Subject: Re: [manet] DLEP last call

From: "Wiggins, David - 0665 - MITLL" <[email-masked]>
Date: Fri, 18 Mar 2016 20:21:26 +0000

I just found a small issue in the credit windowing draft (02).  The Credit
Request data item is now sent in the Link Characteristics Request message
instead of the Destination Update message (as of -01, it seems).  As I
read the DLEP draft, only routers can send Link Characteristics Request
messages, so modems can't request credits.

I think this could be fixed by having the credit windowing extension state
that it is changing the core protocol to allow the Link Characteristics
Request (and Response) messages to be sent by either side.  (I assume
we're allowing extensions to make such changes.)

This draft has to be updated anyway to put in Destination Announce, so
hopefully this can be worked in at the same time.

David

On 3/18/16, 9:05 AM, "manet on behalf of Rick Taylor"
<[email-masked] on behalf of [email-masked]> wrote:

>Hi All,
>
>As we are looking to exit last-call with DLEP, has everyone had a chance
>to read and submit any review comments, as I'd ideally like to get
>draft-21 out ASAP and move the document up the chain.
>
>The same applies to the credit windowing draft.
>
>Cheers,
>
>Rick
>
>_______________________________________________
>manet mailing list
>[email-masked]
>https://www.ietf.org/mailman/listinfo/manet

---

From: Stan Ratliff <[email-masked]>
Date: Fri, 18 Mar 2016 16:25:55 -0400

David,

Yes, I think we can include that.

Regards,
Stan

---

From: Christopher Dearlove <[email-masked]>
Date: Fri, 18 Mar 2016 20:37:18 +0000

I can't see the point of having a base draft that introduces a rule and a simultaneously published extension that modifies that rule. If the rule needs changing and that's known now, put it in the base specification.

--  
Christopher Dearlove
[email-masked]

> On 18 Mar 2016, at 20:25, Stan Ratliff <[email-masked]> wrote:
> 
> David, 
> 
>> On Fri, Mar 18, 2016 at 4:21 PM, Wiggins, David - 0665 - MITLL <[email-masked]> wrote:

---

From: Stan Ratliff <[email-masked]>
Date: Fri, 18 Mar 2016 22:43:10 -0400

David,

I went back and looked at the draft. Here is what I find (in part) in -02
Credit Windowing on Credit Request:

8.3 <https://tools.ietf.org/html/draft-ietf-manet-credit-window-02#section-8.3>.
Credit Request

   The Credit Request data item MAY be sent from either DLEP
   participant, as a data item in a DLEP Destination Update message, to
   indicate the desire for the partner to grant additional credits in
   order for data transfer to proceed on the session.

So, I'm not seeing a problem? Perhaps the text above should also include
Link Characteristics Request, but the original intent was to use
Destination Update, which is still bo-directional.

Regards,
Stan

---

From: "Wiggins, David - 0665 - MITLL" <[email-masked]>
Date: Mon, 21 Mar 2016 14:37:16 +0000

Hi Stan,

Looking at it more closely, I think there is some inconsistency in the use
of Credit Request between Destination Update and Link Characteristics
Request.

7.3 DLEP Destination Update Message does not mention the possibility of
sending a Credit Request data item.

7.4. DLEP Link Characteristics Request Message does allow sending a Credit
Request data item.

8.3 only mentions Credit Request in a Destination Update, as you noted.

My reading is that 8.3 conflicts with both 7.3 and 7.4

I think we should decide which message the Credit Request belongs in,
Destination Update or Link Char Request, and then make everything consistent
with that choice.  (I don't think it should go in both, on the general
principle of not having two different ways of doing the same thing.)  If the
decision is for Destination Update, then 7.3 needs to allow Credit Request
and 7.4 probably goes away entirely.  If we go for Link Char Request, then
8.3 just needs to say that instead of Destination Update.

David

From:  Stan Ratliff <[email-masked]>
Date:  Friday, March 18, 2016 at 10:43 PM
To:  David Wiggins <[email-masked]>
Cc:  Rick Taylor <[email-masked]>, manet IETF
<[email-masked]>
Subject:  Re: [manet] DLEP last call

David, 

8.3 
<https://tools.ietf.org/html/draft-ietf-manet-credit-window-02#section-8.3>
.  Credit Request

So, I'm not seeing a problem? Perhaps the text above should also include
Link Characteristics Request, but the original intent was to use Destination
Update, which is still bo-directional.

Regards,
Stan

---

From: Stan Ratliff <[email-masked]>
Date: Mon, 21 Mar 2016 10:47:23 -0400

David,

> sending a Credit Request data item.

Good catch. I'll add that.

>
> 7.4. DLEP Link Characteristics Request Message does allow sending a
> Credit Request data item.
>

Fixed in my current -03 draft, but I'll double-check.

> Destination Update or Link Char Request, and then make everything
> consistent with that choice.  (I don't think it should go in both, on the
> general principle of not having two different ways of doing the same
> thing.)  If the decision is for Destination Update, then 7.3 needs to allow
> Credit Request and 7.4 probably goes away entirely.  If we go for Link Char
> Request, then 8.3 just needs to say that instead of Destination Update.
>

Here I disagree. The use cases (Destination Update vs. LCR) are slightly
different. And at the end of the day, I don't believe there's two ways of
doing the same thing - to request an increase in the Credit Window, you use
a Credit Request TLV. It can just "piggyback" on multiple carriers.

Regards,
Stan

> Cc: Rick Taylor <[email-masked]>, manet IETF <
> [email-masked]>
> 8.3 <https://tools.ietf.org/html/draft-ietf-manet-credit-window-02#section-8.3>.  Credit Request
>