Chapter 6 Broadband
VMG4380-B10A / VMG4325-B10A User’s Guide
83
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 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
.
Sustainable 
Cell Rate
The Sustainable 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 User Name 
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.
PPP Auto 
Connect
Select this option if you do not want the connection to time out.
IDLE Timeout
This value specifies the time in minutes that elapses before the router automatically 
disconnects from the PPPoE server.
This field is not configurable if you select 
PPP Auto Connect
.
PPPoE Service 
Name 
Enter the name of your PPPoE service here.
Table 8 
Routing Mode (continued)
LABEL
DESCRIPTION