Subject: [Capwap] WaitDTLS/WaitJoin timers in draft-ietf-capwap-protocol-specification-10.txt

From: "Yong Zhang" <[email-masked]>
Date: Fri, 20 Jun 2008 09:53:32 -0700

WaitDTLS by its name should be DTLS session setup related, but this
spec. (6.1/2) requires it deactivated after the Join Req/Resp are
received.

WaitJoin seems no use in this case??

Also the WaitDTLS timer is started earlier than WaitJoin timer,
however, the default value for these two timers (4.7.15/16) are all
60s. if WaitJoin
has some other use, it need to have a less value than WaitDTLS to work.

Yong
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From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Fri, 20 Jun 2008 10:55:13 -0700

The intent for both timers is:

WaitDTLS: This timer is used to make sure that the DTLS session is
established within the required timeframe. If the DTLS session isn't
setup, perhaps because either party is not responding, then the timer
will trigger and the state will change.

WaitJoin: Once the DTLS session has been established, we need to protect
against a WTP that opts to NOT send a Join Request. So in this instance,
the WaitJoin would trigger, and the state would once more change.

PatC 

-----Original Message-----
From: Yong Zhang [mailto:[email-masked]] 
Sent: Friday, June 20, 2008 9:54 AM
To: [email-masked]
Subject: [Capwap] WaitDTLS/WaitJoin timers
indraft-ietf-capwap-protocol-specification-10.txt

Also the WaitDTLS timer is started earlier than WaitJoin timer, however,
the default value for these two timers (4.7.15/16) are all 60s. if
WaitJoin has some other use, it need to have a less value than WaitDTLS
to work.

Yong

---

From: "Yong Zhang" <[email-masked]>
Date: Fri, 20 Jun 2008 11:19:03 -0700

This info is clear. But in the spec., the WaitDTLS covers the
WaitJoin. WairDTLS timer is
not cleared after the DTLS session is esatblished, but it is only
cleared after the Join
REQ/RESP are received. (6.1/2 describes this).

Thanks!

Yong

---

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Thu, 26 Jun 2008 04:53:41 -0700

I believe you may be correct that there is a technical issue.

Originally, the WaitJoin was used to timeout if the WTP did not sent the
Join Request, or the AC did not send the Join Response. However, when
DTLS was introduced, we started to rely on the WaitDTLS timer. It seems
like we've started to rely much more on the WaitDTLS timer in the latter
drafts, to the point where I believe that we could simply remove the
WaitJoin timer and have little impact to the state machine. 

>From what I can tell, the "Join to DTLS Teardown (e)" state transition
currently triggers if the WaitJoin timer expires, and we would have to
change this to WaitDTLS instead. Further, the "DTLS Connect to Join (d)"
state transition would simply need to have its reference to WaitJoin
removed.

So since it appears as if the WaitDTLS timers are initialized properly,
the timeout triggers are properly defined, and it is well specified in
its handling during the Join Request/Response in section 6.1 and 6.2,
this change would have mimimal impact.

Thoughts?

PatC

-----Original Message-----
From: Yong Zhang [mailto:[email-masked]] 
Sent: Friday, June 20, 2008 11:19 AM
To: Pat Calhoun (pacalhou)
Cc: [email-masked]
Subject: Re: [Capwap] WaitDTLS/WaitJoin timers

This info is clear. But in the spec., the WaitDTLS covers the WaitJoin.
WairDTLS timer is not cleared after the DTLS session is esatblished, but
it is only cleared after the Join REQ/RESP are received. (6.1/2
describes this).

Thanks!

Yong

On Fri, Jun 20, 2008 at 10:55 AM, Pat Calhoun (pacalhou)
<[email-masked]> wrote:
> WaitJoin: Once the DTLS session has been established, we need to 
> protect against a WTP that opts to NOT send a Join Request. So in this

> instance, the WaitJoin would trigger, and the state would once more
change.
> 60s. if WaitJoin has some other use, it need to have a less value than

> WaitDTLS to work.