[email protected] said: > Suppose the average NTP packet is 100 bytes, and assume standard 8-10 > encoding no with extra overhead, so 1 byte = 10 bits:
The 10/100/1000 on Ethernet speed refers to net data rate. The actual bit rate on the wire is faster to compensate for things like 8B/10B encoding. For example, 100 megabit Ethernet is actually 125 on the wire if you look at it with a scope. But if you are working on the back of an envelope, 8 == 10. > The speed of light is course always the same... Well, no. Light is slower in fibers and cable.[1] My rule of thumb is that the conversion factor is the same as miles to kilometers. (Crappy cable is significantly slower than good cable.) > So, by far, the network software stack imposes the largest overhead. Agree. But the software delays are roughly predictable. (Cache misses and scheduling are the big ones I can think of right now.) Anybody know anything about the USB/Ethernet stack vs the non-USB Ethernet stack? ------ 1) The high speed traders reactivated a microwave link from New York to Chicago to save a couple of ms. https://www.ft.com/content/2bf37898-b775-11e2-841e-00144feabdc0 -- These are my opinions. I hate spam. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
