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In 1998 we compared the round trip times (RTT) and losses measured by ping with those measured between sending the SYN packet for a TCP stream and receiving the ACK back. we We found that the distributions agreed well, e.g. the median and average RTTs and losses agreed well (well within the Inter Quartile Range) of the distributions.
Since then there may have been increased de-prioritizing which could increase the differences in the two types of measurements, so we decided to re-evaluate the differences.
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Together with this we could use the list of PingER www perfSONAR hosts that respond to pings. Note that sometimes pings are blocked to a host but TCP port 80 packets work, e.g. adl-a-ext1.aarnet.net.au (202.158.195.68).
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Usage: ping-vs-tcp.pl [opts]
Opts:
-v print this USAGE information
-D debug_level (default=0)
-p protocol (6 or '') (default '')
-a application port (default = 80)
-c count of pinfspings to be sent (default = 10)
Function:
Ping the host provided in %NODE_DETAILS (the PingER database of hosts)
For each host it gets the IP address either from NODE_DETAILS (IPv4)
or using the dig command (IPv6).
It then Pings and npings the host and gathers the min, average, maximum
RTTs and losses and reports them to STDOUT. together with a time stamp
and host information such as name, IP address, country, region etc.
Externals:
Requires nping (requires root/sudo privs), dig
Input:
It gets information on the PingER hosts from %NODE_DETAILS using:
wget to get the required file from http://www-iepm.slac.stanford.edu/pinger/pingerworld/slaconly-nodes.cf. The required file is saved
in in /tmp with a unique name /tmp/nodes-3458.cf (based on the process number).
Examples:
ping-vs-tcp.pl
ping-vs-tcp.pl -p 6 -a 22 -c 10
ping-vs-tcp.pl -v
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- PingER targets: 50% of the 36 hosts measured have average(RTTs) within 0.26ms of oneanother).
Again the relative ping vs nping differences for IPv6 is shown below and shows an IQR of the relative average difference is 0.45%:
- perfSONAR targets: There are about 120 perfSONAR hosts that respond to IPv6 pings and npings. Of these 65 are in Europe and 54 in N. America (US and Canada). The spreasheet From the perfSONAR JSON configuration file we found 154 hosts that have IPv6 addresses (see spreadsheet). Of these (using the perl script bin/ping-vs-tcp-ps-sq.pl --conf ps-v6-sq.cf | tee ps-v6-sq.txt, it ran for about 45 minutes) we found 6 hosts that did not respond to ping6 and 50 for which we were was unable to get the information from nping. This yielded 98 IPv6 capable perfSONAR nodes that respond to ping6 and nping. Of these 53 are in N. America (Canada and the U.S.), 30 in Europe (13 in the United Kingdom), 4 in Russia, and 1 each in Africa (Uganda) and Costa Rica. The spreadsheet is here.