Date: Fri, 26 Mar 1999 17:39:54 -0700 From: Wes Peters <wes@softweyr.com> To: Mike Jenkins <mjenkins@carp.gbr.epa.gov> Cc: mm@i.cz, freebsd-net@FreeBSD.ORG Subject: Re: switch vs bridge (fwd) Message-ID: <36FC28DA.73DC2E28@softweyr.com> References: <199903262137.PAA06872@carp.gbr.epa.gov>
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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
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