On Sun, Dec 22, 2024 at 4:15 AM Nick Hilliard <n...@foobar.org> wrote: > There are two main target situations: firstly, when a router unexpectedly > drops off an ixp platform, this won't be explicitly signaled to the other > routers > on the fabric, which can mean that packets to that device will be black-holed > until all the others bgp hold timers kick in.
Hi Nick, I'm missing something. Wouldn't the route server send withdrawals and updates to the rest of the participants as soon as its hold timer with the lost router expires? Could this not be accelerated by the IXP asking the participants to keep low keepalive and hold timers with the route server? How would your solution help when two participants at an IXP have chosen -not- to bilaterally peer, thus needing the route server to intermediate? They're going to agree to build BFD sessions even though they don't want BGP sessions? That... doesn't make sense. > The second situation would be to deal with forwarding plane incongruence > on IXPs, i.e. where router A can reach RS, router B can reach RS, router A > cannot reach router B due to a problem on the IXP fabric itself. Thankfully > this style of problem has become quite unusual over the last several years. Doesn't seem like it would solve the bouncy link problem. Absent bouncy links, simply having a reasonable time out for arp and ND will assure the router quickly finds its neighbor unreachable, which is applied as backpressure into BGP. Regards, Bill Herrin -- William Herrin b...@herrin.us https://bill.herrin.us/
