Subject: Re: [middisc] Poll re vendor ID format

From: Ron Frederick <[email-masked]>
Date: Thu, 1 Jul 2010 18:37:35 -0700

On Jun 30, 2010, at 11:23 AM, Mark Day wrote:
> Yes, I guess so.  Not exactly elegant conceptually, I admit. 
>  
> But if the goal is to have the type byte in a predictable place across all standard, vendor-ID & OUI usages, while minimizing the number of bytes of mandatory overhead, I think it’s the right solution. 

While it's not ideal, I can live with it. So, to summarize, I think we're proposing the following alternatives as supported:

Case 1:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------+---------------+---------------+---------------+
| Opt kind=TBD  |    Opt len    | Vendor = 0x00 | Std type code |
+---------------+---------------+---------------+---------------+
|                                                               |
| ... Optional standard payload data dependent on type code ... |
|                                                               |
+---------------+---------------+---------------+---------------+

Case 2:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------+---------------+---------------+---------------+
| Opt kind=TBD  |    Opt len    | Vendor = 0xFF | Vend typecode |
+---------------+---------------+---------------+---------------+
|              Vendor OUI (3 bytes)             |               |
+---------------+---------------+---------------+               |
|                                                               |
| ...Optional vendor payload data dependent on vend typecode... |
|                                                               |
+---------------+---------------+---------------+---------------+

Case 3:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------+---------------+---------------+---------------+
| Opt kind=TBD  |    Opt len    | Vendor=Other  |               |
+---------------+---------------+---------------+               |
|                                                               |
| ...Optional vendor payload data dependent on vend typecode... |
|                                                               |
+---------------+---------------+---------------+---------------+

In case 3, the byte following the Vendor field SHOULD be a vendor type code, as shown in case 2. However, vendors MAY encode option type information in other ways for their specific vendor code.

Is everyone ok with this?
-- 
Ron Frederick
[email-masked]