STP does not work with hubs. It only works in a completly switched network.
Hubs do not run STP, hence the switch does not get BDPU's from the hub and
does not recognize the non-STP connected ports in order to put the port into
to a mode such as blocking mode.
That said, let's say you do have 2 switch ports (1&2) connected to a same
hub. A broadcast occurs, which comes in on ports 1&2, but since a switched
port does not return traffic to the source port, the broadcasts coming in on
ports 1&2 will not get re-broadcasted back onto themselves...
>From: Brian <[EMAIL PROTECTED]>
>To: Marc Quibell <[EMAIL PROTECTED]>
>CC: [EMAIL PROTECTED]
>Subject: Re: Connecting Switches, hubs..
>Date: Wed, 26 Jul 2000 20:16:32 -0500 (CDT)
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>From [EMAIL PROTECTED] Wed Jul 26 18:21:17 2000
>In-Reply-To: <[EMAIL PROTECTED]>
>Message-ID: <[EMAIL PROTECTED]>
>
>On Wed, 26 Jul 2000, Marc Quibell wrote:
>
> > Actaully, I did another test in the lab and the STP has nothing to do
>with
> > hubs, so BOTH switch ports were able to plug into both hub ports, no
> > problem. Now my next question is: Do I now have an aggregate bandwidth
>of
> > 20mbs?
>
>Actually STP is important in your example.
>
>if you have a switch with two ports connected to a hub, say ports 1 and
>5. A broadcast sent to port 5, will come back into the switch on port
>1. Since switches forward broadcasts, it will go back out port 5, and
>back in port 1, and this will continue infinitly if STP is not enabled.
>
>In multilayer switching networks, you can actually have your broadcasts
>magnified, and things can get REAL ugly.
>
>Brian
>
>
>
> >
> > TIA!
> >
> > Marc
> >
> >
> > >From: Brian <[EMAIL PROTECTED]>
> > >To: Marc Quibell <[EMAIL PROTECTED]>
> > >CC: [EMAIL PROTECTED]
> > >Subject: Re: Connecting Switches, hubs..
> > >Date: Wed, 26 Jul 2000 12:11:21 -0500 (CDT)
> > >MIME-Version: 1.0
> > >Received: from [208.206.76.23] by hotmail.com (3.2) with ESMTP id
> > >MHotMailBB4866B7003DD82197E9D0CE4C1712E90; Wed Jul 26 10:11:20 2000
> > >Received: from mercury.shreve.net (IDENT:[EMAIL PROTECTED]
> > >[208.206.76.23])by mercury.shreve.net (8.9.3/8.9.3) with ESMTP id
> > >MAA04159;Wed, 26 Jul 2000 12:11:22 -0500
> > >From [EMAIL PROTECTED] Wed Jul 26 10:13:33 2000
> > >Newsgroups: groupstudy.cisco
> > >In-Reply-To: <8lmv6b$do7$[EMAIL PROTECTED]>
> > >Message-ID:
><[EMAIL PROTECTED]>
> > >References: <8lmv6b$do7$[EMAIL PROTECTED]>
> > >
> > >On Wed, 26 Jul 2000, Marc Quibell wrote:
> > >
> > > > I have a simple question, and one which I cannot readily answer at
>this
> > > > time. Can I safely connect TWO switch ports from a Cisco 5509 (two
> > >different
> > > > switch blades) to a hub to increase the hub's crossconnection
>bandwidth,
> > > > without having a looping problem? The hub is actually a DEC
>multi-blade,
> > > > with a swithced backplane. The hub is also connect on two different
> > >blades,
> > > > but the same backplane. TIA!
> > > >
> > > > btw, I have already done this and I figured if spanning tree found a
> > >looping
> > > > problem, it wouldv'e set one of the ports to a non-forwarding
>state..
> > >
> > >Correct, so long as you have STP enabled you are ok.
> > >
> > >Brian
> > >
> > >
> > > >
> > > >
> > > > ___________________________________
> > > > UPDATED Posting Guidelines:
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> > > >
> > >
> > >--
> > >-----------------------------------------------
> > >Brian Feeny, CCNA, CCDA [EMAIL PROTECTED]
> > >Network Administrator
> > >ShreveNet Inc. (ASN 11881)
> > >
> >
> > ________________________________________________________________________
> > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com
> >
>
>--
>-----------------------------------------------
>Brian Feeny, CCNA, CCDA [EMAIL PROTECTED]
>Network Administrator
>ShreveNet Inc. (ASN 11881)
>
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