Araknis Spanning Tree

Araknis Spanning Tree

By default Spanning Tree, is enabled in Araknis 210 and 310 switches, but the Root Bridge is usually an overlooked element. 

Spanning Tree Protocol (STP) is a Layer 2 protocol that decides the best path for LAN traffic when multiple options exist, preventing network loops while guaranteeing redundancy in case of link failure. STP data from each switch is aggregated into a logical map of the LAN, with values assigned to each device and each link between. The most central switch in the LAN becomes the root bridge, which manages the spanning tree configuration for the network. Then, for any redundant links, the path with the lowest calculated cost is selected and the others are blocked.

The root bridge of the spanning tree is the bridge with the smallest (lowest) bridge ID. Each bridge has a configurable priority number and a MAC address; the bridge ID is the concatenation of the bridge priority and the MAC address. For example, the ID of a bridge with priority 32768 and MAC 0200.0000.1111 is 32768.0200.0000.1111. The bridge priority default is 32768 and can only be configured in multiples of 4096.

What will be affected on the network if I'm experiencing a network loop or a Broadcast Storm?
You may notice control system latency when sending commands, slow or no traffic in part or all of the LAN, and/ or switch port activity LED indicators flashing wildly or staying on solid.

How can I see if Spanning Tree is the problem?
To check the Root Bridge status, access the switch that is required to be the root. 
Advanced > STP > Global Settings
      Root Bridge Information>Root Address – MAC address of currently-elected root bridge device. 
      Basic Setting>Bridge Address – MAC address of the switch you are currently logged into


If the fields do not match, then the core switch is not the root bridge, meaning that STP may be causing issues. This means the problem device either has a smaller priority value or a lower MAC address. Devices known to cause Spanning Tree issues, are Sky Q and Sonos.

If the root bridge is mismatched, look for the port the device is connected to via its MAC address, which can be traced and found via the MAC address table of each switch on site. Disconnect this device, and refresh the page on the core switch and check if the Root Bridge is now showing the correct information. 
This can help confirm of a Spanning Tree Issue.

Best practice is to set the core switch as a Root Bridge by setting the priority to 4096. Click apply, and reboot the network switch(s) then check that the root bridge information is correct. You can then log into other switches you have on site and check they are seeing the core switch as the Root Bridge. 

Best configuration
Spanning Tree Protocol (STP) is a Layer 2 protocol that decides the best path for LAN traffic when multiple options exist, preventing network loops while guaranteeing redundancy in case of link failure. STP data from each switch is aggregated into a logical map of the LAN, with values assigned to each device and each link between. The most central switch in the LAN becomes the root bridge, which manages the spanning tree configuration for the network. Then, for any redundant links, the path with the lowest calculated cost is selected and the others are blocked.


Customize Bridge Priority Settings - The easiest way to avoid most STP issues. 
Core Managed Switch – Set Priority. This will ensure that another system such as sonos or Sky Q won’t become the root bridge by mistake.
Additional Managed Switches – Use differing Priority values to force the order in which switches would take over as the root bridge in case of failure. Especially important when you have redundant links between switches.

Sky Q Spanning Tree
Sky Q systems are turning to wired and wireless Ethernet for media distribution, using a master device to communicate with secondary slave devices throughout the location. The master device behaves as a switch to control communication and relies on spanning tree features to work correctly. Problems occur because of the way the spanning tree algorithm selects the root bridge for the LAN. Sky Q uses the same default bridge priority setting as Araknis (32768), which means the device with the lowest MAC address will be selected. Since Sky has been in business longer than Araknis, all of their MAC addresses are lower than Araknis MAC addresses.

Solution
The solution to this is to force the core switch as the Root by lowering this priority

Sonos Spanning Tree
Sonos is equipped with a standalone, wireless mesh network called SonosNet that links all in-range wireless Sonos devices (that aren’t connected to a Wi-Fi SSID). SonosNet uses STP to prevent redundant links between SonosNet devices. Sonos suggests using a single hardwired link between the LAN and the Sonos system, and under these conditions, STP works correctly. However, when multiple Sonos devices are hardwired to different network switches, STP for the LAN may no longer behave correctly, resulting in issues. This is due to either incorrect STP settings in network switches, or because Sonos is connected to equipment that does not support STP, such as the Araknis router.

Solutions
1.      Lower the priority of the core switch and force it to be the root bridge. 
2.      Minimize the number of hardwired Sonos devices. If remote devices won’t stay connected to SonosNet, try moving them to the Wi-Fi network. 
3.      Daisy-chain hardwired connections between Sonos devices instead of connecting to the switch. (Only works with Sonos models equipped with two LAN ports.)  4.      Connect all hardwired Sonos equipment to one Araknis switch (not the router). This should eliminate any LAN issues caused by Sonos. Even unmanaged 100 and 110 series switches may be used.

For further Spanning Tree configuration, its recommended to check the CIST setting. You can find configurations instructions at : https://desk.zoho.com/portal/aldoussystems/en/kb/articles/araknis-spanning-tree-procedure



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