User's Manual

Tsunami MP.11 2454-R, 5054-R, and 5054-R-LR Installation and Management
Chapter 3. Management Overview 31
Note that traffic priority refers to the prioritization of this specific Service Flow.
The software tries to deliver the packets within the specified latency and jitter requirements, relative to the
moment of receiving the packets in the unit. For delay-sensitive traffic the jitter must be equal to or less than the
latency. A packet is buffered until an interval of time equal to the difference between Latency and Jitter (Latency –
Jitter) has elapsed. The software will attempt to deliver the packet within a time window starting at (Latency –
Jitter) until the maximum Latency time is reached. If the SFC’s scheduling type is real-time polling (rtPS), and the
packet is not delivered by that time, it will be discarded. This can lead to loss of packets without reaching the
maximum throughput of the wireless link. For example, when the packets arrive in bursts on the Ethernet interface
and the wireless interface is momentarily maxed out, then the packets at the “end” of the burst may be timed out
before they can be sent.
Users are able to set up their own traffic characteristics (MIR, CIR, latency, jitter, etc.) per service flow class to
meet their unique requirements. A good example is provided by the seven predefined SFCs:
1. UL-Unlimited BE
a. Scheduling Type = Best Effort
b. Service Flow Direction = Uplink
c. Initialization State = Active
d. Maximum Sustained Data Rate = 20 Mbps
e. Traffic Priority = 0
2. DL-Unlimited BE (same as UL-Unlimited BE, except Service Flow Direction = Downlink)
3. UL-G711 20 ms VoIP rtPS
a. Schedule type = Real time Polling
b. Service Flow Direction = Uplink
c. Initialization State = Active
d. Maximum Sustained Data Rate = 88 Kbps
e. Minimum Reserved Traffic Rate = 88 Kbps
f. Maximum Latency = 20 milliseconds
g. Traffic Priority = 1
4. DL-G711 20 ms VoIP rtPS (same as UL-G711 20ms VoIP rtPS, except Service Flow Direction =
Downlink)
5. UL-G729 20 ms VoIP rtPS (same as UL-G711 20ms VoIP rtPS, except Maximum Sustained Data Rate
and Maximum Reserved Traffic Rate = 64 Kbps)
6. DL-G729 20 ms VoIP rtPS (same as UL-G729 20ms VoIP rtPS, except Service Flow Direction =
Downlink)
7. DL-2Mbps Video
a. Schedule type = Real time Polling
b. Service Flow Direction = Downlink
c. Initialization State = Active
d. Maximum Sustained Data Rate = 2 Mbps
e. Minimum Reserved Traffic Rate = 2 Mbps
f. Maximum Latency = 20 milliseconds
g. Traffic Priority = 1
Two different VoIP Service Flow classes for each direction of traffic have been defined (index numbers 3 to 6)
which follow the ITU-T standard nomenclatures: G.711 refers to a type of audio companding and encoding that
produces a 64 Kbps bitstream, suitable for all types of audio signals. G.729 is appropriate for voice and VoIP
applications, but cannot transport music or fax tones reliably. This type of companding and encoding produces a
bitstream between 6.4 and 11.8 Kbps (typically 8 Kbps) according to the quality of voice transport that is desired.