What do you think about the future of SDH?

SDH IS REPLACED BY MPLS-TP IN FUTURE.

Based on telecommunications market requirements, low-speed private line services will likely persist for a long time

Customers of TDM (SDH) private line services are from security and finance enterprises, which have stringent requirements on security, reliability, and latency. Therefore, physical pipes are required for data transmission

Although the emergence of innovations in IP/packet and DWDM/Coherent systems appear to challenge the relevance of SDH in the present  and future telecom transmission system deployments, however, SDH stands a chance in developing economies where harsh terrains and cost of laying Fiber optic cables is very high.

I think SDH will phase out with time as more and more telecommunication services move to IP packet. for instance most voice which is a heavy user of SDH technology is gradually been migrated to IP for easy scalability 

With the advancement of optical communications technology, access network has evolved from the common anolog subscriber loop to the optical access network (OAN). On the other hand, with the technical maturation and advancement of synchronous digital hierarchy (SDH), SDH has been deployed massively in toll network, trunk network and access network ultimately. Transmission network is the platform of all services layers including the support layer, and SDH technology is the soul of the platform. In order to satisfy the flexible networking and the dynamic allocation of circuits in access network, SDH technology is widely applied between subscriber end and office end to ensure the security by virtue of its perfect loop protection. So far, no matter in public switched telephone network (PSTN) or mobile base station, the transmission system of access network still concentrates on TDM (time division multiplexing) services.

At present in new technology SDH trying to upgrade into IP base on full network.

 As Telecom world is continuous migrating to the next generation and Telecom operators are taking more interest in packet based technologies (eg Packet core)  on the other hand the TDM-based (SDH,PDH) communication equipment is reaching its end-of-life state and is becoming too expensive to maintain .But Mission-critical communication networks eg ,Energy (electricity, Gas & Oil, nuclear), transportation, water, government agencies and military organizations are still dependednt on TDM based infrastructes. Since the key attributes for their communication networks are reliability, resiliency, and security. Therefore, it is not surprising that they would try to avoid any change from the highly-trusted TDM-based infrastructure to a new packet-based one.

The inevitable move to packet poses new challenges to strategic industries. These include increased security threats, higher network complexity, and above all, maintaining TDM-predictable and deterministic performance over the packet infrastructure. In future SDH may be dimnish or having insginificance role in ISP network but in Mission critical communication networks SDH and  its next generation (Ethernet over SDH,MPLS-TP) will be still key player and will take more time for its replacement.  

People are moving towards full IP based network and DWDM, Carrier grade Ethernet, Metro Over Ethernet technologies. Currently in Batelco Bahrain, SDH is now being upgraded to DWDM rather than serving traditional transmission services.  

It will be obsolete in few years as we will move towards packet network. 

Although it continues to develop and is widely used, SDH is now a legacy transmission technology. I would say that unless you are already working in that space, you'd be better off focusing your (study?) efforts elsewhere – DWDM, carrier grade ethernet, IP etc

I see some parts of the world are trying to move to full IP based transmission networks but I believe there are still many advantages to SDH which may keep it in play for a long time to come. Plus if they are still installing client gear then surely it would have a decent future so i'm wondering what people in that line of work are thinking... ?