1Labeled Optical Burst Switchingand IP/WDM IntegrationChunming Qiao2OVERVIEW– Introduction to IP/WDM– Optical Switching ParadigmsCircuit or Packet Switching?– Optical Burst Switching (OBS)3Just In Case ...• IP: Internet Protocol– not Intellectual Property• ATM: Asynchronous Transfer Mode – not Automatic Teller Machine• SONET: Synchronous Optical NETwork– not as in son et (lumiere) • WDM: Wavelength Division Multiplexing– or Wha’Daya Mean ?4Network Architectures• today: IP over (ATM/SONET) over WDM• trend: Integrated IP/WDM (with optical switching)• goal: ubiquitous, scalable and future-proof5IP / ATM / SONET / WDMIPATMSONETWDM6SONET/SDH• standard for TDM transmissions over fibers– basic rate of OC-3 (155 Mbps) based on 64 kbps PCM channels (primarily voice traffic)– expensive electronic Add-Drop Muxers (ADM) @ OC-192 (or 10 Gbps) and above– many functions not necessary/meaningful for data traffic (e.g., bidirectional/symmetric links)– use predominantly rings: not BW efficient, but quick protection/restoration (<= 50 ms)7Internet Protocol (IP)• main functions– break data (email, file) into (IP) packets– add network (IP) addresses to each packet– figure out the (current) topology and maintains a routing table at each router – find a match for the destination address of a packet, and forward it to the next hop• a link to a popular server site may be congested8Asynchronous Transfer Mode• break data (e.g., an IP packet) into smaller ATM cells, each having 48+5 = 53 bytes• a route from point A to point B needs be pre-established before sending cells.• support Quality-of-Service (QoS), e.g., bounded delay, jitter and cell loss rate• basic rate: between 155 and 622 Mbps– just start to talk 10 Gbps (too late?)9Data Traffic Growth• double every 4 (up to 12) months or so, and will increase by 1,000 times in 5 years – at least 10 x increase in users, and uses per user– at least 100 x increase in BW per use: • current web pages contain 10 KB each• MP3 & MPEG files are 5 & 40 MB each, resp.• beat Moore’s Law (growth rate in electronic processing power)– electronic processing, switching, and transmission cannot and will not keep up – need WDM transmissions and switching10Wavelength Division Multiplex• up to 50 THz (or about 50 Tbps) per fiber (low loss range is now 1335nm to 1625nm) • mature WDM components– mux/demux, amplifier (EDFA), transceiver (fixed-tuned), add-drop mux, static λ-router,• still developing – tunable transceiver, all-optical λ-conversion and cross-connect/switches, Raman amplifiers11WDM Pt-2-Pt Transmission?1?2?n?1?2?nMUX DEMUXEDFA EDFAfiber12Advance in WDM Networking• Transmission (long haul)– 80 λs (1530nm to 1565nm) now, and additional 80 λs(1570nm to 1610nm) soon– OC-48 (2.5 Gbps) per λ (separated by 0.4 nm) and OC-192 (separated by 0.8 nm)– 40 Gbps per λ also coming (>1 Tbps per fiber)• Cross-connecting and Switching– Up to 1000 x 1000 optical cross-connects (MEMS)– 64 x 64 packet-switches (switching time < 1 ns)13ATM and SONET: Legacy• interest in ATM diminished – a high cell tax, and segmentation/re-assembly and signaling overhead– failed to reach desktops (& take over the world)– on-going effort in providing QoS by IP (e.g., IPv6 & Multi-protocol Label Switching or MPLS)• SONET/SDH more expensive than WDM – & IP & WDM can jointly provide satisficatoryprotection/restoration (< 99.999% reliability?)14Datagram (IP) or VC (ATM) • datagram-based packet switching– next-hop determined for each packet based on destination address and (current) routing table• IP finds a longest sub-string match (a complex op)• virtual circuit (VC)-based packet-switching– determines the path (VC) to take before-hand • entry at each node: [VCI -in, next-hop, VCI-out]– assigns packets a VCI (e.g., Rt. 66 )15Benefit of VC (as in ATM)• faster and more efficient forwarding– an exact match is quicker to find than a longest sub-string match• facilitates traffic engineering– paths can be explicitly specified for achieving e.g., network-wide load-balance– packets with the same destination address (but different VCI’s) can now be treated differently16IP-over-ATM• IP routers interconnected via ATM switches• breaks each packet into cells for switching• a flow: consecutive packets with the same source/destination (domain/host/TCP conn.)• Multi-protocol over ATM (MPOA)– ATM-specific signaling to establish an ATM VC between source/destination IP routers– segmentation and re-assembly overhead17IP-centric Control• Tag Switching (centralized, control-driven)– the network sets up end-to-end VC’s– each packet carries a tag (e.g., VCI)• IP Switching (distributed, data-driven)– first few packets are routed at every IP router• up to a threshold value to filter out short “flows”– following packets bypass intermediate routers via a VC (established in a hop-by-hop fashion).18MPLS (Overview)• A control plane integrating network-layer (routing) and data-link layer (switching)– packet-switched networks with VC’s• LSP: label switched path (VC’s)– identified with a sequence of labels (tag/VCI) – set up between label switched routers (LSRs) • Each packet is augmented with a shim containing a label, and switched over a LSP19IP over WDM Architectures• IP routers interconnected with WDM links– with or without built-in WDM transceivers• An optical cloud (core) accessed by IP routers at the edge– pros: provide fat and easy-to-provision pipes – either transparent (i.e., OOO) or opaque (i.e., O-E-O) cross-connects (circuit-switches)– proprietary control and non-IP based routing20Optical/Photonic (OOO) Switching• Pros:– can handle a huge amount of through-traffic – synergetic to optical transmission (no O/E/O)– transparency (bit-rate, format, protocol)• caveats– optical 3R/performance monitoring are hard– more mature/reliable opaque (OEO) switches – SONET or GbE like framing still useful21Emerging Integrated IP/WDM• IP and MPLS on top of every optical circuit or packet switch :– IP-based addressing/routing (electronics), but data is optically switched (circuit or packet)– MPLS-based provisioning, traffic engineering and protection/restoration– internetworking of optical WDM subnets • with interior and exterior (border) gateway routing22Why IP over WDM• IP: the unifying/convergence