Within the router, LANE sorts out
virtual circuits and translates between frames and cells.
This means that ATM DSLAMs must transport each customer's traffic on separate permanent
virtual circuits (PVCs), and each class of traffic for each customer on separate PVCs.
A "PVC" is a "Permanent
Virtual Circuit." It sounds like an oxymoron: How can it be both permanent and virtual?
Virtual concepts have since been used in many architectures and designs including: Virtual Address Extension (VAX);
Virtual Circuit (VC); Virtual Machine (VM); MVS (Multiple Virtual Storage and became OS/390 and now is z/OS); Virtual Memory System (VMS); Virtual Private Network (VPN); Virtual Reality (VR); Virtual Storage Access Method (VSAM); Virtual Storage Extended (VSE; was DOS/VSE); Virtual Tape Subsystem (VTS); and Virtual Telecommunications Access Method (VTAM).
Features include support for over 32,000 conversations at up to OC-12 rates in a diverse multiprotocol environment and support for up to 248 active voice channels per
virtual circuit.
Individual, full-time performance registers track problems at the line and frame relay levels -- even measuring private
virtual circuit (PVC) Quality of Service parameters such as network transit delays, lost frames, and congestion." Reduce Downtime and Increase Throughput FramePath DSU/CSUs are important to NSPs and IS managers as they search for ways to reduce network downtime, increase throughput, and lower networking costs.
* Some ATM equipment is
virtual circuit (VC) based, some is virtual path (VP) based, and some handles both.
Specific statistics should include traffic use tables of top hosts and conversations, traffic usage by
virtual circuit and host lists by application.
A connected pair of Virtual Interfaces forms a bi-directional, memory-to-memory
virtual circuit. Doorbells are used to notify a VI NIC that work (new Descriptor) has been placed on one of the Work Queues.
Also, the general communication network methodologies of datagram versus
virtual circuit models are presented.