Withdrawls and announcements attempt 2

The 30 second figure sounds pretty much like the good ol'
line flap with default cisco keepalive.

I was bothering cisco folks about making static routes
persistent by default for quite a while. Although there's
a workaround very few people actually bother to use it thus
causing bouncing tail links to produce route flap.

My suspiction is that this kind of flap accounts for no less
than 90% of the total.

Another probable contributor is RIP (shouldn't we declare it
RIP already?) Most network administrators never heard of a
simple maxim -- "Never use dynamic routing when you have
a single path". As a result most LANs are plagued by RIP
with no reason whatsoever (and many of them inject their
IGP routes into BGP!)

The lack of any meaningful clock source negotiation and
idiotic defaults in CSU/DSUs is a major source of rapid
link flap, too. It seems that most (if not all) equipment
vendors simply don't have any clue of what effect their
design choices have in the real world.