From: Chris Home (clarson52@comcast.net)
Date: Sat Jul 12 2003 - 13:43:03 GMT-3
If you have one vlan on each access switch with an uplink to 2 cores there
will be no "load balancing" of vlans, only fail over abilities on a lyer 2
configuration. With a layer 3 switch like the 3550 or the 6500 running
native, you could make the uplinks from the access switches layer 3 and
configure load balancing capability for the access switch.
----- Original Message -----
From: "Emad" <emad@zakq8.com>
To: "'Larry Letterman'" <lletterm@cisco.com>; <boby2kusa@hotmail.com>;
"'Larson, Chris'" <CLarson@usaid.gov>; <ccielab@groupstudy.com>
Sent: Saturday, July 12, 2003 7:17 AM
Subject: RE: Switching: OT network design
> Dear all,
> What about if I have only one vlan on every edge switch instead of two
> vlans!! How can I achieve load balancing between the edge switch and
> these two core switches!!
>
> -----Original Message-----
> From: Larry Letterman [mailto:lletterm@cisco.com]
> Sent: Friday, July 11, 2003 11:44 PM
> To: 'Emad '; boby2kusa@hotmail.com; 'Larson, Chris';
> ccielab@groupstudy.com
> Subject: RE: Switching: OT network design
>
> Both vlans are allowed on each trunk..but each trunk will be a
> Root port only for one of the vlans ..based on the root core switch and
> The root secondary core switch for that vlan..so in effect the trunks
> will only
> Carry the vlan data for the vlan that is going to root switch for that
> vlan..
>
>
>
>
> Larry Letterman
> Cisco Systems
>
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Emad
> Sent: Friday, July 11, 2003 1:37 PM
> To: boby2kusa@hotmail.com; 'Larson, Chris'; ccielab@groupstudy.com
> Subject: RE: Switching: OT network design
>
>
> I just have one question,
> All of you stated to have only one vlan is forwarding on each trunk ,
> will that be the default behavior when I configure a trunk on both links
> to the two core switches carrying both vlans and each core is the root
> only for one vlans of the two carried by each trunk , or u are talking
> about trunk pruning but it will not turn the runed vlans to forward when
> one link fails , plz correct me
>
> -----Original Message-----
> From: boby2kusa@hotmail.com [mailto:boby2kusa@hotmail.com]
> Sent: Friday, July 11, 2003 11:30 PM
> To: Larson, Chris; 'Emad '; ccielab@groupstudy.com
> Subject: Re: Switching: OT network design
>
>
>
> for example,
>
> 6509 ----isl/dot1q----4506
> | |
> | isl/dot1q
> |-------isl/dot1q-----4506
>
> Before anyone say that Cat4K does not support ISL, I am assuming that
> the sup is Sup3 or Sup4 which both support ISL and dot1q
>
> The 6509 is the root only one of this port going to 4506 will be
> forwarding for both vlans, so in order to achive load balancing you have
> to make one port going to one 4506 forwarding for that vlan and blockign
> for the other vlan. The same should be done for the other trunk but the
> opposite vlan. I believe you can accomplish by changing the root port
> cost or root port priority for each vlan.
>
> I do not think pruning a vlan on a trunk would make it forward that vlan
> if the other link goes down since it's being pruned.
>
>
> ----- Original Message -----
> From: "Larson, Chris" <CLarson@usaid.gov>
> To: "'Emad '" <emad@zakq8.com>; "Larson, Chris" <CLarson@usaid.gov>;
> <boby2kusa@hotmail.com>; <ccielab@groupstudy.com>
> Sent: Friday, July 11, 2003 1:21 PM
> Subject: RE: Switching: OT network design
>
>
> > Yes both uplinks will be trunked, but one of the vlans will be
> blocked.
> ie.
> > on the uplink to core 1 even would be blocked, but it coudl carry both
> 1
> and
> > 2 (failure of core 2). So they will all be trunked.
> >
> > > -----Original Message-----
> > > From: Emad [SMTP:emad@zakq8.com]
> > > Sent: Friday, July 11, 2003 3:56 PM
> > > To: 'Larson, Chris'; boby2kusa@hotmail.com; ccielab@groupstudy.com
> > > Subject: RE: Switching: OT network design
> > > Importance: High
> > >
> > > Larson
> > > U are right in this point and I already know it , but I don't know
> how
> > > we will treat the two uplinks of the 4000 switch to the two core
> > > switches , will each link carry only one vlan or will be trunk?
> Because
> > > I need redundancy also , if one link or one core switch failed , I
> need
> > > the another link to carry the traffic of both vlans to the another
> core
> > > switch
> > >
> > > Regards
> > >
> > > -----Original Message-----
> > > From: Larson, Chris [mailto:CLarson@usaid.gov]
> > > Sent: Friday, July 11, 2003 10:41 PM
> > > To: 'boby2kusa@hotmail.com'; Emad; ccielab@groupstudy.com
> > > Subject: RE: Switching: OT network design
> > >
> > > If each access layer switch has 2 vlans and a 1 gig uplink to 2 core
>
> > > switches then the simplest thing to do is to make 1 core switch root
> for
> > > 1
> > > of the vlans on each access layer switch and the other core root for
> the
> > > other vlan on each access-layer switch. Etherchannel is not
> appropriate
> > > because etherchannel can only be done to a single switch.
> > >
> > > In the Cisco switching guides they use even and odd vlans as an
> example.
> > > So
> > > for instance if each access switch has consecutive vlans ie.
> > > AccessSwitch1 = Vlan1, Vlan2 AccessSwitch2 = Vlan2, Vlan 3
> > >
> > > Then the config on core 1 is along the lines of
> > >
> > > set spanning root vlan 1,3,5,7,9
> > > set spanning root vlan 2,4,6,8 secondary
> > >
> > > And on Core 2
> > >
> > > set spanning root vlan 2,4,6,8
> > > set spanning root vlan 1,3,5,7,9
> > >
> > >
> > >
> > > Then you will "load balance" across both uplinks from each closet
> switch
> > > to
> > > the core.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: boby2kusa@hotmail.com [SMTP:boby2kusa@hotmail.com]
> > > > Sent: Friday, July 11, 2003 3:22 PM
> > > > To: Emad ; ccielab@groupstudy.com
> > > > Subject: Re: Switching: OT network design
> > > >
> > > > ----- Original Message -----
> > > > From: "Emad " <emad@zakq8.com>
> > > > To: <ccielab@groupstudy.com>
> > > > Sent: Friday, July 11, 2003 11:49 AM
> > > > Subject: Switching: OT network design
> > > >
> > > >
> > > > > Folks,
> > > > >
> > > > > I just wanna share an idea with you all ,
> > > > >
> > > > > I have 4506 switch in a network acting as the access layer and
> > > connected
> > > > > to two 6513 core switches with 2G uplink per each one,
> > > > >
> > > > > Each 4506 switch has 2 vlans and I want to have both uplinks to
> the
> > > core
> > > > > switches working in load balance , how can we guarantee that:
> > > > >
> > > > > - By STP layer2 load balance? If yes , plz tell me how?
> > > > Do you mean load balance the traffic thoughput between the 2 gig
> > > uplinks
> > > > or
> > > > load balance the switches load?
> > > > Load balancing between the 2 gig link can be accomplished by
> > > channeling
> > > > the
> > > > uplinks. Load balancing the the switch's load (for a lack of a
> better
> > > > term)
> > > > can be accomplished by having the one or the other as the bridge
> to
> > > the
> > > > root
> > > > (which should be the 6509). For example, 2 vlans, vlan 1 will be
> > > > forwarding on 4506 A while blocking the vlan 2 and vice versa for
> > > > the other
> > > switch.
> > > > This would be manipulating either the RP cost or the RP priority,
> > > somebody
> > > > will correct me if this is the wrong way to manipulate which
> switch
> > > should
> > > > the vlan take on it's way to the root.
> > > >
> > > > > - By enabling routing protocol between the access layer and the
> core
> > > > > layer , but how?
> > > > This would be load balancing on layer 3 and you would load balance
>
> > > > according to the destination of the traffic, routers look at the
> > > > routing
> table
> > > to
> > > > forward the packet.
> > > >
> > > > >
> > > > > I read the good paper of CISCO AVVID network infrastructure but
> I
> > > didn't
> > > > > get it because most of scenarios are depending on one vlan and
> > > > > redundancy between the two uplinks not load balancing and 2
> vlans,
> > > > >
> > > > > Plz advice
> > > > >
> > > > > Thanx
> > > > >
> > > > >
> > > > >
> > >
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> > >
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