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 http://explorer.msn.co.jp/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=27967&t=27933 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
