>I think the latter. Layer 1 defines both putting 1s and 0s on the wire as >well as physical aspects of connectivity. EIA-232 is a fair example. It >specifies valid voltages/states to represent a 1 or a 0 but it also >specifies that TX Data is on pin 2 of a 25 ping D shell connector, etc. If >that aint layer 1, I don't know what it is. Maybe it is easiest to think of >everything that doesn't fit the layer two definition as defaulting to layer >1. There may be a fallacy in that, but I think its fairly safe.
Do note that EIA RS-232 was developed long before there was an OSI reference model. I do think it fits clearly into the original Layer 1, though, because it is fundamentally a DTE specification. > >Scott > >Steven A. Ridder wrote: >> >> I've read in some books that the physical layer (L1) of the OSI >> model deals >> with the logical functions of putting the 1's and 0's onto a >> wire and not >> the physical act of doing so, and I've read other books that >> state that the >> physical layer deals with not only putting 1's and 0's onto a >> wire, but also >> the mechanical make-up of a wire, the electrical voltage of a >> wire, >> hardware,. etc. >> >> Which is true? >> >> -- >> RFC 1149 Compliant. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=35567&t=35544 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
