sadly such a flow has yet to appear in our months of 
> > discussion on this topic.
> > 
> > As soon as we free some time from fighting off political 
> > maneuvers, we'll get back to that.
> > 
> > > PANA would require something to get identity from the layer 
> > 2 switch 
> > > directly connected to the subscriber site and then 
> > something else to 
> > > enforce policy in the layer 2 provider edge.
> > 
> > Until you explain this more, it is hard to respond to it.
> > 
> > > This is a very different
> > > implementation task but also means that the service edge 
> > which touches 
> > > millions of homes would need to implement and upgrade to whatever 
> > > spaghetti sauce control plain PANA propose to control the layer 2 
> > > switches at this edge. These are not big BRAS's with lots of memory 
> > > and CPU, these are small edge devices, built to be as cheap as 
> > > possible, providers are very, very reluctant to replace them with 
> > > things that could run a big control plain.
> > 
> > There is none of that going on. If DSLF wants to stick to 
> > using Option 82, it can do so with the DHCP messaging that 
> > follows successful PANA authentication. I had explained this before.
> > 
> > > Personally I think the most likely result of specifying 
> > something that 
> > > needs an equipment upgrade to the layer 2 edge for SP's to deploy a 
> > > service without a cost advantage will probably be that we will see 
> > > deployment of proprietary authentication that do not 
> > inflict this cost 
> > > and operation hardship on the SP's.
> > 
> > I don't see where the equipment upgrade necessity came from. 
> > Use of PANA boiled down to edge allowing PANA passthrough 
> > (similar to how it allows DHCP). We had discussed this as 
> > well... All repeat points with no follow ups on your part are 
> > being brought up again....
> > 
> > Alper
> > 
> 
> 
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> 


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