EtherChannels are for aggregate bandwidth, but a pair of EtherChannels can
give you the ability to load-balance. You just have to do as you said about
load balancing before, and put priorities on the respective VLans you want
to direct in which direction of your EtherChannel setup. An example being
that you have Vlans 1-6. Set the priority high for the first 3 vlans to go
over EtherChannel A with lower priority for the other three vlans, and then
set the priority high for the last 3 vlans on EtherChannel B while setting
the priority low for the first 3 vlans. The Vlans that have low priority
will be automatically put into standby mode (better known as blocking
state via STP).
This configuration also lends to the factor or redundancy in your network.
If one of the EtherChannels goes down for some reason, all Vlans are still
able to function because of the fail over of vlans by priority. STP would
recognize one of the primary (high priority vlan) channels as disabled, and
immediately start allowing all vlans to traverse the other channel.
I think though, to answer the original posters' question, what he needs to
do, is either implement the configuration I've described above for
redundancy sake, or simply specify what specific vlans he wants to traverse
each channel to the respective uplink switches, while removing all other
vlans.
PVST is a feature of ISL Trunks, rather than EtherChannels. It runs by
default for each VLan you specify to be allowed on the Trunk. With PVST,
you have to specify Root Port, Root Bridge, Path Costs, and Priorities for
each Vlan. To make the trunk worth the effort, it would need to be on
Gigabit uplinks, as you can't put multiple ether-ports into a single trunk-
that's why they have EtherChannel :)
Hope this clears any confusion.
Good luck Rico.
Mark Odette II
CCNA, 3/4 CCNP, MCSE 4.0/2000, A+ certified
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Tribavan Raina
Sent: Sunday, December 02, 2001 5:27 PM
To: [EMAIL PROTECTED]
Subject: RE: Per vlan Spanntree On Gigabit ether channel. [7:27933]
The thing is to understand the principle behind VLAN load balancing and
etherchannel.In VLAN Load balance you load balance VLANs on trunks which are
not etherchanneled and in case you do etherchannel then you dont need to do
VLAN Load balance,
In vlan load balance you give either high port priority to make it forward
Traffic for that VLAN so which means if you have 2 trunks you can have 5
vlans on 1 trunk and 5 on other trunk.The
disadvantage is that in case there is not much traffic in the first 5 vlans
and there is high traffic in other 5 vlans ,the 2nd trunk becomes congested
and the 1st trunk is slightly used.
Thus it is better to do etherchanneling in which the traffic is distributed
properly and is also recommended by cisco.
May be soembody proves me wrong..
this is all what cisco says.,
regds
tribavan
-Original Message-
From: Washington Rico [mailto:[EMAIL PROTECTED]]
Sent: Sunday, 2 December 2001 2:53 p.m.
To: [EMAIL PROTECTED]
Subject: Per vlan Spanntree On Gigabit ether channel. [7:27933]
As always thank for you for your input and ideas Cisco people.
Situation: I have 3 Cat 6500's (Cat A,Cat B, Cat C) Cat A and B are the
main backbone and have a Gigabit Channel between then. Cat A and B's
MSFC's are routing and each MSFC has a priority routing for a vlan and HSRP
for fail over routing.
Cat C is in the same VTP domain as Cat A and B and Cat C is the only one
which will be using FlexWan card. Cat C has a 2 pairs of Gigabit Channels
one to Cat A and the other to Cat B.
I want to control specific Vlans on the Gigabit channels from Cat C.
Example. Gigabit channel from Cat C to Cat A.. Can I use Per val Spanning
tree and make that channel priority to a vlan which is routing though Cat
A's MSFC. I also, want to do this for the Gigabit ether channel goto up to
Cat B.
Question: Is there a way to use per vlan spanning tree on Gigabit ethernet
Channels?
Thank for all you help...
Rico
_
$B$+$o(B
$B;H$($k%V%i%%6$G!%$%s%?!%M%C%H@83h$b$C$H3Z$7$/$J$k!*(B
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Message Posted at:
http://www.groupstudy.com/form/read.php?f=7i=27967t=27933
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