2. CSIT560 by M. Hamdi 1 Switching Architectures for Optical Networks

3. CSIT560 by M. Hamdi 2 SONET Data Center SONET DWD M Access Long HaulAccessMetro Internet Reality

4. CSIT560 by M. Hamdi 3 Hierarchies of Networks: IP / ATM / SONET / WDM

5. CSIT560 by M. Hamdi 4 Why Optical? Enormous bandwidth made available –DWDM makes ~160 channels/ possible in a fiber –Each wavelength “potentially” carries about 40 Gbps –Hence Tbps speeds become a reality Low bit error rates –10 -9 as compared to 10 -5 for copper wires Very large distance transmissions with very little amplification.

6. CSIT560 by M. Hamdi 5 Dense Wave Division Multiplexing (DWDM) Multiple wavelength bands on each fiber   Transmit by combining multiple lasers @ different frequencies Output fibers Long-haul fiber 1 2 3 4

7. CSIT560 by M. Hamdi Anatomy of a DWDM System Terminal A Terminal B Post- Amp Pre- Amp Line Amplifiers MUXMUX DEMUXDEMUX Transponder Interfaces Transponder Interfaces Direct Connections Direct Connections Basic building blocks Optical amplifiers Optical multiplexers Stable optical sources

8. CSIT560 by M. Hamdi 7 User Services & Core Transport ATM Switch Sonet ADM IP Router TDM Switch Transport Provider Networks Service Provider Networks OC-3 OC-12 STS-1 Frame Relay Users Services Frame Relay IP ATM Lease Lines COREEDGE

9. CSIT560 by M. Hamdi 8 Core Transport Services OC-3 OC-12 STS-1 Provisioned SONET circuits. Aggregated into Lamdbas. Carried over Fiber optic cables. Circuit Origin Circuit Destination

10. CSIT560 by M. Hamdi 9 WDM Network: Wavelength View WDM link Optical Switch Edge Router Legacy Interfaces Legacy Interfaces Legacy Interfaces (e.g.,PoS, Gigabit Ethernet, IP/ATM) Interfaces

11. CSIT560 by M. Hamdi 10 Relationship of IP and Optical Optical brings –Bandwidth multiplication –Network simplicity (removal of redundant layers) IP brings –Scalable, mature control plane –Universal OS and application support –Global Internet Collectively IP and Optical (IP+Optical) introduces a set of service-enabling technologies

12. CSIT560 by M. Hamdi 11 Typical Super POP OXC Core IP router Interconnectio n Network Large Multi-service Aggregation Switch Voice Switch Core ATM Switch SONET Coupler & Opt.amp DWDM + ADM DWDM Metro Ring

13. CSIT560 by M. Hamdi 12 Typical POP OXC DWDMDWDM Voice Switch SONET-XC DWDMDWDM

14. CSIT560 by M. Hamdi 13 What are the Challenges with Optical Networks? Processing: Needs to be done with electronics –Network configuration and management –Packet processing and scheduling –Resource allocation, etc. Traffic Buffering –Optics still not mature for this (use Delay Fiber Lines) –1 pkt = 12 kbits @ 10 Gbps requires 1.2  s of delay => 360 m of fiber) Switch configuration –Relatively slow

15. CSIT560 by M. Hamdi 14 Optical Hardware Optical Add-Drop Multiplexer (OADM) –Allows transit traffic to bypass node optically OADM 1 2 3 1 2 ’ 3 3 Add and Drop DCS

16. CSIT560 by M. Hamdi 15 Wavelength Converters Improve utilization of available wavelengths on links All-optical WCs being developed Greatly reduce blocking probabilities No converters 1 2 3 New request 1  3 1 2 3 New request 1  3 With converters WC

17. CSIT560 by M. Hamdi 16 Late 90s: Backbone Nodes ADM Digital Crossconnect IP Router ATM Switch DWDM Multiplexer & Demultiplexer

18. CSIT560 by M. Hamdi 17 Problems About 80% traffic through each node is “pass- through” –No need to electronically process such traffic 80-channel DWDM requires 80 ADMs Speed upgrade requires replacing all the ADMs in the node

19. CSIT560 by M. Hamdi 18 Today: Optical Cross Connect (OXC) Source: JPMS DWDM Multiplexer & Demultiplexer Optical Crossconnect Digital Cross Connect IP Router ATM Switch Terabit IP Router ATM Backbone Switch

20. CSIT560 by M. Hamdi 19 Wavelength Cross-Connects (WXCs) A WDM network consists of wavelength cross-connects (WXCs) (OXC) interconnected by fiber links. 2 Types of WXCs –Wavelength selective cross-connect (WSXC) Route a message arriving at an incoming fiber on some wavelength to an outgoing fiber on the same wavelength. Wavelength continuity constraint –Wavelength interchanging cross-connect (WIXC) Wavelength conversion employed Yield better performance Expensive

21. CSIT560 by M. Hamdi 20 Wavelength Router Control Plane: Wavelength Routing Intelligence Data Plane: Optical Cross Connect Matrix Single Channel Links to IP Routers, SDH Muxes,... Unidirectional DWDM Links to other Wavelength Routers

22. CSIT560 by M. Hamdi 21 Optical Network Architecture IP Router Optical Cross Connect (OXC) OXC Control unit Control Path Data Path UNI Mesh Optical Network IP Network

23. CSIT560 by M. Hamdi 22 OXC Control Unit Each OXC has a control unit Responsible for switch configuration Communicates with adjacent OXCs or the client network through single-hop light paths –These are Control light paths –Use standard signaling protocol like GMPLS for control functions Data light paths carry the data flow –Originate and terminate at client networks/edge routers and transparently traverse the core

24. CSIT560 by M. Hamdi 23 Optical Cross-connects (No wavelength conversion) Optical Switch Fabric 3 2 2 4 4 1 1 3 All Optical Cross-connect (OXC) Also known as Photonic Cross-connect (PXC)

25. CSIT560 by M. Hamdi 24 Optical Cross-Connect with Full Wavelength Conversion M demultiplexers at incoming side M multiplexers at outgoing side Mn x Mn optical switch has wavelength converters at switch outputs 1, 2,..., n 1, 2,..., n 1, 2,..., n 1 2 M Optical CrossBar Switch Wavelength Converters Wavelength Mux Wavelength Demux 1, 2,..., n 1, 2,..., n 1, 2,..., n...... 1 2 n 1 2 n 1 2 n 1 2 n 1 2 n n 1 2 1 2 M

26. CSIT560 by M. Hamdi 25 Wavelength Router with O/E and E/O Cross-Connect 1 3 Outgoing Interface Outgoing Wavelength Incoming Interface Incoming Wavelength

27. CSIT560 by M. Hamdi 26 Demux 1 Incoming fibers O E O Individual wavelengths Mux Outgoing fibers O-E-O Crossconnect Switch (OXC) O/E N 2 E/O Switches information signal on a particular wavelength on an incoming fiber to (another) wavelength on an outgoing fiber. 1 N 2 WDM (many λs)

28. CSIT560 by M. Hamdi 27 Optical core network Opaque (O-E-O) and transparent (O-O) sections E/O Client signals O/E to other nodes from other nodes EEO O Transparent optical island OO OO E O O O O E O Opaque optical network

29. CSIT560 by M. Hamdi 28 OEO vs. All-Optical Switches Capable of status monitoring Optical signal regenerated – improve signal-to-noise ratio Traffic grooming at various levels Less aggregated throughput More expensive More power consumption Unable to monitor the contents of the data stream Only optical amplification – signal- to-noise ratio degraded with distance No traffic grooming in sub- wavelength level Higher aggregated throughput ~10X cost saving ~10X power saving OEOAll-Optical

30. CSIT560 by M. Hamdi 29 Large customers buy “lightpaths” A lightpath is a series of wavelength links from end to end. cross-connect optical fibers Repeater One fiber

31. CSIT560 by M. Hamdi 30 Hierarchical switching: Node with switches of different granularities Fibers O A. Entire fibers Fibers O O O B. Wavelength subsets O O “Express trains” O C. Individual wavelengths E O “Local trains”

32. CSIT560 by M. Hamdi 31 Wide Area Network (WAN) GAN links OXC: Optical Wavelength/Waveband Cross Connect WAN : Up to 200-500 wavelengths 40-160 Gbit/s/ wavebands (> 10 )

33. CSIT560 by M. Hamdi 32 Packet (a) vs. Burst (b) Switching

34. CSIT560 by M. Hamdi 33 MAN (Country / Region) optical burst formation IP packets

35. CSIT560 by M. Hamdi 34 Optical Switching Technologies MEMs – MicroElectroMechanical Liquid Crystal Opto-Mechanical Bubble Technology Thermo-optic (Silica, Polymer) Electro-optic (LiNb03, SOA, InP) Acousto-optic Others… Maturity of technology, Switching speed, Scalability, Cost, Relaiability (moving components or not), etc.

36. CSIT560 by M. Hamdi 35 MEMS Switches for Optical Cross-Connect Proven technology, switching time (10 to 25 msec), moving mirrors is a reliability problem.

37. CSIT560 by M. Hamdi 36 WDM “transparent” transmission system Wavelengths aggregator multiple λs Fibers (O-O nodes) Wavelengths disaggregator O O O O O O Optical switching fabric (MEMS devices, etc.) Incoming fiber Tiny mirrors Outgoing fibers

38. CSIT560 by M. Hamdi 37 Upcoming Optical Technologies WDM routing is circuit switched –Resources are wasted if enough data is not sent –Wastage more prominent in optical networks Techniques for eliminating resource wastage –Burst Switching –Packet Switching Optical burst switching (OBS) is a new method to transmit data A burst has an intermediate characteristics compared to the basic switching units in circuit and packet switching, which are a session and a packet, respectively

39. CSIT560 by M. Hamdi 38 Optical Burst Switching (OBS) Group of packets a grouped in to ‘ bursts ’, which is the transmission unit Before the transmission, a control packet is sent out –The control packet contains the information of burst arrival time, burst duration, and destination address Resources are reserved for this burst along the switches along the way The burst is then transmitted Reservations are torn down after the burst

40. CSIT560 by M. Hamdi 39 Optical Burst Switching (OBS)

41. CSIT560 by M. Hamdi 40 Optical Packet Switching Fully utilizes the advantages of statistical multiplexing Optical switching and buffering Packet has Header + Payload – –Separated at an optical switch Header sent to the electronic control unit, which configures the switch for packet forwarding Payload remains in optical domain, and is re- combined with the header at output interface

42. CSIT560 by M. Hamdi 41 Optical Packet Switch Has – –Input interface, Switching fabric, Output interface and control unit Input interface separates payload and header Control unit operates in electronic domain and configures the switch fabric Output interface regenerates optical signals and inserts packet headers Issues in optical packet switches – –Synchronization – –Contention resolution

43. CSIT560 by M. Hamdi 42 Main operation in a switch: – –The header and the payload are separated. – –Header is processed electronically. – –Payload remains as an optical signal throughout the switch. – –Payload and header are re-combined at the output interface. payloadhdr Wavelength i input port j Optical packet hdr CPU Optical switch payload hdr Re-combined Wavelength i output port j

44. CSIT560 by M. Hamdi 43 Output port contention Assuming a non-blocking switching matrix, more than one packet may arrive at the same output port at the same time. Output ports payloadhdr payloadhdr payloadhdr...... Optical SwitchInput ports..................

45. CSIT560 by M. Hamdi 44 Sync. Fixed packet size Synchronization stages required Slotted networks OPS Architecture: Synchronization Occurs in electronic switches – solved by input buffering

46. CSIT560 by M. Hamdi 45 Fixed packet size Synchronization stages required Slotted networks Sync. OPS Architecture: Synchronization

47. CSIT560 by M. Hamdi 46 Fixed packet size Synchronization stages required Slotted networks OPS Architecture: Synchronization Sync.

48. CSIT560 by M. Hamdi 47 Fixed packet size Synchronization stages required Slotted networks OPS Architecture: Synchronization Sync.

49. CSIT560 by M. Hamdi 48 Fixed packet size Synchronization stages required Slotted networks OPS Architecture: Synchronization Sync.

50. CSIT560 by M. Hamdi 49 OPS Architecture: Synchronization Sync.

51. CSIT560 by M. Hamdi 50 OPS: Contention Resolution More than one packet trying to go out of the same output port at the same time – –Occurs in electronic switches too and is resolved by buffering the packets at the output – –Optical buffering ? Solutions for contention – –Optical Buffering – –Wavelength multiplexing – –Deflection routing

52. CSIT560 by M. Hamdi 51 OPS Architecture Contention Resolutions 1 1 1 2 3 4 1 2 3 4

53. CSIT560 by M. Hamdi 52 OPS: Contention Resolution Optical Buffering – –Should hold an optical signal How? By delaying it using Optical Delay Lines (ODL) – –ODLs are acceptable in prototypes, but not commercially viable – –Can convert the signal to electronic domain, store, and re- convert the signal back to optical domain Electronic memories too slow for optical networks

54. CSIT560 by M. Hamdi 53 1 1 1 2 3 4 1 2 3 4 Optical buffering OPS Architecture Contention Resolutions

55. CSIT560 by M. Hamdi 54 1 2 3 4 1 2 3 4 Optical buffering OPS Architecture Contention Resolutions

56. CSIT560 by M. Hamdi 55 1 1 1 2 3 4 1 2 3 4 Optical buffering OPS Architecture Contention Resolutions

57. CSIT560 by M. Hamdi 56 OPS: Contention Resolution Wavelength multiplexing – –Resolve contention by transmitting on different wavelengths – –Requires wavelength converters - $$$

58. CSIT560 by M. Hamdi 57 Wavelength conversion 1 1 1 2 1 2 OPS Architecture Contention Resolutions

59. CSIT560 by M. Hamdi 58 1 2 1 2 Wavelength conversion OPS Architecture Contention Resolutions

60. CSIT560 by M. Hamdi 59 1 2 1 2 1 1 Wavelength conversion OPS Architecture Contention Resolutions

61. CSIT560 by M. Hamdi 60 1 2 1 2 Wavelength conversion OPS Architecture Contention Resolutions

62. CSIT560 by M. Hamdi 61 1 2 1 2 1 1 Wavelength conversion OPS Architecture Contention Resolutions

63. CSIT560 by M. Hamdi 62 Deflection routing When there is a conflict between two optical packets, one will be routed to the correct output port, and the other will be routed to any other available output port. A deflected optical packet may follow a longer path to its destination. In view of this: –T he end-to-end delay for an optical packet may be unacceptably high. –Optical p ackets may have to be re-ordered at the destination

64. CSIT560 by M. Hamdi 63 Electronic Switches Using Optical Crossbars

65. CSIT560 by M. Hamdi 64 Scalable Multi-Rack Switch Architecture Switch Core Optical links Line card rack Number of linecards is limited in a single rack –Limited power supplement, i.e. 10KW –Physical consideration, i.e. temperature, humidity Scaling to multiple racks –Fiber links and central fabrics

66. CSIT560 by M. Hamdi 65 Logical Architecture of Multi-rack Switches Optical I/O interfaces connected to WDM fibers Electronic packet processing and buffering –Optical buffering, i.e. fiber delay lines, is costly and not mature Optical interconnect –Higher bandwidth, lower latency and extended link length than copper twisted lines Switch fabric: electronic? Optical? Crossbar Scheduler Switch Fabric System Framer Line Card Laser Local Buffers Framer Line Card Laser Local Buffers Framer Line Card Laser Local Buffers Framer Line Card Laser Local Buffers Fiber I/O

67. CSIT560 by M. Hamdi 66 Optical Switch Fabric Less optical-to-electrical conversion inside switch –Cheaper, physically smaller Compare to electronic fabric, optical fabric brings advantages in –Low power requirement, Scalability, Port density, High capacity Technologies that can be used –2D/3D MEMS, liquid crystal, bubbles, thermo-optic, etc. Hybrid architecture takes advantage of the strengths of both electronics and optics Crossbar Scheduler Switch Fabric System Framer Line Card Laser Local Buffers Framer Line Card Laser Local Buffers Framer Line Card Laser Local Buffers Framer Line Card Laser Local Buffers Fiber I/O

68. CSIT560 by M. Hamdi 67 Electronic Vs. Optical Fabric Trans. Line Buffer Switching Fabric Inter- connection Trans. Line BufferInter- connection Electronic Trans. Line Buffer Switching Fabric Inter- connection Trans. Line BufferInter- connection Optical Electronic E/O or O/E Conversion favorred

69. CSIT560 by M. Hamdi 68 Multi-rack Hybrid Packet Switch

70. CSIT560 by M. Hamdi 69 Features of Optical Fabric Less E/O or O/E conversion High capacity Low power consumption Less cost However, Reconfiguration overhead (50-100ns) –Tuning of lasers (20-30ns) –System clock synchronization (10-20ns or higher)

71. CSIT560 by M. Hamdi 70 Scheduling Under Reconfiguration Overhead Traditional slot-by-slot approach Low bandwidth usage Scheduler Time Line ScheduleReconfigureTransfer

72. CSIT560 by M. Hamdi 71 Reduced Rate Scheduling Challenge: fabric reconfiguration delay –Traditional slot-by-slot scheduling brings lots of overhead Solution: slow down the scheduling frequency to compensate –Each schedule will be held for some time Scheduling task 1.Find out the matching 2.Determine the holding time Fabric setup (reconfigure) Traffic transfer Time slot Slot-by-slot Scheduling, zero fabric setup time Reduced rate Scheduling, each schedule is held for some time Slot-by-slot Scheduling with reconfigure delay

73. CSIT560 by M. Hamdi 72 Scheduling Under Reconfiguration Overhead Reduce the scheduling rate –Bandwidth Usage = Transfer/(Reconfigure+Transfer) Approaches –Batch scheduling: TSA-based –Single scheduling: Schedule + Hold Constant

74. CSIT560 by M. Hamdi 73 Single Scheduling Schedule + Hold –One schedule is generated each time –Each schedule is held for some time (holding time) –Holding time can be fixed or variable –Example: LQF+Hold

75. CSIT560 by M. Hamdi 74 Routing and Wavelength Assignment

76. CSIT560 by M. Hamdi 75 Optical Circuit Switching An optical path established between two nodes Created by allocation of a wavelength throughout the path. Provides a ‘circuit switched’ interconnection between two nodes. –Path setup takes at least one RTT –No optical buffers since path is pre-set Desirable to establish light paths between every pair of nodes. Limitations in WDM routing networks, –Number of wavelengths is limited. –Physical constraints: limited number of optical transceivers limit the number of channels.

77. CSIT560 by M. Hamdi 76 Routing and Wavelength Assignment (RWA) Light path establishment involves –Selecting a physical path between source and destination edge nodes –Assigning a wavelength for the light path RWA is more complex than normal routing because –Wavelength continuity constraint A light path must have same wavelength along all the links in the path –Distinct Wavelength Constraint Light paths using the same link must have different wavelengths

78. CSIT560 by M. Hamdi 77 No Wavelength Converters POP Access Fiber Wavelength 1 Wavelength 2 Wavelength 3 WSXC

79. CSIT560 by M. Hamdi 78 With Wavelength Converters POP Access Fiber Wavelength 1 Wavelength 2 Wavelength 3 WIXC

80. CSIT560 by M. Hamdi 79 Routing and Wavelength Assignment (RWA) RWA algorithms based on traffic assumptions: Static Traffic –Set of connections for source and destination pairs are given Dynamic Traffic –Connection requests arrive to and depart from network one by one in a random manner. –Performance metrics used fall under one of the following three categories: Number of wavelengths required Connection blocking probability: Ratio between number of blocked connections and total number of connections arrived

81. CSIT560 by M. Hamdi 80 Static and Dynamic RWA Static RWA –Light path assignment when traffic is known well in advance –Arises in capacity planning and design of optical networks Dynamic RWA –Light path assignment to be done when requests arrive in random fashion –Encountered during real-time network operation

82. CSIT560 by M. Hamdi 81 Static RWA RWA is usually solved as an optimization problem with Integer Programming (IP) formulations Objective functions –Minimize average weighted number of hops –Minimize average packet delay –Minimize the maximum congestion level –Minimize number of Wavelenghts

83. CSIT560 by M. Hamdi 82 Static RWA Methodologies for solving Static RWA –Heuristics for solving the overall ILP sub-optimally –Algorithms that decompose the static RWA problem into a set of individual sub-problems, and solve a sub-set –http://www.tct.hut.fi/~esa/java/wdm/http://www.tct.hut.fi/~esa/java/wdm/ Methodologies for solving Static RWA – –Heuristics for solving the overall ILP sub-optimally – –Algorithms that decompose the static RWA problem into a set of individual sub-problems, and solve a sub-set – –http://www.tct.hut.fi/~esa/java/wdm/http://www.tct.hut.fi/~esa/java/wdm/ Methodologies for solving Static RWA – –Heuristics for solving the overall ILP sub-optimally – –Algorithms that decompose the static RWA problem into a set of individual sub-problems, and solve a sub-set – –http://www.tct.hut.fi/~esa/java/wdm/http://www.tct.hut.fi/~esa/java/wdm/

84. CSIT560 by M. Hamdi 83 Solving Dynamic RWA During network operation, requests for new light- paths come randomly These requests will have to be serviced based on the network state at that instant As the problem is in real-time, dynamic RWA algorithms should be simple The problem is broken down into two sub-problems –Routing problem –Wavelength assignment problem

85. CSIT560 by M. Hamdi 84 Optical Circuit Switching all the Way: End-to-End !!! Why might this be possible: Huge CS bandwidth (large # of wavelength) – BW efficiency is not very crucial Huge CS bandwidth (large # of wavelength) – BW efficiency is not very crucial Circuit switches have a much higher capacity than Packet switches, and QoS is trivial Circuit switches have a much higher capacity than Packet switches, and QoS is trivial Optical Technology is suited for CS Optical Technology is suited for CS

86. CSIT560 by M. Hamdi 85 How the Internet Looks Like Today The core of the Internet is already “predominantly” CS. Even a “large” portion of the access networks use CS (Modem, DSLs)

87. CSIT560 by M. Hamdi 86 How the Internet Really Looks Like Today SONET/SDH DWDM

88. CSIT560 by M. Hamdi 87 How the Internet Really Looks Like Today Modems, DSL

89. CSIT560 by M. Hamdi 88 Why Is the Internet Packet Switched in the First Place? PS is bandwidth efficient “ Statistical Multiplexing ” PS networks are robust Gallager: “Circuit switching is rarely used for data networks,... because of very inefficient use of the links” Tanenbaum: ”For high reliability,... [the Internet] was to be a datagram subnet, so if some lines and [routers] were destroyed, messages could be... rerouted”

90. CSIT560 by M. Hamdi 89 Are These Assumptions Valid Today? PS is bandwidth efficient PS networks are robust   Routers/Switches are designed for <5s down-time per year.   They take >1min to recover when they do (circuit switches must recover in <50ms). 10-15% average link utilization in the backbone today. Similar story for access networks

91. CSIT560 by M. Hamdi 90 How Can Circuit Switching Help the Internet? Simple switches/routers: No buffering No per-packet processing (just per connection processing) Possible all-optical data path Peak allocation of BW No delay jitter Higher capacity switches Simple but strict QoS

92. CSIT560 by M. Hamdi 91 Myth: Packet switching is simpler A typical Internet router contains over 500M gates, 32 CPUs and 10Gbytes of memory. A circuit switch of the same generation could run ten times faster with 1/10 th the gates and no memory.

93. CSIT560 by M. Hamdi 92 Packet Switch Capacity time Instructions per arriving byte What we’d like: (more features) QoS, Multicast, Security, … What will happen: (fewer features) Or perhaps we’re doing something wrong?

94. CSIT560 by M. Hamdi 93 What Is the Performance of Circuit Switching? End-to-End Packet swCircuit sw 10 Mb/s1 Gb/sFlow BW 1 s0.505 sAvg latency 1 s Worst latency 99% of Circuits Finish Earlier 1 server 100 clients 1 Gb/s File = 10Mbit x 100

95. CSIT560 by M. Hamdi 94 What Is the Performance of Circuit Switching? 10.990 sec10.990 sWorst latency Packet swCircuit sw 10Mb/s+1Gb/s1 Gb/sFlow BW 1.099 sec10.495 sAvg latency A big file can kill CS if it blocks the link 1 server 100 clients 1 Gb/s File = 10Gbit/10Mbit x 99

96. CSIT560 by M. Hamdi 95 What Is the Performance of Circuit Switching? Packet swCircuit sw 1 Mb/s Flow BW 10,000 sec10,000 sWorst latency 109.9sec 109.9sAvg latency No difference between CS and PS in core 1 server 100 clients 1 Gb/s x 99 1 Mb/s File = 10Gbit/10Mbit

97. CSIT560 by M. Hamdi 96 Possible Implementation Create a separate circuit for each flow IP controls circuits Optimize for the most common case –TCP (85-95% of traffic) –Data (8-9 out of 10 pkts) TCP Switching

98. CSIT560 by M. Hamdi 97 TCP Switching Exposes Circuits to IP TCP Switches IP routers

99. CSIT560 by M. Hamdi 98 TCP “ Creates ” a Connection Router Destina- tion Source SYN SYN+ACK DATA Packets

100. CSIT560 by M. Hamdi 99 State Management Feasibility Amount of state –Minimum circuit = 64 kb/s. –156,000 circuits for OC-192. Update rate –About 50,000 new entries per sec for OC-192. Readily implemented in hardware or software.

101. CSIT560 by M. Hamdi 100 Software Implementation Results TCP Switching boundary router: Kernel module in Linux 2.4 1GHz PC Forwarding latency –Forward one packet: 21  s. –Compare to: 17  s for IP. –Compare to: 95  s for IP + QoS. Time to create new circuit: 57  s.