Chapter 6 Broadband
VMG4380-B10A / VMG4325-B10A User’s Guide
88
Mode
Select
Bridge
when your ISP provides you more than one IP address and you want the
connected computers to get individual IP address from ISP’s DHCP server directly. If you
select
Bridge
, you cannot use routing functions, such as QoS, Firewall, DHCP server and
NAT on traffic from the selected LAN port(s).
ATM PVC Configuration (These fields appear when the
Type
is set to
ADSL over ATM
.)
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.
DSL Link Type
This field is not editable. The selection depends on the setting in the
Encapsulation
field.
EoA
(Ethernet over ATM) uses 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.
PPPoA
(PPP over ATM) allows just one PPPoA connection over a PVC.
IPoA
(IP over ATM) allows just one RFC 1483 routing connection over a PVC.
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
.
QoS
Table 10
Bridge Mode (ADSL over ATM) (continued)
LABEL
DESCRIPTION
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