IP telephony There are two types of IP telephony traf?¬?c: signaling information between end
devices (IP phones and softswitches, such as Cisco Uni?¬?ed CallManager) and
the data packets of the voice conversation. Designers often con?¬?gure the data
to and from the IP phones on a separate VLAN designated for voice traf?¬?c so
that they can apply QoS5 measures to give high priority to voice traf?¬?c.
IP multicast IP multicast traf?¬?c is sent from a particular source address to a multicast group
that is identi?¬?ed by a single IP and MAC destination-group address pair.
Examples of applications that generate this type of traf?¬?c are Cisco IP/TV
broadcasts and imaging software used to quickly con?¬?gure workstations and
servers. Multicast traf?¬?c can produce a large amount of data streaming across
the network. For example, video traf?¬?c from online training, security
applications, Cisco Meeting Place, and Cisco TelePresence is proliferating on
some networks. Switches must be con?¬?gured to keep this traf?¬?c from ?¬‚ooding
to devices that have not requested it, and routers must be con?¬?gured to ensure
that multicast traf?¬?c is forwarded to the network areas where it is requested.
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