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If your message was personal or of a "non-urgent" nature, I'll reply as soon as I can. Wayne >>> Erik Auerswald <[email protected]> 11/26/13 03:45 >>> Hi, James, On Tue, Nov 26, 2013 at 10:13:40AM +0800, James Andrewartha wrote: > On 26/11/13 06:13, Geoff Smith wrote: > > I have used both methods and there are advantages and disadvantages to > > each depending on the details of your situation. If all things are equal I > > would recommend using LACP. The primary reason being simplicity of ongoing > > maintenance/management. I had a situation where I needed to add a few more > > VLANS to my network and realised that this would change the hash value of > > my MSTP. I had to create the VLANS on every switch in the MSTP system to > > make it re-converge correctly (even though the VLANS were not required in > > all locations). This all turned out OK in the end but in the process I > > managed to badly break the entire system as the MSTP trees fragmented > > during the process of adding the new VLANS. Luckily I was doing this > > during a maintenance window!!! By contrast adding a new VLAN on a LACP > > system is relatively painless ( just make sure that you egress the new > > VLAN/S on both the LAG port and the underlying physical ports). > > Ahh, I wasn't aware that adding a VLAN would change the MST hash and > cause re-convergence. Given this I might just have my core switches > (which have every VLAN) in the same MSTP region, and will leave the > access switches using LAGs and RST. Moving a VLAN from one instance to another changes the hash. All possible VLANs are allocated to one of the instances -- if you have the default configuration, they are all in instance 0. You could e.g. create two MST instances (SIDs), allocate VLANs 1-2047 to instance 1 and VLANs 2048-4093 to instance 2. When creating a new VLAN you chose the ID from the range of instance 1 or instance 2 for per-VLAN load balancing. The allocation of VLANs to MST instances is independent of the VLANs actually existing on the switches. Anyway, I'd suggest using LAGs instead. Easier operation, perf-flow as opposed to per-VLAN load balancing, automatic instead of manual load balancing. If a single link inside an LAG fails, only two switches are directly affected. If a single link in the spanning tree changes, other switches might need to run the STP algorithm as well. When using LAGs, consider "set lacp singleportlag" _and_ disabling LACP on all ports that are not part of a LAG ("set port lacp port PORTSTRING disable"). (If singleportlag and LACP is enabled on an inter switch link, this link will try to from a LAG. This may happen with LACP capable servers connected to the switch as well.) Best regards, Erik -- Dipl.-Inform. Erik Auerswald http://www.fg-networking.de/ [email protected] T:+49-631-4149988-0 M:+49-176-64228513 Gesellschaft für Fundamental Generic Networking mbH Geschäftsführung: Volker Bauer, Jörg Mayer Gerichtsstand: Amtsgericht Kaiserslautern - HRB: 3630 --- To unsubscribe from enterasys, send email to [email protected] with the body: unsubscribe enterasys [email protected] --- To unsubscribe from enterasys, send email to [email protected] with the body: unsubscribe enterasys [email protected]
