Re: IPv6 prefix lengths - how long?

[Fred Baker <[e-mail]>]

From my perspective, there is no requirement that there be a single prefix. You could have 128 prefixes, each with 8 addresses in use. I'm not sure why you would, but I don't see an architectural reason that you couldn't. You just wouldn't be using SLAAC to assign them.

From my perspective, if a platform contains some number of internal objects (VMs, containers, applications, whatever) that each get one or more addresses, I'd be hard pressed to make a general statement about the platform. If it needs to support 10,000 VMs-or-whatever, I guess it needs to support at least 10,000 addresses. If they are all packaged up into one prefix, that's going to be a /112 prefix at least, and the platform had best support it.

It's not really a technical requirement that all platforms have to support. It's a market requirement, and the platform in question is being designed to meet that market.

> On Jun 7, 2019, at 10:43 AM, Templin (US), Fred L <[e-mail]> wrote:
> 
> Hi, we all know about the tussle regarding the /64 boundary for IPv6 prefixes but
> assuming that we will one day want to allow longer prefixes the question is “how long”?
> 
> We all know about /127 for point to point links, but I am not talking about those. I am
> talking about prefixes that are assigned to nodes that might be acting either as routers
> or as multi-addressed hosts.
> 
> Because of RFC7934, we see the value of Host Address Availability Recommendations.
> It makes the point that, due to the nature of multi-addressing supported by IPv6, it
> would be useful for each node to be able to configure multiple (perhaps even many)
> IPv6 addresses from an IPv6 prefix. But, “how many”?
> 
> My assertion is that a multi-addressed host (or, an End User Network router) should
> support numbering for at least 1K IPv6 addresses. This would imply that (assuming
> at some point the /64 boundary is relaxed) the longest IPv6 prefix should be a /118.
> 
> Thoughts?
> 
> Fred
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