Thread View: mod.protocols.tcp-ip
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Started by mike
Tue, 07 Apr 1987 07:24
Re: ICMP As A Diagnostic Tool?
Author: mike
Date: Tue, 07 Apr 1987 07:24
Date: Tue, 07 Apr 1987 07:24
34 lines
2032 bytes
2032 bytes
BRL uses the "ping" program, which transmits ICMP Echo Request packets with the data field set to a process ID, a sequence number, and a struct timeval (time in seconds and microseconds), plus patterns to pad out any extra length (a command-line parameter). [The BRL ping program is now provided as /etc/ping in 4.3 BSD UNIX]. We use this tool for network troubleshooting *extensively*. Many Lab managers even know how to run PING, so that they can get more information about why connections to far-away hosts may be working poorly. We also have a tool (PINGPOLL) that we use (within the campus net only) to monitor round-trip-times and packet loss, as well as a very simple ICMP-based routing daemon (ROUTER). ICMP is invaluable -- it provides a level of visibility of activity at the link level that is very helpful. Oh yes, another good use to to watch the effects of varying packet size. Good for finding IP reassembly bugs (in days gone by), and various interesting performance problems (back-to-back etherpackets, etc). The "ping -f" (aka FLOODPING) option is very good for stress-testing a particular network, gateway, host, whatever. As the name suggests, it releases ICMP echo request packets as fast as it can. Another version of PING that we have uses the IP option "record route", which is useful to see where the packets are traveling. Very useful, and amusing to watch. Best, -Mike
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