RE: [lir-wg] Discussion about RIPE-261

["Michel Py" <]

Gert,

> Gert Doering wrote:
> The *benefit* of "/48 multihoming" is that you can filter those
> routes if you don't want to see them - then your routers will
> send packets down the /32 road, and eventually hit a router
> that knows about the /48 (which is why I consider this approach
> superior to "everybody gets a independent prefix", which I can't
> properly aggregate).

This does _not_ work in at least two cases:

- If someone implements RPF checks and someone else filters.

- If the primary ISP (the one that announces the /32) dies. The site is
dead as well. This is the #1 reason why organizations do multihome: they
want to be up even if their primary ISP tanks.

Please look at the following (4 slides, very short)
http://arneill-py.sacramento.ca.us/ipv6mh/pa_holes.ppt
Then come back to me and tell me that PA holes and filtering work
together.
The slides should be self-explanatory but they were designed for live
presentation. I do welcome questions.

Michel.