The Open Network Lab Ken Wong, Jonathan Turner, et. al. Applied Research Laboratory Computer Science and Engineering Department http://www.arl.wustl.edu/~kenw kenw@arl.wustl.edu http://www.onl.wustl.edu (ONL) National Science Foundation ANI-023826

The Open Network Laboratory (ONL) Provide hands-on experience with real network Makes education more concrete, provides reinforcement Supports experiment/observation approach Labs can lead to insights and greater understanding through experimentation and real-time observations Student can change configuration settings and observe effect on network traffic Extensive monitoring facility supports direct observations Easy-to-use Remote Laboratory Interface Provide access to advanced router features Gbps links, filters, packet scheduling Program insertion along packet data path Open laboratory facility Remote access, unsupervised learning possible Integrated course material (coming soon)

People Who Make it Happen Ken Wong Admin, Web site, Dist. Sched. Jyoti Parwatikar RLI, Software development Charlie Wiseman Web site, Ops Dist. Sched. Fred Kuhns SPC software FPX hardware John Dehart FPX hardware System integration Stephen Levine Plugins, Apps.

ONL Lab Overview Gigabit routers PCs serve as hosts easily configured thru Remote Lab Interface embedded processors for adding new features PCs serve as hosts half on shared subnets Net configuration switch link routers in virtual topologies traffic generation Tools for configuration and collecting results monitoring traffic data capture and playback Open source all hw & sw sources on web 4 Gigabit Ethernet Switch 2 3 GigE Network Configuration Switch 16

netBSD servers for plugin prep Testbed Organization SSH tunnel YOU usr Internet netBSD servers for plugin prep onl server Remote Lab Interface (RLI) control network CP 2 3 GE 1 2,3 NSP1 CP 2 3 GE 1 2,3 NSP2 16 CP 2 3 GE 1 2,3 NSP3 CP 2 3 GE 1 2,3 NSP4 4-7 4-7 4-7 4-7 experiment network configuration switch

Gigabit Router Architecture ATM Switch Core FPX SPC PP . . . CP external links Lookup . . . SPC plugin env. FPX to/from links to/from switch core Fast Path Scalable architecture built around ATM switch core. core provides 2 Gb/s bandwidth per port (2x speedup) Port processors (PP) implement packet processing Field Programmable Port Extender (FPX) implements routine packet processing Smart Port Card (SPC) hosts programmable extensions Control Processor (Linux PC) handles configuration can support routing protocols, OA&M, etc.

After Logging in Public links Tutorial Get account www.onl.wustl.edu or onl.arl.wustl.edu User links getting started status reservations

Sample ONL Session Bandwidth Usage Network Configuration Routing Table Queue Table Queue Length Filters Packet Drops

Cluster includes router, Configuring Topology Add hosts and links as needed. Default routing table for all ports Drag icons to improve visual layout Port 0 used for Control Processor. Spin handle rotates ports. Cluster includes router, gigE switch and fixed set of hosts

Configuring Topology (cont.) Darker color means commit done “Commit” to request actual resources n2p3 is name. 192.168.2.48 is IP address. Also, has external name and IP address to control network Save config. to a file for use in later session.

Routes, Filters and Rates Set link rate, relative service rates and queue sizes Configure Routes Click on port 6 to access route table (and other stuff). Filters direct pkts to separate queues for service

Monitoring Traffic/Real-Time Displays select desired monitor variable peak per ping packet customized label select which queue select polling rate

Example (1 NSP, 2 TCP Flows) sndr2 starts 10 sec after sndr1 Bottleneck Port 6 egress 100 Mbps Routing (2 flows) Through port 6 Reserved flow queues QIDs 300 and 301 Equal service rates 32,000 byte queues Delay plugins (optional) Delay ACK pkts Port 2 egress,25 msec Port 4 egress,50 msec sndr1 rcvr1 rcvr2 sndr2 bottleneck Port 7 Port 6 Port 2 Port 4 Port 3 Port 1

Traffic Generation Scripts urcvrs-1nsp script Exports control network names to environment Environment variable: Control network name (e.g., onl21) usndrs-1nsp script iperf traffic generator internal host interface

Adding Features with SPC Plugins Lookup . . . SPC plugin env. FPX to/from links to/from switch core SPC uses qid to direct pkt to plugin plugins are kernel modules on egress, pkt mapped to per-flow queue on ingress, pkt mapped to VOQ filter directs pkt to SPC queue

with numerical identifier Adding SPC Plugins pre-defined plugins with numerical identifier outgoing link queue 136 =8+128 filter directs pkt to SPC queue 8

Observe Effect of Delay on TCP longer congestion control cycle (50 msec vs 25 msec)

Larger Queues (320,000 Bytes) 50 ms delay ping pkts travel delay increases as queue grows 50 ms delay plugin acting as propagation delay ping pkts travel along same path as iperf TCP traffic growing queues

Standard Plugins (Growing Number) nullPlugin Just forward pkts COUNTER Count and forwards pkts stats Count ICMP/TCP/UDP pkts and drop Uses auxillliary filter stringSub Substitute “adieu” for “HELLO” Recomputes TCP checksum multicast Multicast pkts to all ports Create packet copies Manipulate shim qsnap (soon) Queue length seen by arriving pkts fpxCtrsAndRegs Read FPX counters/registers on demand udpdump (soon) Send part of pkt to logging daemon Creates UDP pkt psyndemo SYN flood mitigation plugin Monitors traffic for SYN flood pkts Installs EM filter in back channel Sends RESET pkts to Web server

Course Usage Spring 2005 Fall 2005 Spring 2006 A few WUSTL graduate students doing graduate networking protocols projects Fall 2005 About 35 WUSTL Intro networking students Basic routing lab exercise near end of semester About 15 SIUE intro network programming students Spring 2006 About 16 UMass graduate Intro Networking Basic routing lab and Basic bottleneck lab exercises About 20 WUSTL graduate Network Protocols Routing and Bottleneck lab exercise Planned: Router plugins lab exercise

UMass Survey Required grad course for non-networking students Most knew a little about networking but not much Survey after first lab exercise on basic routing Good comments (Summarized) (About 16 Students) Good hands-on learning … can see effect of config on actual traffic Liked its compactness, the skill it demands and its well organised pattern Good tutorial pages Good comments (Instructor: Tilman Wolf) “Great … can offer lab assignment with very little effort” Difficulties Need more routers in the testbed Making the first SSH tunnel was troublesome for some Less networking experience  More time on lab

A Successful First Experience Instructor/Grader tried ONL and worked on some exercises before writing own assignment Even better to do the assignment to be given out Wrote clear instructions and assignment UMass assignment was a cleaned up version of one from the ONL Web site Supplied caveats (based on instructor’s experience) Biggest one was ONL reservation times were CST Fix is to use local time (coming soon) Limited assignment to 1 NSP Emphasizes core ideas and limits encountering “gotchas” Student questions filtered through instructor/graders Backstop was testbed-ops@onl.arl.wustl.edu Keeps instructor in tune with students Helps ONL developers address real problems instead of noise

Current or Near Future Work Supporting 2 courses Web tutorial pages Course material More examples Various topics (e.g., Distributed Queueing) More standard plugins Experiments with Xen to support multiple TCP stacks Near Future Replace APIC interfaces with gigE Upgrade OSes Replace electronic patch panel Firewall

Possible Future Extensions Improve router functionality. improved link queueing, dynamic packet discards include TCP flags in packet filters sampling filters for netFlow type applications Different OSes (and therefore TCP stacks) Hardware plugin modules. insert hardware processing modules into links implemented using extra FPX modules user-specified FPGA bit-files Hardware support for user-specified link delays Expand testbed with NP-based routers. 10 port router implemented with pair of IXP 2850s enable construction of larger networks enable users to more easily modify core router functions queue management, route lookup, packet classification

The End onl.wustl.edu or www.onl.wustl.edu