IP/MPLS or MPLS-TP?

Many utilities want to keep using legacy systems such as SCADA as they embrace IP/Ethernet-based applications and IEC 61850 automation. To get the most from legacy systems, they will need to deploy IP-based remote terminal units (RTUs) and rely on IP unicast support to scale the network. Modern IP-based grid applications will require multicast support over the wide area network (WAN) to minimize traffic flooding and bandwidth utilization.

IP/MPLS is the clear choice in this case. It offers native support for IP-based unicast and multicast applications using layer 3 VPN (L3VPN) and multicast VPN (MVPN). MPLS-TP uses a less flexible and scalable approach that combines emulation and encapsulation with flooding and broadcast. The MVPN capabilities of IP/MPLS also make it easier to adapt IEC 61850 standards such as R-GOOSE and R-SV protocols because it provides efficient point-to-multipoint IP connectivity.

All grid communications networks need the ability to withstand and recover from network failures. But different applications may require different levels of resiliency from the transport layer. For example, some key grid protection automation and control (PAC) systems require deterministic, pre-engineered backup paths and recovery times below 50 ms. IP/MPLS and MPLS-TP can both meet this stringent requirement for single-point failures.

IP/MPLS also supports advanced multi-fault resiliency, a critical capability for grids facing more severe weather events. For example, the Nokia IP/MPLS implementation provides an active multipath pseudowire (AMP) mechanism that uses up to four redundant active paths to provide hitless recovery for TDM-based relay communications for applications such as line differential protection. If faults affect multiple paths, the surviving paths continue to transport data between relays with zero recovery time.

OAM plays a vital role in grid network reliability and redundancy. MPLS-TP and IP/MPLS both provide robust OAM tools for monitoring, checking connectivity and detecting faults on label-switched paths and pseudowires. They also provide recovery speeds equivalent to those of SDH/SONET using Bidirectional Fault Detection (BFD) and ITU-T Y.1731 capabilities.

IP/MPLS goes a step further by providing scalable layer 3 OAM tools tailored for the multipoint environments used by many emerging grid applications. These include virtual private routed network (VPRN) ping, virtual private line service (VPLS) ping, Two-Way Active Measurement Protocol (TWAMP)/Simple Two-Way Active Measurement Protocol (STAMP) and streaming telemetry, which provide real-time visibility into the network. Utilities can use these capabilities to optimize network performance and health and respond to changing traffic demands.

Accurate time synchronization is critical now that utilities are adopting IEC 61850 technologies. More and more utilities are complementing traditional GNSS/GNS-based systems with IEEE 1588v2 systems that can distribute synchronized timing to assets across the grid.

MPLS-TP and IP/MPLS provide the same support for synchronization. However, the Nokia IP/MPLS solution offers more advanced capabilities. It supports boundary clocks, which improve synchronization accuracy, resiliency and performance. In addition to IEEE 1588 power profiles, it supports the 1588v2 telecom profile so that these boundary clocks can also perform interworking between telecom profiles (including ITU-T G.8275.1 and ITU-T G.8275.1) and power profiles to ensure that substations can receive timing from existing telecom core networks. IP/MPLS also supports SyncE, which enhances clock accuracy and stability, and provides a built-in GNSS receiver for direct access to highly accurate timing signals.

Utilities will face new complexities as they migrate legacy systems to packet-based networks and incorporate new digital technologies, including automation and AI. To unlock the value of legacy, new and future systems, they will need a network that can efficiently support every application.

IP/MPLS delivers on this need by enabling utilities to use one network and one technology for all applications. It extends unified networking across the substation LAN, field area network (FAN), WAN and data center to provide end-to-end connectivity that meets the demands of everything from virtualized PAC and SCADA applications to advanced IEC 61850 applications such as fault location, isolation and recovery (FLISR) and falling conductor protection (FCP).