IPoDWDM & Optical

Evolving from Legacy P-OTN to SR-MPLS Based IPoDWDM Networks with OcNOS

IP Infusion Team · · 2 min read

OcNOS 7.0 lets operators evolve legacy P-OTN transport to SR-MPLS IPoDWDM in phases, with no service disruption. It collapses the packet and optical layers by driving coherent optics from the router, adds SR-TE for deterministic paths, and modernizes the core on open hardware. See SR-MPLS in OcNOS.

Networks built on 2nd-generation Packet-Optical Transport Network (P-OTN) technology face a structural refresh challenge. Many OTN platforms are at or approaching end-of-life, spare parts are becoming scarce, and the technology itself predates modern SR-MPLS and coherent optical standards that offer dramatically better scalability, flexibility, and economics.

The migration path from P-OTN to SR-MPLS based IPoDWDM is not a single cutover event. It is a phased architectural evolution that can be executed without service disruption. OcNOS 7.0 provides the migration platform with full SR-TE, SR-MPLS, and IPoDWDM support on a single NOS.

Why P-OTN Networks Need to Evolve

Factor Legacy P-OTN SR-MPLS + IPoDWDM
Circuit flexibility Fixed OTN timeslots (ODU0 to ODU4) Any bandwidth, packet-switched flexibility
Protection model ODU path protection (50ms) SR-TE + TI-LFA (<50ms, topology-independent)
Management Separate IP and optical NMS Unified OcNOS CLI + IP Maestro
Capacity 10G/100G OTN channels 400G per wavelength (ZR/ZR+)
Traffic engineering Static OTN circuits Dynamic SR-TE, Flex-Algo network slicing
Hardware longevity Proprietary chassis, EOL risk Open white-box, multi-ODM sourcing

Migration Architecture: Three Phases

P-OTN to SR-MPLS and IPoDWDM migration roadmap on OcNOS: three phases from SR-MPLS overlay to introducing IPoDWDM to OTN decommission
Three-phase roadmap for migrating a P-OTN transport network to SR-MPLS and IPoDWDM on OcNOS: Phase 1 stands up an SR-MPLS overlay over the existing OTN circuits (Months 1 to 6), Phase 2 introduces OcNOS IPoDWDM nodes with 400G ZR+ running in parallel (Months 7 to 18), and Phase 3 decommissions OTN once all traffic runs on the unified SR-MPLS plus IPoDWDM fabric (Months 19+).

Phase 1: SR-MPLS Overlay on Existing Infrastructure

! OcNOS 7.0 -- Phase 1: Enable IS-IS SR on existing nodes
! OTN circuits remain as transport; SR-MPLS operates as overlay
!
router isis TRANSPORT
  net 49.0003.0000.0000.0001.00
  is-type level-2-only
  segment-routing mpls
  !
  ! BGP-Free Core: remove BGP from transit nodes
  ! PE nodes retain BGP; P nodes use SR labels only
  !
  fast-reroute ti-lfa level-2 proto ipv4    ! Replace OTN 1+1 protection
!
interface lo
  ip address 10.100.0.1/32
  ip router isis TRANSPORT
  prefix-sid index 1
!
! Verify SR is active (OTN circuits still carrying traffic):
show isis segment-routing state
show mpls forwarding-table

IP Infusion Engineering Team

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OcNOS-SP Datasheet

Full OcNOS-SP specification: the access, cell site and aggregation feature set, software SKUs, supported hardware platforms, and the solution ordering guide.

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Solution Brief

IPoDWDM with 400G OpenZR+

Collapse the transponder layer with 400G OpenZR+ coherent optics pluggable directly into the router.

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Solution Brief

SR-MPLS Upgrade with OcNOS

Migrate SR-MPLS onto OcNOS on open hardware: Flex-Algo, TI-LFA, and a proven Cisco-alternative cutover path.

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Tags IPoDWDM Migration OcNOS OTN P-OTN ROADM SR-MPLS Transport

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