A couple of you have asked me how to check the Internet's BGP tables to see which ISP the Internet will send traffic to us through.
The answer is to use a route-server. These are usually Cisco or Juniper routers located at ISPs. They allow anyone to log in without a password and issue "show" commands. Each route-server has its own unique view of the Internet, and will accordingly show different routes that the others.
Here's a good list of route-servers. If you have the "telnet:" URL set up properly on your PC, clicking on a link will fire up your telnet program (PuTTY?) and connect to one of the servers.
Once on the server, just type "sho ip bgp regexp 11322". See below for additional useful commands. Here's a sample session:
.....................................................
.BBBBBB.................WW........WW..uu..uu.........Baden-
.BB...BB..........ll....WW........WW.................Wuerttembergs
.BB...BB.. eeee...ll.....WW......WW...uu..uu.........extended
.BBBBBB...ee..ee..ll.....ww..ww..ww...uu..uu.........
.BB...BB..eeeee...ll.....WW.WWWW.WW...uu..uu.........
.BB...BB..ee......ll......WWW..WWW....uu..uu.........
.BBBBBB....eeeee..lllll...WW....WW.....uuuu..........
.....................................................
BelWue-Cisco-Router Route-Server
cisco software Rel. 12.2
Konfiguration 1.47 erzeugt am 02/12/19 von merdian
01803/235638, [email protected]
route-server>sho ip bgp regexp 11322
BGP table version is 2477141652, local router ID is 193.196.190.135
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
* i12.1.45.0/24 213.248.79.41 0 100 0 1299 7018 11322 i
* i206.24.119.0 213.248.79.41 0 100 0 1299 7018 11322 i
route-server>
This route-server, apparently in Germany, shows routes to both our prefixes via AS 7018, which is AT&T.
Here's another:
This system is the property of Energis
Public access is allowed for the purpose of network management
route-server.as5388.net>sho ip bgp regexp 11322
BGP table version is 2234992752, local router ID is 195.92.201.108
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i12.1.45.0/24 195.92.201.149 90 100 0 5511 3561 11322 i
* i 195.92.201.150 90 100 0 5511 3561 11322 i
*>i206.24.119.0 195.92.201.149 90 100 0 5511 3561 11322 i
* i 195.92.201.150 90 100 0 5511 3561 11322 i
route-server.as5388.net>
This one would route to AS11322, which is us, via AS3561, which is Savvis.
You shold always see a route or a set of routes for each of our two prefixes. The prefix (which means the network number, such as 12.1.45.0/24) is on the left, and the "AS PATH" is on the right.
Note: is it asked that you never type "sho ip bgp" by itself without qualifiers because that would be abusing the router, asking it to show all routes on the Internet. Always use qualifiers to cut down on the output, as I did above.
Here are some other commands to try. Let's assume your AS is 6666.