On Wed, Mar 16, 2011 at 4:42 PM, Jensen Tyler <JTyler@fiberutilities.com> wrote:
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?
This is correct. Note that 90 seconds isn't just a "Juniper default." This suggested value appeared in RFC 1267 §5.4 (BGP-3) all the way back in 1991. In my view, configuring BFD for eBGP sessions is risking increased MTBF for rare reductions in MTTR. This is a risk / reward decision that IMO is still leaning towards "lots of risk" for "little reward." I'll change my mind about this when BFD works on most boxes and is part of the standard provisioning procedure for more networks. It has already been pointed out that this is not true today. If your eBGP sessions are failing so frequently that you are very concerned about this 90 seconds, I suggest you won't reduce your operational headaches or customer grief by configuring BFD. This is probably an indication that you need to: 1) straighten out the problems with your switching network or transport vendor 2) get better transit 3) depeer some peers who can't maintain a stable connection to you; or 4) sacrifice something to the backhoe deity Again, in the case of an IXP interface, I believe BFD has much more potential benefit. -- Jeff S Wheeler <jsw@inconcepts.biz> Sr Network Operator / Innovative Network Concepts