D-Link DES-3350SR Standalone Layer 3 Switch
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Troubleshooting STP
Spanning Tree Protocol Failure
A failure in the STA generally leads to a bridging loop. A bridging loop in an STP environment comes from a port that should be
in the blocking state, but is forwarding packets.
In this example, B has been elected as the designated bridge and port 2 on C is in the blocking state. The election of B as the
designated bridge is determined by the exchange of BPDUs between B and C. B had a better BPDU than C. B continues sending
BPDUs advertising its superiority over the other bridges on this LAN. Should C fail to receive these BPDUs for longer than the
MAX AGE (default of 20 seconds), it could start to transition its port 2 from the blocking state to the forwarding state.
It should be noted: A port must continue to receive BPDUs advertising superior paths to remain in the blocking state.
There are a number of circumstances in which the STA can fail – mostly related to the loss of a large number of BPDUs. These
situations will cause a port in the blocking state to transition to the forwarding state.
Summary of Contents for DES-3350SR
Page 1: ...D Link DES 3350SR Standalone Layer 3 Switch User s Guide...
Page 80: ...D Link DES 3350SR Standalone Layer 3 Switch 70 Figure 7 57 The Client...
Page 138: ...D Link DES 3350SR Standalone Layer 3 Switch 128 Click Apply to implement changes made...
Page 160: ...D Link DES 3350SR Standalone Layer 3 Switch 150 Figure 10 33 PIM Neighbor Table...
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