From: Chuck Church (ccie8776@rochester.rr.com)
Date: Wed Feb 19 2003 - 17:30:29 GMT-3
There's nothing bad about it. That's how you have redundancy. It's no
worse than letting OSPF pick the path in a full-mesh network It'll always
pick the best path, and not create loops. Same as STP. Sounds like your
managers need to go to a switching class.
Chuck Church
CCIE #8776, MCNE, MCSE
----- Original Message -----
From: "jeff gercken" <jeffgercken@hotmail.com>
To: <ccie8776@rochester.rr.com>
Sent: Wednesday, February 19, 2003 3:03 PM
Subject: Re: OT 6500 Topology question
> All the switches are configured with vtp transparent and only the vlans
that
> are allowed on the switch are configured (nothing to prune). It's my
> understanding that per-vlan STP allows you to do a rudementry load
balancing
> by having 1/2 block on link 1 and the other on link 2. I let the switch
> autoset the timers based on a dia of 2. Root Max Age: 10sec, Hello Time:
> 2sec, Forward Delay: 7 sec. This works great and we've never had a state
> change due to the timers.
>
> My question boils down to why is having a STP blocked loop that horrible?
>
> Thanks,
> Jeff
>
>
>
>
>
>
>
>
>
> >From: "Chuck Church" <ccie8776@rochester.rr.com>
> >To: "jeff gercken" <jeffgercken@hotmail.com>
> >Subject: Re: OT 6500 Topology question
> >Date: Wed, 19 Feb 2003 14:12:17 -0500
> >
> >Jeff,
> >
> > There's very few reasons to not have all switch to switch
connections
> >as
> >trunks. Gives you much more flexibility. Cisco uses per-VLAN spanning
> >tree, so there'll be no loops unless someone gets too aggressive with STP
> >timers. Don't play with the timers, and modify the port costs, and it'll
> >work fine. Trunks (either kind) support COS/QOS, and they'll prune
> >themselves to keep unneeded broadcasts off your trunks.
> >
> >Chuck Church
> >CCIE #8776, MCNE, MCSE
> >
> >
> >----- Original Message -----
> >From: "jeff gercken" <jeffgercken@hotmail.com>
> >To: <ccielab@groupstudy.com>
> >Sent: Wednesday, February 19, 2003 10:40 AM
> >Subject: OT 6500 Topology question
> >
> >
> > > I'm hoping someone can help me understand this. I am a network
engineer
> >for
> > > a gov't facility in Indiana. We have (32) 6509's connected (Gig E) in
> >hub
> > > fashion to two 6509 core switches w/ MSFC's (each having priority of
one
> >of
> > > two hsrp gateways). There are also around 53 vlans configured and
> > > statically trunked to various access-layer switches. Our utilization
is
> > > almost nothing with 'sh traffic' indicating a peak of 5%.
> > >
> > > Vlans that are only on 1 access-layer switch are not trunked between
the
> > > core switches meaning there are no STP blocked lines. The DHCP server
> > > assigns the gateways by round-robin.
> > >
> > > I wanted to move to a topology using uplinkfast and balancing by STP
> > > portvlan priorities. My reasoning was as much for monitoring as for
> > > convergence. Right now I have no idea how the traffic is flowing and
> >trying
> > > to use a sniffer is about impossible.
> > >
> > > I've been overruled by the guys in DC who seem to believe that a STP
> >blocked
> > > link is just as bad as a loop. None will explain their position, just
a
> > > 'because I said so' answer. They also wouldn't let me increase the
core
> > > capacity using etherchannel. Our Cisco NSA Engineer(no, not that NSA)
> >was
> > > down pushing AVID so I took the opportunity to ask. He took the same
> > > position as headquarters but really didn't/couldn't explain why.
> > >
> > > Does any of this make sense to anyone? Would you please help me to
> > > understand because it seems to sacrifice a lot just so you can have 2
> > > gigabit links instead of 1.
> > >
> > > I don't mean to clog up the list with this so please reply directly.
> > >
> > > Thanks in advance,
> > > Jeff
> > >
> > >
> > > _________________________________________________________________
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