End-to-End DSL Architectures

ATM Switching in the DSL World

Knowledge of ATM circuit types and virtual circuit mapping is absolutely critical to designing and maintaining a DSL network. The single most common cause of network connectivity issues in the DSL network is also the most easily understood: failure to design and adhere to a good virtual circuit-mapping plan.

Although the ATM Forum defines several connection types that are all theoretically applicable to DSL, the current world of DSL makes common use of only three:

• Permanent virtual circuit (PVC)

• Soft-PVC (SPVC)

• Permanent virtual path (PVP)

ATM virtual circuits are identified by the virtual path and virtual channel. A virtual path contains multiple virtual channels, like a large bundle of smaller pipes. Each individual ...