PWE3 advertises the PW status using LDP signaling Notification messages. A PW is torn down only when PW configurations are deleted or the LDP session is interrupted. PWE3 reduces control packets exchanged between PEs and signaling costs. LDP signaling used by PWE3 is compatible with common LDP and Martini.
Multi-segment PWE3 extends networking modes.
Multi-segment PWE3 has low requirements for the number of LDP sessions supported by an access device. That is, the costs of LDP sessions on the access device are reduced.
The access node on a multi-segment PW provides PW aggregation. This allows for more flexible networking and easily divides a network into access, aggregation, and core layers.
PWE3 supports more low-speed Time Division Multiplexing (TDM) interfaces. PWE3 supports packet sequencing, clock extraction, and clock synchronization using the Real-time Transport Protocol (RTP) on the forwarding plane and the control word.
PWE3 has the following advantages by supporting low-speed TDM interfaces:
Adds encapsulation types (packets on low-speed TDM interfaces can be encapsulated).
Integrates the PSTN, TV, and data networks.
Substitutes the traditional Digital Data Network (DDN) service.
PWE3 has the following extensions at the control plane:
Fragmentation negotiation mechanism
PW connectivity detection, such as VCCV and OAM, which speeds up network convergence and enhances network reliability