Configuring the modem
EN/LZT1083982 R4
61 (87)
2000-12-07
ADSL modems operate in one of serveral modes determined by the DSLAM (equipment
at the ISP side of the ADSL line), central office setup and also by service offered. The
HM220d ADSL modem can be configured to operate in three different "Operating
modes": Routed/PPPoA (default), Routed/RFC1483 or Bridged/RFC1483. Which one
you need to use depends on the configuration specified by your ISP/service provider.
The "ADSL mode" depends on what services you are offered and your ISP/service
provider must provide this information. The HM220dp model can work in four different
ADSL modes which are Multimode (default), T1.413, G.Dmt, and G.Lite. The HM220di
model can work in two different ADSL modes which are G.Dmt and DTAG.
5.5.2
Routed
This section is only shown if either "Routed/PPPoA" or "Routed/RFC1483" operating
mode is selected in the previous LAN section.
The information differs some between the Routed/PPPoA and Routed/RFC1483 mode.
Password handling, User name and Password is only valid for Routed/PPPoA mode.
DHCP client, WAN IP address and WAN Subnet mask are used in Routed/RFC1483
mode.
When the modem operates in Routed mode it sends packets from node to node based on
IP addresses. An IP address can be viewed as a modifiable identifier that is mapped to the
MAC address of network node. The IP address of a node may change dynamically or by
user configuration. Therefore, there are protocols and databases on the network that must
keep track of the IP address assignments for the nodes on the local area network (LAN).
For the Routed mode, information on VP/VC identifiers and some local network
information has to be set.
The "VP and VC identifiers" refer to the technology, Asynchronous Transfer Mode,
ATM, used for data transmission. The data is transmitted over virtual channels that are
designated by specific unique identifiers (Virtual Channel Identifiers or VCIs). There can
be multiple VCIs in one virtual path and the virtual path also has a unique Virtual Path
Identifier, VPI.
The parameters for VP and VC should be one pair identifying DSLAM (equipment at the
ISP side of the ADSL line) and ISP router. This pair should be provided by the access
network operator.
"Encapsulation type" is the specific method used when data is transferred via ATM
Virtual Channels. For Routed/PPPoA operating mode, the default value for the modem is
VC Mux (VC Multiplexing), which uses a separate VC for each carried protocol. For
Routed/RFC1483 operating mode the default value is LLC (Logical Link Control)
encapsulation, which allows multiplexing of multiple protocols over a single ATM virtual
circuit. Refer to your ISP/service provider documentation.
Password handling refers to the Point-to-Point protocol (PPP) which is used by the
modem to establish connections over the ADSL ATM network. When identifying your
modem (password handling) an authentication protocol is used which can be either PAP
(Password Authentication Protocol) or CHAP (Challenge-Handshake Authentication
Protocol). Refer to your ISP/service provider documentation.