Subject: [6lowpan] Generated IID from short addresses.

From: Jon Smirl <[email-masked]>
Date: Sun, 22 Aug 2010 08:26:42 -0400

A short IEEE 802.15.4 address is 16 bits in length.  Short addresses
   are mapped into the restricted space of IEEE EUI-64 addresses by
   setting the middle 16 bits to 0xfffe, the bottom 16 bits to the short
   address, and all other bits to zero.  As a result, an IID generated
   from a short address has the form:

      0000:00ff:fe00:XXXX

Doesn't this section cause problems with the Xerox OUI?  If I have a
Xerox Ethernet card with a 48b MAC address of 0x1 it will generate a
link local address of fe80::ff:fe00:0001 when the 48b address is
expanded to 64b. An 802.15.4 short address will generate the same link
local address. Now I doubt that any of the first 64K Ethernet
addresses are still in use, but to keep everything truly unique
shouldn't there be an IEEE assigned OUI for 802.15.4 short addresses?
http://standards.ieee.org/regauth/oui/index.shtml

With a 24b OUI assigned the whole 64b address space become usable. For
example aaaa:aa00:panid:short where aaaaaa is the OUI. The OUI of
80:21:54 hasn't been assigned, it would be a good choice.

-- 
Jon Smirl
[email-masked]

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From: "Colin O'Flynn" <[email-masked]>
Date: Sun, 22 Aug 2010 13:30:59 +0100

Hi Jon,

There could be a little overlap, true.

But in practice it's not a problem as IPv6 addresses generated from Ethernet
MAC addresses will have the Universal/Local (U/L) bit of the IPv6 address
set to indicate it is a globally unique address. Whereas the IPv6 address
generated from an 802.15.4 short address will have this but clear, since
it's not globally unique.

Hence the IPv6 address from your Xerox MAC will in fact become
fe80::200:0ff:fe00:1.

Regards,

  -Colin

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Jon Smirl
Sent: August 22, 2010 1:27 PM
To: [email-masked]
Subject: [6lowpan] Generated IID from short addresses.

      0000:00ff:fe00:XXXX

-- 
Jon Smirl
[email-masked]
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From: Jon Smirl <[email-masked]>
Date: Sun, 22 Aug 2010 09:42:35 -0400

I'm also unclear on how PAN IDs are dealt with. Does each PAN need a
unique IPv6 prefix? Then I need to track the mapping between prefix
and PAN ID?

-- 
Jon Smirl
[email-masked]

---

From: "Colin O'Flynn" <[email-masked]>
Date: Sun, 22 Aug 2010 16:31:18 +0100

Hi Jon,

PAN-ID was removed from the latest header compression when forming the IPv6
address.

So how you use PAN-ID is totally up to you. That's essentially part of the
bootstrapping question. For example you could scan using 802.15.4 beacon
requests/beacons to decide which PAN-ID to join.

Regards,

  -Colin

-----Original Message-----
From: Jon Smirl [mailto:[email-masked]] 
Sent: August 22, 2010 2:43 PM
To: Colin O'Flynn
Cc: [email-masked]
Subject: Re: [6lowpan] Generated IID from short addresses.

-- 
Jon Smirl
[email-masked]

---

From: Jon Smirl <[email-masked]>
Date: Sun, 22 Aug 2010 11:49:01 -0400

> requests/beacons to decide which PAN-ID to join.

I'm working on a 6lowpan implementation for Linux. I have it partially
running but I haven't implemented fragmentation yet so it isn't very
useful. The end goal is to get RPL implemented too. I haven't dug into
the RPL spec yet so my question may be handled by it.

Say the Linux node is in PAN 1. PAN 1 is meshed into PAN 2, 3, 4. How
do I ping a node in PAN 4?
Or is the answer to just put all of the nodes into a single PAN?

-- 
Jon Smirl
[email-masked]