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Implementing Communication Manager on a data network
The bandwidth required for control network traffic depends on the number of port networks
(PNs), the number of endpoints (both trunks and stations), and the number and complexity of
the calls being controlled. The network must be engineered to support the basic connectivity
and background activity on the port network, arriving call traffic, and periodic maintenance.
There will be cases where the control path traverses several network segments, each with
different configurations and sometimes carrying several signaling channels. In these cases,
each segment must be engineered for its specific needs.
on the control network.
Table 81: Control Network Bandwidth Requirements
Parameter
Idle BW
(active IPSI)
BW (standby
IPSI)
Incremental
traffic per call
The network bandwidth should be engineered to assure that the idle bandwidth (approximately
11kbps), plus the call volume bandwidth, plus additional bandwidth to assure a good grade of
service given the random nature of call events. Typically, 20kbps additional bandwidth is
sufficient to achieve acceptable latency on the connection.
End-to-end delay across the control network should be held below 100 ms. Above 100ms,
users may notice sluggishness in the user interface. Above 300ms, or with significant packet
loss, there will be excessive retransmission at the application layer that will bring the link down.
Delays, even momentary delays exceeding 300ms, may cause the interchange of control
networks or servers, and may generate alarms. Where a common path is used to reach IPSIs,
significant delays will cause a Port Network Warm (or COLD) restart.
Choose a routing protocol that is robust and will converge quickly when there are changes in
the network configuration. OSPF is a highly scalable, non-proprietary Interior Gateway (routing)
Protocol (IGP) that can achieve network convergence within 10 seconds. OSPF also supports
multipath routing, where parallel paths are used concurrently. When properly configured, OSPF
is an appropriate choice for a routing protocol across the control network.
338 Avaya Application Solutions IP Telephony Deployment Guide
Value
Units
10
Kbps
1
Kbps
2500
Octets
21
Packets
Table 81
lists the bandwidth required
Notes
This background sanity checking remains
constant, independent of load. Downlink
traffic is greater than uplink. Allow 10kbps
for good performance.
This value is nearly constant. [To Be
Verified]
With both endpoints controlled by the
same IPSI, less if only one endpoint is
controlled by the IPSI. This value will vary
depending on the complexity of the call.
This typical value, associated with 2500
octets per call yields an average packet
size of 120 octets. This is useful for
calculating Overheads.
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