From owner-freebsd-net Fri Mar 26 16:41:28 1999 Delivered-To: freebsd-net@freebsd.org Received: from xylan.com (postal.xylan.com [208.8.0.248]) by hub.freebsd.org (Postfix) with ESMTP id B018815170 for ; Fri, 26 Mar 1999 16:41:23 -0800 (PST) (envelope-from wes@softweyr.com) Received: from mailhub.xylan.com by xylan.com (8.8.7/SMI-SVR4 (xylan-mgw 2.2 [OUT])) id QAA29385; Fri, 26 Mar 1999 16:40:12 -0800 (PST) Received: from utah.XYLAN.COM by mailhub.xylan.com (SMI-8.6/SMI-SVR4 (mailhub 2.1 [HUB])) id QAA27974; Fri, 26 Mar 1999 16:40:09 -0800 Received: from softweyr.com by utah.XYLAN.COM (SMI-8.6/SMI-SVR4 (xylan utah [SPOOL])) id RAA14723; Fri, 26 Mar 1999 17:40:06 -0700 Message-ID: <36FC28DA.73DC2E28@softweyr.com> Date: Fri, 26 Mar 1999 17:39:54 -0700 From: Wes Peters Organization: Softweyr LLC X-Mailer: Mozilla 4.5 [en] (X11; U; FreeBSD 3.1-RELEASE i386) X-Accept-Language: en MIME-Version: 1.0 To: Mike Jenkins Cc: mm@i.cz, freebsd-net@FreeBSD.ORG Subject: Re: switch vs bridge (fwd) References: <199903262137.PAA06872@carp.gbr.epa.gov> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Mike Jenkins wrote: > > On Fri, 26 Mar 1999 Martin Machacek wrote: > > Layer 4 switch is a pure marketing bullshit. > > If I understand layer 4 switches correctly, they switch > at the tcp/udp port number layer. To a limited extent, yes. Most "layer 4 switches" implement a very limited version of this. > I could therefore slip > a layer 4 switch between my router and my lan, and program If you have a layer 3 switch, you don't need a router. Just put a wide-area "blade" in the switch and route there. *Good* switches router much faster than routers anyhow. I can't tell you how much faster right now, or I'd have to kill you, but it's MUCH faster. ;^) > it to redirect all incoming 25/tcp smtp connections to a > mail filter host. I supposed you could do that. It's usually used the other way around, to try to provide a crude form of load balancing across mutiple http (i.e.) servers. This turns out to be about as effective as round-robin DNS; a true load balancer would be much more effective. > I find that rather useful. I'm sure > some folks use them for 80/tcp http redirection for web > caching. Well, more likely for bandwidth/performance management and hot failover. > Aren't these useful applicatons? Yes, but the actual features of most of these so-called "layer 4 switches" is so minimal that you'll outgrow them almost immediately, at which time you'd be better off with a REAL load balancer and a less expensive but faster layer 3 switch. > I realize routers can be programmed to do this but who wants > to load down (or misconfigure) the router for this chore. The switch *is* the router, unless you've just got balls of money you're aching to get rid of. If so, call me. We can work together on this. ;^) > A dual-homed unix box such as FreeBSD can also do this using > redirection in packet filtering but that usually requires > splitting the network into 2 IP networks (yes i've heard > of dummynet/bridge but that is work in progress). I think > a network appliance like a layer 4 switch would be the right > tool for the job. The you either don't understand the job, or don't understand the (very limited) capabilities of these so-called layer 4 switches. It's not that it's a bad idea, just that there are a couple of vendors out there giving the idea a bad name with their implementations. -- Where am I, and what am I doing in this handbasket? Wes Peters +1.801.915.2061 Softweyr LLC wes@softweyr.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message