Network Troubleshooting or … Is there any hope my Performance will be seen over the network? Bob...

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

•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?

Things to think about when

“stretching” the stage

Issues to consider:Do you need a dirt road or a freeway?

Determine the quality of the Experience•Mpeg1 ~= 1.5 – 3.0 mpbs•H.323 ~= 384 – 1.5 mbps kbps•Mpeg2 ~= 4 – 15 mbps•DV ~= 30 mbps•HDTV ~= 20 – 270 mbps; 1.5 gbps

Determine the type of Experience• One way? (streaming, broadcast)• Two way? (interactive voice, video)• Many way? (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. Run internal tests across your LAN

2. Make sure you’re testing what you plan to use!

3. Find a friend “next door” to test with

4. 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 233.0.73.28–University of Washington 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

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