A Network in a Laptop: Rapid Prototyping for So7ware- Defined Networks

Transcription

1 A Network in a Laptop: Rapid Prototyping for So7ware- Defined Networks Bob Lantz, Brandon Heller, Nick McKeown Stanford University HotNets 2010, 10/20/10 1

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3 Wouldn t it be amazing if systems papers were runnable. 3

4 Wouldn t it be amazing If systems papers made replicasng their results, modifying the described system, and sharing it with others as easy as downloading a file. 4

5 Wouldn t it be amazing if network systems papers were more than runnable. share with others idea prototype deploy on hardware with no code changes!?! 5

6 Mininet: a playorm for rapid network prototyping. scales to usefully large nets runs unmodified applica4ons provides path to hardware facilitates sharing 6

7 openflow.org/mininet 140+ users 45+ on mailing list 20+ insstusons open source (BSD license) [don t download now! save the WiFi!] 7

8 Demo 8

9 Demo Topology: Fat Tree &"'($ )**'(*+,"-$,--'(-./"0$ 1#-($.#*($!"#$%$!"#$/$!"#$)$!"#$0$!"#$*$!"#$1$!"#$+$ described in Scalable Commodity Data Center, SIGCOMM 2008, Al Fares et al. 9

10 (1) share- able (2) runs on hardware 10

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12 Date Nov 2009: deadline in 3 months [based on a true story] 12

13 Resources: a laptop 13

14 Goal: build/eval/demo a realissc new networked system 14

15 Why not a real system? switch s1 + as real as it gets - a pain to reconfigure host h2 host h3 15

16 Why not networked virtual machines? VM1 switch s1 + easier topology changes - scalability VM2 VM3 host h2 host h3 16

17 Why not a simulator? process state switch s1 + good visibility - no path to hardware state state host h2 host h3 17

18 Problem 1: Want scale with unmodified applicasons. Use lightweight, OS- level virtualizason. 18

19 OS- level VirtualizaSon Same system, different view. Almost zero overhead. ex. IMUNES, Emulab user kernel process filesystem hostname user IDs network process filesystem hostname user IDs network one OS kernel 19

20 Problem 2: Want a smooth path to hardware deployment. Use So7ware- Defined Networking. 20

21 Feature Feature Network OS Feature OS Hardware Feature OS Feature OS Hardware Feature OS Hardware Feature Hardware OS Hardware 21

22 So7ware- Defined Network Feature Feature Network OS OpenFlow Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding 22

23 Mininet Walkthrough 23

24 controller switch s1 host h2 host h3 24

25 $> mn --topo minimal \! --switch ovsk \! --controller ref! run Mininet launcher root network namespace mn! 25

26 $> mn --topo minimal \! --switch ovsk \! --controller ref! root network namespace Hosts create bash processes mn! pipes /bin/bash! host h2 /bin/bash! host h3 26

27 $> mn --topo minimal \! --switch ovsk \! --controller ref! root network namespace Hosts unshare(clone_newnet)! mn! pipes /bin/bash! h2 namespace /bin/bash! h3 namespace 27

28 $> mn --topo minimal \! --switch ovsk \! --controller ref! root network namespace Links ip link add mn! pipes veth0 veth1 veth pairs veth2 veth3 /bin/bash! /bin/bash! h2 namespace h3 namespace 28

29 $> mn --topo minimal \! --switch ovsk \! --controller ref! root network namespace Links ip link set name mn! pipes s1- eth1 s1- eth2 veth pairs h2- eth0 h3- eth0 /bin/bash! h2 namespace /bin/bash! h3 namespace 29

30 $> mn --topo minimal \! --switch ovsk \! --controller ref! root network namespace Links ip link set netns mn! pipes s1- eth1 s1- eth2 veth pairs h2- eth0 h3- eth0 /bin/bash! h2 namespace /bin/bash! h3 namespace 30

31 $> mn --topo minimal \! --switch ovsk \! --controller ref! root network namespace Switch create OpenFlow Switch ofdatapath! unix socket ofprotocol! mn! pipes s1- eth1 raw sockets s1- eth2 veth pairs h2- eth0 h3- eth0 /bin/bash! h2 namespace /bin/bash! h3 namespace 31

32 $> mn --topo minimal \! --switch ovsk \! --controller ref! root network namespace Controller create controller ofdatapath! unix socket ofprotocol! mn! pipes h2- eth0 s1- eth1 raw sockets s1- eth2 veth pairs controller! h3- eth0 /bin/bash! h2 namespace /bin/bash! h3 namespace 32

33 Virtual Machine root network namespace ofdatapath! unix socket ofprotocol! mn! pipes h2- eth0 s1- eth1 raw sockets s1- eth2 veth pairs controller! h3- eth0 /bin/bash! h2 namespace /bin/bash! h3 namespace 33

34 Mininet example commands Create a network using mn launcher: mn --switch ovsk --controller nox --topo \ tree,depth=2,fanout=8 --test pingall! Interact with a network using CLI: mininet> h2 ping h3! mininet> h2 py dir(locals())! Customize a network w/api: from mininet.net import Mininet! from mininet.topolib import TreeTopo! tree4 = TreeTopo(depth=2,fanout=2)! net = Mininet(topo=tree4)! net.start()! h1, h4 = net.hosts[0], net.hosts[3]! print h1.cmd( ping -c1 %s % h4.ip())! net.stop()! 34

35 Apps made with the Mininet API 35

36 EvaluaSon 36

37 Startup/Shutdown/Memory iperf nd kerin fig- I will entaerials, Topology H S Setup(s) Stop(s) Mem(MB) Minimal Linear(100) VL2(4, 4) FatTree(4) FatTree(6) Mesh(10, 10) Tree(4ˆ4) Tree(16ˆ2) Tree(32ˆ2) Table 2: Mininet topology benchmarks: setup time, stop time and memory usage lots for networks of switches of H hosts and & S hosts Open vswitch kernel switches, tested in a Debian 5/Linux VM on VMware Fusion w/reasonable 3.0 a MacBook amounts Pro (2.4 GHz intel of Core memory 2 Duo/6 GB). Even in the largest configurations, hosts and switches start up in less than one second each. Operation Time (ms) 37

38 erf ker- fig- will taals, enine he dis- M ine is ely NS Tree(16ˆ2) Tree(32ˆ2) Table 2: Mininet topology benchmarks: setup time, stop time and memory usage for networks of H hosts and S Open vswitch kernel switches, tested Microbenchmarks in a Debian 5/Linux VM on VMware Fusion 3.0 on a MacBook Pro (2.4 GHz intel Core 2 Duo/6 GB). Even in the largest configurations, hosts and switches start up in less than one second each. Operation Time (ms) Create a node (host/switch/controller) 10 Run command on a host ( echo hello ) 0.3 Add link between two nodes 260 Delete link between two nodes 416 Start user space switch (OpenFlow reference) 29 Stop user space switch (OpenFlow reference) 290 Start kernel switch (Open vswitch) 332 Stop kernel switch (Open vswitch) 540 Table 3: Time for basic Mininet operations. Mininet s startup and shutdown performance is dominated by management of virtual Ethernet link management interfaces in the Linux ( ) is slow kernel and ip link utility and Open vswitch startup/shutdown time. of topologies with Mininet. Larger topologies which 38

39 Bandwidth S (Switches) User(Mbps) Kernel(Mbps) RaSo Table 1: Mininet end-to-end bandwidth, measured with iperf through linear chains of user-space (OpenFlow reference) and kernel (Open vswitch) switches. graphical applications, two of which are shown in figures 2 and 3. The hope is that the Mininet API will prove useful for system-level testing and experimenta- ~5x ~50x usable amount of bandwidth 39 Top Min Lin VL2 Fat Fat Mes Tre Tre Tre Table mem switc Fusio Even less t

40 Case Studies 40

41 Research Examples Ripcord: modular data center Asterix: wide- area load balancing SCAFFOLD: new internet architecture Distributed snapshot demo 41

42 Unexpected Uses Tutorials Whole- network regression suites Bug replicason 42

43 LimitaSons 43

44 Inherent LimitaSons OS- level virtualizason one kernel only Linux containers Linux programs only Cannot match the introspecson of an event- driven simulason 44

45 Performance Fidelity switch process p processes c cores host process links links links p >> c? Sme mulsplexing Issues: performance predictability, isolason 45

46 Wouldn t it be amazing if systems papers were runnable. 46

47 Wouldn t it be amazing If systems papers made replicasng their results, modifying the described system, and sharing it with others as easy as downloading a file. 47

48 Wouldn t it be amazing if network systems papers were more than runnable. share with others idea prototype deploy on hardware with no code changes!?! 48

49 A Network in a Laptop is a runnable paper which itself describes how to make other runnable papers. 49

50 Mininet Rapid prototyping Scalable Shareable FuncSonally correct Path to hardware enables runnable papers for a subset of networking openflow.org/mininet 50

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52 The SDN Approach Separate control from the datapath i.e. separate policy from mechanism Datapath: Define minimal network instrucson set A set of plumbling primisves A narrow interface: e.g. OpenFlow Control: Define a network- wide OS An API that others can develop on 52

53 How to get performance fidelity? Careful process- to- core allocason Bandwidth limits Scheduling priorises Real- Sme scheduling Scheduling groups w/resource isolason 53

54 Why not processes? process switch s1 + scales beser - breaks applicasons process process host h2 host h3 54