PVRST

Layer 2 Management > PVRST > Basic Settings

• Select—click to select the context for which the configuration needs to be done.

• Context ID—displays the context ID. Currently PVRST can be enabled only for the Context ID of 0.
• System Control—select the administrative system control status requested by management for the PVRST. This status allows the user to set availability of the PVRST feature on all ports in the switch. The default option is Shutdown. The list contains:
  • Start—specifies that PVRST is active on all ports of the device. The required memory is allocated for the feature.
  • Shutdown—specifies that PVRST is shut down on all ports of the device. The allocated memory is released on all ports.
  Note: The system control status can be set as Start, only if the MSTP System Control is set as Shutdown, RSTP System Control is set as Shutdown, and Dynamic VLAN Status is set as Disabled.The system control status can be set as Shutdown, only if the PVRST Module Status is set as Disabled. Currently PVRST can be enabled only for the Context ID of 0.
• Module Status—select the administrative module status requested by management for the PVRST. The default option is Disabled. The list contains:
  • Enabled—enables the PVRST feature on all ports in the switch.
  • Disabled—disables the PVRST feature on all ports in the switch.
  Note: The module status is grayed out and cannot be configured, if the PVRST System Control is set as Shutdown.The module status can be set as Enabled, only if the PVRST System Control is set as Start.

• Apply—modifies attributes for the selected entry and saves the changes.

Layer 2 Management > PVRST > Port Settings

• Select—click to select the port for which the configuration needs to be done.

• Port—displays the port, which is a combination of interface type and interface ID. The interface ID is a combination of slot number and the port number (slot number/port number).
  Note:

  Only the ports whose Admin State is set as Up are displayed.

• Status—select the PVRST status for the port. The default option is Enabled. The list contains:
  • Enabled—enables PVRST in the port. The port participates in the STP process and is ready to transmit/receive BPDUs and data.
  • Disabled—disables PVRST in the port. The port does not participate in the STP process and will not transmit/receive BPDUs and data.
• Point to Point—select the administrative point-to-point status of the LAN segment attached to the port. The default option is Auto. The list contains:
  • ForceTrue—specifies that the port is connected to a point-to-point link.
  • ForceFalse—specifies that the port is connected to shared media connection.
  • Auto—specifies that the port is connected to point-to-point link or it is configured as a MAC entity.
  Note: The port is considered to have a point-to-point link if it is an aggregator and all of its members can be aggregated.The MAC entity is configured for full Duplex operation, either manually or through auto negotiation process (Negotiation Mode is set as Auto).
• Root Guard—select the administrative status for the root guard feature in the port. The root guard feature prevents the port from becoming root port or blocked port. The port changes to the root-inconsistent state if the port receives a superior BPDU. The port automatically reverts back to forwarding state, once the superior BPDUs are not received. The default option is Disabled. The list contains:
  • Enabled—enables the root guard feature in the port.
  • Disabled—disables the root guard feature in the port.
  Note: The root guard feature can be enabled only for the ports whose Switch Port Mode is configured as Trunk using Layer 2 Management > Port Manager > Port Basic Settings screen.
• BPDU Guard—select the administrative status for the BPDU guard feature in the port. The BPDU guard feature prevents the port from receiving a BPDU for providing security from invalid configurations. The default option is None. The list contains:
  • None—sets the BPDU Guard status as None. This removes the BPDU Guard functionality on this port. Global BPDU guard configuration will take effect if this port is edge port.
  • Enabled—enables BPDU guard feature in the port. This prevents temporary loops and moves the port to disabled discarding state when BPDU is received on this port.

• • Disabled—disables BPDU guard feature in the port. The port state is maintained till is manually enabled

• Encap Type—select type of encapsulation to be used in the port. Encapsulation defines the VLAN services available and identifies/tags frames transmitted between switches. The default option is dot1Q. The list contains:
  • dot1Q—specifies that the encapsulation type is dot1Q.This indicates that the port sends BPDUs to the native VLAN as normal IEEE RSTP BPDUs. BPDUs for other VLAN are sent with proprietary tunneled address. The PVRST unaware bridge considers these BPDUs as data packets and forwards them through VLAN.
    Note: The encapsulation type is always set as dot1Q and cannot be changed if the Switch Port Mode is set as Access using Layer 2 Management > Port Manager > Port Basic Settings screen.
  • isl—specifies that the encapsulation type is isl. This indicates that the port sends BPDUs for all VLANs as normal RSTP BPDUs (including the IEEE Ethernet header) encapsulated within an additional proprietary ISL Ethernet header that contains the VLAN ID.
    Note: The encapsulation type can be configured as isl, only if the Switch Port Mode is configured as Trunk using Layer 2 Management > Port Manager > Port Basic Settings screen.
• Row Status—select the status of the row to create or delete interfaces at PVRST module level. Ports can be created at PVRST module level only for ports that have been created in Interface Manager.
  Note: This field is greyed out since it is applicable only when Automatic Port Create Feature is Disabled. Automatic Port Create Feature can be configured using CLI.
• Loop Guard—select the status of Loop Guard. The Loop Guard does not age out the information even if the peer does not send information. If the port continues to receive information through BPDUs, the operation on this port will be normal. This is useful when the neighbor bridge is faulty, that is, the bridge cannot send BPDUs but continues to send data traffic. The default option is False. The list contains:
  • True—enables the Loop Guard in the port.
  • False—disables the Loop Guard in the port.

• Apply—modifies attributes for the selected entry and saves the changes.

Layer 2 Management > PVRST > Instance Bridge Settings

• Select—click to select the context for which the configuration needs to be done.
• Context ID—displays the context ID. Currently PVRST is enabled only for the Context ID of 0.
• Instance ID—displays the spanning tree instance to which the bridge information belongs. The instance represents the VLAN ID created in the Static VLAN Configuration screen. For example, the instance IDs 1 and 3 are displayed if VLAN IDs 1 and 3 are created. These values range from 1 to 4094. The default value is 1.
• Max-Age (Secs)—enter the maximum age (in seconds) of the bridge information. This value represents the time interval after which the spanning tree protocol information learnt from the network for any port is discarded. This value ranges from 6 to 40 seconds. The default value is 20 seconds.
  Note: The maximum age should be lesser than or equal to 2* (Forward Delay-1.0) and should be greater than or equal to 2* (HelloTime + 1.0)
• HelloTime (Secs)—enter the time interval (in seconds) between two successive configuration BPDUs generated by the root switch. This value ranges from 1 to 10 seconds. The default value is 2 seconds.
• ForwardDelay (Secs)—enter the ForwardDelay of the Root Bridge i.e. the time that is spent in the listening and learning state. This value ranges from 4 to 30 seconds. The default value is 15 seconds.

• Tx HoldCount—enter the value used by the Port Transmit state machine to limit the maximum transmission rate. This value is configured to avoid flooding and limit the maximum transmission rate. This value is from 1 to 10 with default of 6.
• BridgePriority—enter the priority value that is assigned to the switch. This is used during the election of root. This value is from 0 to 61440, the default is 32768.
  Note: The value should be set in increments of 4096; that is, the value can be set as 0, 4096, 8192, 12288, and so on.The configured priority is added to the instance ID, and the total value is displayed. For example, the default priority value is displayed as 32769 if the instance ID is 1 (32768 + 1).

• Apply—modifies attributes for the selected entry and saves the changes.

Layer 2 Management > PVRST > Instance Port Settings

• Select—click to select the context for which the configuration needs to be done.
• Instance—displays the spanning tree instance to which the bridge information belongs. The instance represents the VLAN ID created in the Static VLAN Configuration screen. For example, the instance IDs 1 and 3 are displayed if VLAN IDs 1 and 3 are created. This value ranges from 1 to 4094. The default value is 1.
• Port—displays the port # identifying a port in the switch- from 1 to 65535.
  Note:

  Only the ports whose Admin State is set as Up are displayed.

• Module Status—select the administrative status for the PVRST module. By default, the value is set same as the value shown in the field Status in Port Configuration screen. The list contains:
  • Enabled—enables PVRST in the device on all ports. The port participates in the STP process and is ready to transmit/receive BPDUs and data.
  • Disabled—disables PVRST in the device on all ports. The port does not participate in the STP process and is not ready to transmit/receive BPDUs / data.

• Path Cost—enter the administratively assigned value for the contribution of this port to the path cost of paths toward the spanning tree root. The path cost represents the distance between the root port and designated port. The path cost is used during calculation of shortest path to reach the root. This value ranges from 0 to 200000000. The default value is 200000 for all physical ports and 199999 for port channels.

• Priority—enter the priority value that is assigned to the port. The four most significant bits of the port identifier for a given spanning tree instance can be modified independently for each spanning tree instance supported by the bridge. This value is used during the port role selection process. This value ranges from 0 to 240. The values that are set for Port Priority must be in steps of 16. The default value is 128.

• Apply—modifies attributes for the selected entry and saves the changes.

Layer 2 Management > PVRST > Instance Port Status

• Instance—displays the spanning tree instance to which the bridge information belongs. The instance represents the VLAN ID created in the Static VLAN Configuration screen. For example, the instance IDs 1 and 3 are displayed if VLAN IDs 1 and 3 are created. This value ranges from 1 to 4094. The default value is 1.
• Port—displays the port number that uniquely identifies the specific port in the switch. This value ranges from 1 to 65535.
  Note:

  Only the ports whose Admin State is set as Up are displayed.

• Designated Root—displays the unique identifier of the bridge recorded as the instance root in the transmitted configuration BPDUs. This value is an 8-byte octet string. For example, 80:01:00:01:02:03:04:01.
• Designated Bridge—displays the unique identifier of the bridge, which the port considers to be the designated bridge for the port's segment. The designated bridge is the only bridge allowed to forward frames to and from the segment. This value is an 8-byte octet string. For example, 80:01:00:01:02:03:04:01.
• Designated Port—displays the ID of the port on the Designated Bridge for the port's segment. This represents the port through which the Designated Bridge forwards frames to and from the segment. This is a 2-byte octet string (e.g. 80:05).
• Port State—displays the current state of the port state as defined by the STP. The port states are:
  • Disabled—specifies that the port is disabled manually (PVRST Module Status) or automatically (Link). The port does not take part in the spanning tree process.
  • Discarding—specifies that the port is in the Discarding state i.e. no user data is sent over the port.
  • Learning—specifies that the port is in Learning state i.e. the port is not forwarding frames yet, but it is populating its MAC-address-table by learning source addresses from received frames and storing them in the switching database for using them while sending and receiving data.
  • Forwarding—specifies that the port is in the Forwarding state i.e. the port is operational by sending and receiving data based on the formed spanning tree topology which is loop free.
• Port Role—displays the current role of the port for the spanning tree instance. The port roles are:
  • Disabled—specifies that the port is disabled manually (PVRST Module Status) or automatically (Link). The port does not take part in the spanning tree process.
  • Alternate—specifies that the port is acting as an alternate path to the root bridge which is blocked and not used for traffic. If the root port is blocked, the alternate port is enabled and declared as a root port.
  • Backup—specifies that the port is acting as a backup path to a segment to which another bridge port already connects and which is blocked and not used for traffic. If the active designated port is blocked, the backup drive is enabled and declared as a designated port.
  • Root—specifies that the port is used to forward data to root bridge directly or through an upstream LAN segment.
  • Designated—specifies that the port is used to send to and receive packets from a specific downstream LAN segment/device. Only one designated port is assigned for each segment.