RE: BGP and one backup link [7:33433]
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]
RE: BGP and one backup link [7:33433]
Why not just use floating static routes? With only one active exit point, I don't see the reason for burdening your router with the BGP routing table, unless you are just receiving aggregates from your provider. Even then the floating static's should work. __ Thomas Crowe Senior Systems Engineer / Architect CTS Professional Services - Atlanta __ -Original Message- From: [EMAIL PROTECTED] [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 [GroupStudy.com removed an attachment of type text/x-vcard which had a name of Thomas Crowe.vcf] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=33449&t=33433 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP and one backup link [7:33433]
Well, In fact I have had ultil 3 simultaneos links to Internet working very well. The idea of only have one primary link and one backup link is for saving costs. Addionally I have many customers talking to me BGP. At this moment I can not ask to my clients to change their BGP configutarion. Any idea? Alejandro Acosta -Original Message- From: Thomas Crowe To: [EMAIL PROTECTED] Sent: 28/01/02 12:45 Subject: RE: BGP and one backup link [7:33433] Why not just use floating static routes? With only one active exit point, I don't see the reason for burdening your router with the BGP routing table, unless you are just receiving aggregates from your provider. Even then the floating static's should work. __ Thomas Crowe Senior Systems Engineer / Architect CTS Professional Services - Atlanta __ -Original Message- From: [EMAIL PROTECTED] [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 [GroupStudy.com removed an attachment of type text/x-vcard which had a name of Thomas Crowe.vcf] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=33452&t=33433 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BGP and one backup link [7:33433]
You don't need to ask your customers to change their configuration, but you do probably need to continue to pass them fulls so you need fulls from your upstreams. To better control your 'backup' link: 1)To better control your outbound use local pref, but beware you might recieve some prefixes unique to the view of the backup provider. You'll need to do something else to cover that up or hope the usage is in the noise. 2)To better control your inbound you just need to use methods which will get the backup provider to not prefer that link and thus not advertise it to anyone else. Your AS path prepend isn't doing the job. Likely they set the customer link to have a higher local pref and the traffic you see is from the backup provider, it's customers, and probably peers(since many set local pref on peers higher than transit providers) of backup provider(who don't peer with other provider). Most providers which prefer customer links provide community structure to control advertisements use as backup.(standard customer, customer backup(customer with 2 links), customer fallback(if no other path is available)). Darrell Alejandro Acosta wrote: > > Well, In fact I have had ultil 3 simultaneos links to Internet working very > well. The idea of only have one primary link and one backup link is for > saving costs. Addionally I have many customers talking to me BGP. At this > moment I can not ask to my clients to change their BGP configutarion. > > Any idea? > > Alejandro Acosta > > > > -Original Message- > From: Thomas Crowe > To: [EMAIL PROTECTED] > Sent: 28/01/02 12:45 > Subject: RE: BGP and one backup link [7:33433] > > Why not just use floating static routes? With only one active exit > point, I > don't see the reason for burdening your router with the BGP routing > table, > unless you are just receiving aggregates from your provider. Even then > the > floating static's should work. > > __ > > Thomas Crowe > Senior Systems Engineer / Architect > CTS Professional Services - Atlanta > __ > > -Original Message- > From: [EMAIL PROTECTED] [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 > > [GroupStudy.com removed an attachment of type text/x-vcard which had a > name > of Thomas Crowe.vcf] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=33454&t=33433 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP and one backup link [7:33433]
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 Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=33441&t=33433 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
