Hello,

> 1) computing the address:
> 
> ::ff:fe00:xxxx

I think what was brought up before was perhaps using some 'fake' PAN-ID in
here.

The reason being RFC4944 disallows the use of the "zero address" in the
fake-48. With no PAN-ID (ie: zero's for the PAN-ID bits), this disallows
short address 0. Using some non-zero PAN-ID would remove that problem.

One could use the 0xFFFF PAN-ID, which would not be accidently considered
valid.

Or we could add a note to hc saying that ::ff:fe00:0 is indeed a valid
address with this scheme. This would be the cleanest solution, I'm not sure
if it's "allowed"?

Regards,

  -Colin

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Carsten Bormann
Sent: March 29, 2010 4:35 PM
To: [email protected]
Subject: Re: [6lowpan] #65: Deriving IIDs from Short Addresses

On Mar 29, 2010, at 17:10, 6lowpan issue tracker wrote:

> (0000:0000:0001:xxxx), where xxxx is the short address.

I didn't quite understand from the Discussion in Anaheim what is better
about

::1:xxxx

than

::ff:fe00:xxxx

If we can stick to the latter, we don't really have to change 4944.

In favor of preparing a lasting fix for 4944, I would make the following
change to -06:

> The reconstituted address is built from the 16-bit address xxxx by 
> 
> 1) computing the address:
> 
> ::ff:fe00:xxxx
> 
> 2) replacing the bits in this address by the bits actually given by the
prefix in the context.
> 
> In other words, the prefix in the context overrides the address generated
by step 1.
> For example, if 64-bit prefix pppp:pppp:pppp:pppp is given, the result is:
> 
> pppp:pppp:pppp:pppp::ff:fe00:xxxx
> 
> while if a 112-bit prefix nnnn:nnnn:nnnn:nnnn:nnnn:nnnn:nnnn is given, the
result is:
> 
> nnnn:nnnn:nnnn:nnnn:nnnn:nnnn:nnnn:xxxx

Gruesse, Carsten

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