[nos-bbs] hop irregularity

(Skip) K8RRA k8rra at ameritech.net
Thu Sep 18 12:56:29 EDT 2008

Good morning.

After a chat about network composition in my area, it seemed that I
needed to explore local network topology.  The sysop command "hop check"
is the natural tool but I found the results erratic.

I found quite a number of "hop check" traces to end with "!H" error
messages prior to reaching the target host.  I'd accept this error
normally, but I also found some of these paths showing errors from hop
check to be OK for "ping" and even some ok for TCP sessions of TELNET
and SMTP.

So hop check seems like it could not always be accurate.  What might be
the explanation for such a problem?

The other thing I found a little ambiguous is the documentation for the
error messages provided by the wiki.  If anyone cares to clarify the
meanings, perhaps begin by seeing the page:
and the table for the various "!..." flags.  For example, doesn't the
flag "!H" mean that 
  -> no route could be found leading to the target host 
at the intermediate host?  It seems to me that the existing text
  -> ... unreachable
is the result rather than the cause of the failure.


de [George (Skip) VerDuin] K8RRA k

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