[c-nsp] IOS IP ID generation

[John Kristoff]

Friends,

I'm interested to know, if anyone has definitive knowledge or at least
reasonably credible information, about how IOS generates the IP ID field
values in recent trains of software.  I think it may have changed over
the years, but I'm unfamiliar with the current state.

In addition to the sequence (e.g. random, incremental, zeroes for DF or
some combination therefore), is there a global counter or do different
protocols and processes get their own counter?  Any information about
this and the use of random number generation in IOS would be
appreciated.

Thank you,

John