- alternative ways to get there (branches)
#1 Using only aggregatable addresses throughout in the Internet
The essence of this approach is that a multihomed site will have
multiple address prefixes.
Example approaches under this category:
- SHIM6, with a shim layer between IP and transport to hide the
multiple
IP addresses from transport
- A proposal by Mark Handley, which pushes all multiple IP addresses
all the way up to transport layer to handle
(NOTE: I mention these examples for the sake of illustrating what
this
branch means; by no means we should get into specific proposal debate
here)
#2 Routing on aggregatable addresses only inside the global transit
core (the place that faces scalability challenges today), but do not
push these provider-based addresses into user sites.
The essence of this approach is that a mapping layer must exist at
the
interface between user sites and the transit core.
(the word "layer" is meant an insulation boundary between parts of
the
net; please do not confuse it with "protocol layer". I simply could
not find another word at the moment)
Example approaches under this category:
- map-n-encap, which uses IP-in-IP tunneling at the boundary
- GSE, which uses IP address rewrite at the boundary
Some people prefer to separate out IP-address-rewrite to a 3rd
category, and I would be happy to go that way as well.
Does the above miss any other branches at the top level design tree?
Lixia
PS: I do owe Robin a reply with regard to what are the steps towards
the decision (i.e. whether RRG needs a depth-first search to reach a
decision), but I want to make clear that the above question is
orthogonal to that debate.
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