Transcript ppt
Is Lambda Switching Likely for Applications? Tom Lehman USC/Information Sciences Institute December 2001 Context/Time Frames • Far Future (10 yrs+) – New end system architectures which can source/sink 80Gb/s+ – Large availability of fiber which can support >1000’s lambda’s per fiber • Near Future (5-10 yrs) – Improvements in existing end system architecture – Must live with/use large amounts of non-dispersion compensated fiber currently in place – Following slides will focus on this time frame 2 Network Component Considerations • Before we discuss network architectures, protocols, and features, lets evaluate what we can expect from the components in this time frame – End Systems – Routers & Switches – Optical capacity 3 End System/Router/Switch Performance (order of magnitude) • Currently – – – – 2 GHz processors, 128 bit => 250 Gbit/s processing power 250 MHz SRAM, 128 bit => 32 Gbit/s memory bandwidth 133 MHz PCIx, 64 bit => 8 Gbit/s I/0 bandwidth Router/Switch Interfaces => 10 Gbit/s • Near Future? – – – – – 10 Ghz processors, 128 bit => Terabit/s processing power 1 GHz SRAM, 128 bit => 128 Gbit/s memory bandwidth QDR 133 MHz PCIx, 64 bit => 32 Gbits/s Infiniban12x => 24 Gbit/s (per full duplex channel) Router/Switch Interfaces =>40 Gbit/s 4 Optical Capacity (order of magnitude) • Currently – C Band (1529-1562nm) @50-100Ghz spacing => 64 lambda’s/fiber – 10 Gbit/s/lambda => 640 Gbits/s/fiber • Near Future – 80 Lambda’s/fiber – 40 Gbit/s lambda => 3.2 Terabits/s/fiber – 80 Gbit/s lambda => 6.4 Terabits/s/fiber • End Systems and Router/Switch interfaces will not keep up with the increase in optical speeds – Moore’s law will not allow processor speeds to keep up – End system architecture (complicated OS and protocol stack and slow I/O) will prevent matching speeds – Router switch interfaces beyond 40 Gbit/s will be a challenge (electronic components do not yet exist for those speeds, so gap between optics and electronics will get larger) 5 Assumption on Component Capabilities • End Systems – Source/sink 24 Gbit/s – End system modifications may include • Direct host memory to NIC card dma features • Complete offload of protocol stack to hardware • Router/Switch Interfaces – 40 Gbit/s • Optical Capacity (per fiber) – 80 lambda/fiber @40 Gbit/s => 3.2 Terabits/s/fiber 6 Is Lambda Switching Likely for Applications? • No, in the context of end to end lambda switching between applications across the network on a widescale – not enough lambda’s for this to scale – Special applications (e-Science?) may require end to end lambda’s • Yes, in the context of an interface or network connection which provides real time capacity provisioning based on application requests – this could be part of overall QOS scheme – (some) circuit/lambda switched in the core, IP on the edges • Networks need to be able to support widescale deployment of “fast” end systems and also provide guaranteed QOS – Lambda switching could be a key enabling technology 7 Network Issues • Networks need to provide applications with on demand guaranteed QOS. This should include: – ability for applications to discover/query in real time end to end performance – ability to be guaranteed a level of “performance” on and end to end basis • IP Networks – packet switched networks good for bursty traffic and applications which can live with best effort delivery. – not so good for long flows which require guaranteed performance – currently no well working mechanisms for guaranteed QOS in IP networks. • DiffServ, RSVP, MPLS, IntServ • Circuit switched networks provide QOS, but did not scale well. 8 GMPLS a solution? • GMPLS may be heading in the right direction – allows MPLS to control multiple devices such as LSRs, SONET ADMs, OADMs, OXCs • Allows network to utilize benefits of packet switched and circuit switched networks. • Bulk of traffic should still be packet switched on an end to end basis • Circuit switched lambda’s could be used for provisioning based on aggregation of application demands • Special applications (e-Science?) may require end to end lambda’s 9 GMPLS Architecture • IP is the control plane for setting up “layer 2 circuits” IP Router Lambda Switch 10 QOS in this Environment • The packet switched QOS should be simpler – just guarantees bandwidth? – applications which use this can compensate for loss and jitter (including VOIP) • Circuit switched QOS guarantees bandwidth, delay, jitter • But the same issues that have yet to be solved regarding QOS still need resolution – – – – What is the economic model? Who pays? How is it enforced? The monitoring, enforcement, and accounting must be simple. How is this accomplished across domains? • an ability to create “layer 2” circuits across domains may help this 11