multihoming without BGP

Paul A Vixie paul at
Wed Jun 11 00:58:12 UTC 1997

> : BGP isn't better.  You don't need BGP for multihoming.  My SF NANOG talk
> : was on exactly this topic.  If you get a little bit of PA space from each
> : provider, and run a multihomed server (or a whole pile of them) with the
> : "interface default" mods we made available, you don't need BGP at all.
> You are convinced that ifdefault is production quality? Your slides don't 
> give me the feeling of absolute confidence. Is anyone using it in a 
> production environment?

At the time of the SF NANOG, it was running in production.  That customer has
switched providers for various unrelated reasons and is no longer multihomed.
But it did run a 100Khit/day web server for about three months without trouble.

> >From an operational standpoint BGP is what works, now. 
> Also, your solution only works on servers running BSD/OS 2.1. What about 
> other platforms where the source code is not available (How am I going to 
> magically convert my SGI/NT boxes into BSD/OS 2.1?) What about other
> clients from our end who still need redundant internet connectivity? 

I have received reports that this code ported trivially to NetBSD and to
FreeBSD.  (In fact it was originally developed on NetBSD.)  I don't know how
to get code patches made to SGI or NT, but one assumes that you'd start by
telling your sales rep that you would buy N more boxes next year if they add
this feature.  But that assumes you have a strong strategic relationship with
your system vendor.  If you don't, then you're right that you're not a
candidate for this.  On the other hand you could probably put up a FreeBSD
or NetBSD or BSD/OS box and try this out, and maybe switch system vendors.

> DNS round robin is also a crude way to balance loads over network 
> interfaces compared to path selection.

DNS round robin was never intended to solve the problem.

> I am extremely skeptical that ifdefault is ready for prime time.

You are welcome to that view, ignorant and reality-detached though it is.
I think that if you actually try it out, and then report back, I will listen
with a lot more interest to your comments as to its readiness for prime time.

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