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Advanced

The STP Advanced menu contains the following options:

STP Configuration

The Advanced STP Configuration screen contains parameters for enabling STP on the device.

To configure STP on the device:

  1. Click Switching > STP > Advanced > STP Configuration. The Advanced STP Configuration screen displays:

    Figure 4-21

  2. The Advanced STP Configuration screen contains the following fields:

    Global Settings

    • Spanning Tree State - Select the STP state on the device. The possible field values are:
      • Enable - Enable STP on the device.
      • Disable - Disable STP on the device.
    • STP Operation Mode - Select the STP mode on the device. The possible field values are:
      • STP - Enable classic STP on the device.
      • RSTP - Enable Rapid Spanning Tree (RSTP) on the device.
    • BPDU Handling - Select the method of handling STP BPDUs (Bridge Protocol Data Units) when STP is disabled on the device or interface. The possible field values are:
      • Filtering - BPDUs are filtered. This the default.
      • Flooding - BPDUs are flooded to all ports in the system.
      • Bridging - BPDUs are bridged to all ports in the VLAN.
      • Status

    • Bridge Identifier - Displays the Bridge priority and MAC address.
    • Time Since Topology Change - Displays the amount of time that has elapsed since the bridge was initialized or reset, and the last topographic change that occurred. The time is displayed in a day-hour-minute-second format, such as 2 days 5 hours 10 minutes and 4 seconds.
    • Designated Root - Displays the Root Bridge priority and MAC address.
    • Root Port - Indicates the port number that offers the lowest cost path from this bridge to the Root Bridge. This field is significant when the bridge is not the Root Bridge. The default is zero.
    • Max Age (Sec) - Displays the device Maximum Age Time. The Maximum Age Time is the amount of time in seconds a bridge waits before sending configuration messages. The default Maximum Age Time is 20 seconds.
    • Forward Delay (Sec) - Displays the device Forward Delay Time. The Forward Delay Time is the amount of time in seconds a bridge remains in a listening and learning state before forwarding packets. The default is 15 seconds.
    • Hello Time (Sec) - Displays the device Hello Time. The Hello Time indicates the amount of time in seconds a Root Bridge waits between configuration messages. The default is 2 seconds.
  3. Select Enable or Disable in the Spanning Tree State provided field.
  4. Select the STP Operation Mode in the provided field.
  5. If you selected Disable in the Spanning Tree State field, select the BPDU Handling mode from the list in the provided field.
  6. Click Apply to update the device.

CST Configuration

The Common Spanning Tree (CST) describes the topology connecting STP/RSTP Bridges and MSTP regions.

To configure CST on the device:

  1. Click Switching > STP > Advanced > CST Configuration. The CST Configuration screen displays:

    Figure 4-22

  2. The CST Configuration screen contains the following fields:

    CST Configuration

    • Bridge Priority - Enter the bridge priority value. When switches or bridges are running STP, each is assigned a priority. After exchanging BPDUs, the device with the lowest priority value becomes the Root Bridge. The default value is 32768. The bridge priority value is provided in increments of 4096.
    • Hello Time - Enter the device Hello Time. The Hello Time indicates the amount of time in seconds a Root Bridge waits between configuration messages. The default is 2 seconds.
    • Max Age - Enter the device Maximum Age Time. The Maximum Age Time is the amount of time in seconds a bridge waits before sending configuration messages. The default Maximum Age Time is 20 seconds.
    • Forward Delay - Enter the device Forward Delay Time. The Forward Delay Time is the amount of time in seconds a bridge remains in a listening and learning state before forwarding packets. The default is 15 seconds.
    • Designated Root

    • Root Bridge ID - Displays the priority and MAC Address of the root bridge.
    • Root Port - Displays the port number that offers the lowest cost path from this bridge to the Root Bridge. This field is significant when the bridge is not the Root Bridge. The current root port is zero when the device is not connected to the network.
    • Root Path Cost - Displays the cost of the path from this bridge to the Root Bridge. The current root path cost is zero when the device is not connected to the network.
  3. Enter the Bridge Priority in the provided field.
  4. Select Hello Time, Max Age or Forward Delay and enter the value in the provided field.
  5. Click Apply to update the device.

CST Port Configuration

To configure CST ports on the device:

  1. Click Switching > STP > Advanced > CST Port Configuration. The CST Port Configuration screen displays:

    Figure 4-23

  2. The CST Port Configuration screen contains the following fields:

    • Interface - Displays the port or LAG for which the STP information is displayed.
    • STP Status - Select the STP status on the interface. The possible field values are:
      • Enable - Enable STP on the interface.
      • Disable - Disable STP on the interface.
    • Fast Link - Select the Fast Link state on the interface. If Fast Link mode is enabled for a interface, the Port State is automatically placed in the Forwarding state when the port link is up. Fast Link optimizes the STP protocol convergence. The possible field values are:
      • Enable - Enable Fast Link on the interface.
      • Disable - Disable Fast Link on the interface.
    • Port State - Displays the current STP state of a port. If enabled, the port state determines what forwarding action is taken on traffic. Possible port states are:
      • Forwarding - STP is enabled on the port, and the port is forwarding packets based on the STP topology.
      • Disabled - STP is currently disabled on the port. The port forwards traffic while learning MAC addresses.
      • Blocking - The port is currently blocked and cannot forward traffic or learn MAC addresses.
      • Listening - The port is in Listening mode. The port cannot forward traffic nor can it learn MAC addresses.
      • Learning - The port is in Learning mode. The port cannot forward traffic, however it can learn new MAC addresses.
    • Speed - Displays the speed at which the port is operating.
    • Path Cost - Enter the method used to assign default path cost to STP ports. The possible field range is 1 - 200000000. The default path cost assigned to an interface varies according to the selected CST configuration method (Hello Time, Max Age or Forward Delay).
    • Priority - Select the port priority value. When switches or ports are running STP, each is assigned a priority. After exchanging BPDUs, the device with the lowest priority value becomes the Root Port. The port priority has a range of 0-240 in increments of 16. The default value is 128.
  3. Select the STP Status and Fast Link status in the provided fields.
  4. Enter the Path Cost in the provided field.
  5. Select the Priority from the list in the provided field.
  6. Click Apply to update the device.

Rapid STP

While Classic STP prevents forwarding loops in a general network topology, convergence can take between 30-60 seconds. This time may delay detecting possible loops and propagating status topology changes. Rapid Spanning Tree Protocol (RSTP) detects and uses network topologies that allow a faster STP convergence without creating forwarding loops. The Global System LAG information displays the same field information as the ports, but represents the LAG RSTP information.

To define RSTP on the device:

  1. Click Switching > STP > Advanced > RSTP. The Rapid STP screen displays:

    Figure 4-24

  2. The Rapid STP screen contains the following fields:

    • Interface - Displays the port or LAG on which Rapid STP is enabled.
    • Role - Displays the port role assigned by the STP algorithm to provide to STP paths. The possible field values are:
      • Root - Provides the lowest cost path to forward packets to the root switch.
      • Designated - The port or LAG through which the designated switch is attached to the LAN.
      • Alternate - Provides an alternate path to the root switch from the root interface.
      • Backup - Provides a backup path to the designated port path toward the Spanning Tree leaves. Backup ports occur only when two ports are connected in a loop by a point-to-point link, or when a LAN has two or more connections connected to a shared segment.
      • Disabled - The port is not participating in the Spanning Tree.
    • Mode - Displays the current STP mode. The STP mode is selected in the STP Configuration screen. The possible field values are:
      • STP - Classic STP is enabled on the device.
      • RSTP - Rapid STP is enabled on the device.
    • Fast Link Operational Status - Displays the Fast Link status for the interface. If Fast Link is enabled for a port, the port is automatically placed in the forwarding state. The possible field values are:
      • Enabled - Fast Link is enabled on the interface.
      • Disabled - Fast Link is disabled on the interface.
    • Status - Displays the RSTP status for the interface. The possible field values are:
      • Enabled - RSTP is enabled on the interface.
      • Disable - RSTP is disabled on the interface. This is the default value.
    • Point-to-Point Admin Status - Select whether a point-to-point link is established, or if the device is permitted to establish a point-to-point link. The possible field values are:
      • Enable - Enable a point-to-point link, or configure to automatically establish a point-to-point link. To establish communications over a point-to-point link, the originating PPP first sends Link Control Protocol (LCP) packets to configure and test the data link. After a link is established and optional facilities are negotiated as needed by the LCP, the originating PPP sends Network Control Protocol (NCP) packets to select and configure one or more network layer protocols. When each of the chosen network layer protocols has been configured, packets from each network layer protocol can be sent over the link. The link remains configured for communications until explicit LCP or NCP packets close the link, or until some external event occurs. This is the actual switch port link type. It may differ from the administrative state.
      • Disable - Disable point-to-point link.
      • Auto - Enable the device to automatically establish a point-to-point link.
    • Point-to-Point Operational Status - Displays the point-to-point operating state.
    • Activate Protocol Migration - Activate sending Link Control Protocol (LCP) packets to configure and test that the data link is enabled.
  3. Select the interface.
  4. Select the Point-to-Point Admin Status from the list in the provided field in the first row.
  5. To configure and test the data link, check Activate Protocol Migration in the provided field in the first row.
  6. Click Apply to update the device.

NETGEAR, Inc.
http://www.netgear.com
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