Comment inline. Robert
On 08/11/2012 12:25 PM, Brian E Carpenter wrote:
<RCC>I think it is arguable whether bridging is the least damaging solution. It fundamentally does not work with route-over multi-link subnets and would therefore require some extra L2 weirdness at a LLN border router. If ISPs are going to hobble us with /64s then I think you will find NPTv6 solutions appearing for the same reason NAT is used today. There are alternatives but, as noted in the architecture draft, these break SLAAC. So I think the onus is to push back on ISPs ofering /64s if we want to avoid any kludges.</RCC>On 08/11/2012 12:05, Ted Lemon wrote:On Nov 8, 2012, at 6:41 AM, Brian E Carpenter <[email protected]> wrote:Fine, but when such an end customer buys a second router and plugs it in, will she get an error message that says "Please find a new ISP"?In this case I think our only option is to fall back to bridging.Without some fundamental surgery on the IPv6 specs, I fear that is true, so does it have to become (gulp) a feature of the homenet architecture? I would hate that but at the moment I see no alternative. There is another alternative, routed ULA within the homenet and NPTv6 at the border, but we've already said we don't want to recommend that. I think the following paragraph of the architecture document needs to be revised accordingly: The home network needs to be adaptable to such ISP policies, and thus make no assumptions about the stability of the prefix received from an ISP, or the length of the prefix that may be offered. However, if only a /64 is offered by the ISP, the homenet may be severely constrained (with IPv6 not reaching all devices in the home, or use of some form of IPv6 NAT being forced), or even unable to function. While it may be possible to operate a DHCPv6-only network with prefixes longer than /64, doing so would break SLAAC, and is thus not recommended. Something like: The home network needs to be adaptable to such ISP policies, and thus make no assumptions about the stability of the prefix received from an ISP, or the length of the prefix that may be offered. However, if only a /64 is offered by the ISP, the homenet may be severely constrained. Attempting to use subnet prefixes longer than /64 would break SLAAC, and is thus not recommended. Using ULA prefixes internally with NPTv6 at the boundary would be possible, but is not recommended for reasons given elsewhere. The least damaging solution would be for the internal routers to revert to bridging mode, even though this would destroy the benefits of subnetting.
Brian
Brian
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