In return, would Covad please consider performing some meaningful form of
route
aggregation or other measures to reduce the amount of noise that is being
passed across the global routing tables that originates from Covad?suggests that Covad could withdraw some 483 BGP routing table entries,
reducing the total number of entires originated by Covad from 490
to an equivalent set of 8 aggregate routes.
perhaps this is not the time/place to raise the point,
but I'm coming to the conclusion that there is increasing
pushback to -NOT- announce space that is not in active use.
So-called "dark" space, i.e. the unused interstitial gaps
in delegated space that is the the product of sparse delegation
techniques, is perhaps more of a hazzard, esp. wrt. spam/traffic
generation than might have been considered in the past. think
forged source addresses...
if this is a rational line of argument, then two tactics present
themselves: 1) announce the individual, more specifics. this
has the effect of further bloating the routing table, incuring
the rath of the self-appointed routing table police (so watch out
Covad, don't do what Telstra did... 
2) keep my number of
routing table entries consistant by "grooming" back my sparse
delegations into more homogenous groups, e.g. renumber folks in
the four /28s spread across the /19 into a single /26 - then
withdraw the /19 and announce the /26 in its place.
the number of routing table entries remains consistant and the
number of possible entries for forged source addresses is
dramatically reduced. Of course this will require a major rethink/
rewrite of most ISPs engineering practice/operating procedures,
as it will be much more common to see legitimate, long prefixs in
the routing system.
as usual, YMMV.
--bill