Netgear XCM8810 Chassis User Manual - Page 522

NETGEAR 8800 User Manual 65,535 and was not subject to the multiple of 4,096 restriction (except for MSTP configurations). The default bridge priority remains the same at 32,768. If you have a switch that contains an STP or RSTP bridge priority that is not a multiple of 4,096, the switch rejects the entry and the bridge priority returns to the default value while loading the structure. The MSTP implementation in XCM8800 already uses multiples of 4,096 to determine the bridge priority. To configure the bridge priority, use the following command: configure stpd priority For example, to lower the numerical value of the priority (which gives the priority a higher precedence), you subtract 4,096 from the default priority: 32,768 - 4,096 = 28,672. If you modify the priority by a value other than 4,096, the switch automatically changes the priority to the lower priority value. For example, if you configure a priority of 31,000, the switch automatically changes the priority to 28,672. Port Priority The port priority value is always paired with the port number to make up the 16-bit port identifier, which is used in various STP operations and the STP state machines. Unlike the 802.1D-1998 standard, the 802.1D-2004 standard uses only the four most significant bits for the port priority and it must be a multiple of 16. The new priority range available is 0 to 240 and is subject to the multiple of 16 restriction. The 802.1D-1998 standard uses the eight most significant bits for the port priority. The old priority range was 0 to 31 and was not subject to the multiple of 16 restriction. To preserve backward compatibility and to use 802.1D-1998 configurations, the existing configure stpd ports priority command is available. When you save the port priority value, the switch saves it as the command configure stpd ports port-priority with the corresponding change in value. For example, if the switch reads the configure stpd ports priority 16 command, (which is equivalent to the command configure stpd ports priority 8 entered through CLI), the switch saves the value as configure stpd ports port-priority 128. Edge Port Behavior In XCM8800, NETGEAR had two edge port implementations: edge port and edge port with safeguard. The 802.1D-2004 standard has a bridge detection state machine, which introduced a third implementation of edge port behavior. The following list describes the behaviors of the different edge port implementations: • Edge port: • The port does not send BPDUs • The port does not run a state machine • If BPDUs are received, the port discards the BPDU and enters the blocking state • If subsequent BPDUs are not received, the port remains in the forwarding state • Edge port with safeguard configured: 522 | Chapter 18. STP