Date: Tue, 21 Dec 1999 23:35:07 -0700 From: Wes Peters <wes@softweyr.com> To: Garance A Drosihn <drosih@rpi.edu> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Cool little 100BaseTX switch - they're coming down in price Message-ID: <3860711B.A9098FE3@softweyr.com> References: <199912190410.UAA01049@apollo.backplane.com> <385C789C.DD290597@softweyr.com> <v04210104b484a826ab4b@[128.113.24.47]> <385F2FFD.CA594829@softweyr.com> <v04210105b485c93d9930@[128.113.24.47]>
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Garance A Drosihn wrote: > > At 12:45 AM -0700 12/21/99, Wes Peters wrote: > >Garance A Drosihn wrote: > > > [...] but I was wondering how much one has to fork out before you > > > get extra options like a port-mirroring capability... > > > >Lots more, in terms of dollars. For this, you need at least a managed > >switch, and probably a smart switch. I know for a fact this one, [...] > > >For more info about both, see: > > > >http://www.ind.alcatel.com/enterprise/products/omnistack/ost04.html > > > >Note that these are "Layer 3" switches with VLAN support, IP and IPX routing, > >etc. The per-port prices aren't that different than the simpler managed > >switches, but the port count tends to be high. > > Thanks for all the replies. I should have mentioned that I'm thinking of > this as an "office switch". I have a 10baseT connection coming into my > office (you might ask "why?"-- I know I do!), but several machines in > here which can do 100baseT. I figured that with a switch I can at least > get faster connections between my own machines, and keep all my intra-office > traffic off the 10baseT leg at the same time. > > The upshot of this is that the 80-port options that some people have > mentioned are probably a bit overkill for my office... :-) Yeah. You should see some of the monsters we have in the test lab. 256 ports of switched 10/100 in one chassis. You should see the price tag, too. ;^) > >Caveat: I work on these things daily. Consider whatever I say about them > >to be evangelism. Also note that turning on software-dependent features > >like port mirroring can do terrible things to your throughput if not used > >judiciously. > > My idea was to take the 10baseT connection coming into my office (the > other end of which is on a hub, not a switch...), and mirror it to a > port on a machine which isn't used for much. That way I could use > that machine to do tcpdump's of the traffic on the 10baseT subnet, > even though all the traffic between office machines will be on the > switch. Sounds like I'd be better off financially to have a simple > 10baseT hub, and plug both an unmanaged switch and my spare machine > into that hub. > > But if I were to go with a managed switch, what is it that you're > warning me about? If I mirror all the 10baseT traffic on the port > for my spare machine, will that effect the throughput to just my > spare machine (which is fine by me), or will it also slow down > throughput between machines on other ports of the switch? In the Xylan architecture -- I assume others are similar -- all of the traffic on the mirrored port has to be handled in software instead of the switching hardware. This is handled by the processors in the network interface, or "blade." Trying to mirror too many ports will overwhelm the interface processor and slow down the mirrored ports. Ports that are still being switched by the hardware will be unaffected. Getting a small 8-port switch and a cheap hub would be a LOT less expensive. -- "Where am I, and what am I doing in this handbasket?" Wes Peters Softweyr LLC wes@softweyr.com http://softweyr.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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