Some ISPs can be evil and ignore path stuffing for customers - happens here in .au a lot. One way I've found around it that works very well is BGP Conditional Advertisement.
Basically it can 'see' if a route is in the routing table, and if it isn't, advertise more routes. So, if you stop seeing the default route from your usual provider, you can advertise your netblocks (specified by an ACL or a prefix-list) to a second provider. Outgoing traffic could be left to the floating static, or use the same method to advertise a default route to your customer routers/cores/whatever. Reasons I like it: Works across multiple routers; works even if the physical interface is up (floating statics wont, backup interfaces won't); can be easily 'swung' by shutting down BGP sessions without shutting physical interfaces; is a much cleaner solution than path stuffing (SOMEBODY out there has a longer path than you do :)). Take a look at: http://www.cisco.com/warp/public/459/cond_adv.html Rgds, - I. On Tue, 29 Jan 2002, Joseph Brunner wrote: > Sometimes As prepending won't work.. your best bet is to telnet > to route-views.oregon-ix.net (public route server) and do a show ip bgp with > your > as # (then you will know who is using your prepended path to get there. Most > likely > one peer of your backup link providers, sets local pref or metric > on a private peering arrangement, thereby nullifying your prepends. > Unfortunately > there is nothing you can do.. if you were a hi-cap T-3 or larger customer, > they > might traffic engineer this for you. > > Joseph Brunner > ASN 21572 > MortgageIT MITLending > New York, NY 10038 > (212) 651 - 7695 Voice > (212) 651 - 7795 Fax > > > > -----Original Message----- > From: Alejandro Acosta [mailto:[EMAIL PROTECTED]] > Sent: Monday, January 28, 2002 10:36 AM > To: [EMAIL PROTECTED] > Subject: BGP and one backup link [7:33433] > > > Hi all, > I have a BGP question. > In this moment we have one Internet link with just one provider, now, we > have got a second link just for backup. I mean, we can only use it for 180 > hrs per month. > I can easily manage my outgoing traffic (using local preferece or weight), > however the incomming traffic in more difficult. I added many prepends (9) > in the publication of the second link but there still few traffic on it. > There is not IBGP between my two providers. > > Any ideas? > > Thks in advanced. > > Alejandro Acosta -- Ian Henderson CCNA, CCNP Network Engineer, iiNet Limited Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=33677&t=33433 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
