Chapter 8 Wireless Configuration
NWA-3500/NWA-3550 User’s Guide
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to propagate to the root bridge and unwanted learned addresses are flushed from
the filtering database. In RSTP, the port states are Discarding, Learning, and
Forwarding.
8.5.1.2 STP Terminology
The root bridge is the base of the spanning tree; it is the bridge with the lowest
identifier value (MAC address).
Path cost is the cost of transmitting a frame onto a LAN through that port. It is
assigned according to the speed of the link to which a port is attached. The slower
the media, the higher the cost - see the following table.
On each bridge, the root port is the port through which this bridge communicates
with the root. It is the port on this switch with the lowest path cost to the root (the
root path cost). If there is no root port, then this bridge has been accepted as the
root bridge of the spanning tree network.
For each LAN segment, a designated bridge is selected. This bridge has the lowest
cost to the root among the bridges connected to the LAN.
8.5.1.3 How STP Works
After a bridge determines the lowest cost-spanning tree with STP, it enables the
root port and the ports that are the designated ports for connected LANs, and
disables all other ports that participate in STP. Network packets are therefore only
forwarded between enabled ports, eliminating any possible network loops.
STP-aware bridges exchange Bridge Protocol Data Units (BPDUs) periodically.
When the bridged LAN topology changes, a new spanning tree is constructed.
Once a stable network topology has been established, all bridges listen for Hello
BPDUs (Bridge Protocol Data Units) transmitted from the root bridge. If a bridge
does not get a Hello BPDU after a predefined interval (Max Age), the bridge
assumes that the link to the root bridge is down. This bridge then initiates
negotiations with other bridges to reconfigure the network to re-establish a valid
network topology.
Table 30
STP Path Costs
LINK SPEED
RECOMMENDE
D VALUE
RECOMMENDE
D RANGE
ALLOWED
RANGE
Path Cost
4Mbps
250
100 to 1000
1 to 65535
Path Cost
10Mbps
100
50 to 600
1 to 65535
Path Cost
16Mbps
62
40 to 400
1 to 65535
Path Cost
100Mbps
19
10 to 60
1 to 65535
Path Cost
1Gbps
4
3 to 10
1 to 65535
Path Cost
10Gbps
2
1 to 5
1 to 65535
Summary of Contents for 802.11a/g Wireless CardBus Card ZyXEL AG-120
Page 2: ......
Page 8: ...Safety Warnings NWA 3500 NWA 3550 User s Guide 8...
Page 10: ...Contents Overview NWA 3500 NWA 3550 User s Guide 10...
Page 20: ...Table of Contents NWA 3500 NWA 3550 User s Guide 20...
Page 22: ...22...
Page 34: ...Chapter 1 Introducing the NWA NWA 3500 NWA 3550 User s Guide 34...
Page 52: ...Chapter 4 Management Mode NWA 3500 NWA 3550 User s Guide 52...
Page 108: ...108...
Page 146: ...Chapter 9 SSID Screen NWA 3500 NWA 3550 User s Guide 146...
Page 160: ...Chapter 10 Wireless Security Screen NWA 3500 NWA 3550 User s Guide 160...
Page 178: ...Chapter 14 IP Screen NWA 3500 NWA 3550 User s Guide 178...
Page 186: ...Chapter 15 Rogue AP Detection NWA 3500 NWA 3550 User s Guide 186...
Page 198: ...Chapter 16 Remote Management Screens NWA 3500 NWA 3550 User s Guide 198...
Page 260: ...Chapter 21 Load Balancing NWA 3160 Series User s Guide 260...
Page 264: ...Chapter 22 Dynamic Channel Selection NWA 3160 Series User s Guide 264...
Page 276: ...Chapter 23 Maintenance NWA 3500 NWA 3550 User s Guide 276...
Page 277: ...277 PART III Troubleshooting and Specifications Troubleshooting 279 Product Specifications 285...
Page 278: ...278...
Page 284: ...Chapter 24 Troubleshooting NWA 3500 NWA 3550 User s Guide 284...
Page 292: ...292...
Page 368: ...Appendix D Importing Certificates NWA 3500 NWA 3550 User s Guide 368...
Page 386: ...Appendix F Text File Based Auto Configuration NWA 3500 NWA 3550 User s Guide 386...