Long version:
A primary requirement of any solution to the routing scaling
problem is to provide a new mechanism by which end-user networks
(however defined, potentially those of corporations and
universities, but also down to home-office networks or perhaps
a single mobile host's network) can change their ISP without
significant impediment, including especially the current barrier
formed by the need to renumber their entire network, if their
current address space is PA (Provider Assigned).
There are two solutions to this:
1 - They use non-portable PA address space, including perhaps
two or more prefixes of PA space for the purposes of
multihoming. In order to achieve this in a way which
sufficiently minimises costs and disruption, the following
would need to be true:
The end-user networks would need to be constructed of
hardware, software and to use protocols such that the entire
network and all its hosts, routers etc. can be made to operate
from a different prefix with minimal disruption. (Perhaps not
devices which are only accessed internally, such as printers.)
In order for this to be the case, a very large number of
settings inside routers and hosts would need to be changed
automatically, with great reliability, in response to a single
securely authenticated, system-wide re-addressing command.
Despite the provisions within IPv6 for automatic address
assignment, with continued connectivity while changing from
one prefix to another, current networks are far from being
structured along these lines - and there is no prospect of
this changing in the timeframe within which we need to solve
the routing scaling problem.
The first reason is that almost all current networks are
IPv4 networks - and as I argue in another message, we need to
directly solve the IPv4 routing scaling problem.
The second reason is that IPv6 addressing automation does not
reliably and securely cover all locations where an IP address
is specified. For instance, as far as I know, it doesn't
apply to DNS zone files, or to router ACLs, or to the config
files of things like IMAP servers about which addresses they
respond to. At the very least, any such automation would
require secure rewriting of parts of text files, and secure
restarting of the server, application etc. - all under
centralised control of the system administrator.
There are no realistic prospects for developing such a
wide-ranging architecture for finding all such config files
and securely changing them.
In summary, this is impossible for both IPv4 and IPv6
networks at present. It will remain impossible for the
foreseeable future - any 5, 10, 15 year timeframe in which the
RRG solution needs to work. (I guess we want a fix which
actually works by 2013 or so.)
2 - Portability of address space.
There are changes to the routing and addressing system which
enable end-users to keep their address space no matter which
ISP or multiple ISPs they use - in a way which does not
add to the routing scaling problem.
Assuming the new arrangements perform well, this is providing
end-users with exactly what they want and need.
LISP, APT, Ivip and TRRP all provide this, although there
remain some dependencies in terms of who the address space
is obtained from.
- Robin http://www.firstpr.com.au/ip/ivip/
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