ZyXEL Communications VSG1435-B101 - V1.10, Руководство пользователя

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Chapter 6 Broadband
VSG1435-B101 Series User’s Guide
85
Encapsulation
Mode Select the method of multiplexing used by your ISP from the drop-
down list box. Choices are:
• LLC/SNAP-BRIDGING: In LCC encapsulation, bridged PDUs are
encapsulated by identifying the type of the bridged media in the
SNAP header. This is available only when you select IPoE or PPPoE
in the Select DSL Link Type field.
• VC/MUX: In VC multiplexing, each protocol is carried on a single
ATM virtual circuit (VC). To transport multiple protocols, the ZyXEL
Device needs separate VCs. There is a binding between a VC and
the type of the network protocol carried on the VC. This reduces
payload overhead since there is no need to carry protocol
information in each Protocol Data Unit (PDU) payload.
• LLC/ENCAPSULATION: More than one protocol can be carried
over the same VC. This is available only when you select PPPoA in
the Encapsulation field.
• LLC/SNAP-ROUTING: In LCC encapsulation, an IEEE 802.2
Logical Link Control (LLC) header is prefixed to each routed PDU to
identify the PDUs. The LCC header can be followed by an IEEE
802.1a SubNetwork Attachment Point (SNAP) header. This is
available only when you select IPoA in the Encapsulation field.
Service
Category Select UBR Without PCR or UBR With PCR for applications that are
non-time sensitive, such as e-mail.
Select CBR (Continuous Bit Rate) to specify fixed (always-on)
bandwidth for voice or data traffic.
Select Non Realtime VBR (non real-time Variable Bit Rate) for
connections that do not require closely controlled delay and delay
variation.
Select Realtime VBR (real-time Variable Bit Rate) for applications with
bursty connections that require closely controlled delay and delay
variation.
Peak Cell Rate 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.This field is not available when you
select
UBR Without PCR .
Sustain Cell
Rate The Sustain 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.
This field is available only when you select Non Realtime VBR or
Realtime VBR .
Maximum Burst
Size 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.
This field is available only when you select Non Realtime VBR or
Realtime VBR .
PPP Information This is available only when you select PPPoE or PPPoA in the Mode
field.
PPP Username Enter the user name exactly as your ISP assigned. If assigned a name
in the form user@domain
where domain identifies a service name, then
enter both components exactly as given.
PPP Password Enter the password associated with the user name above.
Table 7 Broadband: Add/Edit: Routing Mode
LABEL DESCRIPTION