ZyXEL Communications P8701T, Руководство пользователя

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Chapter 4 WAN
Basic Home Station VDSL2 P8701T User’s Guide
78
The following table describes the fields in this screen.
Table 14
Layer-2 ATM Interface Configuration
LABEL DESCRIPTION
ATM PVC
Configuration VPI (Virtual Path Identifier) and VCI (Virtual Channel Identifier) define a virtual circuit.
This section is available only when you configure an ATM layer-2 interface.
VPI The valid range for the VPI is 0 to 255. Enter the VPI assigned to you.
VCI The valid range for the VCI is 32 to 65535 (0 to 31 is reserved for local management of
ATM traffic). Enter the VCI assigned to you.
Select DSL Latency Select Path0 (Fast) to use no interleaving and have faster transmission (a “fast
channel”). Suitable only for a good line with little need for error correction.
At the time of writing the VDSL Router supports fast mode only and interleaved is
reserved for future use.
Select DSL Link
Type Select EoA (Ethernet over ATM) to have an Ethernet header in the packet, so that you
can have multiple services/connections over one PVC. You can set each connection to
have its own MAC address or all connections share one MAC address but use different
VLAN IDs for different services. EoA supports ENET ENCAP (IPoE), PPPoE and RFC1483/
2684 bridging encapsulation methods.
Select PPPoA (PPP over ATM) to allow just one PPPoA connection over a PVC.
Select IPoA (IP over ATM) to allow just one RFC 1483 routing connection over a PVC.
Encapsulation
Mode Select the ISP’s method of multiplexing.
• VC/MUX: In VC multiplexing, each protocol is carried on a separate ATM virtual
circuit (VC). To transport multiple protocols, the VDSL Router 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/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 EoA in the Select DSL Link Type field.
• LLC/ENCAPSULATION: More than one protocol can be carried over the same VC.
This is available only when you select PPPoA in the Select DSL Link Type field.
• LLC/SNAP-ROUTING: 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 EoA in the Select DSL Link Type 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.
Sustainable 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.