Hi James, Interesting you mention this, as someone else on Cisco Community Page was interested in the IOS version. Possibly once this design is finished the default may come from somewhere else, but I don't think I will be there when it happens.
They have told me they have no other issues with other customers and same config, but this could be a bug between different IOS versions because I am running IOS-XE and they may be running XR as they have a ASR9K. I am going to ask the question and see what happens. Thanks for the info. Brad ________________________________ From: James Bensley <jwbensley+cisco-...@gmail.com> Sent: Monday, 20 April 2020 6:30 PM To: Bradley Ordner <bradin...@hotmail.com>; cisco-nsp@puck.nether.net <cisco-nsp@puck.nether.net> Subject: Re: [c-nsp] Default Route recalculated every 60 seconds. On Sat, 18 Apr 2020 at 07:11, Bradley Ordner <bradin...@hotmail.com> wrote: > > I am about to leave an Enterprise environment due to Pre Covid-19 redundancy > and I just need to find the root cause of this issue before I leave. > > We recently built a Layer 2 Circuit over a Providers SDN Backbone so we could > get a 2Gb Internet link. We peered with this neighbor and filtered a partial > table, so we get about 30000 routes. For some reason, every 30 seconds the > default route uptime resets to 00:00 in the routing table. I spoke with > Carrier, they made a few changes and one was the BGP advertisement timer. It > is now set to 60 seconds and now the default route resets every 60 seconds. > > The carrier, keeps blaming my side so I opened a Cisco TAC case and they > haven't got around to looking at it yet, probably because it really sounds > like it is the carrier side. I took some packet captures and indeed every 60 > seconds an update with the default is sent. Our router constantly accepts > this, recalculates and enters it into the routing table. > > I can't seem to figure out if this is some type of bug or not. The router has > been rebooted and is due for IOS upgrade shortly, but wanted to see if anyone > has seen this or point me in the right direction. > > Thanks > > Brad Hi Brad, Do you know if your provider uses IOS-XR on their PE? There was a bug a couple of years ago in XR (I've searched on cisco.com but can't find the BugID right now) in which XR was re-advertising the default route every 30 or 60 seconds. We had it, and if I recall correctly it wasn't being withdrawn, just a new BGP UPDATE was sent to supersede the existing route, so as other posters have said, packet capture the BGP TCP packets with your provider or use some "debug bgp" commands to see whats really going on. Also, maybe reconsider if need them to advertise a default route if you're getting a partial table from them. Cheers, James. _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
