ZyXEL Communications ES-4024A manual Select a designated port on each segment

ES-4024A Series Switch Support Notes

2.The bridge ID includes two parts, bridge priority (2 bytes) and bridge MAC address (6 bytes). The 802.1d default bridge priority is 32768. For example, a switch with default priority 32768 (8000 hex), MAC address is 00:A0:C5:12:34:56, its bridge ID is 8000:00A0:C512:3456.

3.On the root bridge, all its ports are designated ports. Designated ports are always in the forwarding state. While in forwarding state, a port can receive and send traffic.

2. Select a root port for the non-root bridge

For the non-root switch/bridge, there will be one root port. The root port is the port through which this non-root switch / bridge communicates with the root bridge (the "leaf" side of the "tree").

1.The root port is the port on the non-root bridge with the lowest path cost to the root bridge. The root port is normally in forwarding state.

2.Path cost is the total cost of transmitting a frame on to a LAN through that port to bridge root. It is assigned according to the bandwidth of the link. The slower the media, the higher the cost. Some of the path costs specified in the IEEE 802.1d specification are listed below.

Link Speed

4Mbps

10Mbps

16Mbps

100Mbps

1Gbps

10Gbps

Recommended

Cost

250

100

62

19

4

2

Recommended

Cost Range

100 to 1000

50 to 600

40 to 400

10 to 60

3 to 10

1 to 5

3.When multiple ports have the same path cost to root bridge, the port with lowest port priority is selected as root port.

3. Select a designated port on each segment

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