Masataka Ohta wrote on 04/09/2023 12:04:
Are you saying you thought a 100G Ethernet link actually consisting
of 4 parallel 25G links, which is an example of "equal speed multi
parallel point to point links", were relying on hashing?
this is an excellent example of what we're not talking about in this thread.
A 100G serdes is an unbuffered mechanism which includes a PLL, and this
allows the style of clock/signal synchronisation required for the
deserialised 4x25G lanes to be reserialised at the far end. This is one
of the mechanisms used for packet / cell / bit spray, and it works
really well.
This thread is talking about buffered transmission links on routers /
switches on systems which provide no clocking synchronisation and not
even a guarantee that the bearer circuits have comparable latencies.
ECMP / hash based load balancing is a crock, no doubt about it; it's
just less crocked than other approaches where there are no guarantees
about device and bearer circuit behaviour.
Nick
