Network Troubleshooting or …
Is there any hope my Performance
will be seen over the network?
Bob Riddle – Technologist
January 2005
What is a network geek doing at a
New World Symphony seminar?
Did I come to share my musical talents?
• I played the bassoon in elementary school & middle school
• I taught myself to play a guitar, I now play it 1 week a year
• My kids gave me a harmonica – want to hear me play?
No? then let’s look at some network stuff
• using the network to “stretch” the stage & the auditorium
• the kind of tools you need in your network “toolbox”?
• how to “stack the deck” in your favor
Issues to consider when stretching
the stage & the auditorium
Things to think about when
“stretching” the stage
•Speed: do you need a freeway, city street,
or a dirt road? (H.323 – HDTV)
•Latency: is it a “telephone” call or a
“movie”? (streaming or interactive)
•Packet Loss: is there any “junk mail” you
can throw away?
Issues to consider:
Do you need a dirt road or a freeway?
Determine the quality of the Experience
• Mpeg1
• H.323
• Mpeg2
• DV
• HDTV
~=
~=
~=
~=
~=
1.5 – 3.0 mpbs
384 – 1.5 mbps kbps
4 – 15 mbps
30 mbps
20 – 270 mbps; 1.5 gbps
Determine the type of Experience
• One way?
• Two way?
• Many way?
(streaming, broadcast)
(interactive voice, video)
(more than 2 end points)
Do the Math & check your “onramp”!
Issues to consider –
unicast or multicast
can’t I get away with just unicast? (Real, QT)
• Depends on the “ road” – 384 kbps or 30 mbps stream(s)
• i.e. stats from earlier Victoria Secrets webcast
 More than 1 million web hits during 1st hour
 283% increase in web traffic during event
• Unicast delivery doesn’t cheaply scale!
 think of multicast as “Broadcast TV”
• If you have a “tuner” and your “antenna” is pointed in the
right direction, just tune in the “channel”
• If you’re on a Internet2 backbone, you’re ready! (well, almost
ready …)
Do the math
(stream * potential endpoints)
• If there’s only 1 endpoint, use unicast
• If it’s a “Victoria Secrets” type thing, use multicast
If the “math” works out – then go
for a test drive
Take a good look at your local “roads”
1.
2.
3.
4.
Run internal tests across your LAN
Make sure you’re testing what you plan to use!
Find a friend “next door” to test with
Learn about ping, traceroute, the Detective,
ethereal, iperf, DVTS, VLC & what they can tell
you about your network situation
5. Start thinking about the on-ramp, the freeway,
and those other “local roads” at your endpoints
and potential endpoints
Network Toolbox: Basic tools
Ping – can I get from here to there?
• History of Ping
• Web Page with Ping & other tools
• Spend $24.95 for pretty pictures
• Beware! ICMP packets are now often blocked
traceroute (tracert) – what roads do I travel
• Web Page with Ping & other tools
• Spend $24.95 for pretty pictures
• When things good one direction but not the other,
check for asymmetrical routes (then check for full
duplex trouble!)
Network Toolbox: more tools
Internet2 Detective
• check your on-ramp to Abilene
• test your multicast capability
• Test your “speed” (bandwidth)
• Check you speed from here to
there using “iperf”
Another “detective”
• SurfNet – NAT, firewall tests,
duplex test, IPv6 test, etc.
Network Toolbox: more tools
check out your network capability:
• DVTS/DVGuide: readily available streams
• MPEG2 example (using VLC client)
– Research Channel
– University of Washington
233.0.73.28
233.0.73.29
• DVTS example (using DVTS WinXP client)
– Research Channel
233.0.73.25
– University of Pennsylvania
233.0.55.10
– University of South Florida
233.22.29.128
– Internet2 Test Channel 233.45.17.50
Network Toolbox: great tools
ethereal – look at the traffic on your road
• Powerful Multi-Platform Analysis
• Useful for checking TTL, determining whether it’s a network
problem or an endpoint problem
iperf – bandwidth measurement tool
• Peer-to-peer tool for performance testing
• Supports tcp, udp, multicast traffic
• Supports uni-directional & bi-directional testing
Mailing lists
• bigvideo@internet2.edu
• wg-multicast@internet2.edu
Stack the deck in your favor
Use an early-warning system!
• Wouldn’t it be nice if you could figure out if there
was any hope your stuff would work without
having to buy/borrow/steal another expensive
device to ship to each end point?
• Wouldn’t it be nice if you could use a cheap PC to
determine if there was any hope?
• Wouldn’t it be nice if you could use free (or almost
free!) software to determine if there was any
hope?
Think about building cakeboxes
Stack the deck using the cakebox
Criteria for the cakebox:
•
•
•
•
Small, inexpensive, easy to ship device
No operator, no monitor, keyboard, or mouse required
Just plug in a network cable & a power cable
Provide web interface for non-network geeks
http://envoy.internet2.edu/pioneer/
What it will allow you to do:
•
•
•
•
Allows representative bandwidth testing
Shows you what “road” you’ll travel
Allows you to exercise “broadcast” (multicast) traffic
You can find out if there is any hope
Stack the deck using the cakebox
Cakebox built using freely available
tools:
• http://dast.nlanr.net/Projects/Iperf/
• http://dast.nlanr.net/Projects/Beacon/
• http://dast.nlanr.net/NPMT/
Packaged on Linux Platform
• “phone-home” to LDAP server
• Secure access via SSL to web server
• Secure access via SSH directly to cakebox