> It's P2P as far as the physical layer (L1) is concerned.

Only in the sense that the L1 "peer" is the switch. As soon as the switch goes to forward the packet, if ports 2 and 3 are both sending to port 1 at 1Gbps and port 1 is a 1Gbps port, 2Gbps won't fit and something's got to give.

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mikepurvis 3 hours ago | parent [-]

Right but the switch has internal buffers and ability to queue those packets or apply backpressure. Resolving at that level is a very different matter from an electrical collision at L1.

	▲	AnthonyMouse 3 hours ago \| parent [-]
		Not as far as TCP is concerned it isn't. You sent the network a packet and it had to throw it away because something else sent packets at the same time. It doesn't care whether the reason was an electrical collision or not. A buffer is just a funny looking wire.