Inter-Tel AXXESS Manual page 163

NOTE:
ets received over the network may be unusable. If this occurs, the unused packets con-
tribute to (and increase) the packet loss.
•
Hops: (The number of router points a data packet must pass through during transmis-
sion) 15 or fewer to minimize the number of potential problem points
•
Committed Information Rate (CIR) and Burst Rate (BR): 512 Kbps each (This
means that 512 Kbps is always available, and the link may burst up to 1024 Kbps for
short periods if the bandwidth is available from the WAN provider.) There is usually no
guarantee of BR availability.
NOTE:
value, packets may begin to queue within the frame relay network. When this happens,
frame packets may become subject to delay and could eventually be tagged as Discard
Eligible (DE). (Packets marked as DE could be discarded before reaching their destina-
tion. This potential queuing delay and packet loss can adversely affect voice quality.
7.5 Whenever possible, Inter-Tel recommends using Ethernet switching mechanisms rather
than Ethernet hubs. The switches offer more inherent Ethernet advantages over hub (shared)
technology, such as segmentation, full-duplex operations, layer 2 prioritization, etc.
NOTE:
tables. Because Call Processing controls the IPRC, the IPRC cannot be installed behind a fire-
wall or use a Network Address Translation (NAT) table.
7.6
If using a private network, these recommended guidelines are relatively easy to attain.
If connected to the public Internet, the IPRC does function, but the quality may suffer due to
the dynamic bandwidth availability. Therefore, Inter-Tel recommends using the IPRC(s) on a
managed private network.
7.7 For any router that has IPRC traffic passing through it, program the router to prioritize
the packets sent by the IPRC. You can usually do this by programming the router to prioritize
the packets sent by a specific IP address (i.e., the IPRC's IP address), by prioritizing UDP
packets (because all audio packets sent by the IPRC are UDP packets), or by prioritizing the
UDP port numbers that the IPRC uses. You can also use Quality of Service (QoS) features, like
Type of Service (ToS) or Differentiated Services (Diffserv). Under the IP Connection folder in
DB Programming, set the Audio RTP Type of Service field to 184 if your routers use ToS or
Diffserv. (Although 184 is the recommended setting for the Audio RTP Type of Service, you
can set this field to any value for a Diffserv code point in your network.) In addition, program
the external router to fragment large data packets into smaller packets. This reduces the possi-
bility that voice packets have to wait for a large data packet at the router.
Performance
INTER-TEL
If the Network Qualifier returns a value greater than 40ms for jitter, voice pack-
Keep the voice traffic below the CIR value. When voice traffic exceeds the CIR
Call Processing does not support firewalls or Network Address Translation (NAT)
® ®
AXXESS MANUAL VERSION 11.0 – May 2008
Specifications
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