Oh it was! :-)
One of the R&D people wanted to be able to access his test server from his
desktop machine. When we told him "No!" he decided to get creative. Our boy
decided to do this while I was out of town at the Las Vegas Networkers.
They had the network crashing 3-4 times/day the entire time I was gone.
I knew there was a good reason I left my pager and cell at home. :-)
At least they won't do it again. Maybe now they'll believe me when I tell
them that what they want is a bad thing... Of course, this person was the
genius who used a sniffer to get the enable password on the switches and
decided to look around. He swears that he didn't change anything but
trunking got turned off and the SC0 interface VLAN got changed _somehow_.
After all that, I'm surprised they let him live.
Anyway, it's more like this:
<switch>
/ \
<switch> <switch>
| |
VLAN 100 VLAN 200
\ /
<hub>
Karen E Young
Network Engineer
ELF Technologies, Inc
[EMAIL PROTECTED]
Brian
<signal@shrev To: [EMAIL PROTECTED]
e.net> cc: [EMAIL PROTECTED]
Subject: Re: Connecting Switches, hubs..
07/27/00
03:15 PM
On Thu, 27 Jul 2000 [EMAIL PROTECTED] wrote:
>
> Since we seen to be doing the Spanning Tree simulations today... Imagine
> what happens when you have two instances of STP running, one per VLAN on
> VLAN 100 and VLAN 200, and then hook both VLAN 100 and VLAN 200 to the
same
> hub. :-)
if you just had it like this:
/---------Hub----------\
| |
| |
vlan 100 vlan 200
then I don't think it would be too bad since I don't see where a storm
could happen. But if you had like this:
/---------Hub----------\
| |
| |
vlan 100 vlan 200
| |
| |
\----switch/hub--------/
then that would be pretty evil
>
> Have fun! <evil grin>
>
> Karen E Young
> Network Engineer
> ELF Technologies, Inc
> [EMAIL PROTECTED]
>
>
>
>
>
> Brian
> <signal@shrev To: Marc Quibell
<[EMAIL PROTECTED]>
> e.net> cc: [EMAIL PROTECTED]
> Sent by: Subject: Re: Connecting
Switches, hubs..
> nobody@groups
> tudy.com
>
>
> 07/27/00
> 07:40 AM
> Please
> respond to
> Brian
>
>
>
>
>
> On Thu, 27 Jul 2000, Marc Quibell wrote:
>
> > 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.
>
> correct.
>
> >
> > 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...
> >
>
> but broadcasts going out port 1 will still goto port 2 (which isn't
> itself), and vice versa. With no STP, this would create looping.
>
> Brian
>
>
> >
> > >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)
> > >MIME-Version: 1.0
> > >Received: from [208.206.76.23] by hotmail.com (3.2) with ESMTP id
> > >MHotMailBB48D86F008DD820F3DAD0CE4C17101E0; Wed Jul 26 18:16:32 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
> > >UAA13766;Wed, 26 Jul 2000 20:16:32 -0500
> > >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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> > > > > > Report misconduct and Nondisclosure violations to
> > >[EMAIL PROTECTED]
> > > > > >
> > > > >
> > > > >--
> > > > >-----------------------------------------------
> > > > >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)
> > >
> >
> >
________________________________________________________________________
> > 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)
>
> ___________________________________
> UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
> FAQ, list archives, and subscription info: http://www.groupstudy.com
> Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
>
>
>
>
> ___________________________________
> UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
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> Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
>
-----------------------------------------------
Brian Feeny, CCNA, CCDA [EMAIL PROTECTED]
Network Administrator
ShreveNet Inc. (ASN 11881)
___________________________________
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
