I'm trying to figure out the appropriate spanning tree protocol settings for a redundant network topology I'm in the process of implementing. The graphic demonstrates what the physical layer will look like(everything in question is labeled accordingly). I'm running all dell powerconnect series switches(2848's & 6224's).
R1 R2 | | | | | | RSW1---RSW2 /\ X /\ / \/ \/ \ | /\ /\ | | / | \ | | / ESW3 \ | |/ \| ESW1 ESW2
- R1-2 are routers setup for high availability
- RSW1-2(6224's) are root bridge switches
- ESW1-3(2848's) are network endpoints and do not directly connect to one another
My intention with this design is to have redundant root/core switches to include redundant router interfaces. In reality, there are 9 ESW* switches, but I scaled it down in my graphic for simplicity.
In order for STP to work efficiently in this design I would need to set the bridge priority to the lowest possible value, let's say 4096, on RSW1 and set the 2nd lowest bridge priority on RSW2 to 8192.
Now, is it necessary to set the switches bridge priority for ESW1-3 in increments of 4096 starting from 12288 or can I set 12288 for all ESW* switches? It seems inefficient/wasteful having to configure a unique bridge priority for ESW1-3 when they are only endpoints. If RSW1-2 both failed then each ESW* would delegate itself as the root bridge switch because it'll see that it's the only lowest bridge priority accessible. I just want to make sure there isn't any complications or gotcha's with that setup.
My next question pertains to the powerconnect STP port settings. Majority of the ports on ESW1-3 are strictly server nodes and not additional network endpoints. Would it be better to:
- disable STP for the ports connected to servers, leaving enabled for network appliances connected to the switch(e.g. additional routers/smaller switches)
- enable fast link+root guard on the ports connected to servers, but disable fast link with root guard enabled for network appliances
My last question, for optimal performance of STP are there settings you can suggest(similar to the above question) for the ESW# <-> RSW# ports? In reality they are vlan trunked LAG ports.
Let me know if you need any clarification. I appreciate any suggestions.