Chapter 11 Spanning Tree Protocol
OLT-1308 Series User’s Guide
112
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 switch 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.
11.1.2 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 switches 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.
11.1.3 STP Port States
STP assigns five port states to eliminate packet looping. A bridge port is not allowed to go
directly from blocking state to forwarding state so as to eliminate transient loops.
11.2 STP Status
Click
Advanced Application
,
Spanning Tree Protocol
in the navigation panel to display the
screen. View current STP status on the switch in this screen.
Refer to
for background information.
Path Cost
1Gbps
4
3 to 10
1 to 65535
Path Cost
10Gbps
2
1 to 5
1 to 65535
Table 29
STP Path Costs (continued)
LINK
SPEED
RECOMMENDED
VALUE
RECOMMENDED
RANGE
ALLOWED
RANGE
Table 30
STP Port States
PORT STATE DESCRIPTION
Disabled
STP is disabled (default).
Blocking
Only configuration and management BPDUs are received and processed.
Listening
All BPDUs are received and processed.
Learning
All BPDUs are received and processed. Information frames are submitted to the
learning process but not forwarded.
Forwarding
All BPDUs are received and processed. All information frames are received and
forwarded.
Summary of Contents for OLT-1308
Page 2: ......
Page 7: ...Safety Warnings OLT 1308 Series User s Guide 7 ...
Page 8: ...Safety Warnings OLT 1308 Series User s Guide 8 ...
Page 28: ...List of Tables OLT 1308 Series User s Guide 28 ...
Page 30: ...30 ...
Page 34: ...Chapter 1 Introducing the OLT OLT 1308 Series User s Guide 34 ...
Page 38: ...Chapter 2 Hardware Installation and Connection OLT 1308 Series User s Guide 38 ...
Page 44: ...44 ...
Page 58: ...Chapter 5 Initial Setup Example OLT 1308 Series User s Guide 58 ...
Page 72: ...Chapter 6 System Status and Port Statistics OLT 1308 Series User s Guide 72 ...
Page 94: ...Chapter 7 Basic Setting OLT 1308 Series User s Guide 94 ...
Page 96: ...96 ...
Page 106: ...Chapter 8 VLAN OLT 1308 Series User s Guide 106 ...
Page 116: ...Chapter 11 Spanning Tree Protocol OLT 1308 Series User s Guide 116 ...
Page 126: ...Chapter 15 Link Aggregation OLT 1308 Series User s Guide 126 ...
Page 132: ...Chapter 17 Queuing Method OLT 1308 Series User s Guide 132 ...
Page 138: ...Chapter 18 Classifier OLT 1308 Series User s Guide 138 ...
Page 143: ...Chapter 19 Policy OLT 1308 Series User s Guide 143 Figure 53 Policy Example ...
Page 144: ...Chapter 19 Policy OLT 1308 Series User s Guide 144 ...
Page 158: ...158 ...
Page 162: ...Chapter 22 Classification Filter Profile OLT 1308 Series User s Guide 162 ...
Page 172: ...Chapter 23 VLAN Profile OLT 1308 Series User s Guide 172 ...
Page 184: ...Chapter 26 Destination Filter OLT 1308 Series User s Guide 184 ...
Page 188: ...Chapter 27 Port Authentication OLT 1308 Series User s Guide 188 ...
Page 190: ...190 ...
Page 200: ...Chapter 29 Maintenance OLT 1308 Series User s Guide 200 ...
Page 212: ...Chapter 30 Access Control OLT 1308 Series User s Guide 212 ...
Page 218: ...Chapter 32 Syslog OLT 1308 Series User s Guide 218 ...
Page 224: ...Chapter 33 Cluster Management OLT 1308 Series User s Guide 224 ...
Page 228: ...Chapter 34 MAC Table OLT 1308 Series User s Guide 228 ...
Page 232: ...Chapter 36 IGMP Table OLT 1308 Series User s Guide 232 ...
Page 234: ...234 ...
Page 285: ...Chapter 38 Command Examples OLT 1308 Series User s Guide 285 ...
Page 286: ...Chapter 38 Command Examples OLT 1308 Series User s Guide 286 ...
Page 294: ...Chapter 39 Troubleshooting OLT 1308 Series User s Guide 294 ...
Page 296: ...296 ...
Page 302: ...Appendix B Legal Information OLT 1308 Series User s Guide 302 ...