Zhone Technologies 6238-I2 - Manual (Page 31)

6238-A2-ZB20-10 6238 Wi-Fi Router with VOIP User’s Guide 31
Find out the following values from your ISP before you change them.
• VPI: Virtual Path Identifier. The valid range is 0 to 255.
• VCI: Virtual Channel Identifier. The valid range is 32 to 65535.
• Service Category: Five classes of traffic are listed:
o UBR Without PCR (Unspecified Bit Rate without Peak Cell Rate)—
UBR service is suitable for applications that can tolerate variable delays
and some cell losses. Applications suitable for UBR service include
text/data/image transfer, messaging, distribution, and retrieval and also
for remote terminal applications such as telecommuting.
o UBR With PCR (Unspecified Bit Rate with Peak Cell Rate)
o CBR (Constant Bit Rate)— Used by applications that require a fixed data
rate that is continuously available during the connection time. It is
commonly used for uncompressed audio and video information such as
videoconferencing, interactive audio (telephony), audio / video
distribution (e.g. television, distance learning, and pay-per-view), and
audio / video retrieval (e.g. video-on-demand and audio library).
o Non Realtime VBR (Non-Real-time Variable Bit Rate)— Can be used
for data transfers that have critical response-time requirements such as
airline reservations, banking transactions, and process monitoring.
o Realtime VBR (Real-time Variable Bit Rate)— Used by time-sensitive
applications such as real-time video. Rt-VBR service allows the network
more flexibility than CBR.
To enable the Quality of Service function, it must be enabled on the previous screen
in order for the traffic classification rule that you specify (later in the Quality of
Service Screen under Advanced Setup) to be activated. Once a PVC is setup with
QoS, two more PVC queues will be used up for this function meaning 3 PVC queues
will be used. Note there is a total of 8 PVC queues available for this unit.