San Diego Supercomputer Center, June 29 & 30, 1999
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There were about 40 attendeess mainly from Research & Education sites and in particular Internet 2 sites. Most of the invitees run various Internet monitoring activities, or fund them.
Programs like NSF are all about demonstrated results, success helps future awards. Thus measurements is very important to the funding agencies. Interest comes from many quarters include: Congress has bipartisan support for NGI, there is the Presidents Information Technical Advisory Committee (PITAC), universities (constituents) expectations, network research community, there is a tension between populism and elitism (e.g. not enough money to support everybody, so fund the more successful universities), tension between putting money into infrastructure versus research.
The motivations for measurements include advancing the state of measurements themselves, and measurements as a tool for demonstrating return on investment (ROI), e.g. how much of a difference has plowing $100M into vBNS made.
For research he identified development of tools and information, problem avoidance & anticipation, identification of behaviors that norms, how to scale for growth, adaptive access.
For ROI demonstration how does it differ from the commodity Internet, what is being done, who is doing it, what is happening in endpoints, in LANs, in CANs (Campus Area Networks), in WANs across LANs, CANs, WANs.
Other issues include educating the people asking the questions, preserving anonymity, non-intrusiveness, responding to multiple constituencies, multi-provider dynamics, involvement of other disciplines (e.g. statisticians).
The review covered advanced network research, NGI testbeds, NGI applications, geographic reach, minority & small college, tech transfer ... Only the 1st 3 were in the original NGI goals.
They (PITAC) want (aka "are not satisfied with"):
What do we do, e.g.: start tabulating testing the 100 sites; set up a measurement mesh between NGI sites; build an acceptable traffic report; keep track of top speeds/apps; greater focus on the campus and end-systems. We need a response in the next 6 months, i.e. by end of year. It would doable to create, configure of the order of 20 AMPs (or ~ $1.5K each) or Surveyors (~$4.5K each, extra cost for GPS stuff) to place at NGI sites. Need to define sites, define mesh, populate the sites with machines. Still need to define the questions as to what the mesh should answer. Other things could be to include stats from OC3MONs, and also TCP analyses from Matt Mathis and provide information back to the users as to how they need to improve their apps/stacks etc. It would also be useful to show improvements in the Internet, such as PingER long term plots with additions for the NGI sites starting ASAP.
Just for background the PITAC has very few network experts and though the people on the sub-committee were smart none of them were network experts.
Need list of 100 (or more) sites with >= 100Mbps connectivity. This list could include the Point OF Contact (POC), Lat/long, test address, nets (DREN, Abilene, vBNS, ESnet etc.), speed of Internet connect, what monitoring they have (Surveyor, NIMI, AMP, Netperf ...) the short name of the site.
Shared information on a proposal from the Federal register from OMB " require Federal awarding agencies to ensure that all research results, including underlying research data, funded by the Federal Government are made available to the public through the procedures established under the Freedom of Information Act". This could give rise to problems with sanitizing data to ensure privacy (e.g. removing addresses from traces). "The amended Circular shall apply to all federally funded research, regardless of the level of funding or whether the award recipient is also using non-Federal funds". A discussion ensued: what if the unsantized data owned by someone else, e.g. MCI, XIWT but available to the federally funded research, who santize it and make their own copy. UCSD are taking up the issue at the president level, since they believe it undermines any scientific research. It is not just the measurement community, it is all research.
Goals are to support advanced applications: high bandwidth, low latency, low loss, multicast, QoS. How to answer the question "my application has a problem"; is it the end-host, the network.
I2 structure has end sites (universities) conected to gigapops which are connected to the backbone. Meaurements goals are for forward engineering, enable network research, feedback to applications (adaptive access), operational data (performance, flows, anomalies).
Measurement classifications: utilization (usually SNMP), active measurements, passive measurements, routing.
Want to know where loss occurs when it happens (or delay). Also want advanced services debugging for multicast, QoS (QBone designing measurement in), service level specification conformance.
Need consistent measurement of utilization, performance, traffic characterization that are made generally available in support of applications and the network themselves.
Large Scale Networking (LSN) JET is a coordination body for 6 major JET networks including Abilene, DREN, ESnet, NISN (NASA Integrated Services Network), NREN (NASA Research & Education Network), vBNS. This is tied to the NGI goal 2.1 for 100 sites at 100x speed (basically 100 Mbps). Goal 2.2 is to connect 10 sites at 1000x (i.e. Gbps).
Focus was on NGI inter-exchanges. West coast was NASA-Ames, midddle was STAR-Tap, E. Coast to be be College Park Md. There are 11 exchange points today.
NGI needs from performance & measurements. Need to tabulate the 100 sites, how does one choose the 100. NSF has connected 150, other agencies have connected sites. Need to test and verify sites exist. Then set up a measurement mesh between the sites. Want to verify that sites do have > 100 Mbps. PITAC requested an Internet traffic report for the layman even though most research folks feel it is bogus, so we need to come up with the same ease of use and understanding and yet is not bogus. Also want to better track top speeds/applications and a greater focus on the campus and end systems.
Important messages: window size is very important (e.g. default of coast to coast with typical default window size of 8KBytes only allows < 2 Mbps, 64KB window gives 11 Mbps coast to coast); latency matters (routes, may need to have better ways to choose a route with low latency vers); loss rate matters; MTU matters (need to use MTU discovery, need a path from every host to DMZ that does not reduce MTU to 1500 Bytes, i.e. preserve the MTU); disable slow interfaces; campus infrastructure matters
Software has to deal with more than 4 orders of magnitude of bandwidth (i.e. from 56 kbps thru Gbps). Most traffic on Internet is TCP and most of TCP is HTTP, and typical HTTP "session" is about 12 packets, which does not allow TCP to get through start-up.
Packet filtering problem increasing unpingable 20 Jul 98 28 Jun 99 10.3% to 14.7%, trace 4.6% to 12.1%. Ideas UDP ping, authenticated traces. People/crackers tunneling IP applications thru ICMP.
Define a campus DMZ measurement machine for making RTT and throughput measurements to. Also need a test suite, create an NGI traffic/status report. Concerning burstiness are 5 minute samples good enough. Would be nice to have a no-brainer that tells you what your network performance is like (e.g. like security scanner but for performance), relationship between utilization and packet loss (RED increases link utilization, but also increases packet loss, does individual flow performance go down); is there a wave phenomena in the Internet (i.e. periodicity in frequency space, analogous to reflections in an audio network).
Other issues/discussion topics:
site-to-site vs. end-to-end performance
They monitor the SNMP MIBS in switches, routers etc. The Cisco routers were found to be reporting incorrect counter values which means the data is only correct from the Fore switches. The RTT are now surpased by the NLANR AMP results. For performance tests firstname.lastname@example.org uses ttcp, mping and treno between Sun Ultras at all terminals and Dec alphas at SCCs (Super Computer Centers). The commercial internet is dominated by Web traffic, games also shows up in the top 3 protocols followed by NNTP. vBNS shows HTTP and FTP about equal. Port 514 shows up and is heavily used by USGS & NCAR for large data transfers of geographic data. vBNS is more bursty, fewer aggregated flows, much larger flows, larger packet sizes, higher percentage of UDP flows. They make a lot of data to the research community. All SNMP data is available, the normal flows data is available, packet & cell traces may be made available (but concern over sensitivity may require node identification filtering).
Relationships with NLANR (NCNE, DAST, MOAT), CAIDA.
They are looking at how to support QoS. Can't run WRED (Weighted Random Early Drop - Cisco code release problem). Looking at a proof of concept of putting in an OCxMON box in-line to intercept all packets, check the precedence and remap the traffic to VCs.
10 Cisco 12008 GSRs, OC48 coast to coast, OC12 links too, POS, Access OC12, OC3. Can't use OC12MON yet, an OC12POS coming, there is no netflow, OC48 counters never worked right, now fixed; there is lots & lots of data.Now getting utilization routing & external performance. They have NEMO (network monitor), Abilene weather map, RPG (router proxy gateway). They also use "what's up" and MRTG. NEMO monitors all the interfaces on all routers every 3 seconds. The data is stored in binary form and they are working on a standard export summary format. The weather map shows traffic between the Abilene backbone nodes, with colored arrows, can click link to come up with MRTG plot, if click on points then get all router links available. The plot is for data aggregated over 5 minutes. Also has animated replay. See http://www.abilene.iu.edu/
The router proxy gateway (RPG) allows you to execute Cisco commands, it checks the command to ensure it is OK, it rate limits, provides access to a limited number of Cisco commands (e.g. show IP *, show interface *,) limits output to 300 lines. See http://hydra.uits.iu.edu/~abilene/proxy/ for more information or contact Steve Wallace at email@example.com.Surveyor
This reported on Surveyor measurements. Internet complex, even providers don't understand how it works in great detail, applications are getting more demanding. Surveyor uses the IETF/IPPM framework in particular one way loss & delay.
Minimum of delay gives transmission/propoagation delay, variability gives queuing. They use measorements for problem determination, engineering (trends, lofas), monitor QoS, network research, feedback to advanced applications etc. They have a centralized database to store data, and web based reporting tools. Will move from BSDI to FreeBSD.
They are making active one way delay and loss, test packets are time-stamped with GPS time, back to back calibration: 95% of measurements +1 100us => 10 us soon. Measurements centrall managed. They also make concurrent routing measurements. Thye are QoS ready (via EF DS byte). Poisson scheduled, average rate of 2 / second. Use a random port number per session (sessions stops if lose GPS lock, or software problem or hardware problems) to stop routers treating them specially.
Modified traceroutes randomly scheduled every 10 minutes.
They use a flat file database (used to be Oracle), collect via ssh. Now have 55 machines with 1883 paths at Universities, tele-immersion Labs, National Labs, APAN, NZ, Canada.
They have daily summary reports, integration with route measurements, Java applet to dynamically graph almost ready, developing aynchronous notification of problems. Have added an indication of when routes were measured, have an animated display of the last month data day by day.
Observe that routing is asymmetric, even if symmetric queuing may be assymmetric, can detect level 2 changes (SONET failover or ATM routing). Have observed low delay with bad loss, high delay without loss. HPC connections provide low-latency low-loss.
Failover to commodity Internet shows how bad it can get. As universities obtain I2 connections measure fewer commodity paths.
Want to look more at correlation of the measurements and applications. They are concerned about the N**2 problem of full mesh measurements.
AMP is a commodity PC based on FreeBSD is used to actively monitor at all or most HPC sites, hope to deploy at every single campus, have 65 monitors so far. Site-to-site measurements between NSF funded HPC sites: to complement pop-to-pop measurements taken by HPNSPs. There is no GPS requirement which makes things simpler. The consistent machine at each sites simplifies things by removing unknowns specific to a particular machine. Measure RTT, loss, topology and throughput between about 65 sites with a full-mesh. NLANR provided hardware and administration. Monitor a few extra machines which are not monitors (e.g. OCxMONs). Have two analysis machines which each store the data for redundancy. Are willing to ship raw data to people who ask for. They sample once/minute. The throughput measurements (see http://moat.nlanr.net/QActmon/) are not made regularly rather on demand via a Web page. One can choose the mechanism (e.g. treno). They can schedule throughput tests on demand from users. Traceroutes are done every 10 minutes. They do nothing with BGP at the moment, they are interested in cross-correlation between BGP & traceroute. Have not done much work between ping loss, RTT and throughput. Tony thinks there will not be a strong correlation in general since there are so many things going on, it may depend on the observation period.
They are working on event detection: using process charts (a simple statistical method used in process management where one takes a window and report the percentiles in the window, then report when have n samples in a row outside the percentile) & heuristics; localization: path decomposition and IPMP (a measurement friendly protocol that is lightweight, can be implemented in the routers (but does not have to be, but if it is, it is as easy to implement in the router as just forwarding a packet so it is a good indicator of router performance, and does not cost extra so ISPs will not limit), and at end nodes). See http://moat.nlanr.net/AMP/IPMP/ for more details on IPMP.
They have surveyors at MC, CA, AK & HI. They see steps in performance due to load balancing on routes. They were looking at reachability to 300 HPCMP PIs with locations from business email addresses & Lat Long from phone number. Approximately 200 of 300 on DREN & 20 of the 100 were on vBNS. Phil has a map of where N. American exchange numbers are located. He pointed out the needs for IP address to ASN mapping (in Europe RIPE will revamp and concentrate on ASN origin authentication and it may be enforced), IP address to Lat/Long & country (RIPE database will give the country by prefix and by AS), ASN to name mapping (RIPE has a database which provides this), connect to a web site to tell you about your system, portable surveyors for use on campus to measure to the DMZ at times (the RIPE machine could be made portable, but has to be up for a couple of hours in order to get better than millisecond accuracy), a test machine at every campus DMZ
This is important for future funding of NGI programs. Their goal for the testbeds is to provide necessary bandwidth, low latency, QoS & security. They are having a problem learning how well the NGI testbeds are operating, they want a systematic measurement of bandwidth latency etc. to desktop. Would be helpful if agencies report daily averages and peak-minute measurements of these metrics for many links (e.g. http://www.internettraffic report.com/). In 1999 review max performance was ~ 10MBytes/sec for IP and 0.6MBps for TCP these are disappointing. They hope for substantial progress.
Hurst parameter is not an accurate indicator of queuing performance. They are looking at bps throughput for TCP, then used tcptrace from Shawn Osterman. An example of the reports is to show all flows with over 1Mbps for port 80 (FTP) and 80 (http). At UCLA they have a netperf client that can access netperf.ucla.edu to run a netperf to the client machine. Performance problems are usually caused by the on and off ramps to the backbones or by the clients.
They have built some bidirectional measurement hardware that is deployed at many sites. DAG is the generic name for a series of boards that they have built. They use an FPGA to get the time from pps and an ARM processor that can provide the GPS to the PC. The physical interfaces working are 25Mbps, E3, DS3, OC3, OC12, OC48 (2 mos), thinking about OC192. For the higher speeds there are difficulties in how to capture the information. They also support POS (Packet Over Sonet)and 10/100 Ethernet. They are looking at Gbps Ethernet. The FPGA now have up to 1M gate equivalents running at 100MHz with a downloaded image from the PC. They support Linux & FreeBSD drivers and they also support CORAL.
The GPS is accurate to +- 0.25us to UTC (1 sec pulses corrected for drift offline (oscillators drift by a few parts per million), will do online soon). They are looking at temperature compensated oscillators.
They have recorded many ATM traces and can do full cell capture of ATM (at OC12) but usually run out of diskspace so tend to get timestamp and CRC header for ATM, for IP get the timestamp, CRC and header for 56 bytes which gets most of the header.
For measurements they are looking at traffic statistics, can measure switch delays down to SONET frame jitter. Current sites are: Aukland, NZIX, vBNS/NLANR, U of Calgary, Monash. They do not run continuously, run for a five minutes twice a day (this is long enough for many flows).
What can go wrong: the OS has bugs which are version dependent, single/multi user etc. So need to validate the measurements, run dual configurations to check setup. The hardware solution removes the OS, so is likely to be more accurate. The more expensive hardware system can be used to calibrate other more lightweight systems.
VoIP measurements between US and NZ shows minimum delay of about 90 msec with good consistency to the US (e.g. < 120 msec. max). US to NZ much more varied 120 msec to 350 msec. Also show little difference in VoIP to non VoIp traffic. They are looking at how to gather long term trends for VoIP by detecting H.323 and other protocols (nb UDP uses non fixed ports). For TCP they want to extract individual sessions, estimate latency, queuing delays, server delays etc.
They would like to make the data available, but where to store it (NZ pays for transit of data across Pacific). They are working on validation and careful recording of OS etc., they are also concerned about security and hiding IP addresses.
More validation of traces is a big issue, need to ensure timestamps are in order, check that merged bidirectional data is properly merged.
For statistics they are using wavelet transforms in collaboration with a group in Melbourne, mixture of exponentials (can heavy tails look like self similarity), non parametric weighted models.
There will be a PAM (Performance Analysis and Measurements) - 2000 NZ conference at Waikato, April 3-4 just after the IETF in Adelaide Australia.
They have a Perl and C interface to their program libraries so can write initially in Perl then port to C later. They have tcpdump support so can read tcpdump files (instead of getting from OCxMON) into their tools (so can use instead of lib/pcap) and they support ATM (which lib/pcap) does not. They provide analysis examples, e.g. how to count bytes for protocols. They have continuous data collection for operational situations with a lot of examples for generating reports. They are working on security modules to filter things (e.g. start doing full trace when see some activity such as a portmapper request). Cleaning up the drivers so better integrated.
End-to-end active user level test for EOS & CEOS. Need to know if network meeting requirements, redolve problems. plan, determine bottlenecks.
Test process runs script hourly runs traceroute (# hops & from changes get congestion analysis), throughput (runs for 30 secs to keep socket buffer full) and pings (100). They have a lot of collaboration sites on vBNS so interested in it. Showed plots of min/max/median throughput. Compared vBNSwith SprintLink. Show correlation of Loss RTT & thruput and they track when plotted hourly for several days.
After the talk I got together with Andy to look in detail at some of his data to see how it might be used to indicate the correlation between thruput, loss and RTT, and a formula for TCP bandwidth (BW < 1460/(RTT*sqrt(loss))). The agreement looks encouraging for data between GSFC and LANL.
There is a new link to STAR-Tap from APAN (AU, JP, KR, SG, US) and they are making measurements on this. The DOE has NGI applications with combustion, global climtae modeling, particle physics, teleimmersion, Xray crystallography, they are identtifying the application characteristics and instrument the network accordingly. A 3rd interest is Globus which needs middleware to enable advanced distributed computing, they use Netperf to make measurements.
Issues: OS + TCP/IP stack (FreeBSD, Linux, Solaris), NICs, tools (b/cprobe, bing, netperf, mping, tcpdump, ttcp), traffic generators (burst, CBR), traffic capture and playback, multicast, jitter, persistence (i.e. it needs to continue working without intervention).
Interchange for many international networks, the NGIX and several universities and research sites (e.g. FNAL). Will install an OC3MON, Surveyor and an AMP at STAR-TAP. Looking at having a second AMP mesh for International sites and then link at the STAR-TAP to the US mesh. Would like to see more Surveyors supported outside the US. Prefer third party measurements rather than self measurements.
Active one way delay, loss, routes, follow relevant RFCs, IPPM, similar to Surveyor, independent platform and inter-ISP traffic. Run FreeBSD, have GPS, get time to few us. Have 43 test boxes, 37 in Europe, 5 in US, 1 in Israel. 33 taking data. Get daily plots, access to data base with routing vectors. Working on delay & loss alarms, weather map. Routing vectors show paths from one host to another user can query, changes in routing can explian changes in delays. Working on delay & loss. Look at distributions to see multiple peaks. Constantly calculate percentiles and compare with previous values looking for a significant difference, then send alarm to sites running boxes. Concerned about false alarms, maybe let site set own thresholds.
They are also looking at long term trends. They will parametrize losses/delays following relevant RFCs. They will plot over time, look for effects, intended as a tool for planning start work in August.
They want to create a quality of the network page summary on 1 page, both short & long term, explain what is in table, be scientically defendable, define some acceptable use plocy, define metrics are needed. Need to discuss what people want to see in a report such as this.
Further analysis projects: delay vs packet sizes, bandwidth vs. throughput, more detailed study of packet losses, relation between delays and routing changes, N**2 problem & modeling paths maybe dynamically reduce the number of paths with as few assumptions on the network as possible.
Will continue to expand with more machines, sites will have to pay for boxes ($2.5K/box), want to improve the clocks, use for external networks only (basic support for "private" experiments), watch RIPE email list firstname.lastname@example.org for details (majordomo list).
Software system to facilitate widespread deployment of measurement platforms. To be scalable (> 1000 nodes) should be no problem. Dynamic so it can run any active measurement tool. Secure, encrypts messages (data & configuration), Self configuring, the nimid downloads configured information from a configuration POC. Support a wide range of policies, each nimid has its own ACL table.
They have 15 sites running for a long time (includes SLAC, CERN, FNAL, LBNL, NASA, PSC ...). Current measurements, traceroute, treno, mtrace and zing (one way measurements without a GPS clock). Platforms are NetBSD & FreeBSD, Linux is on the way.
To do they want to use public key serving, GPS hooks, else absolute time, tool uploading (beta) automatically when the tool is updated. Multicast for measurement coordination and disemminnating results.
I talked to Andrew afterwards, he said he is hoping in the next couple of months to provide some reports on the analysis of the data they have gathered so far. One of the collaborators on this project (Jamshid Mahdavi) has left PSC to join Novell. The main person still working on NIMI is Andrew with guidance from Vern Paxson.
This meeting was held on the third day (Thursday July 1, 1999) and was a smaller meeting (about 20 attendees). The attendance was not a subset of the previous 2 days, in particular there were new attendees for the 3rd day including luminaries such as Guy Almes, Matt Mathis, and Craig Labovitz. The objectives were to identify strategies & opportunities deriving from high performance environments. This includes new applications, new technologies & protocols. There was some overlap, but also a lot of new (typically more technical) information introduced.
NSF needs to report on results from the investment in NGI. The NGI implementation plan has 3 goals, research, testbeds and applications. Bill feels the network enables the NGI goals, and wants to cite the results from network measurement activities. The testbed goals has 2 sub-goals: 100 sites at 100 times speed, 10 at 1000 times speed. The first goal (2.1) is more in the NSF area (the latter is more DARPA). The 3rd goal (applications enabled by the network) requires input more from the applications folks than the network measurement folks. So wants to cite network measurement activities. One important thing is to be able to cite how scientists get better performance as a result of the measurements and research, e.g. the tuning etc. on protocols that improves performance to the desktop.
Since the agencies have to do this evaluation and reporting Bill wants to see: plans for use of results both near (next year) and long term. These should report on testbeds and how they are behaving and what results the people are getting. Longer term create a more sustainable measurement activity, and address things which cannot get into the short term. Secondly Bill wants to see something a bit less self serving to funding agencies, i.e. what should be the nature of the funding agencies to support activities in this area, what kind of dollar levels, how to tie to other activities.
A recent workshop on NGI suggested removing the testbeds as a goal since they enable the other things, i.e. testbeds are not a goal in themselves but rather are part of supporting an application.
One question raised was if the community goes to an NSP and sets up an SLA to provide the needs, then can use the commodity Internet and the R&E networks are no longer specialized out. However, this requires a a whole suite of meaurements and architecture etc. to support both to write the SLA and to check for conformance. However the problem is typically not with the individual NSPs but rather with interconnecting the clouds run by each NSP, and this is much easier to do with a limited community of the R&E community than for commercial Internet due to the competition between the cloud owners.
There is a close feedback loop between engineering and applications, applications motivate engineering and engineering enables applications. What makes it hard is the need for high bandwidth, low latency, wide area, bursty apps, multicast, QoS and need for meaurements, the introduction of new apps and new users, the exponential growth etc.
I2 has 150+ campus LANs about 35 GPops, OC-48 from QWEST, Cisco GSRs, connects at OC12 and OC3. Connections on order or in progress will double the number of connections. Most of current 14 Abilene backbone connections are multi-homed to vBNS & Abilene and currently prefer vBNS. Exchange points are NASA Ames, Chicago. Traffic on Abilene now is low and performance is good. In 3 or 4 months almost all GPops will have Abilene connections.
Current loads understate the need, there is a lot of pent up need, new paradigms will increase the load in unanticipated ways. Part of the problem is that all bugs in the infrastructure (BER, ATM switch problems, mis-tuning, poor stacks, router bugs) result in less than expected performance. Any one cause is easy to fix but hard to know where the problems are. The folklore that vBNS uses is less than expected implies that users don't need the bandwidth. This is not true, since the users need bandwidth but can't get it since they can't easily identify the problems that are causing the poor performance and by-pass these problems.
Javad Boroumand has a nice map of the interconnects between JET nets. Need to enumerate sites that have 100 Mbps connections then verify that can get that performance. Need large MTUs (> 1500 bytes Ethernet limit). With 64KB window size can only get 11Mbps coast to coast. They have concerns about the denial of ICMP and its impact. May need test machines identified at each site.
One suggestion from Matthis was that priming of caches etc. may require > 1 initial ping (in case the ping is lost). Another remark is that simply turning on ICMP limiting effects the code path in the routers and so affects the performance. Would be nice to get some measurements of the commodity Internet performance compared to that of the R&E networks.
They see the challenges as: making data more available; formulating questions that can realistically be answered, getting better answers and results; improving and tighter integration of analysis and visualization tools (e.g. fly though of parts of he Internet such as vBNS map with packets flowing etc.); aggregation of various data sets for comparisons; how do we make the most of the existing data (make available, provide reports).
Thinking of sending a short shockwave from say AMP machines into the network to see the effect on routers etc.
Other things that might be done with AMP. They want to deploy AMP machines back into the campuses; looking at portable AMP; regular thruput tests and if so how many (beware of network impact); triggered throughput meaurements or some other more detailed measure following the occurence of an event (but may make problem worse); reservations about the effort required to progress IPMP (need a serious expectation that it is worth proceeding with and that it would be adopted before putting the effort in).
On validation front is AMP OK, is it producing valid numbers, how precise is it, is kernel level timestamping necessary and how much does one care; is round trip enough, does one also need one way measurements or do the routes in the 2 directions identify things well enough.
One interest is how does recovery work from high load. It may be like a potential barrier (i.e with hysteresis). How do things work at high frequency, e.g. rapid onset of problems and slow recovery, how does one characterize this. Integration of active and passive data (e.g. traceroute with BGP).
Can "sniff" flows at source, destination or somewhere in the middle. If measure passively, at any one of 3 tap points, the loss, window & RTT then can check whether it is application or network limited. Knowing this can decide where to tackle the problem. Can also tell whether it is upstream or downstream limited. If look at destination or in middle then can see receiver mistune, whether it is a cpu or application bottelneck.
Percent duplicate data at receiver indicates how well TCP is coping, it rises monotonically towards the sender, differential rise is quality of any hop. Can even tell which of two ISPs is causing problem.
The measurement infrastructure required is sniffers at the right places. One problem might be privacy issues of passively monitoring data. Matt want to develop his tools to work with tcpdump, OC3MONs.
Another thought is to develop a TCP MIB that can be interrogated. One problem is what happens if the sender runs out of cpu capacity.
Traffic measurements at North Carolina State University. They have been measuring the NC-REN at various points. T
he major results were that the traffic is bursty & non-Poisson. In the late 80s they did some modeling with a Markov modulated Poisson process. Later modeled results from VISTANET with a session level on/off model, packet train models. They also measured NCIH looking at transfer of medical images. Major findings were that the data was extremely bursty, but well behaved (did not hurt network) for most of the tiem. There were some bursts of ATM cell losses associated with a time constant (time for source to dramatically alter behavior, e.g. rate of generation of cells) of 20 to 50 msec. They were using UDP.
Recent work deals with how where & when to make measurement, characterizarion (long-range dependency, stationary versus non-stationary), etc. The stochastic processes have been assumed to be stationary, but are they? They looked at the Bellcore data sets looking for tests for stationarity (Dickey-Fuller, Covarience stationarity), and the result was that there is a high confidence that it is non stationary. They have characterized mathematically the non stationary behavior. They get good agreement with number of arrivals in a time interval. The variability is captured in a precise manner, can use for synthetic generation. They have ongoing measurement activities with OCxMONs. He has good access to statisticians.
We could provide access to our data. They could come up with how to do statistical experiments to optimize results. He has no foot in the religious wars of whether the data is self-similar/multi fractal versus other theories. They are using home grown tools, SPlus and SAS. He will provide a pointer to more information for the proceedings.
Challenges: as the internet grows how does the core scale, how do core routing protocols work as Internet grows, what are the limitations on growth, how far can BGP go in terms of convergence, impact of new policy changes (e.g. moving from hot potato routing), what are the limitations, how does one deal with debugging, how do we provide the highly available, fault tolerant Internet service, what is the impact of dampening, policy filtering authentication.
Multi-homing does not provide near instantaneous fail-over, withdrawals travel slower than announcements, time for failure increases exponentially with the size of the mesh. They have been doing measurements. Injecting faults (into BGP) to see effect.
Growth of topological state, CIDR solves prefix entries (slowly growing) but not the growth in routes. This growth affects convergence. Cumulative frequency of failure versus number of days shows that within 30 days have lost 80% of the routes. The source of failures from a published case study (start at http://www.merit.edu/ipma/) is mainly (16%) due to maintenance (can't do an upgrade without killing peering sessions), power outages (16%), fiber cuts/circuit/carrier problem (15%), unknown 12%, hardware fail 9% ... Given a failure most (50%) are repaired in 30 minutes. The distribution is heavy tailed. Distance vector algorithms (BGP) require multiple passes for convergence, majority changes converge in 5 mins, some take much longer. Withdraws and route-fail over may induce iterations of BGP procesing during convergence. The rate of convergence grows exponentially with meshiness of network. Convergence for 50% of routes after injecting a fault takes about 100 secs and 5% take 3 minutes or more. Convergence of announcements is 90% done in 50 secs, while withdraws is about 120 secs. During convergence one gets packet loss.
Challenge is how to provide highly available Internet services. How does one do maintenance, e.g. hot swappable components, protocol aware swapping etc. Can we reduce the meshiness, e.g. reduce redundant links to help convergence, reduce peering, could providers make their nets less meshy.
See http://www.merit.edu/ipma/ They would like to deploy their tools (IRR & Route Tracker) on the commodity Internet, CAIRN, I2 ...
They are concerned with monitoring at the higher speeds, e.g. OC48MON, OC192MON etc.
If people have comments or position statements relevant to the working group then they should be sent in by email by Wednesday 7th July in order to appear in the proceedings.
Matt Zekauskas demonstrated the new Surveyor long term reports, see http://bsdi7.advanced.org/IPPMApplet/report/Report.html. It uses Jchart (see http://www.klgroup.com/ ). It supports zoom & pan, selection of time window to display, what metrics to show (min, 50%, 90%), scale factors etc.
Gtrace is a new Java tool being developed by email@example.com to provide a visual traceroute that displays on a map and also provides extra information on the nodes passed through. It does a 5 step search to find the location of each node looking in the DNS record, CAIDA databases and NDG, analyzing the name for .net nodes to uncover a city or airport code (he has configuration files for 12 nets now showing how the location information may be available) and then looking these up. In addition to the map output it provides tabular information telling how authoritative the location information is likely to be, the loss on the 3 traceroutes, the RTT. You can click on the node for whois information. He will add the route distance. It is written in Java using the swing graphic utilities. It will be released in October 1999.
A second tool demonstrated by firstname.lastname@example.org is called Geoplot and enables one to develop and display web maps displaying nodes with links between the nodes, apply color and thickness to the links, and make the links and nodes clickable. The nodes and links are described by a simple file which is accessed from an html file that provides the static configuration information. The idea is that the simple file would be constantly updated from a perl script, and he is also going to provide a Perl API to create the simple file. Apart from the Perl API this should be available by the 3rd week in July.
I met with Tony McGregor. He is very interested in us correlating the AMP data with PingER and Ping. He will make the AMP data available to us. To get started we can start pinging between several mutually monitored site-pairs (e.g. representative sites of interest to us such as FNAL, UMD, CMU, ColoState, Waikato ...) for a period. AMP makes measurements 1/minute and does not advertize the names of the sites, so he will provide the IP addresses. I will need to decide on the ping interval. The AMP can also, on demand, make thruput measurements, so we can make some checks on how and when thruput correlates with loss & RTT.
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