nanog mailing list archives
Re: route converge time
From: Greg Foletta <greg () foletta org>
Date: Mon, 23 Nov 2015 11:00:16 +1100
Would be helpful if you let us know what platform you're running on. Assuming a Cisco, make sure next-hop-tracking not disabled (enabled by default on modern IOS), then at "BGP Prefix Independent Convergence", so your BGP process isn't walking the entire RIB to see which next-hops it needs to change. Greg Foletta greg () foletta org +61 408 199 630 On 23 November 2015 at 05:12, Colton Conor <colton.conor () gmail com> wrote:
What types of routers are you currently using? On Sat, Nov 21, 2015 at 7:44 AM, Baldur Norddahl < baldur.norddahl () gmail com> wrote:Hi I got a network with two routers and two IP transit providers, each with the full BGP table. Router A is connected to provider A and router B to provider B. We use MPLS with a L3VPN with a VRF called "internet". Everything happens inside that VRF. Now if I interrupt one of the IP transit circuits, the routers will take several minutes to remove the now bad routes and move everything to the remaining transit provider. This is very noticeable to the customers. Iamlooking into ways to improve that. I added a default static route 0.0.0.0 to provider A on router A and did the same to provider B on router B. This is supposed to be a trick that allows the network to move packets before everything is fully converged. Traffic might not leave the most optimal link, but it will be delivered. Say I take down the provider A link on router A. As I understand it, the hardware will notice this right away and stop using the routes toproviderA. Router A might know about the default route on router B and send the traffic to router B. However this is not much help, because on router B there is no link that is down, so the hardware is unaware until the BGP process is done updating the hardware tables. Which apparently can take several minutes. My routers also have multipath support, but I am unsure if that is goingtobe of any help. Anyone got any tricks or pointers to what can be done to optimize the downtime in case of a IP transit link failure? Or the related case of one my routers going down or the link between them going down (the traffic would go a non-direct way instead if the direct link is down). Thanks, Baldur
Current thread:
- route converge time Baldur Norddahl (Nov 21)
- Re: route converge time Daniel Corbe (Nov 21)
- Re: route converge time William Herrin (Nov 21)
- RE: route converge time Spyros Kakaroukas (Nov 21)
- Re: route converge time Colton Conor (Nov 22)
- Re: route converge time Greg Foletta (Nov 22)
- Re: route converge time Matthew Petach (Nov 28)
- Re: route converge time Jeff Tantsura (Nov 28)
- Re: route converge time Baldur Norddahl (Nov 28)
- RE: route converge time Jürgen Jaritsch (Nov 28)
- Re: route converge time Matthew Petach (Nov 28)
- RE: route converge time Jürgen Jaritsch (Nov 28)
- Re: route converge time William Herrin (Nov 28)
- Re: route converge time Jeff Tantsura (Nov 28)