brian dell wrote: > > help with the following: > > Serial interfaces typically connect to WAN via serial links ? > correct ?
Yes. > and once we say serial links we imply bit oriented traffic via > these links ? correct ?? Nope. Serial means one bit at a time is sent. The opposite is parallel, which is hardly ever used these days for networking, but is used to connect printers. With parallel communications, multiple bits go out at a time. Serial versus parallel is a completey different concern than bit-oriented versus byte-oriented protocols, which are also known as character-oriented protocols. Character-oriented protocols are generally considered obsolete, though that's arguable. The most popular one was Binary Synchronous Communication or BSC, sometimes called BSYNCH. With a character-oriented protocol, control information is inserted in the message stream in the form of multibit characters. For example, with BSC, a SYN or ACK is sent as a 7-bit ASCII character. A bit-oriented protocol lets specific bits within a byte stream mean something. For example, one bit might mean ACK. SDLC, HDLC, 802.3, 802.5, 802.2 and many upper-layer protocols are bit-oriented. Bit-oriented protocols are much more efficient than character-oriented protocols. 802.3 Ethernet is bit-oriented, even though it doesn't use specific bits much. But an obvious example is that a single bit (first bit transmitted) means unicast versus broadcast/multicast. LLC 802.2 is bit-oriented. A single bit means Command or Reply. TCP is bit-oriented too, by the way. A single bit means SYN. IP is bit-oriented. A single bit means "Don't Fragment," for example. Routing protocols tend to by byte-oriented, by the way. A one or two-byte opcode in the routing protocol header says whether the message is an Update or Hello or Query or whatever. Application-layer protocols, such as SMTP and FTP are even less efficient. They are string-oriented. They send human-readable strings, such as RETR and RCTP TO. They are inefficient, but very easy to use and troubleshoot. Hope that helped! _______________________________ Priscilla Oppenheimer www.priscilla.com > > if this is correct then what would be non bit oriented traffic > or links ? > i guess it would the links connected to LAN, like typical > connection between, say a Router and a PC (via 10/100 lan > connection). (would this be correct ?) > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=70811&t=70803 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
