Cisco Cisco Unified MeetingPlace Express 2.0 Libro bianco
Cisco Systems
Network Provisioning and Configuration
Page 5
In a lecture-style meeting, latency generally does not matter. However, in an interactive
discussion, high latency breaks the normal conversation model, causing serious
frustration as people attempt to break into a conversation and discover they can’t without
colliding with someone else. If you are finding that the conversation flow seems
unnaturally difficult, it may be because of high latency on one or more of the connections.
Recommendations for limiting latency:
discussion, high latency breaks the normal conversation model, causing serious
frustration as people attempt to break into a conversation and discover they can’t without
colliding with someone else. If you are finding that the conversation flow seems
unnaturally difficult, it may be because of high latency on one or more of the connections.
Recommendations for limiting latency:
•
Provision the network to give priority to voice traffic.
•
Do not cascade conferences using multiple bridges.
•
Try to minimize the use of VoIP over slow lines.
•
Do not route traffic through transcoders or Media Termination Points (MTPs).
2.1.4 U s i n g Vo i c e Ga t e w a y s
Calls coming in from the Public Switched Telephony Network (PSTN) will need to come
through a VoIP gateway to connect to Cisco MeetingPlace Express. Requirements for
gateways are more stringent than for two-way voice conversations, assuming high voice
quality is desired. In particular:
through a VoIP gateway to connect to Cisco MeetingPlace Express. Requirements for
gateways are more stringent than for two-way voice conversations, assuming high voice
quality is desired. In particular:
•
Cisco MeetingPlace Express depends on gateways to detect and remove the
DTMF tones used for signaling in traditional telephony networks. If the tones are
not accurately detected, even in the presence of speech, users will have difficulty
entering or controlling meetings. If tones are not fully removed from the incoming
stream, users employing in-meeting controls may give other the other meeting
participants an earful of noise.
not accurately detected, even in the presence of speech, users will have difficulty
entering or controlling meetings. If tones are not fully removed from the incoming
stream, users employing in-meeting controls may give other the other meeting
participants an earful of noise.
•
Cisco MeetingPlace Express works best if DTMF tones are converted into in-
band RTP/RFC2833 packets, rather than out-of-band H.245 packets. When using
SIP signaling, Cisco MeetingPlace Express only works with RFC2833.
SIP signaling, Cisco MeetingPlace Express only works with RFC2833.
•
Cisco MeetingPlace Express depends on the gateway for echo cancellation.
Failure to properly cancel echo will result in echo bleeding into the meeting
through traditional telephones, yielding unsatisfactory voice quality. Cisco
recommends that gateways associated with Cisco MeetingPlace Express provide
echo cancellation with a tail of at least 128ms. International calls may benefit
from even longer tails.
through traditional telephones, yielding unsatisfactory voice quality. Cisco
recommends that gateways associated with Cisco MeetingPlace Express provide
echo cancellation with a tail of at least 128ms. International calls may benefit
from even longer tails.
•
If you want to use the Cisco MeetingPlace Express pager notification features or
if you wish to navigate through Interactive Voice Response (IVR) systems on
outgoing calls through a gateway, the gateway should be configured to convert
outgoing RFC2833 digits into real DTMF tones. Cisco MeetingPlace Express will
not generate H.245 signals for this purpose.
outgoing calls through a gateway, the gateway should be configured to convert
outgoing RFC2833 digits into real DTMF tones. Cisco MeetingPlace Express will
not generate H.245 signals for this purpose.
2.2 W e b Con f e r e n c i n g
Cisco MeetingPlace Express web conferencing employs the Macromedia Real-Time
Messaging Protocol (RTMP) between the server and Macromedia Flash clients on the
desktop. Traffic consists of:
Messaging Protocol (RTMP) between the server and Macromedia Flash clients on the
desktop. Traffic consists of:
•
Screen updates sent by the presenter to the server.
•
Screen updates sent by the server to each client.
•
Roster updates and meeting control messages.