What is ATM PVC?
An ATM PVC is a Permanent Virtual Circuit (PVC) implemented specifically within an Asynchronous Transfer Mode (ATM) network. It represents a pre-configured, dedicated path for data transmission between two endpoints across the ATM network.
Understanding Permanent Virtual Circuits (PVCs)
Based on the provided information:
A Permanent Virtual Circuit is a permanently established logical connection between two devices on a packet switched network. Examples of PVC can be found on ATM (Asynchronous Transfer Mode) and Frame Relay networks.
In essence, a PVC is not a physical line but a defined logical path configured within the network infrastructure. Unlike connections that are set up and torn down for each communication session, a PVC is persistently active and available for data transfer between its designated source and destination points.
ATM and PVCs
ATM is a cell-based networking technology where data is segmented into small, fixed-size units called cells. When an ATM PVC is established, the network devices along the path (like ATM switches) are pre-configured with the necessary routing information to ensure that all cells associated with that specific PVC traverse the network along the same predetermined route from origin to endpoint. This setup is static and remains in place unless manually modified by a network administrator.
Key Characteristics of ATM PVCs
- Permanently Established: The connection is always active and available for use without requiring any call setup procedures by the end devices.
- Logical Connection: It defines a specific path through the network's infrastructure rather than being a direct physical link between the two endpoints.
- Fixed Path: All data cells for a given PVC follow the same defined route across the network.
- Pre-configured: Network devices hold static routing information for each PVC.
Benefits of Using ATM PVCs
Implementing ATM PVCs offers several advantages, particularly for applications demanding consistent and predictable performance:
- Predictable Performance: Due to the fixed path and potential for dedicated resource allocation per PVC, they provide predictable latency, jitter, and throughput, which is critical for time-sensitive traffic.
- Simplified Endpoint Configuration: End devices connected via a PVC do not need complex protocols to establish connections; they simply send data.
- Cost-Effectiveness for Constant Traffic: For consistent, high-volume data streams between fixed locations, the static nature of PVCs can be more economical than usage-based alternatives.
- Ideal for Voice and Video: Their predictable nature makes them well-suited for transporting real-time voice and video traffic where consistent delay and minimal jitter are paramount.
ATM PVCs vs. SVCs
Contrasting PVCs with Switched Virtual Circuits (SVCs) helps highlight their distinct nature within ATM:
| Feature | Permanent Virtual Circuit (PVC) | Switched Virtual Circuit (SVC) |
|---|---|---|
| Setup | Configured manually and remains active | Established dynamically for each communication session |
| Duration | Always active | Active only for the duration of the specific session |
| Complexity | Simpler for connected devices (no setup required) | Requires signaling protocols to establish/tear down |
| Use Case | Constant or heavy traffic between fixed points | Intermittent or variable traffic patterns |
In conclusion, an ATM PVC provides a reliable, permanently available logical connection within an ATM network, designed for stable and predictable data flow between specific endpoints.
