Subject: [Softwires] 6rd SP prefix

From: WashamFan <[email-masked]>
Date: Wed, 25 Nov 2009 15:03:17 +0800

Hi,

sec6.1:

   The 6rd IPv6 prefix includes the domain ID embedded within it, sizing
   the v6prefix-length accordingly to cover both the 6rd SP prefix size
   and domain ID for this 6rd route entry.

Neither figure 1 nor other place illustrate how domain ID embedded in 
6rd SP prefix. There is no domain ID definition either.

Besides, v6prefix-length indicates the length of SP prefix (not 6rd SP
prefix), right? if yes, how could 6rd CE extract 6rd SP prefix from 
SP 6rd IPv6 prefix field in the DHCP option (i.e. how to figure out
the bit seperating the prefix and padding zeros?)

6rd SP prefix defined in terminology section, but SP 6rd prefix appears
almost anywhere. Shouldn't  it be consistent?

washam

---

From: Mark Townsley <[email-masked]>
Date: Wed, 25 Nov 2009 13:52:46 +0100

> 6rd SP prefix. There is no domain ID definition either.
In earlier versions of the document, identifying the domain ID 
specifically seemed helpful. However, after presenting 6rd many times 
and gaining feedback from reviewers, it actually seemed to cause more 
confusion than it was worth (...Particularly among implementors. 
Operationally, it was nice to see the domain ID specifically in the 
protocol, but as this is more of an implementation spec, it's probably 
better overall without it). It looks like this Domain ID reference is a 
bit of a holdover from that, and I think should be removed.

Multiple domains are of course still supported, just via separate 6rd 
prefixes.... which works out to essentially the same thing.
> the bit seperating the prefix and padding zeros?)
v6prefix-length should refer to the "6rd Prefix" ... I can see that "SP 
6rd Prefix" causes confusion. Perhaps just dropping "SP" here is the 
best thing to do.
> almost anywhere. Shouldn't  it be consistent?
Yes. Perhaps we should just drop "SP" entirely here. We'll get that in 
the next rev which should be out Real Soon Now!

Thanks for the review!

- Mark
> washam
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