Technical Concepts - Efficient Networks SpeedStream 5100 Series User Manual

SpeedStream PPPoE Modem

Technical Concepts

This section provides very brief descriptions of some of the features available on the SpeedStream PPPoE
modem.
Asynchronous Transfer Mode (ATM)
ATM is a fast, cell-based technology defined by the ITU-T. It works by taking an ordinary, variable-
length data packet and segmenting it into 53-byte cells prior to 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. The virtual path also has a unique virtual path identifier
(VPI). Data transmitted over ATM VCs is routed by ATM switches. At the destination node, the cells are
reassembled into packets. In router mode, only one virtual channel is supported. In bridge mode, up to 16
virtual channels can be configured to be used as individual bridge ports; however, all the virtual channels
must reside on the same virtual path.
ATM Adaption Layer 5 (AAL5)
AAL5 is a network layer for adapting data traffic into the format of ATM fixed-length packet networks.
Dynamic Host Configuration Protocol (DHCP) Server
When operating as a DHCP server, the router will dynamically assign IP addresses to LAN nodes. The
DHCP server verifies a device's identity, leases it an IP address for a predetermined period of time, and
reclaims the address for reassignment at the end of the lease period. The DHCP server supports DHCP
client hosts on the LAN side only. The router will ignore all DHCP requests which arrive from the WAN
interface.
Digital Subscriber Line (DSL)
DSL describes a family of digital services provided by local telephone companies to local subscribers.
There are many forms of DSL: Asymmetric DSL (DSL), Symmetric (or single pair) DSL (SDSL), and
many others. DSL can carry voice and data signals at the same time in both directions.
Domain Name Service (DNS)
The router supports Domain Name Service (DNS) which provides hostname-to-IP address resolution for
LAN-side clients.
Point-to-Point Protocol (PPP) Encapsulation Method
PPP is a single or multi-link interface between two packet switching devices, such as a bridge or router.
PPP has built-in negotiation for addresses and connection parameters and can route multiple protocols
over a single link. One benefit of using PPP is it offers interoperability of multi-vendor equipment as well
as support for dynamic configuration between the connecting devices.
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