From: Larson, Chris (CLarson@usaid.gov)
Date: Fri Jul 11 2003 - 16:40:58 GMT-3
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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