bit patterns and routers

Hi, All

I'm new here and really this isn't directly related to ccrtp.

Over the years I've been told and heard stories of routers that would fail to pass "bit patterns" causing interruption of data flow.   It was my surmise that if such a thing were 
actual, it might well have been observed here and I've come to ask just how common this is.  I can't find ANYTHING by googleing this

Is this something real or just a tale spun to deal with deficiencies in other pieces of code?

Inquiring minds want to know

Thanks in advance


Bruce