Subject: Re: why doesn't NetBSD support bridge in kernel?
To: Markus A. Boeing <firstname.lastname@example.org>
From: Will Waites <email@example.com>
Date: 07/05/2001 14:23:40
On Thu, Jul 05, 2001 at 09:46:28AM +0200, Markus A. Boeing wrote:
> Well, probably bridging is the most basic network function. Probably it is
> the least desirable network function as well. If you're going to build
> large networks that scale well and provide rich functionality, you're
> better of using IP routing function instead of bridging technology.
Not true. Bridging is still usefull in some circumstances. For
example: two providers interconnect and they each have their own
802.1Q vlan tags that they use. Maybe one is a transport layer
provider doing LAN extensions and the other is an ISP. Most likely,
since there are only 4095 useable tags, there will be collisions
between the two tag domains. Solution: rewrite the tags. Unfortunately
none of the router and switch vendors (excluding some high end
catalyst switches and juniper routers -- very costly, at any rate)
support tag rewriting. You can do it on a unix such as NetBSD with
bridging support simply by bridging one vlan interface into another.
Blanket statements like "routing is better than bridging" are
nonsense. Granted people sometimes will use one or the other where it
is not appropriate and cause themselves headaches, but that doesn't
mean that either is "better".