Re: [pacnog] Multihoming Problem
- To: "'Aloiamoa Anesi'" <Alo.Anesi at bluesky dot as>, "'PacNOG'" <pacnog at pacnog dot org>
- Subject: Re: [pacnog] Multihoming Problem
- From: "Bernie" <bernie.tauaanae at samoatel dot ws>
- Date: Mon, 2 Jul 2007 08:54:52 -1100
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A good option Alo… if there’s no other way……
pacnog-bounces at pacnog dot org [mailto:pacnog-bounces at pacnog dot org] On Behalf Of Aloiamoa Anesi
After attending PACNOG3, I had a moment of clarity and managed to fix my multihoming problem.
I thought you guys might be interested in the solution even though it's not something I would usually recommend.
My main problem was that I only had a T1 connection to my secondary upstream provider. However, even with as-path prepends, I was getting more inbound traffic than the T1 could provide and ran into congestion problems. This secondary link is purely used as a backup since it is much smaller than our primary path.
The fix was to advertise two /21 prefixes out of my /20 on my primary provider. This would force BGP path selection to only use the primary provider since it had the longest prefix match.
For redundancy, I still advertise my full /20 to both upstreams.
Now, this is actually bad CIDR practice, but I would deem it a necessary evil in my case.
But feel free to flame me if you have the urge. =)
On Feb 7, 2007, at 4:18 PM, Terry Manderson wrote:
On 08/02/2007, at 12:24 PM, Gaurab Raj Upadhaya wrote:
In the very brief look at had at the configs, I didn't see any way that you are consciously selecting your outbound path with local-preference or other outbound traffic engineering mechanisms.
Maybe a show int on the (secondary provider) interface in question will tell you if the traffic is inbound our outbound..
Terry Manderson email: terry at apnic dot net
Network Operations Manager, APNIC sip: info at voip dot apnic dot net
http://www.apnic.net phone: +61 7 3858 3100