A badly chosen root bridge could certainly affect data flow. Imagine two
switches which have separate equal paths to a root bridge through many other
switches, but also a connection between them. The connection between them
may well be blocked, because it is not their least cost path to the root
bridge.
Now a device connected to one of the switches needs to get to its default
gateway which is connected to the other switch.
The un-blocked path in this case may be all the way down to the root bridge
and back.
So I'd say yes, a well placed root bridge can help with data flow.
Anyone feel free to pick at the above and chuck it back at me.
Gaz
""Farhan Ahmed"" wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> u wrote
>
> The selection of the root
> > bridge and which interfaces are blocking might not be optimized for all
> the
> > applications and devices in the large, switched network.
> >
> > With per-VLAN spanning tree, each VLAN becomes a single spanning tree
with
> > its own root bridge and own set of blocked ports. This way you can
> optimize
> > traffic flow and reduce the amount of work to converge to a spanning
tree.
>
> my question
>
> does the root bridge helps in data path flow...? i dont think so..
> also if u can define the data flow in the network
> with and without vlan
>
> regards
>
>
> have a good day!!
>
> fa
>
> ----- Original Message -----
> From: "Picciani Francesco Saverio"
> To:
> Sent: Tuesday, August 07, 2001 5:09 PM
> Subject: R: vtp, spanning tree [7:14961]
>
>
> > I thing that the main benefit of having per-VLAN spanning tree is that a
> > problem on a VLAN does not impact the other VLANs also if they lay on
the
> > same ISL trunk.
> >
> > -----Messaggio originale-----
> > Da: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]]
> > Inviato: lunedl 6 agosto 2001 20.05
> > A: [EMAIL PROTECTED]
> > Oggetto: Re: vtp, spanning tree [7:14961]
> >
> >
> > At 02:13 PM 8/5/01, Cisco Troubleshooter wrote:
> > >can any body tell,
> > >
> > >why we need spanning tree protocol per vlan
> >
> > If you have a large, switched network, all the switches are in the same
> > spanning tree. Converging the spanning tree can take a long time. In
> > addition, traffic flow may not be optimized. The selection of the root
> > bridge and which interfaces are blocking might not be optimized for all
> the
> > applications and devices in the large, switched network.
> >
> > With per-VLAN spanning tree, each VLAN becomes a single spanning tree
with
> > its own root bridge and own set of blocked ports. This way you can
> optimize
> > traffic flow and reduce the amount of work to converge to a spanning
tree.
> > It's somewhat analogous to dividing a routed network into areas or
> > autonomous systems.
> >
> > Also, at least with Catalyst 1900 switches, if you allow all VLANs to
> > travel across both trunks, you will have a loop. If you don't configure
> > per-VLAN spanning tree, you will have a broken network. You would think
> > spanning tree would just work around this problem, but it doesn't seem
to
> > when VLANs are configured.
> >
> >
> > >and vtp why it is needed what purpose it serves
> >
> > VTP is a management protocol that allows switches to share information
> > about VLAN names and IDs. It reduces configuration because you can
> > configure VLAN names and IDs on just one or two server switches. The
rest
> > of the switches act as clients and pick up the info when they boot.
> >
> > By default, the switches do not keep track of which switches have which
> > VLANs configured, however. I disagree with the other responder who said
> VTP
> > reduces bandwidth usage on links and switches. It's VTP pruning that
does
> > that.
> >
> > If you configure VTP pruning, then an added VTP message gets sent. The
> > added message includes VLAN membership information. With VTP pruning,
the
> > switches become a bit smarter and do not forward traffic for a VLAN
across
> > a link or to a switch that has no ports in that VLAN. This must be
> > configured. Without pruning, VTP just shares info about VLAN names and
> IDs.
> >
> > Priscilla
> >
> >
> > >thnx in advance
> > >
> > >jd
> > >
> > >__________________________________________________
> > >Do You Yahoo!?
> > >Make international calls for as low as $.04/minute with Yahoo!
Messenger
> > >http://phonecard.yahoo.com/
> > ________________________
> >
> > Priscilla Oppenheimer
> > http://www.priscilla.com
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=15126&t=14961
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