Correct me if I am wrong but to detect a failure by default BGP would wait the "hold-timer" then declare a peer dead and converge. So you would be looking at 90 seconds(juniper default?) + CPU bound convergence time to recover? Am I thinking about this right? -----Original Message----- From: Jeff Wheeler [mailto:jsw@inconcepts.biz] Sent: Wednesday, March 16, 2011 1:55 PM To: nanog@nanog.org Subject: Re: bfd-like mechanism for LANPHY connections between providers On Wed, Mar 16, 2011 at 2:33 PM, Jensen Tyler <JTyler@fiberutilities.com> wrote:
We have many switches between us and Level3 so we don't get a "interface down" to drop the session in the event of a failure.
This is often my topology as well. I am satisfied with BGP's mechanism and default timers, and have been for many years. The reason for this is quite simple: failures are relatively rare, my convergence time to a good state is largely bounded by CPU, and I do not consider a slightly improved convergence time to be worth an a-typical configuration. Case in point, Richard says that none of his customers have requested such configuration to date; and you indicate that Level3 will provision BFD only if you use a certain vendor and this is handled outside of their normal provisioning process. For an IXP LAN interface and associated BGP neighbors, I see much more advantage. I imagine this will become common practice for IXP peering sessions long before it is typical to use BFD on customer/transit-provider BGP sessions. -- Jeff S Wheeler <jsw@inconcepts.biz> Sr Network Operator / Innovative Network Concepts