Subject: [Capwap] Questions on the CAPWAP Protocol Specification

From: "Richard Gwee" <[email-masked]>
Date: Tue, 7 Mar 2006 15:44:59 +0800

Hi,

After reading the CAPWAP protocol specification, I have two questions to
ask.

1)       In page 13, on the state machine, after the DTLS-Complete,
there are two states named Configure and Image Data. It is not very
clear on what basis will the protocol transverse from the DTLS-complete
to the Configure state or to the Image Data state. What information is
required for the protocol to choose between the two transitions?
Appreciate some enlightenment here.

2)       In Section 5.2.5 WTP Manager Control, I understand that there
is some load balancing functionality from the message element. However,
I only see a WTP count and several IP addresses. Are these information
sufficient as decision-making factors for a WTP to perform load
balancing?

Appreciate any reply.

Thanks and regards

Richard Gwee

Republic Polytechnic, 9 Woodlands Avenue 9, Singapore 738964 (Near Woodlands MRT/Interchange)
. www.rp.sg . Fax: +65 6415-1310 . 

Republic Polytechnic, the first Institute of Higher Learning to fully adopt the Problem-Based Learning approach in Singapore, continues to strive towards best practices and maintain excellence in service standards with the following certifications: Singapore Innovation Class (SIC), Singapore Quality Class (SQC), People Developer Standards and QEHS (ISO 9001, 14001 and OHSAS 18001)
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From: "Scott Kelly" <[email-masked]>
Date: Mon, 13 Mar 2006 08:22:35 -0800

Comments inline below...

> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]
> Sent: Sunday, March 12, 2006 11:58 PM
> To: Scott Kelly; 'Richard Gwee'; [email-masked]
> Subject: RE: [Capwap] Questions on the CAPWAP Protocol Specification
> 
> Hi Scott,
>  Thanks for the response.
>  I agree  that if we add all the relevant Message Elements to
Configure
> Request, my problem will be solved.
> 
> The suggested Message Elements from Join Request to be added to the
> Configure Request are
> 1. WTP name - this is the way the WTP identifies itself to the AC.
> 2.WTP descriptor  - the AC should know the encryption capabilities of
the
> WTP
> 3.Location Data
> 4. WTP radio information - radio type and radio id
> 
> But I am not sure if this will solve Richard's Problem . I was under
the
> assumption that the  WTP should use the
> AC Descriptor (Firmware Version/ SW version etc) to make that
decision.
> The AC descriptor is part of the
> Discovery REsponse from the AC to the WTP.

Perhaps I'm misunderstanding Richard's complaint. I thought he was
concerned about the ambiguity as to how the AC knows which state to
transition to, and that this ambiguity arose due to the fact that with
the join removed, the AC has no idea which is appropriate - firmware
upgrade vs configuration. 

I guess the question is, who makes the decision about the necessity of
firmware upgrade: the AC or the WTP? You seem to indicate it should be
the WTP, but I've been thinking it should be the AC. If this is correct,
then placing the fields you've described above into the configure
exchange resolve this. Am I missing something?

Scott

---

From: "Peter Nilsson J (LI/EAB)" <[email-masked]>
Date: Wed, 15 Mar 2006 09:25:30 +0100

Hi All,

As already mentioned in this track. By removing the Join phase the AC
really miss some intressting information about the WTP. I would say that
the AC would need about the same WTP information as anounced in the
Discovery Request.

I also agree in that the AC should decide if the firmware should be
updated in the WTP or not.

There is some ambigutiy regarding the firmware update
Chapter 8.2 Image Data Response. Says that this message carries no
information elements.
However
On page 16 Image Data to Image Data (n): indicates that the Image Data
Response would carry information elements such as more data indication.

Also the text in 8.1 Image Data Request indicate this message can be
sent both from WTP and AC, how would the update sequence look like if
the WTP initiated the update?

Regards
Peter

-----Original Message-----
From: Richard Gwee [mailto:[email-masked]] 
Sent: den 14 mars 2006 07:29
To: Scott Kelly; [email-masked];
[email-masked]

Hi Scott,

Thanks for the email. My "complaint" is about the ambiguity which is
your initial understanding. You have not misunderstood my meaning in the
first place :). However, you did raise a valid point in who determine
the necessity to upgrade the firmware. My opinion all the while is that
the decision making should lies with the AC.

Hi Sujatha,

Thanks for the email reply. The AC descriptor you mentioned does contain
some value on the hardware and software version. Unfortunately, the
draft specification does not seem to indicate clearly on how these
values are to be used in answering my question. Perhaps some
confirmation from others rather than we assume?

Thanks and Regards
Richard 

-----Original Message-----
From: Scott Kelly [mailto:[email-masked]]
Sent: Tuesday, March 14, 2006 12:23 AM
To: [email-masked]; Richard Gwee;
[email-masked]

Comments inline below...

Configure
> Configure Request are 1. WTP name - this is the way the WTP identifies

> itself to the AC.
the
the
> assumption that the  WTP should use the AC Descriptor (Firmware 
> Version/ SW version etc) to make that
decision.

Scott

Republic Polytechnic, 9 Woodlands Avenue 9, Singapore 738964 (Near
Woodlands MRT/Interchange) . www.rp.sg . Fax: +65 6415-1310 . 

Republic Polytechnic, the first Institute of Higher Learning to fully
adopt the Problem-Based Learning approach in Singapore, continues to
strive towards best practices and maintain excellence in service
standards with the following certifications: Singapore Innovation Class
(SIC), Singapore Quality Class (SQC), People Developer Standards and
QEHS (ISO 9001, 14001 and OHSAS 18001)
------------------------------------------------------------------------
--------
CONFIDENTIALITY CAUTION: This message is intended only for the use of
the individual or entity to whom it is addressed and contains
information that is privileged and confidential. If you, the reader of
this message, are not the intended recipient, you should not
disseminate, distribute or copy this communication. If you have received
this communication in error, please notify us immediately by return
email and delete the original message. Thank you.

---

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Mon, 20 Mar 2006 11:20:50 -0800

> Perhaps I'm misunderstanding Richard's complaint. I thought 
> he was concerned about the ambiguity as to how the AC knows 
> which state to transition to, and that this ambiguity arose 
> due to the fact that with the join removed, the AC has no 
> idea which is appropriate - firmware upgrade vs configuration. 
> 
> I guess the question is, who makes the decision about the 
> necessity of firmware upgrade: the AC or the WTP? You seem to 
> indicate it should be the WTP, but I've been thinking it 
> should be the AC. If this is correct, then placing the fields 
> you've described above into the configure exchange resolve 
> this. Am I missing something?

Currently, the AC communicates the info to the WTP, but it is the
latter who initiates the firmware download 

Pat Calhoun
CTO, Wireless Networking Business Unit
Cisco Systems