peter o’neil executive director [email protected] november 29, 2007 max fall member meeting
TRANSCRIPT
Looking Ahead Topics
• Strategic Planning
• Governance Issues
• High Performance Networking
• Partner with members on large proposals
• Flow Data
“And what is good, Phaedrus, And what is not good - Need we ask anyone to tell us these things?”
Robert Pirsig, ZAMM (1974)
"Quality ... you know what it is, yet you don't know what it is. But that's self-contradictory. But some things are better than others, that is, they have more quality. But when you try to say what the quality is, apart from the things that have it, it all goes pouf! There's nothing to talk about. But if you can't say what Quality is, how do you know what it is, or how do you know that it even exists? If no one knows what it is, then for all practical purposes it
doesn't exist at all. But for all practical purposes it really does exist. What else are the grades based on? Why else would people pay fortunes for some things and throw others in
the trash pile? Obviously some things are better than others ... but what's the `betterness'? ... So round and round you go, spinning mental wheels and nowhere finding
anyplace to get traction.”
ZAMM (1974)
Quality is not something you believe in, Quality is something you experience.”
Robert M. Pirsig (2000)
MAX is striving for you to experience working with us has having more Quality
than working with any other provider.
Strategic Planning• Began projecting into future with current fiscal year budget
and 2 years past history– Examining cost elements for services: colo space & power, cross
connects, fiber rings, hardware, software, maintenance, spares, lab, training
– NOC (sore topic needs addressing)– Evaluating Research Group focus areas– Support & Outreach services– Adding value to solid high performance pipes and plumbing
• Engage in discussions with you to articulate consensus technical direction for next 3 to 5 years
Governance
• Internal issues dominated thus far, starting to look out and ahead more
• Re-engage Governance Committee– Quilt Business Case study
– 501c3 not-for-profit as operating entity
– Evaluate LLC or foundation to hold assets to insure RTU
– Quilt’s independence has revisited by-laws & charter we can learn and benefit from
• Strengthen alliances across our region
Regional Optical Networks• Quilt focusing on best current business practices for RONs
– cost effective and flexible for regional growth
• Partnering with other RONs– organically spawning collapsed backbone interconnections with other
RONs
• Quilt issuing RFP to carriers for fiber and waves – Need alternative path options to just Level 3
• Enable others to learn and solve hard problems to:– promote discovery, – allow for long distance collaboration– inform policy decisions, and – contribute to promising new regional research funding directions – be the bellwethers for our region
High Performance Networking
• Hard problem when you delve into it– e2e Jumbo frame support still difficult– Wiring types and closet switches – Equipment purchasing considerations for proper
buffers, frame support, and interoperability with other devices
– Tuning servers, desktops, and laptops– Application tuning– Diagnostic tool suites– NPAD servers
TCP Flows
• TCP silently adapts to the sender, network, and receiver capabilities at time of flow but hides the particular performance difficulties it works around
• The efforts associated with Web100, Net100, and NPAD projects focus on building tools that uncover (discover) protocol interactions along path
• Makes what is impacting flows explicit and suggests tuning improvements and areas to look at
TCP Protocol
• Used for both bulk data transfer and interactive data applications
• Supports transfer of over 90 percent of all traffic across the public Internet today
• Performance of TCP forms a significant part of the perceived service offered by IP networks
TCP tuning is painful debugging
• All problems limit performance– IP routing, long round trip times
– Improper MSS negotiations or path MTU discovery
– IP Packet reordering
– Packet losses, congestion, lame hardware
– TCP sender or receive buffer space
– Inefficient applications
• Any one problem can mask all the others and confound all but the best (and few) tuning gurus
• Need for better diagnostics and visibility into problems
TCP-MIB Extensions
• kernel instrumentation set for TCP variables• Ietf-draft describes extended performance statistics for TCP • designed to use TCP's ideal vantage point to diagnose performance
problems in both the network and the application• If a network based application is performing poorly, TCP can determine if
the bottleneck is in the sender, the receiver or the network itself• If the bottleneck is in the network, TCP can provide specific information
about its nature• OS vendors incorporating standards enhancements and auto-tuning into
their stacks - Linux, IBM, M$oft, Apple, Sun investigating
Problem Space Evolution
• Our work on Web100 and Net100 helped us recognize why e2e diagnosis is such a difficult problem: the symptoms of all flaws scale with path delay, and those symptoms that scale with path delay cause classical diagnostic strategies to yield misleading results:– False reassurance on short path test flows being ok– Uncertainty and lack of proper tools leads to reasonable but flawed
assumption that problem lies with wide-area path– Stymies sufficient e2e diagnosis– Promotes network diagnosis as “one off workarounds”– Unscalable time sync for network engineers & sys admins
• Network Path & Application Diagnosis (NPAD) project
Example Scaling Impacts• Chat application (e.g., 50ms RTT per user request)
– On 1ms LAN, this adds 50ms to user response time (un-perceptible)– On 100ms WAN, the same 50 transactions add 5s to user experience
» Need better application design or parallelize request-responses
• Non auto-tuned fixed TCP socket buffer space (e.g., 32kBytes)– Reliable delivery of data to the application requires sufficient buffer space to
hold one round trip of data– On a 1ms LAN, about 200Mb/s throughput can be supported– On a 100ms WAN, only about 2Mb/s throughput actually achieved
• Flaw introduces packet loss (e.g., 1% loss with 9kB MTU packets on a 1000 Mb/s network)– On a 1ms LAN, 500 Mb/s throughput calculated data rate for link– On a 100ms WAN, calculated rate drops to about 5Mb/s throughput
Alternative Way to View Behavior
• When path delay is short, TCP can quickly compensate for the flaws in the network or the application
• With longer path delays, TCP’s ability to compensate for flaws is diminished
• Flows intrinsic sensitivity to delay creates a confusing situation when trying to perform diagnosis, as TCP performance tuning is called
Observed Behavior & Symptom Scaling
• On a short path TCP can hide and compensate for the flaw
– Local Client to Server: all applications work
– Including all standard diagnostics
• Remote Client to Server: all applications fail (100ms delay)– Leading to faulty implication of other components
• Symptoms appear to scale with increasing RTT path delay– Reflective of many (most) types of flaws
– Impacts are multiplicative since the delay of the backbone path length magnifies symptoms of an existing flaw
Regional Partnerships
• Large Proposals– Maryland Life Sciences initiative
– Petascale Solicitation
– Clinical Translation Science
• Data and DR centers
Flow Analysis Data
• Topic for discussion this afternoon• An hour snapshot of data…
– People apparently do read the newsletter» Flows to npad links
– Multiple climate and atmospheric modeling flows to NCAR and Colorado State University
– Number of Planetlab servers spread across our region» GENI involvement
• Sensitive policy issues staff & TAC must deal with• What slices of your data would interest/help you?
Adaptation to changing conditions is our central challenge
Groups like the MAX need to provide us with a supportive environment to trust, risk, create value, have fun, learn, and
adapt.
“They said, ‘You have a blue guitar,
You do not play things as they are.’
The man replied, ‘Things as they are
Are changed upon the blue guitar.”
Wallace Stevens
From The Man with The Blue Guitar
Thoughts? Questions?