A communication system includes a number of communication devices coupled to a data network using communication servers. The communication system supports communication sessions between a variety of networks and devices using, at least in part, XDSL communication techniques. Specifically, information associated with a session passes between a device and an associated server using a modifiable number of XDSL modems and associated twisted pair lines.

An option request protocol allows dynamic negotiation of options between a host computer and a control unit of a computer network. The protocol is manifested as an exchange of novel control messages over a control link used to establish logical data links for communication between the host and control unit. The options negotiated by the control message exchange generally pertain to additional functions performed by the control unit or host, or additional parameters for communication over the dat…

A technique maintains priority of packets transmitted over a heterogeneous network by a hybrid node coupled to the network. The hybrid node assigns each packet a transmission priority (TP) level as it traverses protocol layers of a communications stack of the node. An application programming interface extension provides a tagging mechanism for conveying the TP levels from higher protocol layers of the stack to lower layers. The TP levels are then converted to information that is “tagged” to the …

An apparatus and method for supporting multiple types and configurations of random access memory devices in a single dual in line memory module (DIMM) socket architecture is provided. Typically, this architecture allows a user to select either SDRAM or EDO to be located in the socket(s) without substantially altering the connectivity between circuit components. A switching arrangement, that can be either active switches or fixed circuit traces, is used to selectively interconnect various control…

A rate adaptive digital subscriber line (XDSL) communication system and method are disclosed. An XDSL link for XDSL equipment is trained at a data rate set by a baud rate and a constellation size. Actual operating characteristics of the XDSL equipment are then obtained from parameters for the trained XDSL link. One or more rate adaptive data tables storing empirical data for performance of the XDSL equipment are accessed. Then, it is determined whether the trained data rate will provide a desire…

A frame relay communications network consists of a number of interconnected nodes. The network nodes include segmentation and reassembly device for fragmenting variable length frames of user data into packets of a predefined length. A preferred embodiment uses ATM AAL5 segmentation and reassembly to construct cells. Header and trailer information is added to each of the cells for transport across the frame relay network.

A data communications system consists of a number of interconnected nodes forming a frame relay network. A user accesses the network by dialing in via a dial access server (DAS). The DAS-to-frame relay interface supports CCITT Recommundation Q.931 protocols for call control. A data link connection identifier (DLCI) for use in the DAS-to-frame relay network interface is provided in a Q.931 call establishment message.

A router (10) in a packet-based telecommunications system assembles an outgoing packet by inserting between an incoming packet’s link-layer and network-layer headers a shim header containing a label that the next-hop router will use as an index into its forwarding table. The shim header also includes a time-to-live field, and the router determines on a case-by-case basis whether to propagate into that field the value from a corresponding time-to-live field in the incoming packet’s network-layer …

A communications network is made up of a number of nodes. Frames of data transported on a circuit line are received at a first node of the network and segmented into packets such that a first packet includes a first portion of data from a frame and a second packet includes a second portion of data from the frame. A frame count value is added to a header in each of the first packet and the second packet. In addition, a first offset value is added to the first header and a second offset value is a…

A color blocking logic (CBL) mechanism implements spanning tree states with respect to data frames transported between port interface circuitry over a link connecting different switches in a network. Each port interface circuit preferably supports multiple virtual local area network (VLAN) designations and associates those VLAN designations with data frames transmitted to and from the switch over the link. The CBL mechanism cooperates with a forwarding engine of the switch to selectively enable …