1.7 Traffic Engineering
At the time of this writing it is not clear what requirements for
traffic engineering make sense for the shim6 protocol, since the
requirements must both result in some useful behavior as well as
be
implementable using a host-to-host locator agility mechanism like
shim6. What is clear that whatever they are, shim6 will not be
able
to provide identical capabilities to traffic engineering using
BGP
and Provide Independent IP addresses.
It was not clear to me what the above paragraph means.
Could someone elaborate more on this ?
Let me know if this is more clear:
Inherent in a scalable multihoming mechanism that separates locators
from identifiers is that each host ends up with multiple locators.
This means that at least for initial contact, it is the remote peer
that
needs to select which peer locator to try first. In the case of shim6
this is performed by applying RFC 3484 address selection.
This is quite different than the common case of IPv4 multihoming where
the site has a single IP address prefix, since in that case the peer
performs no destination address selection.
Thus in "single prefix multihoming" the site, and in many cases its
upstream ISPs, can use BGP to exert some control of the ingress used
to
reach the site. This capability can't easily be recreated in "multiple
prefix multihoming" such as shim6.
I am not sure if I understand the above texts correctly, but my
interpretation of above texts is that the host centric approach
(or the concept of id-locator split) of SHIM6 in which a host should
deal with multiple locators at a time has implications on source &
destination address selection to be done by the end nodes.
In contrasts, under single prefix multihoming environment, there is
no such requirements for the end nodes but routers inside the network
are required to somehow manage routing information so that the IP
packets destined to the node which has IP address derived from the
multihomed prefix. But,, I wonder how this relates to Traffic
Engineering. I should admit that I don't have deep insight into
Traffic Engineering, though.