File: inetutils.info,  Node: Data patterns,  Next: TTL details,  Prev: Duplicate and damaged packets,  Up: ping invocation

7.4 Trying different data patterns
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The (inter)network layer should never treat packets differently
depending on the data contained in the data portion.  Unfortunately,
data-dependent problems have been known to sneak into networks and
remain undetected for long periods of time.  In many cases the
particular pattern that will have problems is something that doesn't
have sufficient "transitions", such as all ones or all zeros, or a
pattern right at the edge, such as almost all zeros.  It isn't
necessarily enough to specify a data pattern of all zeros (for example)
on the command line because the pattern that is of interest is at the
data link level, and the relationship between what you type and what the
controllers transmit can be complicated.

   This means that if you have a data-dependent problem you will
probably have to do a lot of testing to find it.  If you are lucky, you
may manage to find a file that either can't be sent across your network
or that takes much longer to transfer than other similar length files.
You can then examine this file for repeated patterns that you can test
using the '-p' option of ping.