[ On Tuesday, March 13, 2001 at 12:52:41 (-0800), Roeland Meyer wrote: ]
Subject: Broken Internet?
Even co-lo boils down to single-home dependency.
It doesn't have to.
Yes, there are a bunch of hacks to work around this problem. But, that is exactly what they are ... hacks. They are not something I could build a sustainable business around.
For _small_ businesses it is extremely trivial to multi-home (i.e. to truly multi-home all their network-visible servers). Well there's one small trick that requires each host have decent support for something like IP Filter that's capapble of re-directing packets based on source address. (I'll post a technical description the trick I use with IP Filter if enough people don't think it's obvious how it works. There have also been hacks by others to the BSD networking stack to allow multiple default routes and to do source-routing kinds of tricks.) With a small amount of planning and skill it's possible to make this kind of real multi-homing fully functional through the DNS (and even to enjoy some load-balancing as a result). For most any _small_ business this works very well (been there, done that, would even do it with my machines here at home if Rogers@Home didn't charge as much as they do for IP addresses). Conveniently about the time your network gets big enough that this scheme gets too hard to manage, you're up to the size where network multi-homing via BGP, etc. is possible.
Any business needs: 1. to be able to change upstream providers without having to renumber.
Why? If you're _small_ then renumbering is relatively easy! It's the big guys (who didn't use DHCP from the start) who have a hard time renumbering.
2. to be able to change access providers without having to suffer multi-month down-times.
If you're multi-homed then all your providers have to go down before you'll suffer any down-time that's not your own doing. The real issue is with lead times on ordering local loops, etc. If you've already got them in place because you are already connected to multiple providers and are doing host-based multi-homing then you don't have to worry.
3. to be able to have its net-block(s) visible regardless of which ISPs they are currently using.
By properly multi-homing all your servers (and not networks via routing) there's no issue about net-block visibility, BGP peering, or the like. You simply use as many/few IP addresses from each provider as you need to multi-home all your servers, and they aggregate them into their own routes as necessary. Same thing goes for co-locating multiple identical servers in multiple locations.
Currently the only ones that can do that are those that; 1. Are large enough to justify a /20 (begging the question of how they got that large). 2. Can afford their own datacenter.
Yes, exactly. They're the only ones who really need network multi-homing (which is such a poor phrase to describe what it is). Everyone else can afford to multi-home their servers one way or another.
It looks like our technical solutions are raising unreasonable barriers to entry for small businesses.
I think not. I fully agree that Internet-based businesses critically require multiple network access points. However since this can be done trivially with either multiple co-located servers, or properly multi-homed servers, there's no reason to consider /20 netblocks, etc., to be barriers of any sort. -- Greg A. Woods +1 416 218-0098 VE3TCP <gwoods@acm.org> <robohack!woods> Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>