This command enables the spanning tree operation in the Switch for the selected spanning tree Mode.

Spanning tree operation provides path redundancy while preventing undesirable loops in the network that are created by multiple active paths between stations. It logically breaks such loops and prevents looping traffic from clogging the network.

The no form of this command disables the spanning tree operation in the Switch. The spanning tree operation is automatically enabled in the Switch, once the spanning tree Mode is changed.

The spanning tree operation can be enabled in the Switch only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

spanning-tree

no spanning-tree

This command sets the type of spanning tree to be executed, enables spanning tree operation and starts spanning tree functionality in the Switch. The current selected type of spanning tree is enabled and the existing spanning tree type is disabled in the Switch.

spanning-tree mode {mst|rst}

• mst - Configures the Switch to execute MSTP for preventing undesirable loops. MSTP configures spanning tree on per VLAN basis or multiple VLANs per spanning tree. The Mode cannot be set as mst, if the base bridge Mode is configured as transparent bridging.

• rst - Configures the Switch to execute RSTP for preventing undesirable loops. RSTP provides rapid recovery of connectivity following the failure of a bridge/bridge port or a LAN

This command sets the spanning tree timers such as hello time, that are used for controlling the transmission of BPDUs during the computation of loop free topology.

The no form of this command resets the spanning tree timers to its default values. The spanning tree timers are reset to its default value, even if the spanning tree Mode is changed.

The values configured for the spanning tree timers should satisfy the following conditions:

2 * (forward-time - 1) >= max-age, and max-age >= 2 * (hello-time +1)

The STP timers can be configured in the Switch, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

This spanning tree timer’s configuration is not supported in PVRST Mode.

spanning-tree {forward-time <seconds(4-30)> | hello-time

<seconds(1-2)> | max-age <seconds(6-40)>}

no spanning-tree { forward-time | hello-time | max-age }

• forward-time - Configures the number of seconds, a port waits before changing from the blocking state to the forwarding state. This value ranges between 4 and 30 seconds. In MSTP, this time configuration is applied for IST root (that is, MSTI 0).

• hello-time - Configures the time interval (in seconds) between two successive configuration BPDUs generated by the root Switch. This value should be either 1 or 2 seconds. This value is configured on per-port basis for MSTP and is configured globally for RSTP.

• max-age - Configures the maximum expected arrival time (in seconds) of hello BPDUs. STP information learned from network on any port is discarded, once the configured arrival time expires. The spanning tree topology is re- computed after this time interval. This value ranges between 6 and 40 seconds. In MSTP, this time configuration is applied for IST root (that is, MSTI 0).

This command sets the transmit hold-count value for the Switch. The transmit hold count value is a counter that is used to limit the maximum transmission rate of the Switch and to avoid flooding. This value specifies the maximum number of packets that can be sent in a given hello time interval. This value ranges between 1 and 10.

The no form of this command sets the transmit hold-count to its default value. The transmit hold-count is changed to its default value even if the spanning tree Mode is changed.

The transmit hold-count value can be configured in the Switch, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

spanning-tree transmit hold-count <value (1-10)>

no spanning-tree transmit hold-count

• hold-count - This value specifies the maximum number of packets that can be sent in a given hello time interval. This value ranges between 1 and 10.

This command configures the priority value that is assigned to the Switch.

The no form of this command resets the priority to its default value. The priority value is changed to its default value even if the spanning tree Mode is changed.

In RSTP, this value is used during the election of root. In MSTP, this value is used during the election of CIST root, CIST regional root and IST root.

The priority value can be configured in the Switch, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

spanning-tree [mst <instance-id>] priority <value(0-61440)>

no spanning-tree [mst <instance-id(1-64)>] priority

• mst <instance-id> - Configures the ID of MSTP instance already created in the Switch. This value ranges between 1 and 64. The special value 4094 can be used only in the Switch that supports PBB-TE. This special value represents PTETID that identifies VID used by ESPs. This option is applicable, only if the spanning tree Mode is set as mst.

• priority <value(0-61440)> - Configures the priority value for the Switch and for the MSTI, in RSTP and MSTP respectively. This value ranges between 0 and 61440. The value should be set in steps of 4096, that is, you can set the value as 0, 4096, 8192, 12288 and so on.

This command configures the forward timer of the spanning tree and the no form of the command sets the forward timer to the default value. The forward timer controls the speed at which a port changes its spanning tree state from Blocking state to Forwarding state. The timer value ranges between 4 and 30 seconds.

The values configured for the spanning tree forward timers should satisfy the following conditions:

2* (forward-time - 1) >= max-age, and max-age >= 2 * (hello- time +1)

This command is a standardized implementation of the existing command; spanning-tree timers. It operates similar to the existing command.

The STP forward timers can be configured in the Switch, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

spanning-tree mst forward-time <seconds(4-30)>

no spanning-tree mst forward-time

This command configures the max-age timer of the spanning tree.The max-age timer denotes the time (in seconds) after which the spanning tree protocol information learnt from the network on any port will be discarded. The timer value ranges between 6 and 40 seconds.

The no form of the command sets the max-age timer to the default value.

The values configured for the spanning tree forward timers should satisfy the following conditions:

2* (forward-time - 1) >= max-age, and max-age >= 2 * (hello- time +1)

This command is a standardized implementation of the existing command; spanning-tree timers. It operates similar to the existing command.

The STP forward timers can be configured in the Switch, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

spanning-tree mst max-age <seconds(6-40)>

no spanning-tree mst max-age

This command configures the spanning tree hello time.

The no form of this command resets the hello time to its default value.

The hello time represents the time interval (in seconds) between two successive configuration BPDUs generated by the Switch on the port. This value is either 1 or 2 seconds. This value is applied to all active MSTIs.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set as mst.

spanning-tree mst hello-time<value(1-2)>

no spanning-tree mst hello-time

This command deletes all bridge and port level spanning tree statistics information.

For RSTP, the information contains number of:

• Transitions to forwarding state

• RSTP BPDU count received / transmitted

• Config BPDU count received / transmitted

• TCN BPDU count received / transmitted

• Invalid BPDU count transmitted

• Port protocol migration count

For MSTP, the information contains number of:

• Port forward transitions

• Port received BPDUs

• Port transmitted BPDUs

• Port invalid BPDUs received

• Port protocol migration count

• BPDUs sent / received for each MSTI

The statistics information can be deleted, only if the spanning tree functionality is not shutdown in the Switch. The type of

spanning tree Mode should be set, if the functionality is already shutdown.

clear spanning-tree [mst <instance-id>] counters[interface

<interface-type> <interface-id>]

• mst <instance-id>] - Clears the statistical counters specific to the MSTP instance already created in the Switch. This value ranges between 1 and 64. This option is applicable, only if the spanning tree Mode is set as mst.

• interface - Clears all port-level spanning-tree statistics information for the given port.

  • <interface-type> - Clears all port-level spanning-tree statistics information for the specified type of interface. The interface can be:

    • gigabitethernet - A version of LAN standard architecture that supports data transfer upto 1 Gigabit per second.

    • port-channel - Logical interface that represents an aggregator which contains several ports aggregated together.

• <interface-id> - Clears all port-level spanning-tree statistics information for the specified interface identifier. This is a unique value that represents the specific interface. This value is a combination of slot number and port number separated by a slash. For Example: 0/1 represents that the slot number is 0 and port number is 1. Only port-channel ID is provided, for interface type port-channel. For Example: 1 represents port-channel ID.

This command configures the maximum number of active MSTIs that can be created. This value ranges between 1 and 64.

The no form of this command resets maximum MSTP instance value to its default value.

This command can be executed successfully, only if the spanning tree functionality is started and enabled in the Switch. The type of spanning tree Mode should be set as mst.

spanning-tree mst max-instance <short(1-64)>

no spanning-tree mst max-instance

This command enables BPDU (Bridge Protocol Data Unit) transmission and reception on the interface.

This command is a standardized implementation of the existing command; spanning-tree priority. It operates similar to the existing command.

The no form of the command disables BPDU transmission and reception on the interface.

This command executes only if:

• instance is created
• spanning tree Mode is set as mst.

spanning-tree mst {instance-id <instance-id(1-64)>} root

{primary | secondary}

no spanning-tree mst {instance-id <instance-id(1-64)>} root

• instance-id <instance-id(1-64)> - Configures the ID of MSTP instance already created in the Switch. This value ranges between 1 and 64. This option is applicable, only if the spanning tree Mode is set as mst.

• primary - Sets high enough priority (low value) for the Switch so that the Switch can be made as the bridge root of the spanning-tree instance. The priority value is set as 24576.

• secondary - Sets the Switch as a secondary root, if the primary root fails. The priority value is set as 28672.

This command enters into MSTP configuration Mode, where instance specific and MST region configuration can be done.

This command can be executed successfully, only if the spanning tree functionality is started and enabled in the Switch. The type of spanning tree Mode should be set as mst.

spanning-tree mst configuration

This command configures the name for the MST region.

The name is unique and used to identify the specific MST region. Each MST region contains multiple spanning tree instances and runs special instance of spanning tree known as IST to disseminate STP topology information for other STP instances.

The no form of this command resets the name to its default value.

name <string(32)>

no name

This command configures the revision number for the MST region. This value ranges between 0 and 65535.

The no form of this command resets the revision number to its default value.

revision <value(0-65525)>

no revision

This command creates an MST instance and maps it to VLANs.

The no form of this command deletes the instance / unmaps specific VLANs from the MST instance.

instance <instance-id(1-64)> vlan <vlan-range>

no instance <instance-id (1-64)> [vlan <vlan-range>]

This command enables automatic detection of Edge port parameter of an interface.

The no form of this command disables automatic detection of Edge port parameter of an interface. The automatic detection of Edge port parameter is disabled, even if the spanning tree Mode is changed.

Once automatic detection is enabled, the Edge port parameter is automatically detected and set. The port is set as edge port, if no BPDU is received on the port. The port is set as non-edge port, if any BPDU is received.

The automatic detection of Edge port parameter can be configured in the Switch, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

spanning-tree auto-edge

no spanning-tree auto-edge

This command configures the port related spanning tree information for all kinds of STPs. This can be applied for any port, in RSTP/MSTP Mode. This command creates port in STP when Automatic Port Create feature is disabled. The no form of this command resets the port related spanning tree information to its default value. The port related spanning tree information is changed to its default value even if the spanning tree Mode is changed. This command also deletes port in STP when Automatic Port Create feature is disabled.

In STP module, whenever a port is mapped to any context, the corresponding port is created irrespective of whether STP is intended to be enabled on that interface. This leads To STP scaling issues and this problem is solved by having control at STP module on the port entry creation at STP module itself.

spanning-tree [{cost <value(0-200000000)>|disable|link- type{point-to-point|shared}|port-priority <value(0-240)>}]

no spanning-tree [{cost |disable|link-type|port-priority}]

• cost <value(0-200000000)> - Configures the port’s path cost value that contributes to the path cost of paths containing this particular port. The paths’ path cost is used during calculation of shortest path to reach the root. The path cost represents the distance between the root port and designated port. This value ranges between 1 and 200000000. The configured path cost is used, even if the dynamic pathcost calculation feature or LAGG speed feature is enabled.

• disable - Disables the spanning tree operation on the port. The port does not take part in the execution of spanning tree operation for preventing undesirable loops in the network.

• link-type - Configures the link status of the LAN segment attached to the port. The options available are:

  • point-to-point - The port is treated as if it is connected to a point-to-point link.

  • shared - The port is treated as if it is using a shared media connection.

  • port-priority – (0-240) - Configures the priority value assigned to the port. This value is used during port role selection process. This value ranges between 0 and 240. This value should be set in steps of 16, that is, you can set the value as 0, 16, 32, 48, and so on. The MSTP puts the interface with lowest number in forwarding state and blocks all other interfaces, if all interfaces have the same priority value. Default value of port priority is 128.

This command configures the port related spanning tree information for a specified MSTI in a port.

The no form of this command resets the spanning tree information of a port to its default value.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set as mst.

spanning-tree mst <instance-id(1-64)> { cost <value(1- 200000000)>| port-priority <value(0-240)> | disable }

no spanning-tree mst <instance-id(1-64)>{cost|port-priority | disable}

• <instance-id(1-64)> - Configures the ID of MSTP instance already created in the Switch. This value ranges between 1 to 64.

• cost<value(1-200000000)> - Configures the port’s path cost value that contributes to the path cost of paths containing this particular port. The paths’ path cost is used during calculation of shortest path to reach the root. The path cost represents the distance between the root port and designated port. This value ranges between 1 and 200000000. The configured path cost is used, even if the dynamic pathcost calculation feature or LAGG speed feature is enabled.

• port-priority<value(0-240)> - Configures the priority value assigned to the port. This value is used during port role selection process. This value ranges between 0 and 240. This value should be set in steps of 16, that is, you can set the value as 0, 16, 32, 48, and so on. The MSTP puts the interface with lowest number in forwarding state and blocks all other interfaces, if all interfaces have the same priority value.

• disable - Disables the spanning tree operation on the port. The port does not take part in the execution of spanning tree operation for preventing undesirable loops in the network.

This command displays spanning tree related information available in the Switch for the current STP enabled in the Switch.

The information contain priority, address and timer details for root and bridge, status of dynamic pathcost calculation feature, status of spanning tree function, STP compatibility version used, configured spanning tree Mode, bridge and port level spanning tree statistics information, and details of ports enabled in the

Switch. The port details contain port ID, port role, port state, port cost, port priority and link type.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

show spanning-tree [{ summary | blockedports | pathcost method }] [ switch <context_name>]

• summary - Displays the currently used STP, applied path cost method and port details such as port ID, port role, port state and port status.

• blockedports - Displays the list of ports in blocked state and the total number of blocked ports.

• pathcost method - Displays the port pathcost method configured for the switch.

• switch <context_name> - Displays the STP related information in the Switch, for the specified context. This value represents unique name of the Switch context. This value is a string with the maximum size as 32. This parameter is specific to multiple instance feature.

This command displays detailed spanning tree related information of the Switch and all ports enabled in the Switch.

The information contains status of spanning tree operation, current selected spanning Mode, current spanning tree compatibility version, bridge and root priority, bridge and root addresses, port path cost, port priority, port timers, bridge and port level spanning tree statistics information, transmit hold- count value, link-type, and status of L2GP, loop guard, BPDU receive, BPDU transmit, restricted TCN, restricted role and portfast features.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

show spanning-tree detail [ switch <context_name>]

• switch <context_name> - Displays detailed spanning tree related information, for the specified context. This value represents unique name of the Switch context. This value is a string with the maximum size as 32. This parameter is specific to multiple instance feature.

This command displays spanning tree related information available in the Switch for the current STP enabled in the Switch.

The information contains priority, address and timer details for root and bridge, status of dynamic pathcost calculation feature, status of spanning tree function, STP compatibility version used, configured spanning tree Mode, bridge and port level spanning tree statistics information, and details of ports enabled in the Switch. The port details contain port ID, port role, port state, port cost, port priority and link type.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

show spanning-tree active [detail] [ switch <context_name>]

• detail - Displays detailed spanning tree related information of the Switch and all ports enabled in the Switch. The information contains status of spanning tree operation, current selected spanning Mode, current spanning tree compatibility version, bridge and root priority, bridge and root addresses, port path cost, port priority, port timers, bridge and port level spanning tree statistics information, transmit hold-count value, link-type, and status of L2GP, loop guard, BPDU receive, BPDU transmit, restricted TCN, restricted role and portfast features.

• switch <context_name> - Displays spanning tree related information available in the Switch, for the specified context. This value represents unique name of the Switch context. This value is a string with the maximum size as 32. This parameter is specific to multiple instance feature.

This command displays the port related spanning tree information for the specified interface.

The information contains port ID, port role, port state, port cost, port priority and link type.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

show spanning-tree interface <interface-type> <interface-id> [{ cost | priority | portfast | rootcost | restricted-role | restricted-tcn | state | stats | detail }]

• <interface-type> - Displays the port related spanning tree information for the specified type of interface. The interface can be:

  • gigabitethernet - A version of LAN standard architecture that supports data transfer upto 1 Gigabit per second.

  • port-channel - Logical interface that represents an aggregator which contains several ports aggregated together.

• <interface-id> - Displays the information about the specified interface identifier. This is a unique value that represents the specific interface. This value is a combination of slot number and port number separated by a slash. For Example: 0/1 represents that the slot number is 0 and port number is 1. Only port-channel ID is provided, for interface type port-channel. For Example: 1 represents port-channel ID.

• cost - Displays the cost of the port or instances assigned to that port.

• priority - Displays the priority of the port or instances assigned to that port.

• rootcost - Displays the root cost of the port or instances assigned to that port. The root cost defines the pathcost to reach the root bridge.

• state - Displays the state of the port.

• stats - Displays the port level spanning tree statistics information.

• detail - Displays detailed spanning tree related information for the port. The information contains current selected spanning Mode, bridge and root priority, bridge and root addresses, port path cost, port priority, port timers, bridge and port level spanning tree statistics information, link-type, and status of L2GP, loop guard, BPDU receive, BPDU transmit, restricted TCN, restricted role and portfast features.

• Portfast - Enabling the PortFast feature causes a Switch or a trunk port to enter the STP forwarding-state immediately or upon a linkup event.

• restricted-role - Enables the root-guard feature on the interface.

• restricted-tcn - Enables the BPDU-guard feature on the interface.

This command displays the spanning tree root information. The information contain root ID, root path cost, maximum age time, forward delay time and root port, for the RSTP. The information also contains the instance ID for MSTP.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

show spanning-tree root [{ address | cost | forward-time | id | max-age | port | priority | detail }] [ switch <context_name>]

• address - Displays the MAC address of the root bridge.

• cost - Displays the cost of the root bridge.

• forward-time - Displays the forward delay time of the root bridge.

• id - Displays the ID of the root bridge.

• max-age - Displays the maximum age time of the root bridge.

• port - Displays the ID of the root port.

• priority - Displays the priority of the root bridge.

• detail - Displays the root priority, root address, root cost, root port, forward delay time and maximum age time.

• switch <context_name> - Displays spanning tree root information, for the specified context. This value represents unique name of the Switch context. This value is a string with the maximum size as 32. This parameter is specific to multiple instance feature.

This command displays the spanning tree bridge information. The information contain bridge ID, hello time, maximum age time, forward delay time and protocol enabled, for the RSTP.

The information also contains the instance ID for MSTP.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set, if the functionality is already shutdown.

show spanning-tree bridge [{ address | forward-time | hello- time | id | max-age | protocol | priority | detail }] [ switch <context_name>]

• address - Displays the MAC address of the bridge.

• forward-time - Displays the forward delay time of the bridge.

• hello-time - Displays the hello time of the bridge.

• id - Displays the ID of the bridge.

• max-age - Displays the maximum age time of the bridge.

• protocol - Displays the protocol currently enabled in the bridge.

• priority - Displays the priority of the bridge.

• detail - Displays the priority, address, maximum age time and forward delay time for the bridge.

• switch - Displays spanning tree bridge information, for the specified context. This value represents unique name of the Switch context. This value is a string with the maximum size as 32. This parameter is specific to multiple instance feature.

This command displays multiple spanning tree information for all MSTIs in the Switch.

The information contain MSTI ID, VLAN IDs mapped to the instance, bridge address and priority, root address and priority, IST root address, priority and path cost, forward delay, maximum age, maximum hop count, and port details of interfaces enabled in the Switch. The port details contain interface ID, port role, port state, port cost, port priority and port link type.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set as mst.

show spanning-tree mst [<instance-id(1-64)>] [detail] [ switch <context_name>]

• <instance-id(1-64)> - Displays the multiple spanning tree information for the specified MSTI. This value ranges between 1 to 64.

• detail - Displays the detailed multiple spanning tree information for the MSTI. This information contain MSTI ID, VLAN IDs mapped to the instance, bridge address and priority, root address and priority, IST root address, priority and path cost, forward delay, maximum age, maximum hop count, and BPDUs sent and received in the port.

• switch<context_name> - Displays multiple spanning tree bridge information, for the specified context. This value represents unique name of the Switch context. This value is a string with the maximum size as 32. This parameter is specific to multiple instance feature.

This command displays multiple spanning tree instance related information. This information contains the MST region name, MST region revision, and a list containing MSTI IDs and VLAN IDs mapped to the corresponding MSTI.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set as mst.

show spanning-tree mst configuration [ switch <context_name>]

• switch <context_name> - Displays multiple spanning tree instance related information, for the specified context. This value represents unique name of the Switch context. This value is a string with the maximum size as 32. This parameter is specific to multiple instance feature.

This command displays multiple spanning tree port specific information for the specified port. This information contain interface ID, edge port status, port link type, port hello time,

BPDUs sent and received on the port, and instance related details. The instance details contain MSTI ID, MSTI role, MSTI status, MSTI cost and MSTI priority.

This command can be executed successfully, only if the spanning tree functionality is not shutdown in the Switch. The type of spanning tree Mode should be set as mst.

show spanning-tree mst [<instance-id(1-64)>] interface <interface-type> <interface-id> [{ stats | hello-time | detail }]

• <instance-id(1-64)> - Displays the multiple spanning tree port specific information for the specified MSTI. This value ranges between 1 to 64.

• <interface-type> - Displays the port related spanning tree information for the specified type of interface. The interface can be:

  • gigabitethernet - A version of LAN standard architecture that supports data transfer upto 1 Gigabit per second.

  • port-channel - Logical interface that represents an aggregator which contains several ports aggregated together

• <interface-id> - Displays the information about the specified interface identifier. This is a unique value that represents the specific interface. This value is a combination of slot number and port number separated by a slash. For Example: 0/1 represents that the slot number is 0 and port number is 1. Only port-channel ID is provided, for interface type port-channel. For Example: 1 represents port-channel ID.

• stats - Displays the number of BPDUs sent and received for the MSTIs assigned to the specified interface.

• hello-time - Displays the hello time of the MSTIs assigned to the specified interface.

• detail - Displays detailed multiple spanning tree port specific information for the specified interface. The information contain port priority, port cost, root address, priority and cost, IST address, priority and cost, bridge address, priority and cost, forward delay, maximum age, maximum hop count, and BPDUs sent and received.