On Sat, 29 Sep 2007 15:37:50 -1000 Randy Bush <randy@psg.com> wrote:
The model isn't very new at all.
no it isn't. many of us remember atm-1, so atm-2 is no big surprise.
I'd argue it's not the quite same situation. From what I understand of the way ATM/IP was deployed (ATM core, IP routers at the edge with direct IP adjacencies over ATM PVCs), the ATM topology wasn't visible to the IP layer. The IP layer then wasn't able to make informed path decisions for IP traffic, yet it had no choice but to take responsibility for choosing those forwarding paths, because that's it's function. The model we're talking about seems to me to be that old model on it's head. The devices at the edge of the core network are fully aware of the underlying topology of the core network so they can make informed forwarding decisions. The tunnelling encapsulation only serves the purpose of transporting protocols/payloads, that aren't native in the core, from edge-to-edge. The tunnelling function doesn't try to control or have to take responsibility for the selecting paths taken across the core. Regards, Mark. -- "Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"