From: Barra, Keith (KBarra@sequoianet.com)
Date: Fri Nov 28 2003 - 19:42:08 GMT-3
I believe that the following configuration would preserve full duplex capability between all switches.
Setup all connections between the switches using full duplex point-to-point connections.
For example:
Switch#1/GBIC#1 attaches to Switch#2/GBIC#1 (This forms a single point-to-point connection)
Switch#2/GBIC#2 attaches to Switch#3/GBIC#1 (This forms another point-to-point connection)
To paraphrase the documentation on the following link.......
http://www.cisco.com/en/US/products/hw/switches/ps607/products_tech_note09186a00800a2cac.shtml
"One switch can have multiple point-to-point connections with neighbors as long as you are only using one per port on separate GigaStacks to neighboring switches" (The documentation does not state that the presence of multiple GS modules in a chassis forces the Half-duplex shared medium condition only)
This will allow full-duplex (2 GB) connections between all of the switches in a stack.
If the last switch in the stack was then connected to the first switch.....For Example:
Switch#3/GBIC#2 attaches to Switch#1/GBIC#2. (This would complete the loop using a point-to-point connection)
Either the connection between Switch#3/GBIC#2 and Switch#1/GBIC#2 or the connection between Switch#1/GBIC#1 and Switch#2/GBIC#1 would be shut down by spantree until it was needed in case of failure of the primary link.
There are still major limitations to this type of a setup if it grows past three switches due to the fact that traffic from the fourth or fifth switch will have to flow through other switche(s)to get to the target switch. That's why Cisco recommends that a full star topology based on an aggregation switch and point-to-point links from each switch back to the aggregation switch be used.
See the following link:
http://www.cisco.com/en/US/products/hw/switches/ps646/products_data_sheet09186a00800a1789.html
Keith Barra
Senior Network Engineer
CCIE #12547
ANALYSTS
INTERNATIONAL
Sequoia Services Group - Auburn Hills, Mi
Direct (248) 373-4391
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Email: Kbarra@Analysts.com <mailto:Kbarra@Analysts.com>
-----Original Message-----
From: P729 [mailto:p729@cox.net]
Sent: Friday, November 28, 2003 2:08 PM
To: Kenneth Wygand
Cc: ccielab@groupstudy.com
Subject: Re: Gigastacks & Clustering
You are correct. As soon as the Gigastack grows beyond two switches it
essentially becomes a shared half-duplex medium, albeit with
"point-to-point" capability (think of it as an Ethernet bus with the ARP
tables pre-populated). Beware of the shared characteristic if you are
considering running QoS-sensitive traffic across the stack, as it's not
advisable.
Regards,
Mas Kato
https://ecardfile.com/id/mkato
----- Original Message -----
From: "Kenneth Wygand" <KWygand@customonline.com>
To: "Jason Buszta" <groupstudy@buszta.com>; "Kelly, Russell G"
<Russell_Kelly@eu1.bp.com>
Cc: <ccielab@groupstudy.com>
Sent: Friday, November 28, 2003 10:07 AM
Subject: RE: Gigastacks & Clustering
> Jason,
>
> Thanks and I agree with you. However, each Gigastack module has 2 ports,
so only a single gigastack module is required for each switch, even if
running in a complete redundant loop topology.
>
> Someone please correct me if I am wrong?
>
> Thanks,
> Ken
>
> -----Original Message-----
> From: Jason Buszta [mailto:groupstudy@buszta.com]
> Sent: Fri 11/28/2003 12:35 PM
> To: Kelly, Russell G
> Cc: Kenneth Wygand; ccielab@groupstudy.com
> Subject: RE: Gigastacks & Clustering
>
>
>
>
>
> I also believe that if you connect two switches to a single gigastack
> module the GBIC-Gigastack will run them both in half-duplex. You should
> spend the extra money and on the switch that completes the loop put dual
> GBIC-Gigastacks in it.
>
>
>
>
>
> On Fri, 28 Nov 2003, Kelly, Russell G wrote:
>
> > -----Original Message-----
> > From: Kenneth Wygand [mailto:KWygand@customonline.com]
> > Sent: 28 November 2003 16:14
> > To: ccielab@groupstudy.com
> > Subject: Gigastacks & Clustering
> >
> >
> > Hello and hope everyone had a great Thanksgiving...
> >
> > I am going to be "gigastacking" several switches together but I can't
> > find too much configuration information on Cisco.com for doing this.
> > All I found was a document that said to configure the gigastack
> > interface as a trunk.
> >
> > If more than one vlan exists across the stack then yes, the gig
> > interface needs to be configured as a trunk.
> >
> > I've also looked into switch "clustering". Are "clustering" and
> > "gigastacking" mutually exclusive?
> >
> > Yes they are mutually exclusive. Gigastacking is just uplinking
> > switches, whilst clustering is a convenient way of a single point of
> > management for a whole load of switches.
> >
> > Do you have to cluster if you gigastack switches? -No.
> >
> > I know a switch cluster is a single managed unit across all switches,
> > but I really want to manage each switch individually but to leverage the
> > gigastacking capability. Is this possible? - Yes this is possible just
> > assign each switch an IP (with the clustering too). I have done this to
> > allow HP Openview to monitor each switch individually. A few issues
> > around TACACS+ access to a switch that is not the cluster commander but
> > each switch can be managed/monitored separately
> >
> >
> > Does anyone have any more information on this and/or any documents you
> > can point me to in order to clarify these differences?
> >
> > Thanks in advance,
> > Ken
> >
> > _______________________________________________________________________
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