ZyXEL Communications P-2612HW-F1 User Manual page 103

Table 13 Internet Access Setup: Advanced Setup (DSL Mode) (continued)
LABEL
Multicast
ATM QoS
ATM QoS Type
Peak Cell
Rate
Sustain Cell
Rate
Maximum
Burst Size
MTU
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P-2612HW-F1 User's Guide
DESCRIPTION
Multicast packets are sent to a group of computers on the LAN and are
an alternative to unicast packets (packets sent to one computer) and
broadcast packets (packets sent to every computer).
IGMP (Internet Group Multicast Protocol) is a network-layer protocol
used to establish membership in a multicast group. The ZyXEL Device
supports both IGMP version 1 (IGMP-v1) and IGMP-v2. Select None
to disable it.
Select CBR (Continuous Bit Rate) to specify fixed (always-on) bandwidth
for voice or data traffic.
Select UBR (Unspecified Bit Rate) for applications that are non-time
sensitive, such as e-mail.
Select VBR-RT (real-time Variable Bit Rate) type for applications with
bursty connections that require closely controlled delay and delay
variation.
Select VBR-nRT (non real-time Variable Bit Rate) type for connections
that do not require closely controlled delay and delay variation.
Divide the DSL line rate (bps) by 424 (the size of an ATM cell) to find the
Peak Cell Rate (PCR). This is the maximum rate at which the sender can
send cells. Type the PCR here.
The Sustained Cell Rate (SCR) sets the average cell rate (long-term)
that can be transmitted. Type the SCR, which must be less than the
PCR. Note that system default is 0 cells/sec.
Maximum Burst Size (MBS) refers to the maximum number of cells that
can be sent at the peak rate. Type the MBS, which is less than 65535.
The Maximum Transmission Unit (MTU) defines the size of the largest
packet allowed on an interface or connection. Enter the MTU in this field.
For ENET ENCAP, the MTU value is 1500.
For PPPoE, the MTU value is 1492.
For PPPoA and RFC 1483, the MTU is 65535.
Click Back to return to the previous screen.
Click Apply to save the changes.
Click Cancel to begin configuring this screen afresh.
Chapter 6 WAN Setup
103