The following recommendations apply to Ethernet switches to optimize operation with Avaya endpoints. These recommendations are meant to provide the simplest configuration by removing unnecessary features.

• Enable spanning tree fast start feature or disable spanning tree at the port level. The Spanning Tree Protocol (STP) is a Layer 2 loop-avoidance protocol. When a device is first connected or reconnected to a port that is running spanning tree, the port takes 31 to 50 s to cycle through the Blocking, Listening, and Learning states. This delay is neither necessary nor desired on ports that are connected to IP endpoints. Instead, enable a fast start feature on these ports to put them into the Forwarding state almost immediately. If this feature is not available, you can consider the option of disabling the spanning tree on the port. Do not disable spanning tree on an entire switch or VLAN. Also, Rapid Spanning Tree Protocol (802.1w) is always preferred over STP (802.1D). When using RSTP, the Ethernet switch ports connected to IP phones must be in the Edge-Type mode. This places the port in a fast-start mode. Bridge Protocol Data Unit (BPDU) guard is also desirable if it is available on the Ethernet switch to protect against a loop created through the IP phone.

• Disable the vendor features that are not required. Some vendor features that are not required by Avaya endpoints include EtherChannel/LAG, cdp, and proprietary (not 802.3af) inline power. These features are nonstandard mechanisms that are relevant only to vendor-specific devices and can sometimes interfere with Avaya devices.

• Properly configure 802.1Q trunking on Cisco switches. When trunking is required on a Cisco CatOS switch that is connected to an Avaya IP telephone, enable it for 802.1Q encapsulation in the no-negotiate mode. This causes the port to become a plain 802.1Q trunk port with no Cisco autonegotiation features. When trunking is not required, explicitly disable it.