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Developments in Transmission Technologies. Dr. John S. Graham University of London Computer Centre. Key Areas. Speed Agility ROADM Technology Digital Wrapper Reliability Mesh Protection Access (Ethernet Everywhere) Ethernet OA&M, PM and APS Provider Backbone Transport (PBT).
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Developments in Transmission Technologies Dr. John S. Graham University of London Computer Centre
Key Areas • Speed • Agility • ROADM Technology • Digital Wrapper • Reliability • Mesh Protection • Access (Ethernet Everywhere) • Ethernet OA&M, PM and APS • Provider Backbone Transport (PBT)
40 Gb/s: Deployment Challenges • Deployment over existing infrastructure: • Fibre PMD audit • Line cards require: • Adaptive Dispersion Compensators • Powerful FEC for improved OSNR • Increased transmission distances: • Fibre type • Amplification scheme • Complex line codes
DWDM Network Express VOA + Attenuation OSC OSC DCM Transponders ROADM Implementation Pre-Amp ROADM Post-Amp
ROADM Architectures (1/2) Wavelength Blocker Add Wavelengths Drop Wavelengths
ROADM Applications OADM: DWDM ACCESS Rings or Linear Segments 2D-ROADM: Core Network Rings MD-ROADM: Inter-Ring Switching and Mesh Networks
Digital Wrapper (OTN or G.709) • Includes FEC for improved OSNR at high bit rates • Small, efficient OAM structure without need to convert all client signals to TDM • Transports native line-rate 10 G LAN-PHY • Particularly useful for WDM gateway application. • Soon consolidated OTN, SONET/SDH and Layer II MAC switching in a single chassis.
Use of GFP with OTN • Rate adaptation of packet-based client into CBR carrier • Multiple different Ethernet streams can be carried in same OTN frame using GFP CID field • Multiple different client signals can be carried in same OTN frame using GFP PTI field • Multiple different client signals cannot be separately switched
F A B F A B SNCP Mesh E C C D D E Mesh Displacing Rings 2-fibre counter-rotating ring
Provider Backbone Transport Ethernet over SDH or OTN PBT or VPLS
PBT = Deterministic Ethernet • Dispense with flood and learn • No more spanning tree (Hurray!) • Distribute bridging tables using control plane • Carrier switching uses 802.1ah at the edge • Carrier protected from customer’s loops & storms • Fast failover uses reserved 802.1ad B-VID
B-VID = 75 B-VID = 76 B-MAC B-MAC PBT: Ethernet Trunks
Metro Ethernet OAM • 802.3ah = Ethernet in the First Mile OAM • 802.1ag = Ethernet Connectivity Fault Management (CFM)
Context for Ethernet CFM Operator 1 Operator 2 Operator 3 Operator 4 E2E Provider
Connectivity Fault Management • Continuity Check (CC) • multicast from MEPs • catalogued by receiving MEP • Link Trace • Loopback (ping) • Alarm Indication Signal
Ethernet in the First Mile • Discovery • Remote Loopback • Remote Failure Indication • Link Fault • Dying Gasp • Critical Event • Threshold Crossing Events • MIB Variable Retrieval