General Cisco Managed Switch Settings

These are settings that were configured for a Cisco SG300-52 managed switch that played the role of the Root Bridge for the Sonos network. Even while the following parameters are derived from the SG300-52 settings, they may be adapted to switch hardware of other vendors, too.

Global Settings:

• Spanning Tree State: Enable
• STP Operation State: Classic STP
• BPDU Handling: Flooding
• Path Cost Default Values: Short

Bridge Settings:

• Priority: 4096
• Hello Time: 2
• Max Age: 20
• Forward Delay: 15

STP Interface Settings:

For each network port with a player being connected, the following settings apply:

• STP: Enable
• Edge Port: Auto
• Root Guard: Disable
• BPDU Guard: Disable
• BPDU Handling: Use Global Settings
• Path Cost: User Defined 10
• Priority: 128

All other network devices that don't participate in the Sonos player spanning tree may be set up like this:

• STP: Enable
• Edge Port: Auto
• Root Guard: Disable
• BPDU Guard: Disable
• BPDU Handling: Use Global Settings
• Path Cost: Use Default
• Priority: 128

Typically  "STP: Enable" or "STP: Disable" *do* work for all non Sonos ports.

Cisco does not suggest disabling the STP option on single switch ports because "non-network experienced people" may use those ports and then have difficulty diagnosing loop and broadcast storm issues quickly.

IGMP snooping should be enabled with Multicast filtering enabled, to lower the overall network load.

Multicast Settings:

• Bridge Multicast Filtering Status: Enable VLAN ID: your ID - e.g. 1
• Forwarding method for IPv4/v6: MAC Group Address
• IGMP Snooping Status: Enable

Make sure that your router provides support for Multicast traffic pass through and has implemented an IGMP querier - e.g. IGMP v2 compatible.

You don't have to elect an available IGMP querier by yourself. This will be done by the Multicast handling network devices (router, switches) automatically.

Concerning the Cisco SG300-52 switch hardware it's absolutely essential that you disable (and apply) the "Spanning Tree State" after you've done changes to the "STP Interface Settings" and enable (and apply) "Spanning Tree State" again, or the spanning tree won't be rebuilt and run correctly. 

Here are the settings of a CISCO SF-200-24 with almost the same STP Settings:

Global Settings

• Spanning Tree State: Enable
• STP Operation State: Classic STP
• BPDU Handling: Flooding
• Path Cost Default Values: Short 

Bridge Settings

• Priority: 4096*       
• Hello Time: 2
• Max Age: 20
• Forward Delay: 15
  
  *The Sonos Root Bridge has the Bridge Priority 8000 anything with a lower value as in this example the switch with 4096 will take over the role of the Sonos Root Bridge, this makes sense when more than 50 % of the devices are wired to this switch the default value is 32768