Time & date
Next meeting: Tuesday December 11th at 8 pm Pacific time; Wednesday December 12th, 2018 9:00 am Pakistan time; 9:30 am India time; 12:00 noon Malaysian & Guangzhou time; and 11 am Thailand time; 6:
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00 am Jordan time (I think)
Time and Date Converter: https://www.timeanddate.com/worldclock/converter.html
Format
New items and updates are in boldface.
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- Membership of pinger-my is in https://groups.google.com.
- Bebo pointed out that the International Web Conference will be in San Francisco in 2019 (see http://www.wikicfp.com/cfp/servlet/event.showcfp?eventid=77195©ownerid=85335). There are a whole range of topics. He would love to see something submitted related to PingER.
- Maybe something on Android PingER and potential uses.
- This meeting was scheduled with the aid of a Doodle poll.
- It will be via Zoom. Meeting URL: https://stanford.zoom.us/j/185360638
Use of Zoom
Include Page PingER Meeting use of Zoom PingER Meeting use of Zoom
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| Host | State | last seen | Status |
|---|---|---|---|
| pinger.gzhu.edu.cn | Is not working | 10/20/2018 | |
| pingersonar-um.myren.net.my | No response | 6/26/2018 | |
| pinger.isra.edu.pk | Down, it came up Sep 2-4, 2018. It is pinging, however, all the targets are not responding after 31 tries, email sent to Wajahat 9/18/2018. As of 10/14/2018 it is not pingable. | March 6, 2018 | |
| pingeramity.in | It has been working since 28th July. It is unclear how stable it is. It is down again 9/5/2018. Worked again from 9/24/2018 to 9/28/2018. Emailed Amity requesting clarification 10/3/2018. They are looking at it. | April 27, 2018 |
Context:
- Is there any statistical difference between ICMP and TCP Ping? The context here is the Internet (not data center). This is important because the network stack is different (e.g., MPI over infiniband) and latencies are significantly less.
Questions:
- Why should we focus on minimum RTT instead of average RTT
- Min RTT essentially reflects fixed delay, while average RTT subsumes variations and path load
- Link to raw results with minRTT results:
- Are the R plots generated using minRTT?
- Averages and computed. Min RTT is available. Scripts need to be updated to use minRTT.
- What is the breakdown of latency between endpoints? If there is a difference, is it because of the type or location of the source? What if the source of traffic was not SLAC? Is there a correlation with the distance between the endpoints?
- Latency for an echo packet to travel up the stack and back down is about 3.75 micro seconds (see StackMap https://www.usenix.org/conference/atc16/technical-sessions/presentation/yasukata). As expected, this is negligible when considered with milli second latencies.The remaining components would be propagation and queuing delay. As we can not breakdown the two in a public network without using an active look like
- To replicate use system tap. See: https://unix.stackexchange.com/questions/419449/how-can-i-determine-if-a-latency-is-due-to-a-driver-or-the-scheduler
- pathchirp etc, we'll continue to consider these as a single component.
- Latency for an echo packet to travel up the stack and back down is about 3.75 micro seconds (see StackMap https://www.usenix.org/conference/atc16/technical-sessions/presentation/yasukata). As expected, this is negligible when considered with milli second latencies.The remaining components would be propagation and queuing delay. As we can not breakdown the two in a public network without using an active look like
- Are the differences limited to a particular region? How do we determine/understand if traffic prioritization is implemented?Test in a controlled environment to avoid variables such as traffic prioritization, queuing delay due to cross traffic. Review the time series of latencies for both ICMP and TCP ping, instead of averages?Is there a difference between IPv4 measurements vs. IPv6.
- It may be that end hosts which are farther away have larger variances and thus the pronounced differences.
- .
Next Meeting
Next meeting: There will be a Doodle poll. January week of of 14-18, 8 pm Pacific time (Nb now on winter time); a day later 9:00 am Pakistan time; 9:30 am India time; 12:00 noon Malaysian & Guangzhou time; 11 am Thailand time; 6:00am Jordan time (I think). If Shadi and Co. can attend we will move the time forward by 2 hours to accomodate the time in Jordan.
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