I have 2 switch groups.
2 SGE2010's with VLAN's defined as 10,20 and 30
Vlan 10 is the management VLAN, and it uplinks to our border router.
Vlan 20 is the workstation VLAN, and all workstations point to the switch as their default GW
Vlan 30 is the ip phone VLAN, and all phones use this as their gateway.
I would like to put a LAG between said switches, we have some servers on the ip phone switch that need to be accessed by the workstation clients, and the single 100mb link through the router is probably not going to be enough.
As I understand it, because the switches have different networks on them, a simple lag will not work. I did create a lag, and assign ip addresses to each side, however in that mode, it doesn't appear I can block vlan 10 from transiting the LAG, and with out that block I will end up with a logical loop, and spanning-tree will block one of the uplinks, or the LAG itself.
I have attached an image with a diagram of our current set up.
Any help/advice would be much appreciated.
Hi John, the vlan 1 isn't relevant. I think I goofed making the picture is all.
But the same thing applies, there is vlan 10, 20, 30.
Vlan 10 link is 10u and 20t and the other link is 10u, 30t.
The trick is not putting all of the vlans on all the links and the mstp should separate it from there.
John, the original 802.1q standard specifies there is only global spanning tree regardless of the vlan membership. That is why you're running in to problems. Cisco developed PVST to run over ISL trunks. MSTP was originally defined as 802.1S which is a combination of 802.1q + RSTP. The 802.1s was later ammended to become a part of the 802.1q.
The person is incorrect as they quote "since spanning tree is construct per vlan." They are incorrect because you have to define spanning tree properties to allow spanning tree per vlan. The small business switches do not support Cisco proprietary PVST or PVST+. However, the SB switches support MSTP which is an IEEE standard.
How the MSTP works is you have what is called Instance, which is each spanning tree construct. Then you have region, the SB switches support only 1 region. The region maintains the instances. Essentially how it works, you enable the MSTP globally. You then specify the instance. As example, vlan 1 is instance 1. Vlan 2 is instance 2. This will allow you to run 2 physical wire between the switches on different vlan without looping. If you use classic STP or RSTP, the lower cost path will go to block/discard state which is working as intended.