RE: survivability, rewriting

["marcelo bagnulo" <mbagnulo@ing.uc3m.es>]

> > An obvious comment about source address based routing is that
> >  source address based routing only has to be implemented
> > within the multihomed site.
>
> Is that true when you have a tree of reseller ISPs?
>
> For instance
>
> 		DFZ
> 	    /     |    \
> 	 ISP1	ISP2	ISP3
> 	/  \    /   \  /   \
>  ISPA  ISPB      ISPC   ISPD
> 	      \      /
> 	       my site
>
>

Good question IMHO...

I guess this depends on how do you expect that provider multi-homing will
be.

I assume that in your example above you are considering the case where ISPA
obtains addresses form ISP1 and ISPB from (ISP1 and ISP2), and ISPC from
(ISP2 and ISP3), right?

This implies that my site has 4 prefixes and in that case source address
based routing is also required in ISPB and ISPC, correct?

But IMHO this is not how provider multihoming will be. IMHO ISPs will be
able to get a /32 each one, especially those ISP that are multi-homed to
multilpe upstream providers.
I guess that sub allocation will only make sense to isps that have a single
upstream provider.

I mean, i don't see signs that multihomed isps will have to obtain their
IPv6 address range from their upstream providerS, implying that those isps
will have several prefixes in their networks. (reducing the need of source
address based routing to the end sites only)
What is your view about this provider multihoming issue?

Regards, marcelo

   Erik
>