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FSPF Global Configuration

By default, FSPF is enabled on switches in the Cisco MDS 9000 Family.

Some FSPF features can be globally configured in each VSAN. By configuring a feature for the entire VSAN, you do not have to specify the VSAN number for every command. This global configuration feature also reduces the chance of typing errors or other minor configuration errors.

Note FSPF is enabled by default. Generally, you do not need to configure these advanced features.

About SPF Computational Hold Times

The SPF computational hold time sets the minimum time between two consecutive SPF computations on the VSAN. Setting this to a small value means that FSPF reacts faster to any fabric changes by recomputing paths on the VSAN. A small SPF computational hold time uses more switch CPU time.

About Link State Record Defaults

Each time a new switch enters the fabric, a link state record (LSR) is sent to the neighboring switches, and then flooded throughout the fabric. Table 22-1 displays the default settings for switch responses.

The LSR minimum arrival time is the period between receiving LSR updates on this VSAN. Any LSR updates that arrive before the LSR minimum arrival time are discarded.

The LSR minimum interval time is the frequency at which this switch sends LSR updates on a VSAN.

About FSPF Link Cost

FSPF tracks the state of links on all switches in the fabric, associates a cost with each link in its database, and then chooses the path with a minimal cost. The cost associated with an interface can be administratively changed to implement the FSPF route selection. The integer value to specify cost can range from 1 to 65,535. The default cost for 1 Gbps is 1000 and for 2 Gbps is 500.

About Hello Time Intervals

You can set the FSPF Hello time interval to specify the interval between the periodic hello messages sent to verify the health of the link. The integer value can range from 1 to 65,535 seconds.

Note This value must be the same in the ports at both ends of the ISL.

About Dead Time Intervals

You can set the FSPF dead time interval to specify the maximum interval for which a hello message must be received before the neighbor is considered lost and removed from the database. The integer value can range from 1 to 65,535 seconds.

Note This value must be the same in the ports at both ends of the ISL.

About Retransmitting Intervals

You can specify the time after which an unacknowledged link state update should be transmitted on the interface. The integer value to specify retransmit intervals can range from 1 to 65,535 seconds.

Note This value must be the same on the switches on both ends of the interface.

About Disabling FSPF for Specific Interfaces

You can disable the FSPF protocol for selected interfaces. By default, FSPF is enabled on all E ports and TE ports. This default can be disabled by setting the interface as passive.

Note FSPF must be enabled at both ends of the interface for the protocol to work.

FSPF Routes

FSPF routes traffic across the fabric, based on entries in the FSPF database. These routes can be learned dynamically, or configured statically.

About Fibre Channel Routes

Each port implements forwarding logic, which forwards frames based on its FC ID. Using the FC ID for the specified interface and domain, you can configure the specified route (for example FC ID 111211 and domain ID 3) in the switch with domain ID 1 (see Figure 22-1).

Figure 22-1 Fibre Channel Routes

Note Other than in VSANs, runtime checks are not performed on configured and suspended static routes.

About Broadcast and Multicast Routing

Broadcast and multicast in a Fibre Channel fabric uses the concept of a distribution tree to reach all switches in the fabric.

FSPF provides the topology information to compute the distribution tree. Fibre Channel defines 256 multicast groups and one broadcast address for each VSAN. Switches in the Cisco MDS 9000 Family only use broadcast routing. By default, they use the principal switch as the root node to derive a loop-free distribution tree for multicast and broadcast routing in a VSAN.

To interoperate with other vendor switches (following FC-SW3 guidelines), the Cisco SAN-OS and Cisco NX-OS Release 4.1(1b) and later releases uses the lowest domain switch as the root to compute the multicast tree in interop mode.

About Multicast Root Switch

By default, the native (non-interop) mode uses the principal switch as the root. If you change the default, be sure to configure the same mode in all switches in the fabric. Otherwise, multicast traffic could encounter potential loop and frame-drop problems.

Note The operational mode can be different from the configured interop mode. The interop mode always uses the lowest domain switch as the root.

Use the mcast root lowest vsan command to change the multicast root from the principal switch to lowest domain switch.

In-Order Delivery

In-order delivery (IOD) of data frames guarantees frame delivery to a destination in the same order that they were sent by the originator.

Some Fibre Channel protocols or applications cannot handle out-of-order frame delivery. In these cases, switches in the Cisco MDS 9000 Family preserve frame ordering in the frame flow. The source ID (SID), destination ID (DID), and optionally the originator exchange ID (OX ID) identify the flow of the frame.

On any given switch with IOD enabled, all frames received by a specific ingress port and destined to a certain egress port are always delivered in the same order in which they were received.

Use IOD only if your environment cannot support out-of-order frame delivery.

Tip If you enable the in-order delivery feature, the graceful shutdown feature is not implemented.

About Reordering Network Frames

When you experience a route change in the network, the new selected path may be faster or less congested than the old route.

Figure 22-2 Route Change Delivery

In Figure 22-2, the new path from Switch 1 to Switch 4 is faster. In this scenario, Frame 3 and Frame 4 may be delivered before Frame 1 and Frame 2.

If the in-order guarantee feature is enabled, the frames within the network are treated as follows:

• Frames in the network are delivered in the order in which they are transmitted.
• Frames that cannot be delivered in order within the network latency drop period are dropped inside the network.

About Reordering PortChannel Frames

When a link change occurs in a PortChannel, the frames for the same exchange or the same flow can switch from one path to another faster path.

Figure 22-3 Link Congestion Delivery

In Figure 22-3, the port of the old path (red dot) is congested. In this scenario, Frame 3 and Frame 4 can be delivered before Frame 1 and Frame 2.

The in-order delivery feature attempts to minimize the number of frames dropped during PortChannel link changes when the in-order delivery is enabled by sending a request to the remote switch on the PortChannel to flush all frames for this PortChannel.

Note Both switches on the PortChannel must be running Cisco SAN-OS Release 3.0(1) for this IOD enhancement. For earlier releases, IOD waits for the switch latency period before sending new frames.

When the in-order delivery guarantee feature is enabled and a PortChannel link change occurs, the frames crossing the PortChannel are treated as follows:

• Frames using the old path are delivered before new frames are accepted.
• The new frames are delivered through the new path after the switch latency drop period has elapsed and all old frames are flushed.

Frames that cannot be delivered in order through the old path within the switch latency drop period are dropped. See the “Configuring the Drop Latency Time” section.

About Enabling In-Order Delivery

You can enable the in-order delivery feature for a specific VSAN or for the entire switch. By default, in-order delivery is disabled on switches in the Cisco MDS 9000 Family.

Tip We recommend that you only enable this feature when devices that cannot handle any out-of-order frames are present in the switch. Load-balancing algorithms within the Cisco MDS 9000 Family ensure that frames are delivered in order during normal fabric operation. The load-balancing algorithms based on source FC ID, destination FC ID, and exchange ID are enforced in hardware without any performance degradation. However, if the fabric encounters a failure and this feature is enabled, the recovery will be delayed because of an intentional pausing of fabric forwarding to purge the fabric of resident frames that could potentially be forwarded out-of-order.

About Flow Statistics

If you enable flow counters, you can enable a maximum of 1 K entries for aggregate flow and flow statistics for Generation 1 modules, and 2 K entries for Generation 2 modules. Be sure to assign an unused flow index to a module for each new flow. Flow indexes can be repeated across modules. The number space for flow index is shared between the aggregate flow statistics and the flow statistics.

Generation 1 modules allow a maximum of 1024 flow statements per module. Generation 2 modules allow a maximum of 2048-128 flow statements per module.

Note For each session, fcflow counter will increment only on locally connected devices and should be configured on the switch where the initiator is connected.

Configuring FSPF on a VSAN

To configure an FSPF feature for the entire VSAN, follow these steps:

To configure an FSPF feature for the entire VSAN, follow these steps:

Step 1 Expand a Fabric, expand a VSAN and select FSPF for a VSAN that you want to configure for FSPF.

You see the FSPF configuration in the Information pane.

Step 2 The RegionID, Spf Comp Holdtime , LSR Min Arrival, and LSR Min Interval field values are applied across all interfaces on the VSAN. You can change them here or, if they do not exist create them here.

Step 3 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Resetting FSPF to the Default Configuration

To return the FSPF VSAN global configuration to its factory default, follow these steps:

To return the FSPF VSAN global configuration to its factory default, follow these steps:

Step 1 Expand a Fabric, expand a VSAN, and select FSPF for a VSAN that you want to configure for FSPF.

You see the FSPF configuration in the Information pane.

Step 2 Check the SetToDefault check box for a switch.

Step 3 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Enabling or Disabling FSPF

To enable or disable FSPF routing protocols, follow these steps:

To enable or disable FSPF, follow these steps:

Step 1 Expand a Fabric, expand a VSAN, and select FSPF for a VSAN that you want to configure for FSPF.

You see the FSPF configuration in the Information pane.

Step 2 Set the Status Admin drop-down menu to up to enable FSPF or to down to disable FSPF.

Step 3 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Clearing FSPF Counters for the VSAN

To clear the FSPF statistics counters for the entire VSAN, follow this step:

Configuring FSPF Link Cost

To configure FSPF link cost, follow these steps:

To configure FSPF link cost, follow these steps:

Step 1 Expand Switches, expand FC Interfaces, and then select Physical.

You see the interface configuration in the Information pane.

Step 2 Click the FSPF tab.

You see the FSPF interface configuration in the Information pane.

Step 3 Double-click in the Cost field of a switch and change the value.

Step 4 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Configuring Hello Time Intervals

To configure the FSPF Hello time interval, follow these steps:

To configure the FSPF Hello time interval, follow these steps:

Step 1 Expand Switches, expand FC Interfaces, and then select Physical.

You see the interface configuration in the Information pane.

Step 2 Click the FSPF tab.

You see the FSPF interface configuration in the Information pane.

Step 3 Change the Hello Interval field for a switch.

Step 4 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Configuring Dead Time Intervals

To configure the FSPF dead time interval, follow these steps:

To configure the FSPF dead time interval, follow these steps:

Step 1 Expand Switches, expand FC Interfaces, and then select Physical.

You see the interface configuration in the Information pane.

Step 2 Click the FSPF tab.

You see the FSPF interface configuration in the Information pane.

Step 3 Double-click the Dead Interval field for a switch and provide a new value.

Step 4 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Configuring Retransmitting Intervals

To configure the FSPF retransmit time interval, follow these steps:

To configure the FSPF retransmit time interval, follow these steps:

Step 1 Expand Switches, expand FC Interfaces, and then select Physical.

You see the interface configuration in the Information pane.

Step 2 Click the FSPF tab.

You see the FSPF interface configuration in the Information pane.

Step 3 Double-click the ReTx Interval field and enter a value.

Step 4 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Disabling FSPF for Specific Interfaces

You can disable the FSPF protocol for selected interfaces. By default, FSPF is enabled on all E ports and TE ports. This default can be disabled by setting the interface as passive.

You can disable the FSPF protocol for selected interfaces. By default, FSPF is enabled on all E ports and TE ports. This default can be disabled by setting the interface as passive.

To disable FSPF for a specific interface, follow these steps:

To disable FSPF for a specific interface, follow these steps:

Step 1 Expand Switches, expand FC Interfaces, and then select Physical.

You see the interface configuration in the Information pane.

Step 2 Click the FSPF tab.

You see the FSPF interface configuration in the Information pane.

Step 3 Set a switch Admin Status drop-down menu to down.

Step 4 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Clearing FSPF Counters for an Interface

To clear the FSPF statistics counters for an interface, follow this step:

Configuring Fibre Channel Routes

To configure a Fibre Channel route, follow these steps:

If you disable FSPF, you can manually configure a Fibre Channel route.

To configure a Fibre Channel route using Device Manager, follow these steps:

Step 1 Click FC > Advanced > Routes.

You see the FC Static Route Configuration dialog box.

Step 2 Click Create to create a static route.

You see the Create Route dialog box.

Step 3 Select the VSAN ID that you are configuring this route.

Step 4 Fill in the destination address and destination mask for the device you are configuring a route.

Step 5 Select the interface that you want to use to reach this destination.

Step 6 Select the next hop domain ID and route metric.

Step 7 Select either the local or remote radio button.

Step 8 Click Create to save these changes or click Close to discard any unsaved changes.

Setting the Multicast Root Switch

To use the lowest domain switch for the multicast tree computation, follow these steps:

To display the configured and operational multicast mode and the selected root domain, use the show mcast command.

To use the lowest domain switch for the multicast tree computation, follow these steps:

Step 1 Expand a fabric, expand a VSAN, and then select Advanced for the VSAN that you want to configure FSPF on.

You see the advanced Fibre Channel configuration in the Information pane.

Step 2 Click the Multicast Root tab.

You see the multicast root configuration in the Information pane.

Step 3 Set the Config Mode drop-down menu to lowestDomainSwitch.

Step 4 Click Apply Changes to save these changes or click Undo Changes to discard any unsaved changes.

Enabling In-Order Delivery Globally

To ensure that the in-order delivery parameters are uniform across all VSANs on an Cisco MDS 9000 Family switch, enable in-order delivery globally.

Only enable in-order delivery globally if this is a requirement across your entire fabric. Otherwise, enable IOD only for the VSANs that require this feature.

Note Enable in-order delivery on the entire switch before performing a downgrade to Cisco MDS SAN-OS Release 1.3(3) or earlier.

To enable in-order delivery for the switch, follow these steps:

Enabling In-Order Delivery for a VSAN

When you create a VSAN, that VSAN automatically inherits the global in-order-guarantee value. You can override this global value by enabling or disabling in-order-guarantee for the new VSAN.

To use the lowest domain switch for the multicast tree computation, follow these steps:

To use the lowest domain switch for the multicast tree computation, follow these steps:

Step 1 Expand a fabric and select All VSANS.

Step 2 Select the Attributes tab.

You see the general VSAN attributes in the Information pane.

Step 3 Check the InOrder Delivery check box to enable IOD for the switch.

Step 4 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Configuring the Drop Latency Time

You can change the default latency time for a network, a specified VSAN in a network, or for the entire switch.

To configure the network and the switch drop latency time, follow these steps:

To configure the drop latency time for a switch, follow these steps:

Step 1 Expand a fabric and select All VSANS.

You see the VSAN configuration in the Information pane.

Step 2 Click the Attributes tab.

You see the general VSAN attributes in the Information pane.

Step 3 Double-click the Network Latency field and change the value.

Step 4 Click Apply Changes to save these changes, or click Undo Changes to discard any unsaved changes.

Counting Aggregated Flow Statistics

To count the aggregated flow statistics for a VSAN, follow these steps:

Counting Individual Flow Statistics

To count the flow statistics for a source and destination FC ID in a VSAN, follow these steps:

Clearing FIB Statistics

Use the clear fcflow stats command to clear the aggregated flow counter (see Examples 22-1 and 22-2 ).

Examples

Example 22-1 Clears Aggregated Flow Counters

Example 22-2 Clears Flow Counters for Source and Destination FC IDs

Displaying the FSPF Database

The FSPF database for a specified VSAN includes the following information:

• Link State Record (LSR) type
• Domain ID of the LSR owner
• Domain ID of the advertising router
• LSR age
• LSR incarnation member
• Number of links

To display the FSPF database using Device Manager, follow these steps:

Step 1 Choose FC > Advanced > FSPF.

You see the FSPF dialog box.

Step 2 Click the LSDB LSRs tab.

You see the FSPF database information.

Step 3 Click Close to close the dialog box.

Displaying FSPF Statistics

To view FSPF statistics using DCNM-SAN, follow these steps:

Step 1 Expand a Fabric, expand a VSAN, and then select FSPF in the Logical Domains pane.

You see the FSPF configuration dialog box.

Step 2 Click the Statistics tab.

You see the FSPF VSAN statistics in the Information pane.

Step 3 Click the Interface Statistics tab.

You see the FSPF interface statistics in the Information pane.

Displaying the In-Order Delivery Status

Use the show in-order-guarantee command to display the present configuration status:

Displaying Latency Information

You can view the configured latency parameters using the show fcdroplatency command (see Example 22-3).

Example 22-3 Displays Administrative Distance

Displaying Flow Statistics

Use the show fcflow stats commands to view flow statistics (see Example 22-4 to 22-6 ).

Example 22-4 Displays Aggregated Flow Details for the Specified Module

Example 22-5 Displays Flow Details for the Specified Module

Example 22-6 Displays Flow Index Usage for the Specified Module

Displaying Global FSPF Information

Example 22-7 displays global FSPF information for a specific VSAN:

• Domain number of the switch.
• Autonomous region for the switch.
• Min_LS_arrival: minimum time that must elapse before the switch accepts LSR updates.
• Min_LS_interval: minimum time that must elapse before the switch can transmit an LSR.

Tip If the Min_LS_interval is higher than 10 seconds, the graceful shutdown feature is not implemented.

• LS_refresh_time: interval time lapse between refresh LSR transmissions.
• Max_age: maximum time aa LSR can stay before being deleted.

Example 22-7 Displays FSPF Information for a Specified VSAN

Displaying the FSPF Database

Example 22-8 displays a summary of the FSPF database for a specified VSAN. If other parameters are not specified, all LSRs in the database are displayed:

• LSR type
• Domain ID of the LSR owner
• Domain ID of the advertising router
• LSR age
• LSR incarnation member
• Number of links

You could narrow the display to obtain specific information by issuing additional parameters for the domain ID of the LSR owner. For each interface, the following information is also available:

• Domain ID of the neighboring switch
• E port index
• Port index of the neighboring switch
• Link type and cost

Example 22-8 Displays FSPF Database Information

Displaying FSPF Interfaces

Example 22-9 displays the following information for each selected interface.

• Link cost
• Timer values
• Neighbor’s domain ID (if known)
• Local interface number
• Remote interface number (if known)
• FSPF state of the interface
• Interface counters

Example 22-9 Displays FSPF Interface Information

Fault Tolerant Fabric

Figure 22-4 depicts a fault tolerant fabric using a partial mesh topology. If a link goes down anywhere in the fabric, any switch can still communicate with all others in the fabric. In the same way, if any switch goes down, the connectivity of the rest of the fabric is preserved.

Figure 22-4 Fault Tolerant Fabric

For example, if all links are of equal speed, the FSPF calculates two equal paths from A to C: A-D-C (green) and A-E-C (blue).

Redundant Links

To further improve on the topology in Figure 22-4, each connection between any pair of switches can be replicated; two or more links can be present between a pair of switches. Figure 22-5 shows this arrangement. Because switches in the Cisco MDS 9000 Family support PortChanneling, each pair of physical links can appear to the FSPF protocol as one single logical link.

By bundling pairs of physical links, FSPF efficiency is considerably improved by the reduced database size and the frequency of link updates. Once physical links are aggregated, failures are not attached to a single link but to the entire PortChannel. This configuration also improves the resiliency of the network. The failure of a link in a PortChannel does not trigger a route change, thereby reducing the risks of routing loops, traffic loss, or fabric downtime for route reconfiguration.

Figure 22-5 Fault Tolerant Fabric with Redundant Links

For example, if all links are of equal speed and no PortChannels exist, the FSPF calculates four equal paths from A to C: A1-E-C, A2-E-C, A3-D-C, and A4-D-C. If PortChannels exist, these paths are reduced to two.

Failover Scenarios for PortChannels and FSPF Links

The SmartBits traffic generator was used to evaluate the scenarios displayed in Figure 22-6. Two links between switch 1 and switch 2 exist as either equal-cost ISLs or PortChannels. There is one flow from traffic generator 1 to traffic generator 2. The traffic was tested at 100 percent utilization at 1 Gbps in two scenarios:

• Disabling the traffic link by physically removing the cable (see Table 22-3 ).
• Shutting down either switch 1 or switch 2 (see Table 22-4 ).

Figure 22-6 Failover Scenario Using Traffic Generators

FSPF General

FSPF Interfaces

FSPF Interface Stats

FSPF LSDB Links

FSPF LSDB LSRs

FSPF Statistics

Related Document

Standards

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