>That would be like if I asked you how TCP works and you said, isn't TCP >just data within an IP packet? Now I'm asking you to consider how >application-layer protocols work. They have operations also. In the case of >HTTP, there are many commands. The question is how are the commands >encoded? It's yet another variety (beyond bit-oriented and byte-oriented) >that is worth considering.
To say nothing about self-defining data provided to the application layer by presentation layer protocols such as ASN.1, XDR, etc. These are not particularly bit-at-a-time, but variable length type-length-value strings. > >The data is HTML-encoded text, GIFs, etc, which isn't too interesting (from >our perspective). HTTP is rather interesting, however. So is FTP, >especially since it has a tendency to break in many environments. > >And you didn't answer me how TCP operations, such as SYNs are encoded. > >Well, we've gotten off topic. I think it should be "on topic," but Cisco >test developers don't tend to consider these issues. ;-) > >Priscilla > > >At 03:51 PM 2/7/02, Steven A. Ridder wrote: >>""Priscilla Oppenheimer"" wrote in message >>[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... >> > At 03:26 PM 2/7/02, Priscilla Oppenheimer wrote: >> > >> > >What is TCP? How is a SYN represented in TCP? >> > > >> > >What is HDLC? How is a GET represented in HDLC? >> > >> > That was supposed to say HTTP! HTTP, FTP, SMTP, POP and probably others, >> > have yet another way of encoding control information. >> >>Isn't it all just data within the packets and not flags in a packet, like in >>TCP? >> >>It's byte-oriented >> > but a little different. >> > >> > And how about routing protocols? For example, how does EIGRP encode an >> > Update opcode? Is it different from how HTTP, FTP, etc. send control >info? >> > And different from TCP? >> > >> > >> > >What is FTP? How is a RETR represented in FTP? >> > > >> > >And how about Token Ring with its starting delimiter and ending >>delimiters? >> > >And how should one interpret the Ethernet preamble? >> > > >> > >Also, aren't all protocols at some level processed a bit at a time? >> > > >> > >This is bad as the 7-layer discussions! ;-) >> > > >> > >Priscilla >> > >> > >> > ________________________ >> > >> > Priscilla Oppenheimer >> > http://www.priscilla.com >________________________ > >Priscilla Oppenheimer >http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=34796&t=34629 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
