Re: BGP on dialup links?

John Storms (jstorms@livingston.com)
Thu, 24 Jul 1997 05:51:51 -0700

Actually you can run BGP over a network dialup connection, but this would
be a very, very BAD idea. The reason you can run BGP over a dialup
connection is because BGP runs on the application layer. All it requires
to connect to another BGP peer is the ability to make a TCP/179 connection
over a reliable media. There is no BGP configuration that is port
specific. It all lies in the global settings and general BGP tables.

You would Never want to receive the entire Internet routing table over a
dialup connection. Currently BGP contains 44,000+ routes. And a BGP route
update contains 1 or more destination/netmask/gateway combinations, route
withdraw information and several attributes so this adds up to alot of
traffic very quickly. After the Internet table is loaded there is a
constant trickle of new routing information. Routes being added, others
being removed and so forth. A dialup connection would not be capable of
handling such a load.

Lets say though that you set up a BGP router to only advertise one or two
routes to your provider, who also have to be running BGP, to advertise them
to the Internet. I guess this would work over a smaller bandwidth since
you are not receiving incoming routes. The upstream BGP speaker would have
to be configured to only accept information from you and not to send it.
Blocking it on your end would be pointless because the bandwidth would
still get choked with incoming data.

The only other application I can think of for using BGP over a dialup
connection is if you decided to use BGP as an internal gateway protocol
(IGP). This also is not a good idea. OSPF should be used internally and
BGP should be used externally, but since BGP is a routing protocol to
distribute routing information, technically, though bad form it can be
done. Using BGP as and IGP is like swatting flys with a sledge hammer,
you'll probably kill the fly, but you risk breaking things as well.
Vice-versa using a dialup connection to run BGP is like using a fly to swat
a sledge hammer.

In short, I wouldn't do it if I were you.

At 09:14 PM 7/23/97 -0400, Dick St.Peters wrote:
>I know most people will think it an insane question, but does the new
>Portmaster BGP4 run over dialup links?
>
>--
>Dick St.Peters, stpeters@NetHeaven.com
>Gatekeeper, NetHeaven, Saratoga Springs, NY, 1-800-910-6671 (voice)
>Albany/Saratoga/Glens Falls/North Creek/Lake Placid/Blue Mountain Lake
>Soon: Elizabethtown/Greenwich/Keene/Plattsburgh/Saranac Lake/Ticonderoga
> First Internet service based in the 518 area code
>
>

---
jstorms@livingston.com
Diplomacy:  The art of saying good doggie
while seaching for a big rock.