Dear all,
A wise question arises about "why not use NTP directly if can find one at four
hops maximum?” I was answered (off-mic) that in Latin-America (and other places
like Africa as an example), the network is not so good. I provide here a case
in Argentina, trying to reach an NTP server from 4 different points at the
Buenos Aires city.
As you will appreciate, the distances of each trace are entirely different
times; also and take a special look at the STD, average and maximum: you will
see huge variations. I also repeated the experiment with fewer samples, and
again the numbers are entirely different (i.e., the traffic introduces a lot of
noise).
When we developed SIC the objective was to compute one-way-measurements en any
place of the Internet; and as these measurements are related with the dynamics
of the latency, frequency synchronization is enough when MTIE is 20 microsecond
by a minute.
The delays are here:
host1$ mtr -r -c 100 time.afip.gov.ar
Start: Tue Mar 27 19:03:51 2018
HOST: raspbian-server Loss% Snt Last Avg Best Wrst StDev
1.|-- gw-vlan-srv.innova-red.ne 0.0% 100 2.2 2.8 2.1 37.7 4.9
2.|-- rnoc5.BUENOS-AIRES.innova 0.0% 100 2.3 3.8 2.1 55.8 7.9
3.|-- 10.5.10.2 0.0% 100 2.5 2.6 2.2 3.1 0.0
4.|-- 200.0.17.104 0.0% 100 3.1 3.1 2.4 13.7 1.1
5.|-- 172.18.2.53 0.0% 100 4.8 5.7 3.8 12.4 1.7
6.|-- time.afip.gob.ar 0.0% 100 5.2 5.2 3.8 12.0 1.3
host2$ mtr -r -c 100 time.afip.gov.ar
Start: Tue Mar 27 19:03:47 2018
HOST: ws-david Loss% Snt Last Avg Best Wrst StDev
1.|-- 10.10.96.1 0.0% 100 0.3 0.2 0.2 0.3 0.0
2.|-- 200.16.116.171 0.0% 100 1.0 5.9 0.6 158.4 22.9
3.|-- static.33.229.104.190.cps 1.0% 100 1.6 2.5 1.5 80.6 8.0
4.|-- static.129.192.104.190.cp 0.0% 100 2.1 1.9 1.8 3.0 0.1
5.|-- 200.0.17.104 1.0% 100 2.0 2.2 1.8 9.4 0.7
6.|-- 172.18.2.53 0.0% 100 3.2 4.2 3.1 12.0 1.5
7.|-- auth.afip.gob.ar 0.0% 100 4.2 4.5 3.3 9.8 1.2
host3$ mtr -r -c 100 time.afip.gov.ar
Start: 2018-03-27T19:03:51-0300
HOST: aleph.local Loss% Snt Last Avg Best Wrst StDev
1.|-- 10.17.71.254 0.0% 100 4.7 30.3 3.5 280.4 52.4
2.|-- 10.255.254.250 0.0% 100 2.5 31.1 1.8 285.4 59.2
3.|-- 209.13.133.10 0.0% 100 30.5 43.9 2.3 237.2 64.9
4.|-- host169.advance.com.ar 3.0% 100 36.0 64.8 3.1 404.4 86.9
5.|-- 200.32.33.33 2.0% 100 106.9 70.6 2.8 315.0 80.4
6.|-- 200.32.34.66 5.0% 100 93.1 56.8 2.7 336.1 74.5
7.|-- 200.32.33.38 7.0% 100 42.8 58.0 2.9 357.8 76.7
8.|-- 209.13.139.211 4.0% 100 46.2 56.7 2.8 298.8 69.9
9.|-- 209.13.139.209 1.0% 100 84.5 57.1 2.6 277.7 72.3
10.|-- 209.13.166.211 1.0% 100 43.4 63.5 3.2 390.6 78.7
11.|-- 200.32.34.137 2.0% 100 68.7 64.1 3.7 259.5 75.5
12.|-- 200.32.33.37 0.0% 100 4.1 56.9 3.3 249.6 64.3
13.|-- 200.32.34.121 3.0% 100 10.9 65.0 4.1 415.7 85.1
14.|-- 200.32.33.241 2.0% 100 252.6 61.8 3.8 355.9 74.5
15.|-- 200.16.206.198 3.0% 100 188.0 54.6 3.1 461.7 74.9
16.|-- 172.18.2.53 2.0% 100 133.4 53.1 4.3 402.1 69.2
17.|-- time.afip.gob.ar 4.0% 100 72.5 54.1 4.9 343.2 66.9
host4$ mtr -r -c 100 time.afip.gov.ar
Start: 2018-03-27T19:03:51-0300
HOST: cnet Loss% Snt Last Avg Best Wrst StDev
1.|-- 157.92.58.1 0.0% 100 6.6 2.8 0.3 12.8 2.5
2.|-- ??? 100.0 100 0.0 0.0 0.0 0.0 0.0
3.|-- ??? 100.0 100 0.0 0.0 0.0 0.0 0.0
4.|-- host98.131-100-186.static 0.0% 100 5.7 5.6 1.5 9.4 2.2
5.|-- host130.131-100-186.stati 0.0% 100 6.5 6.3 2.5 10.3 2.2
6.|-- 200.0.17.104 0.0% 100 2.4 2.7 2.3 15.6 1.4
7.|-- ??? 100.0 100 0.0 0.0 0.0 0.0 0.0
8.|-- time.afip.gob.ar 0.0% 100 4.9 7.6 3.9 243.0 23.9
————————————————————————————————————————————
host1$ mtr -r -c 100 time.afip.gov.ar
Start: Tue Mar 27 18:57:06 2018
HOST: raspbian-server Loss% Snt Last Avg Best Wrst StDev
1.|-- gw-vlan-srv.innova-red.ne 0.0% 50 2.4 2.8 2.0 34.2 4.5
2.|-- rnoc5.BUENOS-AIRES.innova 0.0% 50 2.1 3.8 2.1 52.8 7.7
3.|-- 10.5.10.2 0.0% 50 2.7 2.9 2.2 15.6 1.8
4.|-- 200.0.17.104 0.0% 50 2.8 3.0 2.3 3.9 0.0
5.|-- 172.18.2.53 0.0% 50 4.5 5.8 3.8 17.8 2.2
6.|-- time.afip.gob.ar 0.0% 50 4.7 9.9 4.2 238.5 33.0
host2$ mtr -r -c 100 time.afip.gov.ar
Start: Tue Mar 27 18:57:00 2018
HOST: ws-david Loss% Snt Last Avg Best Wrst StDev
1.|-- 10.10.96.1 0.0% 50 0.3 0.3 0.2 0.7 0.0
2.|-- 200.16.116.171 0.0% 50 0.9 6.7 0.7 196.5 29.1
3.|-- static.33.229.104.190.cps 2.0% 50 1.6 1.7 1.5 2.2 0.0
4.|-- static.129.192.104.190.cp 0.0% 50 2.1 2.0 1.7 2.4 0.0
5.|-- 200.0.17.104 0.0% 50 2.0 2.1 1.8 2.6 0.0
6.|-- 172.18.2.53 0.0% 50 4.8 4.3 3.2 9.1 1.3
7.|-- time.afip.gob.ar 0.0% 50 4.3 9.4 3.3 234.9 32.7
host3$ mtr -r -c 100 time.afip.gov.ar
Start: 2018-03-27T18:57:05-0300
HOST: aleph.local Loss% Snt Last Avg Best Wrst StDev
1.|-- 10.17.71.254 0.0% 50 125.6 88.1 3.7 392.4 79.3
2.|-- 10.255.254.250 0.0% 50 62.1 54.8 2.1 333.2 68.0
3.|-- 209.13.133.10 0.0% 50 4.0 33.9 2.4 280.8 51.3
4.|-- host169.advance.com.ar 2.0% 50 4.1 21.3 2.9 236.7 40.4
5.|-- 200.32.33.33 2.0% 50 4.5 32.2 3.2 341.3 69.4
6.|-- 200.32.34.66 4.0% 50 7.7 26.0 3.5 278.8 55.8
7.|-- 200.32.33.38 2.0% 50 4.8 29.4 3.0 221.3 43.4
8.|-- 209.13.139.211 0.0% 50 84.8 40.3 3.1 250.4 53.0
9.|-- 209.13.139.209 0.0% 50 25.1 35.0 2.8 249.2 55.4
10.|-- 209.13.166.211 0.0% 50 3.7 33.5 2.6 188.9 54.3
11.|-- 200.32.34.137 0.0% 50 5.6 28.2 3.7 224.3 51.1
12.|-- 200.32.33.37 0.0% 50 3.7 24.2 3.5 189.5 44.9
13.|-- 200.32.34.121 0.0% 50 4.7 30.8 4.0 213.2 51.6
14.|-- 200.32.33.241 0.0% 50 14.4 33.1 3.9 364.6 67.2
15.|-- 200.16.206.198 0.0% 50 5.0 58.2 3.1 300.7 88.5
16.|-- 172.18.2.53 0.0% 50 9.4 117.8 4.4 315.1 103.4
17.|-- time.afip.gob.ar 0.0% 50 199.6 120.2 5.2 484.0 96.2
host4$ mtr -r -c 100 time.afip.gov.ar
Start: Tue Mar 27 18:41:40 2018
HOST: cnet Loss% Snt Last Avg Best Wrst StDev
1.|-- 157.92.58.1 0.0% 50 4.0 1.6 0.3 9.1 1.6
2.|-- ??? 100.0 50 0.0 0.0 0.0 0.0 0.0
3.|-- ??? 100.0 50 0.0 0.0 0.0 0.0 0.0
4.|-- host98.131-100-186.static 0.0% 50 4.7 5.5 1.5 10.9 2.4
5.|-- host130.131-100-186.stati 0.0% 50 8.4 6.5 2.6 10.5 2.2
6.|-- 200.0.17.104 0.0% 50 2.5 2.8 2.3 11.0 1.2
7.|-- ??? 100.0 50 0.0 0.0 0.0 0.0 0.0
8.|-- time.afip.gob.ar 0.0% 50 4.9 9.2 3.8 226.7 31.4
Best,
J. Ignacio
_______________________________________________________________
Dr. Ing. José Ignacio Alvarez-Hamelin
CONICET and Facultad de Ingeniería, Universidad de Buenos Aires
Av. Paseo Colón 850 - C1063ACV - Buenos Aires - Argentina
+54 (11) 5285 0716 / 5285 0705
e-mail: [email protected]
web: http://cnet.fi.uba.ar/ignacio.alvarez-hamelin/
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