Why is the MTU on Ethernet 1500 bytes? I have looked through various docs (eg IEEE Std 802.x) and can find where maxUntaggedFrameSize is listed as 1518 octets, but there is no mention of why this was chosen. I know where the minimum frame size comes from (CSMA/CD and propagation times, etc), but the maximum frame size number sounds fairly arbitrary.

I believe Rich Seifert once said (on comp.dcom.lans.ethernet) that the cost of the necessary buffer memory for the first Ethernet cards was a relevant factor. Steinar Haug, Nethelp consulting, sthaug@nethelp.no