2002 Computer Forum Circuit switching in the Internet Pablo Molinero-Fernández, Nick McKeown IP will conquer the world, because it is Feasibility of TCP SwitchingLet TCP Leave State BehindTCP Switching Exposes Circuits to IP One proposal for integrating circuits in an evolutionary way What is the performance of circuit switching? Reality check for IP What The Internet Is Really Like TodayHow Textbooks Say The Internet Is Technology trends Modems, DSL LAN SONET/SDH DWDM More efficient More robust Simpler Can provide QoS Statistical multiplexing No hard state No signaling, no state WFQ/DRR/DiffServ Over-provisioning More efficient More robust Simpler Can provide QoS True, but links are lightly utilized anyways SONET %, 50 ms IP 99.78%, 30 min Commercial cct sw’s are 4-10x faster than equivalent routers Perfect traffic isolation with ccts 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 sec sWorst latency Packet swCircuit sw 10Mb/s+1Gb/s1 Gb/sFlow BW sec 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 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 Create a separate circuit for each flow IP controls circuits Optimize for the most common case –TCP (90-95% of traffic) –Data (9 out of 10 pkts) TCP Switching TCP Switches IP routers Boundary TCP-SW Core TCP-SW Boundary TCP-SW Destina- tion Source SYN SYN+ACK DATA ACCEPTED One CircuitPackets ACCEPTED 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. Lookup rate for boundary router –Exact match lookup, similar to 10G Ethernet Readily implemented in hardware or software. What is the performance of circuit switching? Link speed x2/7 months Router capacity X2.2/18 months Moore’s law X2/18 months Memory latency X1.1/18 months

2002 Computer Forum Feasibility of TCP SwitchingLet TCP Leave State BehindTCP Switching Exposes Circuits to IP One proposal for integrating circuits in an evolutionary way Create a separate circuit for each flow IP controls circuits Optimize for the most common case –TCP (90-95% of traffic) –Data (9 out of 10 pkts) TCP Switching TCP Switches IP routers Boundary TCP-SW Core TCP-SW Boundary TCP-SW Destina- tion Source SYN SYN+ACK DATA ACCEPTED One CircuitPackets ACCEPTED 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. Lookup rate for boundary router –Exact match lookup, similar to 10G Ethernet Readily implemented in hardware or software. IP will conquer the world, because it isReality check for IP What The Internet Is Really Like TodayHow Textbooks Say The Internet Is Technology trends Link speed x2/7 months Router capacity X2.2/18 months Moore’s law X2/18 months Memory latency X1.1/18 months Modems, DSL LAN SONET/SDH DWDM More efficient More robust Simpler Can provide QoS Statistical multiplexing No hard state No signaling, no state WFQ/DRR/DiffServ Over-provisioning More efficient More robust Simpler Can provide QoS True, but links are lightly utilized anyways SONET %, 50 ms IP 99.78%, 30 min Commercial cct sw’s are 4-10x faster than equivalent routers Perfect traffic isolation with ccts What is the performance of circuit switching? 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 sec sWorst latency Packet swCircuit sw 10Mb/s+1Gb/s1 Gb/sFlow BW sec 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 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 What is the performance of circuit switching? Circuit switching in the Internet Pablo Molinero-Fernández, Nick McKeown