[cmullaparthi]

Yes, I agree. There are a few ways around that:

- Some out of band signalling between the edge and the core to indicate current load levels at the core.

- Implement similar form of overload protection at the core. You might now say, "Aha! But you're throwing away messages you've accepted". The answer is no: the edge nodes are typically just relaying messages after some checks, application layer processing is typically done in the core.

This thread is becoming slightly hand-wavy but I hope you get the gist of what I'm saying :)

[anamax]

> Some out of band signalling between the edge and the core to indicate current load levels at the core.

In-band/out-of-band doesn't make any difference - the edge nodes can't communicate fast enough. Remember, they're O(N) from each other. (Yes, two neighbors are adjacent, but there are nodes on the other side of the grid.)

Long wires doesn't help either - distance always matters.

> You might now say, "Aha! But you're throwing away messages you've accepted". The answer is no

Actually the answer is "yes" - The original claim was "In telco networks, once a message is accepted into a system, it is expected to be processed. You should throw away any messages you can't handle (because of overload) at the edge of the system."

> I hope you get the gist of what I'm saying

I get the gist - the problem is that you must either waste capacity, drop in the interior, or both because of distance and the fact that there are more interior nodes than there are edge nodes. (And, you can't have all edge nodes because of distance and fan-in.)

One of the subtle ways to waste capacity is to run the control signals faster than the data signals.