Re: [6lowpan] ND-18 Multiple Prefix

Erik Nordmark <> Fri, 03 February 2012 17:42 UTC

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Date: Fri, 03 Feb 2012 09:42:32 -0800
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Subject: Re: [6lowpan] ND-18 Multiple Prefix
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On 2/3/12 9:32 AM, Tom wrote:
> Hello Everyone,
> Kindly clarify does ND-18 support multiple prefix (and multiple
> address/node derived from these prefixes).

Yes it does.

> I raise this doubt because the assumption section,  bullet 4 says -> a
> 6lowpan is configured with one or more prefixes,
> and the final bullet says -> since the 6lowpan shares one single prefix
> through out the network.

That inconsistency was pointed out in the IESG review. The final bullet 
is supposed to point out that the prefix or prefixes are shared across 
all the links in the 6lowpan network.

> Further, if 6LBR is advertising multiple prefix and host configures
> multiple global addresses based on these prefix how will they be useful.

They will be useful the same way multiple IPv6 prefixes are useful in 
general. For example, a site could have a ULA prefix plus a global 
prefix. Or a site might have multiple prefixes due to multihoming either 
permanently or while moving from one ISP to another. There are issues 
with multi-prefix multihoming for IPv4 and IPv6, but none of those are 
specific to 6lowpan networks.

> Will not the 6LR/6LBR reject registration through ARO from different
> source address but same EUI-64 (same node auto configuring with
> different prefixes).

Shouldn't be. There is nothing in the document that says that the same 
EUI-64 can't be used to register multiple addresses. I don't know if it 
makes sense to state this explicitly in the document.