The building block method works in the campus. The access layer switches are
layer-2 devices. The distribution layer switches have routing capabilities
(either built-in such as a RSM or router-on-a-stick.) The core may be
layer-2 or layer-3. See Cisco LAN Switching by Clark and Hamilton Chapters
14 & 15. Pages 630-637 particularly.
VLANs exist in each Switch Block. The routing function provides for
communication between VLANs in the block. Each switch block has its own VTP
domain. If the core is layer-2, the connecting links are access links not
trunks. Therefore VTP information will not traverse the links to other
Switch Blocks. (Clark p539)
Communication between Switch Blocks is at layer-3 between/among the
Distribution switches of the various blocks.
> -----Original Message-----
> From: Leigh Anne Chisholm [mailto:[EMAIL PROTECTED]]
> Sent: Friday, September 07, 2001 9:59 PM
> To: [EMAIL PROTECTED]
> Subject: RE: Question about Cisco's Hierarchical Model [7:19069]
>
>
> Chuck, that's an excellent point. I've been thinking in
> terms of Campus
> core, but Daniel Cotts reference applies to an Enterprise
> core. And I think
> what he had to offer definitely works. If that's what Cisco
> meant, then
> does that mean that the hierarchical model only applies to enterprise
> networks and not campus environments?
>
> I've been thinking campus core because the beginning of "The
> Building Block
> Approach" section of the BCMSN courseware talks about network building
> blocks being "any one of the following fundamental campus elements or
> contributing variables. Campus Elements: Switch block, Core Block".
>
> They're talking about a campus network environment--and in
> that type of
> situation, I don't quite see how to terminate VLANs at the
> distribution
> layer.
>
>
> -- Leigh Anne
>
> PS. Where's Howard? I wonder if he's got any input on this. He's
> definitely a design guru!
>
> > -----Original Message-----
> > From: Chuck Larrieu [mailto:[EMAIL PROTECTED]]
> > Sent: Friday, September 07, 2001 8:35 PM
> > To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
> > Subject: RE: Question about Cisco's Hierarchical Model [7:19069]
> >
> >
> > Leigh Anne, suppose we were to distinguish between a
> "campus core" and
> > "enterprise core"?
> >
> > I have a campus of several buildings, and servers /
> services distributed
> > across them. VLAN's across this "campus core" make perfect sense.
> >
> > OTOH, even with centralized servers / services in corporate
> data centers,
> > VLAN's across multiple campus locations make no sense.
> >
> > I'm trying to get at a clarification of what is meant by
> "core" in your
> > question.
> >
> > Saw another post on another topic, but which might be
> relevant. Maybe you
> > could bridge across your core?
> >
> > Naw. Back to the coal mines.
> >
> > Chuck
> >
> > -----Original Message-----
> > From: Leigh Anne Chisholm [mailto:[EMAIL PROTECTED]]
> > Sent: Friday, September 07, 2001 7:26 PM
> > To: Chuck Larrieu; [EMAIL PROTECTED]
> > Subject: RE: Question about Cisco's Hierarchical Model [7:19069]
> >
> >
> > Yes, a single device can represent the core and distribution
> > layers. That's
> > your typical collapsed core. However, what of a link between two
> > collapsed
> > core devices. If it's not a trunk link, how does it carry
> traffic that
> > originated in a VLAN? How do you truly terminate the VLAN at the
> > distribution layer?
> >
> > I've got an idea, but I just can't solidify all the pieces
> currently.
> >
> > I eagerly await Tony's answer.
> >
> >
> > -- Leigh Anne
> >
> > > -----Original Message-----
> > > From: Chuck Larrieu [mailto:[EMAIL PROTECTED]]
> > > Sent: Friday, September 07, 2001 8:15 PM
> > > To: Leigh Anne Chisholm; [EMAIL PROTECTED]
> > > Subject: RE: Question about Cisco's Hierarchical Model [7:19069]
> > >
> > >
> > > got a link to a diagram, LA?
> > >
> > > seriously, recall that core and distribution do not have
> to be separate
> > > devices. your 4006's terminate on the gigabit cards on your
> > > 6513's, and the
> > > MLS module does the routing on your core?
> > >
> > > Tony M will have a practical answer to this one, BTW. I happen
> > to know he
> > > was intimately involved with just this kind of issue with a
> > > certain company
> > > in Sacrapimento. :->
> > >
> > > Chuck
> > >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of
> > > Leigh Anne
> Chisholm
> > > Sent: Friday, September 07, 2001 6:55 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Question about Cisco's Hierarchical Model [7:19069]
> > >
> > >
> > > I've been going through the BCMSN course and I'm a bit baffled on
> > > how to do
> > > something. There's the statement that:
> > >
> > > Because VLANs terminate at the distribution device, core links
> > > are not trunk
> > > links and traffic is routed across the core.
> > >
> > > What I'm puzzled by is how to terminate a VLAN at the
> > distribution layer.
> > > What am I missing here?
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