BGP announcements and small providers

Knowing that NSPs are filtering /24s, how does an Internet Content
Provider (ICP) with just a /24 (all that is needed) that is wishing
to be dual-homed see all of the net?

Swamp /24, or use most of a /18|/19 underutilized, or better use more
intelligence than "just" BGP - for instance Paul Vixie's stuff at the
last NANOG.

Alex Bligh
Xara Networks


Swamp /24, or use most of a /18|/19 underutilized, or better use more

Given current address allocation policies, how are you supposed to go
about getting a /19 to waste in the first place?

intelligence than "just" BGP - for instance Paul Vixie's stuff at the
last NANOG.

Paul's solution certainly adds more reliability as long as the clients
doing the connecting do the right thing WRT rotating through the A
records for your servers. As far as I can tell, it still doesn't do
anything to solve the problem of choosing the "best" interface for the
connection to happen on. Obviously the definition of "best" is up for
debate, but if the squid machine was doing BGP, there would at least
be some path optimization done.

As it is, if the interface-defaulted squid machine was dual-homed to
providers X and Y that don't peer, a customer of X could get the A
record for the interface in Y's space. The client would then have to
take the transit path between X and Y, which for many X's and Y's,
sucks. If the dual-homed machine was doing BGP, the customer of X
would always use the interface on X's side, and vice versa.

Of course, we all know that we need to aggregate, shrink the routing
table, shrink peer lists, etc., and Paul's solution certainly wins
in that repect.

Navigator versions up to and including 3.01 (excluding a special release
version made for @home) do not go rotate through the A records. If the
first one fails they don't bother with the rest.

MSIE 3.0 does time out and try later addresses (although it seems to
have a silly bug where it displays the wrong address in the status line
at the bottom).

Navigator also exhibits another problem (I'm not sure if MSIE has this
problem or not, it probably does). It caches DNS results forever.
I've renumbered web servers, done the ttl game, and seen traffic at the
old ips three weeks after the change "should" have propagated everywhere
and the old records timed out everywhere. I'm guessing people running
unix boxes who don't restart their browser...

Assuming you don't have an address on your network you can
try <>.


You could take in all the BGP data from your providers (read-only as it
were) then link that into your DNS server so that it returns an IP
address according to the 'best' (however you define that...) route
that you have back to them...?


I think the whole purpose t Paul V's madness in creating this solution was
to avoid doing just that.

Also I seem to remember something in Paul's take that took care of this
situation. Maybe he can elaborate.

          Geoff White
          Virtual Sites