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Re: RFC 3178 mh (was Re: I-D ACTION:draft-huston-multi6-architectures-00.txt)


IMHO the problem is that RFC 3178 multihoming situation not only fails
when the complete ISP fails, but it also fails when
- one of the access routers of the ISPs fail,
- one of the exit routers of the site fail
- one of the links between the ISPs and their upstream provider fail

While i agree that probably the complete failure of the ISP may be a
low probability event, i guess that the above mentioned events may be
more common.


No, this is definitely not the case.  The first two bullet points are
only valid if site site does not have tunnels to from the other exit
routers to the other ISPs (or the tunnel is terminated at the ISP to
the same router as the physical link), right?

Well, this is possible but this is not described in RFC 3178 and it imposes additional configuration, for instance of the IGP of the ISP. But i agree that it is possible to support this configuration, with some added complexity. My point was aimed to identify another possible cause for the non success of this solution, which could be related to operational complexity? I mean, tunnel management, and added features like the support for additional failure modes may require additional manual configuration, which may make the solution less attractive.


The third point is only
valid if the ISP has only one link to an upstream provider -- and no
self-respecting ISP has only one upstream link.


Well, you are assuming that very small sites will obtain its own address block from the RIR, which may not hold, i guess


The other reality check that i would like to do is how common is RFC
3178? if it is not very common, what do you think are the reasons for
its non adoption?


True enough.  I don't think there is sufficient evidence to make
conclusions of this, as the number of v6-enabled enterprises which
don't have IPv6 /32 prefixes (but which multihome w/ v4) is very
low..?


Well, i guess this is an important issue to understand, since if rfc 3178 multihoming is enough for some small sites (for instance), the new solution should be focused to satisfy the needs of the remaining sites (medium/big) sites, and the scalability required may be different.

In other words, understanding the reasons why rfc 3178 is not a good option may provide us good information for the design of the new solution, especially w.r.t to deployability.

regards, marcelo


--
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings