nanog mailing list archives
Re: Dual Homed BGP
From: Baldur Norddahl <baldur.norddahl () gmail com>
Date: Sat, 25 Jan 2020 01:49:21 +0100
lør. 25. jan. 2020 00.40 skrev Jon Lewis <jlewis () lewis org>:
On Fri, 24 Jan 2020, Baldur Norddahl wrote:Full tables will not make much noticeable difference if you are notpeering. However you want to make sure bothlinks get used. It can be a 90%/10% split but 100%/0% is bad becausethen you may discover that the alternate pathis actually broken the moment the primary fail. If you choose onlydefault then you need to think about that.If you join any peering exchanges, full tables will be mandatory. Someparties will export prefixes and then expecta more specific prefix received from your transit to override a part ofthe space received via the peering. 90/10 will suck when the link carrying 90% of your traffic needs more pipe and you have a ton of unused capacity on the other one. Full tables from both providers gives you more options to tune things (assuming outbound is your larger direction). If you're an eyeball provider and most of your traffic is inbound, your outbound traffic routing decisions aren't quite as relevant.
If your goal is to maximize your capacity, you should run a default route with equal cost multi path for perfect load balancing. Just beware that there is effectively no redundancy when exceeding the capacity of a single link. Also consider the typical two transits each connected to a separate router, each router handling a single circuit. I will wager that the majority of such dual homed organisations have no idea that those two routers by default will make different routing decisions. You get more control but you also need the experience and talent to use it. For many it might be better to have a solution that is understood.
Have those suggesting "multihoming with two partial feeds and default routes" forgotten peering pissing matches, long lasting inter-network capacity issues, or that certain "tier 1" providers don't even have/provide a full v6 table?
The solution is to stay clear of tier 1 networks. Find a good local tier 3. Whatever you are going to do, they will do better. Regards Baldur
Current thread:
- Re: Dual Homed BGP, (continued)
- Re: Dual Homed BGP Mel Beckman (Jan 24)
- Re: Dual Homed BGP Ben Cannon (Jan 24)
- Re: Dual Homed BGP Cummings, Chris (Jan 24)
- Re: Dual Homed BGP Ben Cannon (Jan 24)
- Re: Dual Homed BGP Job Snijders (Jan 24)
- Re: Dual Homed BGP Chriztoffer Hansen (Jan 24)
- Re: Dual Homed BGP Amir Herzberg (Jan 27)
- Re: Dual Homed BGP Jay Hennigan (Jan 24)
- Re: Dual Homed BGP Gavin Henry (Jan 24)
- Re: Dual Homed BGP Baldur Norddahl (Jan 24)
- Re: Dual Homed BGP Jon Lewis (Jan 24)
- Re: Dual Homed BGP Baldur Norddahl (Jan 24)
- Re: Dual Homed BGP Tore Anderson (Jan 25)
- Re: Dual Homed BGP Baldur Norddahl (Jan 25)
- RE: Dual Homed BGP Aaron Gould (Jan 25)
- Re: Dual Homed BGP Anurag Bhatia (Jan 27)
- Re: Dual Homed BGP Jon Lewis (Jan 24)
- Re: Dual Homed BGP Mel Beckman (Jan 24)