IPv6 multihoming

[Mohacsi Janos]

On Wed, 9 Feb 2011, Brian E Carpenter wrote:

> On 2011-02-08 22:55, Siraj 'Sid' Rakhada wrote:
> ...
>> To be honest, in my scenario, the idea was actually to split (at most)
>> upto /40s, and hopefully aggregate them up to /39s or bigger, depending
>> on growth in certain areas. It's just thought processes at the moment.
>> I wouldn't want to put out a solution that deaggregated into /48s - if I
>> ever got forced to do that, I definitely wouldn't want my name anywhere
>> near it. :)
>
> It seems to me that there are two cases of deaggregation of a PA prefix:
>
> 1. One or more customers of the ISP in question decide to multihome,
> using the RFC 4116 method in IPv6. So the customer persuades their
> second ISP to advertise their /48.
>
> In this case, if the operators in general or in parts of the Internet
> choose to filter out the route, the customer partially loses their multihoming,
> but that's all. They don't get what they think they are paying for, but
> they still have connectivity most of the time.


Moreover in a smaller geographical scale (e.g. in IX) can agree not to 
filter at /48. In this case multihoming in this scale can be a working 
option.

>
> 2. A customer leaves the ISP and insists on taking their /48 with them.
> Well, in IPv6, they're not supposed to do that. And if they do, and the
> prefix gets filtered, they lose connectivity. Boo hoo.
>
> So from the 10,000 metre view - it doesn't matter if some or even most
> operators filter PA /48s. The IPv6 Internet doesn't break, and for the
> time being, until one of the better methods becomes viable, big sites
> can get PI prefixes that will not be filtered.
>
>   Brian
>