Talk:CCNA Certification/Transport Layer

Just wanted to say great "living" book so far. You've covered most of the 640-821 test with this information, and its a great way to study while at work, in between actual work.

I just wanted to clear up a little confusion about the UDP section. The whole part on UDP says: The User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. Using UDP, programs on networked computers can send short messages sometimes known as datagrams to one another. UDP is sometimes called the Universal Datagram Protocol or Unreliable Datagram Protocol.

UDP does not provide the reliability and ordering that TCP does. Datagrams may arrive out of order, appear duplicated, or go missing without notice. Without the overhead of checking whether every packet actually arrived, UDP is faster and more efficient for many lightweight or time-sensitive purposes. Also, its stateless nature is useful for servers that answer small queries from huge numbers of clients. Compared to TCP, UDP is required for Broadcasting (send to all on local network) and multicast (send to all subscribers).

Common network applications that use UDP include the Domain Name System (DNS), streaming media applications such as IPTV, Voice over IP (VoIP), Trivial File Transfer Protocol (TFTP) and online games.

That last part explains applications of UDP is VoIP... Now I won't argue that VoIP isn't using UDP, but its not exactely UDP that does the real portion of it, its really Real-Time Transfer Protocol. I would put a little bit of information in there about that, just to make sure people don't think VoIP is that unreliable.

If you're going to throw in the VoIP information to get some references when people go for a CCNP, make sure you atleast throw that in there cause it can DEFINATELY cause some confusion in the beginning. I know this is the CCNA not the CCNP, but its still nice to have proper information.

Though you shouldn't confuse it with RTP Protocol, cause that Real-Time Transfer Protocol has been called RTP, from what i've seen. I do not have any experience with Real-Time Transfer Protocol, but I have read about it from a few sources, though most of them internet based, I'm not sure how well you can trust them.