Maybe I am slow this Friday morning, but I still do not see the light.
If we forget about them being three VLAN's on one switch, let's instead say
they are three LAN's - one on each switch. You would now connect those three
switches to the router with a cable per switch - thus using three cables. On
the other side of the router we only had one VLAN, so we just forget about
the VLAN and make it a LAN which then only need one switch, and thus only
one cable to the router.
What we have now is four switches - each in a separate LAN, that are
interconnected via the router.
If we say that the three LAN's are in building A and the fourth LAN are in
building B, and the router we could place in the parking garage. We would
now need three cables from the router to building A and one cable from the
router to building B.
So far, so good.
It would make sense to connect the first three switches to each other and
separate the LAN's by making VLAN's instead (we are now getting back to the
original plot). The switch in building B only has one LAN, so we would only
need to make one VLAN over there.
Now, why should I suddenly have to run three cables instead of only one
between the router and the switch in building B???
Thanks for your comments (and time) on this,
Ole
~~~~~~~~~~~~~~~~~~~~~~~~~~
Ole Drews Jensen
Systems Network Manager
CCNA, MCSE, MCP+I
RWR Enterprises, Inc.
[EMAIL PROTECTED]
~~~~~~~~~~~~~~~~~~~~~~~~~~
-----Original Message-----
From: Dinesh B [mailto:[EMAIL PROTECTED]]
Sent: Friday, September 15, 2000 10:12 AM
To: Ole Drews Jensen; 'Scott Nelson'; '[EMAIL PROTECTED]'
Subject: RE: BCMSN: Inter VLAN communication
Hi
In the first scenario, the book explains the setup without ISL being
configured, and hence each one of the 3 VLANs need a separate link to
communicate to VLAN60. Only when ISL is configured , your argument holds
good.
Hope this clears your doubt.
Regds
--- Ole Drews Jensen <[EMAIL PROTECTED]> wrote:
> A little bit Scott, but the first scenario shows it without trunking:
>
> (this should be viewed with a fixed font)
>
> [SWITCH] [ROUTER] [SWITCH]
> [vlan10]----------[ ]----------[vlan20]
> [vlan11]----------[ ]----------[ ]
> [vlan12]----------[ ]----------[ ]
>
> This I believe is wrong, since it should only need one physical
> connection
> between the router and the second switch (to the right) - like this:
>
> [SWITCH] [ROUTER] [SWITCH]
> [vlan10]----------[ ]----------[vlan20]
> [vlan11]----------[ ] [ ]
> [vlan12]----------[ ] [ ]
>
> The purpose of the router is to route from one network to another, and
> if
> you would send data from a workstation on vlan11 to a workstation on
> vlan20,
> it should go via the cable connected to the port on the first switch
> that is
> assigned to vlan11. In the router it would be routed to vlan20 which
> should
> only have one connection from that switch.
>
> If you (or anyone else) disagree, please let me know why.
>
> Thanks,
>
> Ole
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> Ole Drews Jensen
> Systems Network Manager
> CCNA, MCSE, MCP+I
> RWR Enterprises, Inc.
> [EMAIL PROTECTED]
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> -----Original Message-----
> From: Scott Nelson [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, September 14, 2000 6:08 PM
> To: '[EMAIL PROTECTED]'
> Subject: Re: BCMSN: Inter VLAN communication
>
>
> > I have just started reading about devices on different VLAN's
> communicating
> > with eachother via a Router.
> >
> > The thing I find odd (page 190/191 in Karen Webb's book) is the
> following:
> >
> > Three (3) VLAN's are configured on the first switch, and one (1) VLAN
> is
> > configured on the second switch.
>
> On the first switch, there are 3 VLANs that are configured to go to 3
> interfaces on the first router and on the 2nd switch, it could be using
> ISL
> or 802.1q trunking to a second router. You don't need 3 separate
> interfaces
> when you are doing trunking as long as the switch and the router can do
> ISL
> or 802.1q or whatever proprietary protocol you want to use for trunking,
> both have to speak the same trunking language.
>
> Does that clear it up a little?
>
> Scott
>
>
>
> > The first switch has three physical connections to the router, which
> makes
> > sense, but the second switch has three physical connections to the
> router
> > too, which doesn't make sense (to me at least).
> >
> > The way I see it, is that a VLAN would be (in theory) similar to a
> physical
> > LAN, so if I change the three (3) VLAN's on one switch to three
> switches
> > with one VLAN each, I would have one physical connection from each
> switch
> to
> > the router, and one physical connection from the second, or in this
> case
> the
> > fourth switch to the router.
> >
> > I know that I will probably know the answer to this if I just finish
> the
> > chapter, but I hate not being sure about the information that the rest
> of
> > the information is related to.
> >
> > Can someone clarify that for me?
> >
> > Thanks,
> >
> > Ole
> >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Ole Drews Jensen
> > Systems Network Manager
> > CCNA, MCSE, MCP+I
> > RWR Enterprises, Inc.
> > [EMAIL PROTECTED]
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> >
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>
> ----------------------------------------------------------
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