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Re: [RRG] Which Side to Control Ingress Link Selection?



Well, we'd need to understand why there might be a change to the very
old reluctance to pass any kind of topological knowledge to the host.
Up to now, hosts have been strictly address-driven, and treated the
network as an opaque cloud with no internal topology. Do you think
that will change?

Brian,

the tussle of who should select the receiving edge network's ingress
link is not limited to host-based solutions.  It also exists in
network-based ones.  In fact, I primarily had network-based solutions in
mind when writing my email.  But I was unclear because I wrote "sender"
rather than "sending edge network".  Apologies.

Still, your related question of why there is reluctance to give hosts
topological knowledge is a related and very interesting one.  My believe
is that there is no reluctance to let hosts /know/; it is rather a
reluctance to let hosts /control/.  Because if we give hosts multiple
topologically-significant addresses to choose from, at the same time we
give them control over selecting (a portion of) the path.

Edge network operators don't want to give away control over path
selection.  This is the old issue with Shim6, which Six/One avoids
through its address rewriting capabilities.

But whether host-based or network-based path selection, it is widely
accepted that the egress link of a sending edge network should be
selected by the "sending side".  However, it is not so clear who should
select the ingress link at the receiving edge network.  I don't think
this question has ever been answered in due manner...

- Christian




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