1. The Open Network Lab
Ken Wong, Jonathan Turner, et. al. Applied Research Laboratory Computer Science and Engineering Department
(ONL)
National Science Foundation ANI

2. 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)

3. 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.

4. 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

5. 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

6. 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.

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

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

9. 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

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

11. 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

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

13. 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

14. 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

15. 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

16. 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

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

18. 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

19. 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

20. 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

21. 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

22. 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
Keeps instructor in tune with students
Helps ONL developers address real problems instead of noise

23. 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

24. 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

25. The End
onl.wustl.edu or