Cisco Cisco Customer Response Solution Downloads Guía De Diseño
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Cisco Unified Contact Center Express Solution Reference Network Design, Release 4.1
Chapter 6 Bandwidth, Security, and QoS Considerations
Estimating Bandwidth Consumption
Cisco Desktop Administrator Bandwidth Usage
The bandwidth requirements for CDA are very small and are only seen when an administrator is actively
changing configurations. In general, the bandwidth used by CDA is negligible from a provisioning
standpoint.
changing configurations. In general, the bandwidth used by CDA is negligible from a provisioning
standpoint.
Remote Agent Traffic Profile
Unified CCX signaling represents only a very small portion of control traffic (Cisco Unified
CallManager CTI and ICD subsystems) in the network. For information on TCP ports and Differentiated
Services Code Point (DSCP) marking for Unified CCX ICD and CTI traffic, see the sections on
CallManager CTI and ICD subsystems) in the network. For information on TCP ports and Differentiated
Services Code Point (DSCP) marking for Unified CCX ICD and CTI traffic, see the sections on
, and
.
Bandwidth estimation becomes an issue when voice is included in the calculation. Because WAN links
are usually the lowest-speed circuits in an IP Telephony network, particular attention must be given to
reducing packet loss, delay, and jitter where voice traffic is sent across these links. G.729 is the preferred
codec for use over the WAN because the G.729 method for sampling audio introduces the least latency
(only 30 milliseconds) in addition to any other delays caused by the network.
are usually the lowest-speed circuits in an IP Telephony network, particular attention must be given to
reducing packet loss, delay, and jitter where voice traffic is sent across these links. G.729 is the preferred
codec for use over the WAN because the G.729 method for sampling audio introduces the least latency
(only 30 milliseconds) in addition to any other delays caused by the network.
Where voice is included in bandwidth, system architects should consider the following factors:
•
Total delay budget for latency (taking into account WAN latency, serialization delays for any local
area network traversed, and any forwarding latency present in the network devices). The generally
agreed-upon limit for total (one-way) latency for applications in a network is 150 milliseconds.
area network traversed, and any forwarding latency present in the network devices). The generally
agreed-upon limit for total (one-way) latency for applications in a network is 150 milliseconds.
•
Impact of delays inherent in the applications themselves. 25 seconds is the initial Unified CCX agent
login setup time with no WAN delay. The overall time to log in agents and base delay adds
approximately 30 seconds of delay per 70 milliseconds of WAN delay.
login setup time with no WAN delay. The overall time to log in agents and base delay adds
approximately 30 seconds of delay per 70 milliseconds of WAN delay.
•
Impact of routing protocols. For example, Enhanced Interior Gateway Routing Protocol (EIGRP)
uses quick convergence times and conservative use of bandwidth. EIGRP convergence also has a
negligible impact on call processing and Unified CCX agent logins.
uses quick convergence times and conservative use of bandwidth. EIGRP convergence also has a
negligible impact on call processing and Unified CCX agent logins.
Use Table 8-1 to estimate the number of Unified CCX agents that can be maintained across the WAN
(with IP Telephony QoS enabled). These numbers are derived from testing where an entire call session
to Unified CCX agents, including G.729 RTP streams, is sent across the WAN. Approximately 30% of
bandwidth is provisioned for voice. Voice drops are more of an issue when you are running RTP in
conjunction with Cisco Agent Desktop and other background traffic across the WAN. These voice drops
might occur with a specific number of agents at a certain link speed, and those possible scenarios are
denoted by the entry N/R (not recommended) in Table 6-9.
(with IP Telephony QoS enabled). These numbers are derived from testing where an entire call session
to Unified CCX agents, including G.729 RTP streams, is sent across the WAN. Approximately 30% of
bandwidth is provisioned for voice. Voice drops are more of an issue when you are running RTP in
conjunction with Cisco Agent Desktop and other background traffic across the WAN. These voice drops
might occur with a specific number of agents at a certain link speed, and those possible scenarios are
denoted by the entry N/R (not recommended) in Table 6-9.
In remote agent deployments, QoS mechanisms should be used to optimize WAN bandwidth utilization.
Advanced queuing and scheduling techniques should be used in distribution and core areas as well. For
information on QoS traffic classification, see
Advanced queuing and scheduling techniques should be used in distribution and core areas as well. For
information on QoS traffic classification, see
. For
provisioning guidelines for centralized call processing deployments, refer to the Cisco IP Telephony
Solution Reference Network Design (SRND) Cisco Unified CallManager Releases 4.0 and 4.1
documentation, available online at
Solution Reference Network Design (SRND) Cisco Unified CallManager Releases 4.0 and 4.1
documentation, available online at
Table 6-9
Remote Agents Supported by Unified CCX Across a WAN Link
Frame Relay
128 KB
256 KB
512 KB
768 KB
T1
G.729
3
7
15
25
38
G. 711
N/R
N/R
N/R
N/R
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