How are interface priorities calculated

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The priority of the VGMP group is lowered by 2 only when:
-A physical interface in the VGMP group fails.
-An Eth-Trunk interface in the VGMP group fails. The failure of a member interface of the Eth-Trunk does not affect the priority of the VGMP group.
-A member interface of the VGMP group in a VLAN fails.
-A member interface of an IP-Link fails.

Other related questions:
How is the cost of an OSPF interface calculated
The principles of calculating the cost of an OSPF interface are as follows: The cost configured on the interface is preferred. If no cost is configured on the interface, the formula for calculating the cost of the interface is as follows: Cost = Reference bandwidth/Interface bandwidth. The default reference bandwidth of OSPF is 100 Mbit/s. For example, the cost of a 10 Mbit/s Ethernet interface = 100 Mbits per second/10 Mbits per second = 10. If the calculation result is smaller than 1, the cost is set to 1. For example, the cost of a GE interface is 100 Mbits per second/1000 Mbits per second = 0.1, which is less than 1. Therefore, the cost of this interface is 1. The default cost on the loopback interface, which is a virtual interface, is 0.

What is the function of interface priorities
The port priority command sets the interface priorities, that is, specifies the default priorities of incoming packets on the interface. AR series routers send packets to different queues based on the interface priority. By default, the AR interface does not trust packet priorities. Packets enter queues according to the interface priority.

If all packets enter queues according to the interface priority, all packets on an interface enter the same queue. Differentiated services cannot be provided. Using the trust command, you can specify the priority to be mapped for packets, that is, search for a priority mapping to the packet priority in the priority mapping table. -The AR120&AR150&AR160&AR200&AR500 series and AR1200 series send packets to different interface queues based on the mapped 802.1p priorities, and use the queue scheduling to provide services for packets with different priorities. -On AR2200 series, --From V200R001C00, the device sends packets to different interface queues based on the mapped 802.1p priorities, and use the queue scheduling to provide services for packets with different priorities. --From V200R003C00, the AR2204 or AR2220E sends packets to different interface queues based on the mapped 802.1p priorities, and use the queue scheduling to provide services for packets with different priorities. While the AR2201, AR2202, AR2220, AR2240C and AR2240 send packets to different interface queues based on the mapped local priorities, and use the queue scheduling to provide services for packets with different priorities. -The AR3200&AR3600 series send packets to different interface queues based on the mapped local priorities, and use the queue scheduling to provide services for packets with different priorities.


Configure STP on an interface of the S1728GWR-4P switch
Configure STP on an interface of an S1728GWR-4P switch as follows: 1. Choose Spanning Tree > STP. 2. Select Configure Interface from the Step drop-down list box. 3. Select Configure from the Action drop-down list box. 4. Configure the parameters such as Spanning Tree, Admin Link Type, Priority, and Admin Path Cost. 5. Click Apply.

How to calculate the timeout period of packets on the STP interface
The timeout period of packets on the STP interface can be calculated based on the following formula: hello timer out = hello time * 3 * timer factor By default, the value of hello time is 2s and the value of timer factor is 3s.

Calculating the cost of an OSPF interface on the firewall
Calculating the cost of an OSPF interface on the USG2000&5000&6000 series as follows: The cost configured on the interface is preferred. If no cost is configured on the interface, the formula for calculating the cost of the interface is as follows: Cost = Reference bandwidth/Interface bandwidth. The default reference bandwidth of OSPF is 100 Mbit/s. For example, the cost of a 10 Mbit/s Ethernet interface = 100 Mbits per second/10 Mbits per second = 10. If the calculation result is smaller than 1, the cost is set to 1. For example, the cost of a GE interface is 100 Mbits per second/1000 Mbits per second = 0.1, which is less than 1. Therefore, the cost of this interface is 1. The default cost on the loopback interface, which is a virtual interface, is 0.

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