Configuring and Monitoring the Switch Fabric Functionality

This chapter describes how to configure the switching mode and monitor the switch fabric functionality that is included on the Supervisor Engine 720-10GE and the Supervisor Engine 720:

•Understanding the Switch Fabric Functionality

•Configuring the Switch Fabric Functionality

•Monitoring the Switch Fabric Functionality

Note For complete syntax and usage information for the commands used in this chapter, see the Cisco IOS Master Command List, at this URL:

http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html

Tip For additional information about Cisco Catalyst 6500 Series Switches (including configuration examples and troubleshooting information), see the documents listed on this page:

http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home.html

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Understanding the Switch Fabric Functionality

These sections describe how the switch fabric functionality works:

•Switch Fabric Functionality Overview

•Forwarding Decisions for Layer 3-Switched Traffic

•Switching Modes

Switch Fabric Functionality Overview

The switch fabric functionality is built into the supervisor engine and creates a dedicated connection between fabric-enabled modules and provides uninterrupted transmission of frames between these modules. In addition to the direct connection between fabric-enabled modules provided by the switch fabric funtionality, fabric-enabled modules also have a direct connection to the 32-Gbps forwarding bus.

Forwarding Decisions for Layer 3-Switched Traffic

Either a PFC3 or a Distributed Feature Card 3 (DFC3) makes the forwarding decision for Layer 3-switched traffic as follows:

•A PFC3 makes all forwarding decisions for each packet that enters the switch through a module without a DFC3.

•A DFC3 makes all forwarding decisions for each packet that enters the switch on a DFC3-enabled module in these situations:

–If the egress port is on the same module as the ingress port, the DFC3 forwards the packet locally (the packet never leaves the module).

–If the egress port is on a different fabric-enabled module, the DFC3 sends the packet to the egress module, which sends it out the egress port.

–If the egress port is on a different nonfabric-enabled module, the DFC3 sends the packet to the supervisor engine. The supervisor engine fabric interface transfers the packet to the 32-Gbps switching bus where it is received by the egress module and is sent out the egress port.

Switching Modes

With a Supervisor Engine 720-10GE or a Supervisor Engine 720, traffic is forwarded to and from modules in one of the following modes:

•Compact mode—The switch uses this mode for all traffic when only fabric-enabled modules are installed. In this mode, a compact version of the DBus header is forwarded over the switch fabric channel, which provides the best possible performance.

•Truncated mode—The switch uses this mode for traffic between fabric-enabled modules when there are both fabric-enabled and nonfabric-enabled modules installed. In this mode, the switch sends a truncated version of the traffic (the first 64 bytes of the frame) over the switch fabric channel.

•Bus mode (also called flow-through mode)—The switch uses this mode for traffic between nonfabric-enabled modules and for traffic between a nonfabric-enabled module and a fabric-enabled module. In this mode, all traffic passes between the local bus and the supervisor engine bus.

Table 14-1 shows the switching modes used with fabric-enabled and nonfabric-enabled modules installed.

Table 14-1 Switch Fabric Functionality Switching Modes

Modules
Switching Modes

Between fabric-enabled modules (when no nonfabric-enabled modules are installed)

Compact1

Between fabric-enabled modules (when nonfabric-enabled modules are also installed)

Truncated2

Between fabric-enabled and nonfabric-enabled modules

Bus

Between non-fabric-enabled modules

Bus

1 In show commands, displayed as dcef mode for fabric-enabled modules with DFC3 installed; displayed as fabric mode for other fabric-enabled modules.

2 Displayed as fabric mode in show commands.


Configuring the Switch Fabric Functionality

To configure the switching mode, perform this task:

Command
Purpose

Router(config)# [no] fabric switching-mode allow {bus-mode | {truncated [{threshold [number]}]}

Configures the switching mode.


When configuring the switching mode, note the following information:

•To allow use of nonfabric-enabled modules or to allow fabric-enabled modules to use bus mode, enter the fabric switching-mode allow bus-mode command.

•To prevent use of nonfabric-enabled modules or to prevent fabric-enabled modules from using bus mode, enter the no fabric switching-mode allow bus-mode command.

Caution When you enter the no fabric switching-mode allow bus-mode command, power is removed from any nonfabric-enabled modules installed in the switch.

•To allow fabric-enabled modules to use truncated mode, enter the fabric switching-mode allow truncated command.

•To prevent fabric-enabled modules from using truncated mode, enter the no fabric switching-mode allow truncated command.

•To configure how many fabric-enabled modules must be installed before they use truncated mode instead of bus mode, enter the fabric switching-mode allow truncated threshold number command.

•To return to the default truncated-mode threshold, enter the no fabric switching-mode allow truncated threshold command.

Monitoring the Switch Fabric Functionality

The switch fabric functionality supports a number of show commands for monitoring purposes. A fully automated startup sequence brings the module online and runs the connectivity diagnostics on the ports.

These sections describe how to monitor the switch fabric functionality:

•Displaying the Switch Fabric Redundancy Status

•Displaying Fabric Channel Switching Modes

•Displaying the Fabric Status

•Displaying the Fabric Utilization

•Displaying Fabric Errors

Displaying the Switch Fabric Redundancy Status

To display the switch fabric redundancy status, perform this task:

Command
Purpose

Router# show fabric active

Displays switch fabric redundancy status. 


Router# show fabric active 

Active fabric card in slot 5

No backup fabric card in the system

Router#

Displaying Fabric Channel Switching Modes

To display the fabric channel switching mode of one or all modules, perform this task:

Command
Purpose

Router# show fabric switching-mode [module {slot_number | all]

Displays fabric channel switching mode of one or all modules.


This example shows how to display the fabric channel switching mode of all modules: 

Router# show fabric switching-mode module all 

Module Slot     Switching Mode

    3                      Bus

    5                      Bus

Router#

Displaying the Fabric Status

To display the fabric status of one or all switching modules, perform this task:

Command
Purpose

Router# show fabric status [slot_number | all]

Displays fabric status.


This example shows how to display the fabric status of all modules: 

Router# show fabric status 

slot  channel speed module   fabric   hotStandby  Standby  Standby

                     status   status      support  module   fabric

    1        0   20G     OK       OK          N/A

    1        1   20G     OK       OK          N/A

    2        0   20G     OK       OK   Y(not-hot)

    2        1   20G     OK       OK   Y(not-hot)

    3        0   20G     OK       OK   Y(not-hot)

    4        0   20G     OK       OK   Y(not-hot)

    4        1   20G     OK       OK   Y(not-hot)

Router#

Displaying the Fabric Utilization

To display the fabric utilization of one or all modules, perform this task:

Command
Purpose

Router# show fabric utilization [slot_number | all]

Displays fabric utilization.


This example shows how to display the fabric utilization of all modules: 

Router# show fabric utilization all 

slot    channel      speed    Ingress %     Egress %

    1          0        20G            0            0

    1          1        20G            0            0

    2          0        20G            0           24

    2          1        20G            0           24

    3          0        20G           48            0

    4          0        20G            0            0

    4          1        20G            0            0

Router#

Displaying Fabric Errors

To display fabric errors of one or all modules, perform this task:

Command
Purpose

Router# show fabric errors [slot_number | all]

Displays fabric errors.


This example shows how to display fabric errors on all modules: 

Router# show fabric errors 

 
   
 
    
   
 
    
Module errors:

 
   
 
    
   
 
    
 slot    channel        crc      hbeat       sync   DDR sync

 
   
 
    
   
 
    
    1          0          0          0          0          0

 
   
 
    
   
 
    
    8          0          0          0          0          0

 
   
 
    
   
 
    
    8          1          0          0          0          0

 
   
 
    
   
 
    
    9          0          0          0          0          0

 
   
 
    
   
 
    
 
   
 
    
   
 
    
Fabric errors:

 
   
 
    
   
 
    
 slot    channel       sync     buffer    timeout

 
   
 
    
   
 
    
    1          0          0          0          0

 
   
 
    
   
 
    
    8          0          0          0          0

 
   
 
    
   
 
    
    8          1          0          0          0

 
   
 
    
   
 
    
    9          0          0          0          0

 
   
 
    
   
 
    
Router#

 
   
 
   
 
     
   
 
   
 
    
   
 Tip For additional information about Cisco Catalyst 6500 Series Switches (including configuration examples and troubleshooting information), see the documents listed on this page: 
 
    
   
 http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home.html 
 
    
   
 Participate in the Technical Documentation Ideas forum