[Bloat] Servers, time

[Hal Murray <halmurray+bufferbloat@sonic.net>]

[I work on NTP software so I'm interested in network delays.]

> I've been holding off on iperf 2 public servers until I found an additional
> value add and a way to pay for them.

AT&T ran fiber down my street.  I can get a gigabit link, symmetric, no data 
caps, for $80/month.  I'll be happy to setup a server if that will help.  I'm 
in Silicon Valley.

>                                                                     Much of the iperf 2 work has been
> around one way delay (OWD) or latency. Doing this well requires GPS clock
> sync on both the data center servers and the end host devices

How accurate do you need the time?

> I checked into this a few years ago and found that this level of clock sync
> wasn't available via rented servers (e.g. linode or Hurricane Electric) so I
> put on hold any further investigation of public servers for iperf 2 as being
> redundant with iperf 3. Those that need true e2e latency (vs RTTs) have to
> build their own so-to-speak. 

I can see 2 approaches.

One is to find good local NTP servers.

HE has NTP servers.
  https://www.he.net/adm/ntp.html

NIST has servers in Gaithersburg MD and Boulder and Fort Colins in Colorado.
  https://tf.nist.gov/tf-cgi/servers.cgi

Google and Cloudflare have good servers and they probably have good 
connectivity.
  https://developers.google.com/time
  https://www.cloudflare.com/time/

In Germany, PTB has good servers:
  https://www.ptb.de/cms/en/ptb/fachabteilungen/abtq/gruppe-q4/ref-q42/time-syn
chronization-of-computers-using-the-network-time-protocol-ntp.html

.....

The other approach would be to do your own NTP like time sync with the server 
before and after a test run.  This assumes you can find a quiet time to get a 
good measurement.  NTP assumes that the routing delays are symmetric.  Unless 
something wild is going on, that's a reasonable assumption.  Less so on longer 
paths.

I'll be glad to help set something up and/or run some tests.


-- 
These are my opinions.  I hate spam.