Copyright VersaTel Telecom 2000 Marc Teichtahl Large Scale Packet Optimized Rings Part II
Copyright VersaTel Telecom 2000 Marc Teichtahl Part One: The Design Brief “effect the migration from traditional transmission technologies to a next generation platform optimized for the transmission of purely packetized data”
Copyright VersaTel Telecom 2000 Marc Teichtahl The General Business Drivers Provide all services over IP based infrastructure Reducing costs & Increasing revenues = $PROFIT$ Single management platform Ease of on-going operations and support Lower maintenance costs Lead the technology push into IP optics Influence the early adopters
Copyright VersaTel Telecom 2000 Marc Teichtahl Our Specific Business Drivers Utilize “owned” fiber network Match fiber topology against network architecture Decrease $/Mbps Shorten provisioning lead-time Shorten product time to market Provide “endless” scalability Allow for DWDM “plug & play” Provide forward consideration to MPLS and MPλS
Copyright VersaTel Telecom 2000 Marc Teichtahl CAPEX (USD Millions) PRODUCTS IP Circuits WAN Services MPLS Services Streaming Media TECHNOLOGY SDH/DPT DPT x4 x80 Note: Revenues in millions USD VOIP WAN Carriage ???? The Business Drivers
Copyright VersaTel Telecom 2000 Marc Teichtahl Our Choices and Decisions Key Challenges-: Mapping the topologies Matching segment parameters Designing optical regeneration SRP overhead considerations PoP Selection Fitting the rings together
Copyright VersaTel Telecom 2000 Marc Teichtahl To SDH or not to SDH ? SDH provides circuit capabilities DPT does not offer circuit capacity but pure IP Does this impact our business model ? Lower unit revenue from IP sales – IP is cheaper Cheaper to implement DPT Key factor to financial success Must yield high volume sales to be more profitable
Copyright VersaTel Telecom 2000 Marc Teichtahl To SDH or not to SDH ? SDH will always have a higher incremental cost You still have to add the router SDH will yield a broader range of more profitable products DPT will offer pure optimised IP capacity
Copyright VersaTel Telecom 2000 Marc Teichtahl To SDH or not to SDH ? Some segments may utilize SDH due to Optical Length or path loss Fibre requirements to close the ring
Copyright VersaTel Telecom 2000 Marc Teichtahl The Problems 9 Fiber Rings 35 PoP 3 Countries Geographical distances and optical limitations Traffic distribution Line card limitations The Solutions International Core ring Local distribution rings Optical Regeneration Mapping The Topologies
Copyright VersaTel Telecom 2000 Marc Teichtahl Mapping The Topologies - Logical
Copyright VersaTel Telecom 2000 Marc Teichtahl Mapping The Topologies - Logical
Copyright VersaTel Telecom 2000 Marc Teichtahl Line Card Limitations Proprietary to Cisco Currently in IETF for standards ratification Optical path loss limitations of 25dB Currently limited to OC-48 Maximum 32 SRP nodes per ring Slot capacity for OC-48 and OC-192
Copyright VersaTel Telecom 2000 Marc Teichtahl Matching Segment Parameters Each optical segment must be within the optical tolerance for all components Achieved by the use of optical regenerators On some paths consideration was given to using SDH Not used due to capacity constraints Unable to scale as quickly as a purely optical solution “plug&play”
Copyright VersaTel Telecom 2000 Marc Teichtahl Optical Regenerations Based upon tolerances of SRP line cards Maximum loss 25dB Maximum optical path length 80Km This was achievable due to the physical fibre paths and ability to easily splice where needed
Copyright VersaTel Telecom 2000 Marc Teichtahl Overhead Considerations SRP enforces additional overhead to SDH IPS only travels between adjacent nodes Topology discovery messages natively 32 bytes + 8 bytes per node sent every 5 seconds 10 node ring provides ~1.5Kbps for IPS This is negligible Total overhead = IPS+Topology Disc+Usage control For 10 nodes ~2Mbps On a OC-12 Ring overhead is ~0.31%
Copyright VersaTel Telecom 2000 Marc Teichtahl Overhead Considerations
Copyright VersaTel Telecom 2000 Marc Teichtahl PoP Selection PoPs selected on two criteria Commercial – ROI Technical Optical distances Proximity to IP interesting sites such as exchange points.
Copyright VersaTel Telecom 2000 Marc Teichtahl International Core Ring OC-48 International core ring Based on Cisco Covering route Kms / Miles Utilizing 5 optical regenerators Optical loss tolerance 4.2dB<<OL<<24.2dB
Copyright VersaTel Telecom 2000 Marc Teichtahl Local Distribution rings OC-12 Local distribution rings 8 Distribution rings Based on Cisco Covering route > 3000Kms / 1875M Utilizing 19 optical regenerators
Copyright VersaTel Telecom 2000 Marc Teichtahl SRP Interconnect Issues We require a ring interconnect methodology that allows for the overlay of a complex routing architecture.
Copyright VersaTel Telecom 2000 Marc Teichtahl SRP Interconnect Issues Unknown inter ring SRP issues. Statistical possibility of run away restore conditions Both Rings wrapping at same time Inter-Ring IPS over-head OC-48 -> OC-12 serialization issues
Copyright VersaTel Telecom 2000 Marc Teichtahl Routing Issues Use of a per PoP border router Utilizes ISIS and BGP DPT Overhead issues SDH comparisons
Copyright VersaTel Telecom 2000 Marc Teichtahl Standard PoP Design
Copyright VersaTel Telecom 2000 Marc Teichtahl PoP Router Designations Each PoP has a border router. Connected to distribution routers –Speed of transport between PoPs in event of failure –Lower costs Multiple full tables
Copyright VersaTel Telecom 2000 Marc Teichtahl Each PoP has a designated “net” identifier All inter-PoP routes are kept as level-1 All intra-PoP, core and distribution routes are summarized on the PoP border routers into level-2 Dial supernets are summarized at the dial aggragation router into level-2 Core only carries level-2 summary routes. ISIS Configuration
Copyright VersaTel Telecom 2000 Marc Teichtahl Summarization is only allowed at level borders Causes internal PoP summarization issues Maintainence of huge topology tables. Integration with legacy OSPF networks may still prove to be an issue in the future Lack of flexibility in route selection and metric preferences ISIS Issues
Copyright VersaTel Telecom 2000 Marc Teichtahl Ease of configuration Simple adaptation for MPLS Via ISIS-extensions for MPLS Convergence speeds Flexibility in PoP and “net” naming schemes ISIS Benefits
Copyright VersaTel Telecom 2000 Marc Teichtahl All PoP border and customer aggragation routers are bgp speakers Utilization of full mesh between the PoP Utilization of confederations on a per PoP basis Use of route reflectors in the PoP BGP Design
Copyright VersaTel Telecom 2000 Marc Teichtahl BGP Design
Copyright VersaTel Telecom 2000 Marc Teichtahl Optically aware IP – Utilizing both IP layer and optical layer MPLS signaling we aim to provide intelligent IP lambda capacity – Allowing the IP layer to request further capacity from the optical. – Allowing the optical layer to request a layer three re- route to avoid optical “congestion” The Future Vision
Copyright VersaTel Telecom 2000 Marc Teichtahl Migration of dark fiber to an intelligent DWDM solution. –Providing customer distribution rings at OC-48 and above. Provide intelligent optical switching –Optical path selection and re-route The Future Vision