g software management tools to assess voice and video quality to analyze the following: Packet loss This refers to the packets that are dropped when there is network congestion. Packet loss results in uneven voice quality. Voice conversations "break up" when packet loss is too high. Latency This term refers to delays (in milliseconds) that are incurred when voice packets traverse the network. Latency results in long pauses within conversations, and clipped words. www.TechnicalPDF.com Jitter This refers to uneven latency and packet loss, which results in noisy calls that contain pops and clicks or crackling sounds. Echo This is the annoying effect of hearing your voice repeated, an issue with which SO many of us are familiar. It is often caused when voice data is translated from a circuit-switched format to the IP format. This is usually corrected during installation by special echo- canceling software. Prioritizing Voice and Video on a Virtual Local Area Network Organizations can program voice telephony as a separate Virtual Local Area Network (VLAN). These "virtual" networks act as separate LANs. IP PBX components use common protocols and control the types of devices that are able to communicate with IP telephones and hold audio and video conferences. See Table 2-3 in the Appendix for additional protocols and VoIP terms. VLANs perform the following special treatment for IP endpoints: 802.1P protocols tag voice and multimedia packets to prioritize them for improved availability with less delay. The tag distinguishes voice and video packets. In addition to multimedia, tagging protocols such as 802.1P are used for conferencing services, as well. VLANs shield endpoints from hackers by allowing only certain types of packets through firewalls to reach them. This is accomplished by means of policies for firewall logical ports that are dedicated to voice and video traffic. Logical firewall ports are defined in software rather than actual physical ports. IP PBX Architecture Private Branch Exchange (IP PBX) architecture v