Cisco Small Business Managed Switches (Linksys Business Series)

There are many reasons why computers behind the switch are getting network problems. It might be caused by the firmware of the switch, stacking configuration or redundant links especially if you are cascading switches.

To avoid this ensure that you are using the updated firmware for the switch. For instructions on how to upgrade the firmware of the switch click here .

Ensure as well proper connections and status of the switch LED lights, for instructions click here .

If there are switches are stacked, make sure you have followed the guideline for properly stacking the switches. For instructions, click here .

If have done the firmware upgrade for the switch, check bandwidth requirements of the network. If the bandwidth requirements are enough to cater the network setup, try to configure Spanning Tree in the switch to eliminate redundant links.

Configuring Spanning Tree

The Spanning Tree Protocol (STP) provides tree topography for any arrangement of bridges. STP also provides one path between end stations on a network, eliminating loops.

Loops occur when alternate routes exist between hosts. Loops in an extended network can cause bridges to forward traffic indefinitely, resulting in increased traffic and reducing network efficiency.

The device supports the following Spanning Tree versions:

• Classic STP - Provides a single path between end stations, avoiding and eliminating loops.
• Rapid STP - Detects and uses network topologies that provide faster convergence of the spanning tree, without creating forwarding loops.
• Multiple STP - Provides full connectivity for packets allocated to any VLAN. Multiple STP is based on the RSTP. In addition, Multiple STP transmits packets assigned to different VLANs through different MST regions. MST regions act as a single bridge.

Configuring the Spanning Tree section contains the following:

•  Defining STP on Interfaces
•  Defining Interface Settings
•  Defining Rapid Spanning Tree
•  Defining Multiple Spanning Tree

Defining STP on Interfaces

The STP Properties Page contains parameters for enabling STP on the device. The STP Properties Page
is divided into three areas, Global Settings, Bridge Settings, and Designated Root.

Step 1:
Access the web based setup page of the switch, for instructions click here .

Step 2:
Click Bridging > Spanning Tree > Properties. The STP Properties Page opens.

The Global Settings area contains the following fields:

• Spanning Tree State - Indicates if STP is enabled on the device. The possible field values are:

- Enable - Enables STP on the device. This is the default value.
- Disable - Disables STP on the device.

• STP Operation Mode - Indicates the STP mode by which STP is enabled on the device. The
  possible field values are:

- Classic STP - Enables Classic STP on the device. This is the default value.
- Rapid STP - Enables Rapid STP on the device.
- Multiple STP - Enables Multiple STP on the device.

•  BPDU Handling - Determines how BPDU packets are managed when STP is disabled on the port/device. BPDUs are used to transmit spanning tree information. The possible field values are:

- Filtering - Filters BPDU packets when spanning tree is disabled on an interface. This is the
default value.

- Flooding - Floods BPDU packets when spanning tree is disabled on an interface.

• Path Cost Default Values - Specifies the method used to assign default path costs to STP ports.
  The possible field values are:

- Short - Specifies 1 through 65,535 range for port path costs. This is the default value.
- Long - Specifies 1 through 200,000,000 range for port path costs. The default path costs assigned to an interface varies according to the selected method.

The Bridge Settings area contains the following fields:

• Priority - Specifies 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 port priority value is provided in increments of 4096. For example, 4096, 8192, 12288, etc. The range is 0 to 65535.
  
• Hello Time - Specifies 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. The range is 1
  to 10 seconds.
  
• Max Age - Specifies the device Maximum Age Time. The Maximum Age Time indicates the amount of time in seconds a bridge waits before sending configuration messages. The default max age is 20 seconds. The range is 6 to 40 seconds.
  
• Forward Delay - Specifies the device forward delay time. The Forward Delay Time indicates the amount of time in seconds a bridge remains in a listening and learning state before forwarding packets. The default is 15 seconds. The range is 4 to 30 seconds.

The Designated Root area contains the following fields:

• Bridge ID - Identifies the Bridge ID and MAC address.
• Root Bridge ID - Identifies 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. It is significant when the Bridge is not the Root. The default is zero.
• Root Path Cost - The cost of the path from this bridge to the root.
• Topology Changes Counts - Indicates the total amount of STP state changes that have occurred.
• Last Topology Change - Indicates the amount of time that has elapsed since the bridge was initialized or reset, and the last topographic change occurred. The time is displayed in a day hour minute second format, for example, 2 days 5 hours 10 minutes and 4 seconds:

Step 3:
Define the relevant fields.

Step 4:
Click Apply. STP is enabled, and the device is updated.

Defining Interface Settings

Network administrators can assign STP settings to specific interfaces using the STP Interface Settings
Page. To assign STP settings to an interface:

Step 1:
Click Bridging > Spanning Tree > Interface Settings. The Interface Settings Page opens.

The STP Interface Settings Page contains the following fields:

•  Ports - Indicates the port number on which Spanning Tree is configured.
•  LAGs - Indicates the LAG number on which Spanning Tree is configured.
•  Of Unit - Displays the stacking member for which the Spanning Tree parameters are displayed.
•  Port - Indicates the port or LAG on which STP is enabled.
•  STP - Indicates if STP is enable on the port. The possible field values are:

- Enable - Indicates that STP is enabled on the port.
- Disables - Indicates that STP is disabled on the port.

• Port Fast - Indicates if Fast Link is enabled on the port. If Fast Link mode is enabled for a port, the
  Port State is automatically placed in the Forwarding state when the port link is up. Fast Link optimizes the STP protocol convergence. STP convergence can take 30-60 seconds in large networks.
•  Root Guard - Prevents devices outside the network core from being assigned the spanning tree root.
•  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:

- Disabled - Indicates that STP is currently disabled on the port. The port forwards traffic while learning MAC addresses.
- Blocking - Indicates that the port is currently blocked and cannot forward traffic or learn MAC addresses. Blocking is displayed when Classic STP is enabled.
- Listening - Indicates that the port is in Listening mode. The port cannot forward traffic nor can it learn MAC addresses.
- Learning - Indicates that the port is in Learning mode. The port cannot forward traffic, however it can learn new MAC addresses.
- Forwarding - Indicates that the port is in Forwarding mode. The port can forward traffic and learn new MAC addresses.

• Port 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.

• Path Cost - Indicates the port contribution to the root path cost. The path cost is adjusted to a higher or lower value, and is used to forward traffic when a path being rerouted.
• Priority - Priority value of the port. The priority value influences the port choice when a bridge has two ports connected in a loop. The priority value is between 0 -240. The priority value is provided in increments of 16.
• Designated Bridge ID - Indicates the bridge priority and the MAC Address of the designated bridge.
• Designated Port ID - Indicates the selected port's priority and interface.
• Designated Cost - Indicates the cost of the port participating in the STP topology. Ports with a lower cost are less likely to be blocked if STP detects loops.
• Forward Transitions - Indicates the number of times the port has changed from the Blocking state to Forwarding state.
• LAG - Displays the LAG of which this port is a member, if relevant. If a port is a member of a LAG, the LAG settings override the port settings.

Step 2:
Define the relevant fields.

Step 3:
Click Apply. STP is enabled on the interface, and the device is updated.

Modifying Interface Settings

Step 1:
Click Bridging > Spanning Tree > Interface Settings. The Interface Settings Page opens.

Step 2:
Click the Edit button. The Interface Settings Pageopens.

The Interface Settings Page contains the following fields:

• Ports - Indicates the port number on which Spanning Tree is configured.
• STP - Indicates if STP is enable on the port. The possible field values are:

- Enable - Indicates that STP is enabled on the port.
- Disable - Indicates that STP is disabled on the port.

• Port Fast - Indicates if Fast Link is enabled on the port. If Fast Link mode is enabled for a port, the
  Port State is automatically placed in the Forwarding state when the port link is up. Fast Link optimizes the STP protocol convergence. STP convergence can take 30-60 seconds in large networks.
• Enable Root Guard - Enable the prevention of a devices outside the network core from being assigned the spanning tree root.
• 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:

- Disabled - Indicates that STP is currently disabled on the port. The port forwards traffic while learning MAC addresses.
- Blocking - Indicates that the port is currently blocked and cannot forward traffic or learn MAC addresses. Blocking is displayed when Classic STP is enabled.
- Listening - Indicates that the port is in Listening mode. The port cannot forward traffic nor can it learn MAC addresses.
- Learning - Indicates that the port is in Learning mode. The port cannot forward traffic, however it can learn new MAC addresses.
- Forwarding - Indicates that the port is in Forwarding mode. The port can forward traffic and learn new MAC addresses.

• Speed - Indicates the speed at which the port is operating.
• Path Cost - Indicates the port contribution to the root path cost. The path cost is adjusted to a higher or lower value, and is used to forward traffic when a path being rerouted.
• Default Path Cost - Indicates the default path cost.
• Priority - Priority value of the port. The priority value influences the port choice when a bridge has two ports connected in a loop. The priority value is between 0 -240. The priority value is provided in increments of 16.
• Designated Bridge ID - Indicates the bridge priority and the MAC Address of the designated bridge.
• Designated Port ID - Indicates the selected port's priority and interface.
• Designated Cost - Indicates the cost of the port participating in the STP topology. Ports with a lower cost are less likely to be blocked if STP detects loops.
• Forward Transitions - Indicates the number of times the port has changed from the Blocking state to Forwarding state.
• LAG - Displays the LAG of which this port is a member, if relevant. If a port is a member of a LAG, the LAG settings override the port settings.

Step 3:
Define the relevant fields.

Step 4:
Click Apply. The interface settings are modified, and the device is updated.

Defining Rapid Spanning Tree

While the classic spanning tree prevents Layer 2 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.

Step 1:
Click Bridging > Spanning Tree > RSTP. The RSTP Page open.

The RSTP Page contains the following fields:

• Ports - Indicates the port number on which RSTP is configured.
• LAGs - Indicates the LAG number on which RSTP is configured.
• Of Unit - Displays the stacking member for which the RSTP parameters are displayed.
• Interface - Displays the port or LAG on which Rapid STP is enabled.
• Role - Indicates the port role assigned by the STP algorithm in order to provide to STP paths. The possible field values are:

- Root - Provides the lowest cost path to forward packets to root switch.
- Designated - Indicates that the port or LAG via 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. Backup ports also occur when a LAN has two or more connections connected to a shared segment.
- Disabled - Indicates the port is not participating in the Spanning Tree.

• Mode - Indicates the current Spanning Tree mode. The Spanning Tree mode is selected in the Global STP page. The possible field values are:

- Classic STP - Indicates that Classic STP is enabled on the device.
- Rapid STP - Indicates that Rapid STP is enabled on the device.
- Multiple STP - Indicates that Multiple STP is enabled on the device.

• Fast Link - Indicates if Fast Link is enabled or disabled for the port or LAG. If Fast Link is enabled
  for a port, the port is automatically placed in the forwarding state.
• Port Status - Indicates if RSTP is enabled on the interface. The possible field values are:
  - Enable - Indicates that RSTP is enabled on the port.
  - Disable - Indicates that RSTP is disabled on the port.
• Point-to-Point Operational Status - Indicates the Point-to-Point operating state.
• Activate Protocol Migration - Runs a Protocol Migration Test. The test sends Link Control
  Protocol (LCP) packets to test if a data link is enabled.

Step 2:
Define the relevant fields.

Step 3:
Click Apply. The Rapid Spanning Tree Settings are defined, and the device is updated.

Modifying RTSP

Step 1:
Click Bridging > Spanning Tree > RSTP. The RSTP Page opens:

Step 2:
Click the Edit button. The Edit Rapid Spanning Tree Page opens:

The Edit Rapid Spanning Tree Page contains the following fields:

• Interface - Displays the port or LAG on which Rapid STP is enabled.
• Role - Indicates the port role assigned by the STP algorithm in order to provide to STP paths. The possible field values are:

- Root - Provides the lowest cost path to forward packets to root switch.
- Designated - Indicates that the port or LAG via 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. Backup ports also occur when a LAN has two or more connections connected to a shared segment.
- Disabled - Indicates the port is not participating in the Spanning Tree.

• Mode - Indicates the current Spanning Tree mode. The Spanning Tree mode is selected in the Global STP page. The possible field values are:

- Classic STP - Indicates that Classic STP is enabled on the device.
- Rapid STP - Indicates that Rapid STP is enabled on the device.
- Multiple STP - Indicates that Multiple STP is enabled on the device.

• Fast Link Operational Status- Indicates if Fast Link is enabled or disabled for the port or LAG. If
  Fast Link is enabled for a port, the port is automatically placed in the forwarding state.
• Port State - Indicates if RSTP is enabled on the interface. The possible field values are:

- Enable - Indicates that RSTP is enabled on the port.
- Disable - Indicates that RSTP is disabled on the port.

• Point-to-Point Admin Status - Indicates if a point-to-point links is established, or permits the device to establish a point-to-point link. The possible field values are:

- Enable - Enables the device to establish a point-to-point link, or specifies for the device to automatically establish a point-to-point link. To establish communications over a point-topoint 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 asneeded by the LCP, the originating PPP sends Network Control Protocols (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 - Disables point-to-point link.

• Point-to-Point Operational Status - Indicates the Point-to-Point operating state.
• Activate Protocol Migration Test- Runs a Protocol Migration Test. The test sends Link Control Protocol (LCP) packets to test if a data link is enabled.

Step 3:
Define the relevant fields.

Step 4:
Click Apply. The Rapid Spanning Tree Settings are modified, and the device is updated.

Defining Multiple Spanning Tree

MSTP provides differing load balancing scenarios. For example, while port A is blocked in one STP instance, the same port is placed in the Forwarding State in another STP instance. The MSTP Properties page contains information for defining global MSTP settings, including region names, MSTP revisions, and maximum hops.

The MSTP section contains the following pages:

• Defining MSTP Properties
• Instance to VLAN
• Instance Settings
• Interface Settings

Defining MSTP Properties

The MSTP Properties Page contains information for defining global MSTP settings, including region names, MSTP revisions, and maximum hops. To define MSTP:

Step 1:
Click Bridging > Spanning Tree > MSTP > Properties. The MSTP Properties Page opens:

The MSTP Properties Page contains the following fields:

• Region Name - Provides a user-defined STP region name.
• Revision - Defines unsigned 16-bit number that identifies the revision of the current MST configuration. The revision number is required as part of the MST configuration. The possible field range 0-65535.
• Max Hops - Indicates the total number of hops that occur in a specific region before the BPDU is discarded. Once the BPDU is discarded, the port information is aged out. The possible field range is
  1-40. The field default is 20 hops.
• IST Master - Identifies the Spanning Tree Master instance. The IST Master is the specified instance root.

Step 2:
Define the relevant fields.

Step 3:
Click Apply. The MSTP properties are defined, and the device is updated.

Instance to VLAN

The VLAN screen enables mapping VLANs to MSTP Instances.

Click Bridging > Spanning Tree > MSTP > Instance to VLAN. The Instance to VLAN Page opens.

The Instance to VLAN Page contains the following fields:

• VLAN - Indicates the VLAN for which the MSTP instance ID is defined.
• Instance ID - Indicates the MSTP instance ID assigned to the VLAN.

Instance Settings

Network Administrators can define MSTP Instances settings using the MSTP Instance Settings Page.

Step 1:
Click Bridging > Spanning Tree > MSTP > Instance Settings. The MSTP Instance Settings Page opens.

The Instance to VLAN Page contains the following fields:

• VLAN - Indicates the VLAN for which the MSTP instance ID is defined.
• Instance ID - Indicates the MSTP instance ID assigned to the VLAN.

Instance Settings

Network Administrators can define MSTP Instances settings using the MSTP Instance Settings Page.

Step 1:
Click Bridging > Spanning Tree > MSTP > Instance Settings. The MSTP Instance Settings Page opens.

The MSTP Instance Settings Page contains the following fields:

• Instance ID - Defines the VLAN group to which the interface is assigned.
• Included VLAN - Maps the selected VLAN to the selected instance. Each VLAN belongs to one instance.
• Bridge Priority - Specifies the selected spanning tree instance device priority. The field range is 0-
  61440
• Designated Root Bridge ID - Indicates the ID of the bridge with the lowest path cost to the instance ID.
• Root Port - Indicates the selected instance's root port.
• Root Path Cost - Indicates the selected instance's path cost.
• Bridge ID - Indicates the bridge ID of the selected instance.
• Remaining Hops - Indicates the number of hops remaining to the next destination.

Interface Settings

Network Administrators can define MSTP Instances settings using the MSTP Instance Settings Page.

Step 1:
Click Bridging > Spanning Tree > MSTP > Interface Settings. The MSTP Interface Settings Page opens.

The MSTP Instance Settings Page contains the following fields:

• Instance ID - Lists the MSTP instances configured on the device. Possible field range is 0-15.
• Interface - Displays the interface for which the MSTP settings are displayed. The possible field values are:

- Port - Specifies the port for which the MSTP settings are displayed.
- LAG - Specifies the LAG for which the MSTP settings are displayed.

• Port State- Indicates whether the port is enabled for the specific instance. The possible field values are:

- Enable - Enables the port for the specific instance.
- Disable - Di

Related Information

• Technical Support & Documentation - Cisco Systems

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Updated: Dec 12, 2008

Document ID: 109071

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