We are soon starting up bgp and multihoming. Two ISPs and we have one site. We have already PI number and ASN assign to us. A Cisco 3825 with 3 ethernet interface with IOS advanced feature pack is order. No full routing table.
" firstname.lastname@example.org" wrote in news: email@example.com:
You could do it two ways:
Use one ISP as primary and one as secondary
Use both ISPs and recieve default routes from both ISP along with their "own" IPs
For both ISPs you setup standard BGP settings as described in the documentation from Cisco (take a look at CCO and do a search on BGP).
With option 1 you tag the inbound routes from both ISPs, setting the local-preference for 200 on the primary routes and leave the secondary ISP with default local-preference (that'll be 100). When you advertise your own routes, do a prepend to the routes you advertise to the secondary ISP.
With option 2 you simply accept any routes advertised by the ISP and advertise your own routes with default settings.
If you need further information / help, please respond to this group.
Don't worry about the age of the docs on the web! Not much has changed with BGP since version 4 was released last century. If you can track down a copy of my book, read the chapter on connecting to an ISP, it still applies.
As for your proposal, I do not recommend it if your goal is to minimize potential for black holes. Rather than using static default routes, have your ISPs advertise a default route to you (that way, you only get a default route if your link to the ISP is up). There are even better ways to protect against problems in your ISP or upstream, but they take more effort, as does setting up reasonable load balancing.