Why Do We Need Advanced OTN Features When MPLS-TP or Similar Packet Transport Technologies Exist?

Transport Networks
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1

As a service provider, suppose all customers only need Ethernet services (L2 and L3 VPN). In that case, why is an OTN layer necessary? Wouldn’t a simple physical layer infrastructure—like amplification or signal regeneration—plus MPLS-TP (or SR-MPLS as transport) be sufficient? For example, I could run MPLS-TP over a 400G link and provide services to different clients through that link.

Am I missing something here?

2

Without OTN (MPLS over DWDM only)

  1. No hard bandwidth guarantees
  2. Limited fault localization across layers
  3. Weak correlation between packet loss and optical problems
  4. Inefficient grooming of lower-rate services into high-capacity wavelengths
  5. Challenges in multi-vendor optical environments
  6. Protection depends on only MPLS convergence

Why OTN is required

  1. Deterministic bandwidth using ODUk/ODUflex containers
  2. Strong fault isolation with multi-layer OAM (TCM)
  3. Standardized transport layer for multi-vendor interoperability
  4. Precise performance monitoring (BER, BIP, defects, alarms)
  5. Efficient grooming and multiplexing into high-capacity wavelengths
  6. Fast and deterministic protection (SNCP)