• Low delay:
  • VoIP requires a very low delay between the sending phone and the receiving phone—typically less than 200 milliseconds (.2 seconds).
  • This is a much lower delay than what is required by typical data applications.
• Low jitter:
  • Jitter is the variation in delay.
  • VoIP requires very low jitter as well, whereas data applications can tolerate much higher jitter.
  • For example, the jitter for consecutive VoIP packets should not exceed 30 milliseconds (.03 seconds), or the quality degrades.
• Loss:
  • If a VoIP packet is lost in transit because of errors or because a router doesn’t have room to store the packet while waiting to send it, the VoIP packet is not delivered across the network.
  • Because of the delay and jitter issues, there is no need to try to recover the lost packet.
  • It would be useless by the time it was recovered.
  • Lost packets can sound like a break in the sound of the VoIP call

Protocol used to transfer data, the name of the server, and the particular web page on that server. The URL can be broken into three parts:

• The protocol is listed before the //.
• The hostname is listed between the // and the /.
• The name of the web page is listed after the /.

• For example:
  • http://www.cisco.com/go/prepcenter
• In this case, the protocol is Hypertext Transfer Protocol (HTTP), the hostname is www.cisco.com, and the name of the web page is go/prepcenter.
• This URL is particularly useful, because it is the base web page for the Cisco CCNA Prep Center.