How to renew SDH/SONET networks with MPLS-TP

Critical infrastructure networks have been built over the past twenty years using SDH/SONET technology. This blog post from our partner and supplier OTN Systems describes how these can be renewed with MPLS (Multiprotocol Label Switching), or the more recent MPLS-TP, and why this technology is a perfect successor.

In view of the dramatic increase in Internet data traffic, network operators began several years ago to replace their older SDH/SONET technology with packet-based technologies such as MPLS (Multiprotocol Label Switching) or industrial Ethernet.

The past: SDH/SONET

Since SDH/SONET has been on the retreat, no new products of this technology are coming onto the market and deliveries are mainly limited to extensions of existing networks.

Therefore, a future-proof network for energy suppliers must definitely be packet-based. This is confirmed by the preparations taking place in the energy world for migration to packet-based data. For example, the IEC 61850-90-1 standard describes the application of IEC 61850, which extends a communication protocol for packet transmission within a substation to communication between substations.

The future: Packet-carrying technologies

In the meantime, there are various packet-transmitting transport technologies available to replace the traditional SDH/SONET: MPLS, Carrier Ethernet and the more recent MPLS-TP (Multiprotocol Label Switching – Transport Profile). MPLS was introduced at the beginning of the century and was positively received by many network operators. The first drafts of MPLS-TP are still quite young.

MPLS-TP supports all the essential features of MPLS and also provides functions for critical, reliable data transport. This standard was jointly developed by the ITU-T (International Telecommunication Union) and the IETF (Internet Engineering Task Force).

Advantages of MPLS-TP over MPLS

Deterministic behavior and improved network settings:

  • Some features of MPLS, such as PHP, ECMP, or LSP Merge, have been removed to improve network settings.
  • Bidirectional MPLS-TP tunnels use the same path (congruent paths). This ensures that delays are always symmetric and error analysis is easy.
  • Predefined backup paths can be easily set up to increase redundancy (switching < 50 ms) and thus network stability.
  • Improved OAM (operations, administration and maintenance) benefits error analysis and performance – and this increases network transparency from the operator’s perspective
The recommendation of OTN Systems

MPLS-TP is the ideal packet transmission solution for the utilities sector to cope with the increasing data volumes. MPLS-TP is virtually the packet-based alternative to “good old” SDH/SONET technology. This packet-based technology offers the same qualities of network stability and settings as SDH/SONET. By significantly reducing complexity, MPLS-TP makes life easier for network administrators.


OTN Systems has contributed this article to our blog. Thanks a lot!

Christoph Good

Co-Founder and CTO May I introduce you to the appropriate product family?