Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
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- Updated:
- February 11, 2018
Chapter: Configuring Fibre Channel Interfaces
- About Generations of Modules and Switches
- Port Groups and Port Rate Modes
- Combining Generation 1, Generation 2, and Generation 3 Modules
- Configuring Module Interface Shared Resources
- Displaying Interface Capabilities
- Configuration Guidelines for 48-Port, 24-Port, and 4/44-Port 8-Gbps Fibre Channel Switching Modules
- Configuration Guidelines for 48-Port and 24-Port 4-Gbps Fibre Channel Switching Modules
- Configuration Guidelines for 12-Port 4-Gbps Switching Module Interfaces
- Configuration Guidelines for 4-Port 10-Gbps Switching Module Interfaces
- Configuring Port Speed
- Configuring Rate Mode
- Configuring Oversubscription Ratio Restrictions
- Configuring Bandwidth Fairness
- Taking Interfaces Out of Service
- Releasing Shared Resources in a Port Group
- Disabling ACL Adjacency Sharing for System Image Downgrade
- Displaying SFP Diagnostic Information
- Example Configurations
- Configuring a 48-Port 8-Gbps Fibre Channel Switching Module Example
- Configuring a 24-Port 8-Gbps Fibre Channel Switching Module Example
- Configuring a 4/44-Port 8-Gbps Fibre Channel Switching Module Example
- Configuring a 24-Port 4-Gbps Fibre Channel Switching Module Example
- Configuring a 48-Port 4-Gbps Fibre Channel Switching Module Example
- Default Settings
Configuring Fibre Channel Interfaces
Cisco MDS 9000 Family hardware modules and switches are categorized into generations based on the time of introduction, capabilities, features, and compatibilities:
- Generation 1—Modules and switches with a maximum port speed of 2 Gbps.
- Generation 2—Modules and switches with a maximum port speed of 4 Gbps.
- Generation 3—Modules and switches with a maximum port speed of 8 Gbps.
This chapter describes how to configure these Fibre Channel interfaces, including the following sections:
- About Generations of Modules and Switches
- Port Groups and Port Rate Modes
- Combining Generation 1, Generation 2, and Generation 3 Modules
- Configuring Module Interface Shared Resources
- Configuring Port Speed
- Configuring Rate Mode
- Configuring Oversubscription Ratio Restrictions
- Configuring Bandwidth Fairness
- Taking Interfaces Out of Service
- Releasing Shared Resources in a Port Group
- Disabling ACL Adjacency Sharing for System Image Downgrade
- Displaying SFP Diagnostic Information
- Example Configurations
- Default Settings
About Generations of Modules and Switches
The Cisco MDS 9500 Series switches, Cisco MDS 9222i, Cisco MDS 9216A and Cisco MDS 9216i switches support a set of modules called the Generation 2 modules. Each module or switch can have one or more ports in port groups that share common resources such as bandwidth and buffer credits.
In addition to supporting Generation 2 modules, the Cisco MDS 9500 Series switches and the Cisco MDS 9222i switch support another set of modules called Generation 3 modules. Similar to Generation 2, each Generation 3 module can have one or more ports in port groups that share common resources such as bandwidth and buffer credits.
Generation 3 Fibre Channel modules are supported on the Cisco MDS 9506 and 9509 switches with Supervisor-2 modules. The MDS 9513 Director supports 4/44-port Host-Optimized Fibre Channel switching module with either Fabric 1 or Fabric 2 modules, but requires Fabric 2 module for support of the 48-port and the 24-port 8-Gbps Fibre Channel switching modules. The MDS 9222i switch supports the 4/44-port Host-Optimized Fibre Channel switching module. MDS NX-OS Release 4.1(1) is required to support the Generation 3 modules.
Table 1-1 identifies the Generation 2 and Generation 3 modules, as well as the Fabric switches.
Note
Generation 2 Fibre Channel switching modules are not supported on the Cisco MDS 9216 switch; however, they are supported by both the Supervisor-1 module and the Supervisor-2 module.
For detailed information about the installation and specifications for these modules and switches, refer to the hardware installation guide for your switch.
Port Groups and Port Rate Modes
This section includes the following topics:
- Port Groups
- Port Rate Modes
- Dedicated Rate Mode Configurations for the 8-Gbps Modules
- Dynamic Bandwidth Management
- Out-of-Service Interfaces
Port Groups
Each module or switch can have one or more ports in port groups that share common resources such as bandwidth and buffer credits. Port groups are defined by the hardware consisting of sequential ports. For example, ports 1 through 12, ports 13 through 24, ports 25 through 36, and ports 37 through 48 are the port groups on the 48-port 4-Gbps Fibre Channel switching modules.
Table 1-6 shows the port groups for the Generation 2 and Generation 3 Fibre Channel modules, and Generation 2 and Generation 3 Fabric switches.
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4/44-port 8-Gbps Host-Optimized Fibre Channel switching module |
8/4 Gbps1 |
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18-port 4-Gbps Fibre Channel switching module with 4-Gigabit Ethernet ports |
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18-port 4-Gbps, 4 Gigabit Ethernet ports and a modular expansion slot. |
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Port Rate Modes
In Generation 2 and Generation 3 modules, you can configure the port rate modes. The port rate mode configuration is used to determine the bandwidth allocation for ports in a port group. Two port rate modes are supported:
- Dedicated Rate Mode—A port is allocated required fabric bandwidth to sustain line traffic at the maximum operating speed configured on the port. For more information, see the “Dedicated Rate Mode” section.
- Shared Rate Mode—Multiple ports in a port group share data paths to the switch fabric and share bandwidth. For more information, see the “Shared Rate Mode” section.
Note In Generation 1 modules, you cannot configure the port rate modes. The mode is determined implicitly based on the port mode and line card type.
Note Port rate modes are not supported on the Cisco Fabric Switch for HP c-Class BladeSystem, and the Cisco Fabric Switch for IBM BladeCenter.
Table 1-3 shows the modules that support dedicated, shared, and the default rate modes.
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Yes2 |
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4/44-Port 8-Gbps Host-Optimized Fibre Channel switching module |
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48-port 4-Gbps Fibre Channel switching module3 |
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18-port 4-Gbps Fibre Channel switching module with 4-Gigabit Ethernet ports |
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24-port 4-Gbps Fabric switch 4 |
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18-port 4-Gbps Fibre Channel switch with 4-Gigabit Ethernet IP storage services ports, and a modular expansion slot to host Cisco MDS 9000 Family Switching and Services Modules |
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Dedicated Rate Mode
When port rate mode is configured as dedicated, a port is allocated required fabric bandwidth and related resources to sustain line rate traffic at the maximum operating speed configured for the port. In this mode, ports do not use local buffering and all receive buffers are allocated from a global buffer pool (see the “Buffer Pools” section).
Table 1-4 shows the bandwidth provided by the various port speed configurations on the 8-Gbps Fibre Channel switching modules.
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Table 1-5 shows the amount of bandwidth reserved for a configured port speed on 4-Gbps switching modules.
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Note The 4-Port 10-Gbps Fibre Channel module ports in auto mode only support auto speed mode at 10 Gbps.
Shared Rate Mode
When port rate mode is configured as shared, multiple ports within a port group share data paths to the switch fabric so that fabric bandwidth and related resources are shared. Often, the available bandwidth to the switch fabric may be less than the negotiated operating speed of a port. Ports in this mode use local buffering for the BB_credit buffers.
All ports in 4-Gbps Fibre Channel switching modules where bandwidth is shared support 1-Gbps, 2-Gbps, or 4-Gbps traffic. However, it is possible to configure one or more ports in a port group to operate in dedicated rate mode with 1-Gbps, 2-Gbps or 4-Gbps operating speed.
All ports in the 48-Port and 24-Port 8-Gbps Fibre Channel switching modules where bandwidth is shared support 1-Gbps, 2-Gbps, 4-Gbps, or 8-Gbps traffic.
In the 4/44-Port 8-Gbps Host-Optimized Fibre Channel switching module, all the ports where bandwidth is shared support 1-Gbps, 2-Gbps, 4-Gbps in a maximum of 44 ports, or 8 Gbps in a maximum of 4 ports.
Dedicated Rate Mode Configurations for the 8-Gbps Modules
Table 1-6 shows the maximum possible dedicated rate mode configuration scenarios for the Generation 3 Fibre Channel modules.
Dynamic Bandwidth Management
On port switching modules where bandwidth is shared, the bandwidth available to each port within a port group can be configured based on the port rate mode and speed configurations. Within a port group, some ports can be configured in dedicated rate mode while others operate in shared mode.
Ports configured in dedicated rate mode are allocated the required bandwidth to sustain a line rate of traffic at the maximum configured operating speed, and ports configured in shared mode share the available remaining bandwidth within the port group. Bandwidth allocation among the shared mode ports is based on the operational speed of the ports. For example, if four ports operating at speeds 1 Gbps, 1 Gbps, 2 Gbps, and 4 Gbps share bandwidth of 8 Gbps, the ratio of allocation would be 1:1:2:4.
Unutilized bandwidth from the dedicated ports is shared among only the shared ports in a port group as per the ratio of the configured operating speed. A port cannot be brought up unless the reserved bandwidth is guaranteed for the shared ports (see Table 1-9 ). For dedicated ports, configured bandwidth is taken into consideration while calculating available bandwidth for the port group. This behavior can be changed using bandwidth fairness by using the rate-mode bandwidth-fairness module number command.
For example, consider a 48-port 8-Gbps module. This module has 6 ports per port group with 12.8 Gbps bandwidth. Ports three to six are configured at 4 Gbps. If the first port is configured at 8 Gbps dedicated rate mode, and the second port is configured at 4-Gbps dedicated rate mode, then no other ports can be configured at 4 Gbps or 8 Gbps because the left over bandwidth of 0.8 Gbps (12.8-(8+4)) cannot meet the required 0.96 Gbps for the remaining four ports. A minimum of 0.24 Gbps reserved bandwidth is required for the for the rest of the four ports. However, if the two ports (for example, 5 and 6) are taken out of service (note that it is not same as shut-down), required reserved bandwidth for the two ports (3 and 4) is 0.48 and port 2 can be configured at 4 Gbps in dedicated rate mode. Note this behavior can be overridden by bandwidth fairness command in which case reserved bandwidth is not enforced. Once the port is up, ports 3 and 4 can share the unutilized bandwidth from ports 1 and 2.
Out-of-Service Interfaces
On supported modules and fabric switches, you might need to allocate all the shared resources for one or more interfaces to another interface in the port group or module. You can take interfaces out of service to release shared resources that are needed for dedicated bandwidth. When an interface is taken out of service, all shared resources are released and made available to the other interface in the port group or module. These shared resources include bandwidth for the shared mode port, rate mode, BB_credits, and extended BB_credits. All shared resource configurations are returned to their default values when the interface is brought back into service. Corresponding resources must be made available in order for the port to be successfully returned to service.
If you need to bring an interface back into service, you might disrupt traffic if you need to release shared resources from other interfaces in the same port group.
Combining Generation 1, Generation 2, and Generation 3 Modules
Cisco MDS NX-OS Release 4.1(1) and later supports combining Generation 1, Generation 2, and Generation 3 modules and switches with the following considerations:
- MDS NX-OS Release 4.1(1) and later features are not supported on Generation 1 switches and modules.
- Generation 3 modules do not support the following Generation 1 hardware:
– 4-Port IP Storage Services module
– 8-Port IP Storage Services module
- Supervisor-1 modules must be upgraded to Supervisor-2 modules on the MDS 9506 and MDS 9509 Directors.
- IPS-4 and IPS-8 modules must be upgraded to the MSM-18/4 Multiservice modules.
- Fabric 1 modules must be upgraded to Fabric 2 modules on the MDS 9513 Director to use the 48-port or the 24-port 8-Gbps module.
- MDS Fabric Manager Release 4.x supports MDS SAN-OS Release 3.x and NX-OS 4.x in mixed mode through Interswitch Link (ISL) connectivity.
Note When a Cisco or another vendor switch port is connected to a Generation 1 module port (ISL connection), the receive buffer-to-buffer credits of the port connected to the Generation 1 module port must not exceed 255.
Port Indexes
Cisco MDS 9000 switches allocate index identifiers for the ports on the modules. These port indexes cannot be configured. You can combine Generation 1, Generation 2, and Generation 3 switching modules, with either Supervisor-1 modules or Supervisor-2 modules. However, combining switching modules and supervisor modules has the following port index limitations:
- Supervisor-1 modules only support a maximum of 252 port indexes, regardless of the type of switching modules.
- Supervisor-2 modules support a maximum of 1020 port indexes when all switching modules in the chassis are Generation 2 or Generation 3.
- Supervisor-2 modules only support a maximum of 252 port indexes when only Generation 1 switching modules, or a combination of Generation 1, Generation 2, or Generation 3 switching modules, are installed in the chassis.
Note On a switch with the maximum limit of 252 port index maximum limit, any new module that exceeds the limit when installed does not power up.
You can use the show port index-allocation command to display the allocation of port indexes on the switch.
Generation 1 switching modules have specific numbering requirements. If these requirements are not met, the module does not power up. The port index numbering requirements include the following:
- If port indexes in the range of 256 to 1020 are assigned to operational ports, Generation 1 switching modules do not power up.
- A block of contiguous port indexes is available. If this block of port indexes is not available, Generation 1 modules do not power up. Table 1-7 shows the port index requirements for the Generation 1 modules.
Note If the switch has Supervisor-1 modules, the block of 32 contiguous port indexes must begin on the slot boundary. The slot boundary for slot 1 is 0, for slot 2 is 32, and so on. For Supervisor-2 modules, the contiguous block can start anywhere.
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14-port Fibre Channel/2-port Gigabit Ethernet Multiprotocol Services (MPS-14/2) module |
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The allowed mix of Generation 1 and Generation 2 switching modules in a chassis is determined at run-time, either when booting up the switch or when installing the modules. In some cases, the sequence in which switching modules are inserted into the chassis determines if one or more modules is powered up.
When a module does not power up because of a resource limitation, you can display the reason by using the show module command.
The running configuration is updated when modules are installed. If you save the running configuration to the startup configuration (using the copy running-config startup-config command), during reboot the switch powers up the same set of modules as before the reboot regardless of the sequence in which the modules initialize. You can use the show port index-allocation startup command to display the index allocation the switch uses at startup.
Note The output of the show port index-allocation startup command does not display anything in the Allowed range column because the command extracts the indices from the persistent storage service (PSS) and displaying an allowed range for startup indices is meaningless.
If a module fails to power up, you can use the show module slot recovery-steps command to display the reason.
For information on recovering a module powered-down because port indexes are not available, refer to the Cisco MDS 9000 Family Troubleshooting Guide.
Tip Whenever using mixed Generation 1 and Generation 2 modules, power up the Generation 1 modules first. During a reboot of the entire switch, the Generation 1 modules power up first (default behavior).
PortChannels
PortChannels have the following restrictions:
- The maximum number of PortChannels allowed is 256 if all switching modules are Generation 2 or Generation 3, or both.
- The maximum number of PortChannels allowed is 128 whenever there is a Generation 1 switching module in use with a Generation 2 or Generation 3 switching module.
- Ports need to be configured in dedicated rate mode on the Generation 2 and Generation 3 switching module interfaces to be used in the PortChannel.
Note The number of PortChannels allowed does not depend on the type of supervisor module. However, Generation 3 modules require the Supervisor 2 module on the MDS 9506 and 9509 switches.
The Generation1, Generation 2, and Generation 3 modules have the following restrictions for PortChannel configuration:
- Generation 1 switching module interfaces do not support auto speed with a maximum of 2 Gbps.
- Generation 1 and Generation 2 module interfaces do not support auto speed with maximum of 4 Gbps.
- Generation 2 and Generation 3 switching module interfaces cannot be forcefully added to a PortChannel if sufficient resources are not available.
Note Before adding a Generation 2 or Generation 3 interface to a PortChannel, use the show port-resources module command to check for resource availability.
When configuring PortChannels on switches with Generation 1, Generation 2, and Generation 3 switching modules, follow one of these procedures:
- Configure the PortChannel, and then configure the Generation 2 and Generation 3 interfaces to auto with a maximum of 2 Gbps.
- Configure the Generation 1 switching modules followed by the Generation 2 switching modules, and then the Generation 3 switching modules, and then configure the PortChannel.
When configuring PortChannels on switches with only Generation 2 and Generation 3 switching modules, follow one of these procedures:
- Configure the PortChannel, and then configure the Generation 3 interfaces to auto with a maximum of 4 Gbps.
- Configure the Generation 2 switching modules, followed by the Generation 3 switching modules, and then configure the PortChannel.
Table 1-8 describes the results of adding a member to a PortChannel for various configurations.
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Pass or fail5 |
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Use the show port-channel compatibility parameters command to obtain information about PortChannel addition errors.
Configuring Module Interface Shared Resources
This section describes how to configure Generation 2 and Generation 3 module interface shared resources and contains the following sections:
- Displaying Interface Capabilities
- Configuration Guidelines for 48-Port, 24-Port, and 4/44-Port 8-Gbps Fibre Channel Switching Modules
- Configuration Guidelines for 48-Port and 24-Port 4-Gbps Fibre Channel Switching Modules
- Configuration Guidelines for 12-Port 4-Gbps Switching Module Interfaces
- Configuration Guidelines for 4-Port 10-Gbps Switching Module Interfaces
- Configuring Port Speed
- Configuring Rate Mode
- Configuring Oversubscription Ratio Restrictions
- Configuring Bandwidth Fairness
- Taking Interfaces Out of Service
- Releasing Shared Resources in a Port Group
Displaying Interface Capabilities
Before configuring a Generation 2 or Generation 3 interface, you can use the show interface capabilities command to display detailed information about the capabilities of the interface.
This example shows the capabilities of a Generation 2 Fibre Channel interface:
This example shows the capabilities of an interface on the 48-port 8-Gbps Fibre Channel switching module:
Configuration Guidelines for 48-Port, 24-Port, and 4/44-Port 8-Gbps Fibre Channel Switching Modules
The 48-Port, 24-Port, and 4/44-Port 8-Gbps Fibre Channel switching modules support the following features:
Migrating from Shared Mode to Dedicated Mode
To configure 48-port, 24-port, 4/44-port 8-Gbps Fibre Channel switching modules when starting with the default configuration or when migrating from shared rate mode to dedicated rate mode, follow these guidelines:
1. Take unused interfaces out of service to release resources for other interfaces, if necessary.
See the “Taking Interfaces Out of Service” section.
2. Configure the traffic speed to use (1 Gbps, 2 Gbps, 4 Gbps, 8 Gbps, or autosensing with a maximum of 2 Gbps or 4 Gbps).
See the “Configuring Port Speed” section.
3. Configure the rate mode (dedicated or shared).
See the “Configuring Rate Mode” section.
See the “About Interface Modes” section.
Note ISL ports cannot operate in shared rate mode.
5. Configure the BB_credits and extended BB_credits, as necessary.
See the “About Extended BB_Credits” section.
Migrating from Dedicated Mode to Shared Mode
To configure 48-port, 24-port, 4/44-port 8-Gbps Fibre Channel switching modules migrating from dedicated rate mode to shared rate mode, follow these guidelines:
1. Take unused interfaces out of service to release resources for other interfaces, if necessary.
See the “Taking Interfaces Out of Service” section.
2. Configure the BB_credits and extended BB_credits, as necessary.
See the “BB_Credit Buffers for Switching Modules” section, “BB_Credit Buffers for Switching Modules” section, and the “About Extended BB_Credits” section.
See the “About Interface Modes” section.
Note ISL ports cannot operate in shared rate mode.
4. Configure the rate mode (dedicated or shared) to use.
See the “Configuring Rate Mode” section.
5. Configure the traffic speed (1 Gbps, 2 Gbps, 4 Gbps, 8 Gbps, or autosensing with a maximum of 2 Gbps or 4 Gbps) to use.
See the “Configuring Port Speed” section.
Configuration Guidelines for 48-Port and 24-Port 4-Gbps Fibre Channel Switching Modules
The 48-port and 24-port 4-Gbps Fibre Channel switching modules support the following features:
Migrating from Shared Mode to Dedicated Mode
To configure 48-port and 24-port 4-Gbps Fibre Channel switching modules when starting with the default configuration or when migrating from shared rate mode to dedicated rate mode, follow these guidelines:
1. Take unused interfaces out of service to release resources for other interfaces, if necessary.
See the “Taking Interfaces Out of Service” section.
2. Configure the traffic speed to use (1 Gbps, 2 Gbps, 4 Gbps, or autosensing with a maximum of 2 Gbps or 4 Gbps).
See the “Configuring Port Speed” section.
3. Configure the rate mode (dedicated or shared) to use.
See the “Configuring Rate Mode” section.
Note ISL ports cannot operate in shared rate mode.
5. Configure the BB_credits and extended BB_credits, as necessary.
See the “About Extended BB_Credits” section.
Migrating from Dedicated Mode to Shared Mode
To configure 48-port and 24-port 4-Gbps Fibre Channel switching modules migrating from dedicated rate mode to shared rate mode, follow these guidelines:
1. Take unused interfaces out of service to release resources for other interfaces, if necessary.
See the “Taking Interfaces Out of Service” section.
2. Configure the BB_credits and extended BB_credits, as necessary.
See the “BB_Credit Buffers for Switching Modules” section, “BB_Credit Buffers for Fabric Switches” section, and the “About Extended BB_Credits” section.
See the “About Interface Modes” section.
Note ISL ports cannot operate in shared rate mode.
4. Configure the rate mode (dedicated or shared) to use.
See the “Configuring Rate Mode” section.
5. Configure the traffic speed (1 Gbps, 2 Gbps, 4 Gbps, or autosensing with a maximum of 2 Gbps or 4 Gbps) to use.
See the “Configuring Port Speed” section.
Configuration Guidelines for 12-Port 4-Gbps Switching Module Interfaces
The 12-port 4-Gbps switching modules support the following features:
- 1-Gbps, 2-Gbps, and 4-Gbps speed traffic
- Only dedicated rate mode
- ISL (E or TE) and Fx (F or FL) port modes
- Extended BB_credits
- Performance buffers
To configure 4-port 10-Gbps switching modules when starting with the default configuration, follow these guidelines:
1. Configure the traffic speed (1 Gbps, 2 Gbps, 4 Gbps, or autosensing with a maximum of 2 Gbps or 4 Gbps) to use.
See the “Configuring Port Speed” section.
3. Configure the BB_credits, performance buffers, and extended BB_credits, as necessary.
See the “BB_Credit Buffers for Switching Modules” section, “BB_Credit Buffers for Fabric Switches” section, and the “About Extended BB_Credits” section.
Note If you change the port bandwidth reservation parameters on a 48-port or 24-port module, the change affects only the changed port. No other ports in the port group are affected.
Configuration Guidelines for 4-Port 10-Gbps Switching Module Interfaces
The 4-port 10-Gbps switching modules support the following features:
- Only 10-Gbps speed traffic
- Only dedicated rate mode
- ISL (E or TE) and F port modes
- Extended BB_credits
- Performance buffers
Use the following guidelines to configure 4-port 10-Gbps switching modules when starting with the default configuration:
See the “About Interface Modes” section.
2. Configure the BB_credits, performance buffers, and extended BB_credits, as necessary.
See the “BB_Credit Buffers for Switching Modules” section, “BB_Credit Buffers for Fabric Switches” section, and the “About Extended BB_Credits” section.
Configuring Port Speed
The port speed on an interface, combined with the rate mode, determines the amount of shared resources available to the ports in the port group on a 48-port, 24-port 4-Gbps, or any 8-Gbps Fibre Channel switching module. Especially in the case of dedicated rate mode, the port group resources are reserved even though the bandwidth is not used. For example, on Generation 2 modules, if an interface is configured for autosensing (auto) and dedicated rate mode, then 4 Gbps of bandwidth is reserved even though the maximum operating speed is 2 Gbps. For the same interface, if autosensing with a maximum speed of 2 Gbps (auto max 2000) is configured, then only 2 Gbps of bandwidth is reserved and the unused 2 Gbps is shared with the other interface in the port group.
Note ● The Generation 2, 4-port 10-Gbps switching module supports 10-Gbps traffic only.
- On Generation 3, 8-Gbps modules, setting the port speed to auto enables autosensing, which negotiates to a maximum speed of 8 Gbps.
- On Generation 2, 4-Gbps modules, setting the port speed to auto enables autosensing, which negotiates to a maximum speed of 4 Gbps.
Changing port speed and rate mode disrupts traffic on the port. Traffic on other ports in the port group is not affected.
To configure the port speed on an interface on a 4-Gbps or 8-Gbps switching module, follow these steps:
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Selects the interface and enters interface configuration submode. |
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Configures the port speed in megabits per second. Valid values are 1000, 2000, 4000 and auto. The auto parameter enables autosensing on the interface. |
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(8-Gbps modules only6) Configures the port speed in megabits per second to 8-Gbps. Valid values are 1000, 2000, 4000, 8000 and auto. The auto parameter enables autosensing on the interface. |
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On 4-Gbps modules, configures autosensing for the interface with 4 Gbps of bandwidth reserved. On 8-Gbps modules, configures autosensing for the interface with 8 Gbps of bandwidth reserved. 2 |
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Configures autosensing with a maximum of |
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(8-Gbps modules only 1) Configures autosensing with a maximum of 4Gbps of bandwidth reserved. |
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Reverts to the default7 speed for the interface ( auto). |
Use the show interface command to verify the port speed configuration for an interface on a 4-Gbps or 8-Gbps Fibre Channel switching module.
Configuring Rate Mode
To configure the rate mode (dedicated or shared) on an interface on a 48-port or 24-port 4-Gbps, or any 8-Gbps Fibre Channel switching module, follow these steps:
Changing port speed and rate mode disrupts traffic on the port.
Use show port-resources module command to verify the rate mode configuration for interfaces on a 48-port or 24-port 4-Gbps, or any 8-Gbps Fibre Channel switching module.
This example shows the port rate mode configuration for interfaces on a 4-Gbps module:
This example shows the port rate mode configuration for interfaces on a 48-port 8-Gbps module:
This example shows the port rate mode configuration for interfaces on a 4/44-port 8-Gbps module:
Configuring Oversubscription Ratio Restrictions
The 48-port and 24-port 4-Gbps, and all 8-Gbps Fibre Channel switching modules support oversubscription on switches with shared rate mode configurations. By default, all 48-port and 24-port 4-Gbps, and 8-Gbps Fibre Channel switching modules have restrictions on oversubscription ratios enabled. As of Cisco SAN-OS Release 3.1(1) and NX-OS Release 4.1(1), you can disable restrictions on oversubscription ratios.
Table 1-9 describes the bandwidth allocation for oversubscribed interfaces configured in shared mode on the 4-Gbps and 8-Gbps modules.
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All ports in the 48-port and 24-port 4-Gbps modules can be configured to operate at 4 Gbps in shared mode even if other ports in the port group are configured in dedicated mode, regardless of available bandwidth. However, when oversubscription ratio restrictions are enabled, you may not have all shared 4-Gbps module ports operating at 4 Gbps.
All ports in the 48-port and 24-port 8-Gbps modules can be configured to operate at 8 Gbps in shared mode even if other ports in the port group are configured in dedicated mode, regardless of available bandwidth. However, when oversubscription ratio restrictions are enabled you may not have all shared 8-Gbps module ports operating at 8 Gbps.
On the 48-port and 24-port 8-Gbps modules, if you have configured one 8-Gbps dedicated port in one port group, no other ports in the same port group can be configured to operate at 8-Gbps dedicated mode. You can have any number of 8-Gbps shared and 4-Gbps dedicated or shared ports. On the 4/44-port 8-Gbps module, only one port per port group can be configured in 8-Gbps dedicated or shared mode.
In the following example, a 24-port 4-Gbps module has oversubscription ratios enabled and three dedicated ports in one port group operating at 4-Gbps. No other ports in the same port group can be configured to operate at 4 Gbps.
For dedicated ports, oversubscription ratio restrictions do not apply to the shared pool in port groups. So if oversubscription ratio restrictions are disabled, and you have configured three 4-Gbps dedicated ports in one port group, then you can configure all other ports in the same port group to operate at a shared rate of 4 Gbps.
In the following example, a 24-port module has a group of six ports, three dedicated ports are operating at 4 Gbps, and three shared ports operating at 4 Gbps:
When disabling restrictions on oversubscription ratios, all ports in shared mode on 48-port and 24-port 4-Gbps or any 8-Gbps Fibre Channel switching modules must be shut down. When applying restrictions on oversubscription ratios, you must take shared ports out of service.
Note When restrictions on oversubscription ratios are disabled, the bandwidth allocation among the shared ports is proportionate to the configured speed. If the configured speed is auto on Generation 2 modules, then bandwidth is allocated assuming a speed of 4 Gbps. For example, if you have three shared ports configured at 1, 2, and 4 Gbps, then the allocated bandwidth ratio is 1:2:4.
As of Cisco SAN-OS Release 3.0 and NX-OS Release 4.1(1) or when restrictions on oversubscription ratios are enabled, the port bandwidths are allocated in equal proportions, regardless of port speed, so, the bandwidth allocation for the same three ports mentioned in the example would be 1:1:1.
Disabling Restrictions on Oversubscription Ratios
Before disabling restrictions on oversubscription ratios, ensure that you have explicitly shut down shared ports.
To disable restrictions on oversubscription ratios on a 48-port or 24-port 4-Gbps, or any 8-Gbps Fibre Channel switching module, follow these steps:
Use the show running-config command to view oversubscription ratios for a module. If oversubscription ratios are enabled, then no restriction appears in the output.
Example 1-1 Module with Restrictions on Oversubscription Ratios Disabled
Oversubscription Ratio Restrictions Example
To disable restrictions on oversubscription ratios for ports on a 48-port Generation 2 switch that is configured with both shared and dedicated ports, follow these steps:
Step 1 To disable restrictions on oversubscription ratios, you must shut down any shared ports. Use the show port-resources command to view the configuration on a module and to identify shared ports.
Step 2 Shut down all shared ports for which you want to remove restrictions on oversubscription ratios.
Step 3 Display the interface status to confirm the shutdown of all shared ports.
Step 4 Disable restrictions on oversubscription ratios for the ports.
Step 5 Bring up the ports that you shut down in step 2, and display their status to confirm that they are no longer shut down.
Step 6 Confirm that the ports are now operating with no restrictions on oversubscription ratios.
Step 7 Save the new oversubscription ratio configuration to the startup configuration.
Enabling Restrictions on Oversubscription Ratios
You must enable restrictions on oversubscription ratios before you can downgrade modules to a previous release.
Before enabling restrictions on oversubscription ratios, ensure that you have explicitly configured shared ports to out-of-service mode.
To enable restrictions on oversubscription ratios on a 48-port or 24-port 4-Gbps, or any 8-Gbps Fibre Channel switching module, follow these steps:
Configuring Bandwidth Fairness
This feature improves fairness of bandwidth allocation among all ports and provides better throughput average to individual data streams. Bandwidth fairness can be configured per module.
As of Cisco SAN-OS Release 3.1(2), all 48-port and 24-port 4-Gbps Fibre Channel switching modules, as well as 18-port Fibre Channel/4-port Gigabit Ethernet Multiservice modules, have bandwidth fairness enabled by default. As of Cisco NX-OS Release 4.1(1), all the 8-Gbps Fibre Channel switching modules have bandwidth fairness enabled by default.
When you disable or enable bandwidth fairness, the change does not take effect until you reload the module.
Use the show module bandwidth-fairness command to check whether ports in a module are operating with bandwidth fairness enabled or disabled.
This section includes the following topics:
Note This feature is supported only on the 48-port and 24-port 4-Gbps modules, the 8-Gbps modules, and the 18/4-port Multiservice Module (MSM).
Enabling Bandwidth Fairness
To enable bandwidth fairness on a switching module, follow these steps:
Disabling Bandwidth Fairness
Note If you disable bandwidth fairness, up to a 20 percent increase in internal bandwidth allocation is possible for each port group; however, bandwidth fairness is not guaranteed when there is a mix of shared and full-rate ports in the same port group.
To disable bandwidth fairness on a switching module, follow these steps:
Upgrade or Downgrade Scenario
When you are upgrading from a release earlier than Cisco SAN-OS Release 3.1(2), all modules operate with bandwidth fairness disabled until the next module reload. After the upgrade, any new module that is inserted has bandwidth fairness enabled.
When you are downgrading to a release earlier than Cisco SAN-OS Release 3.1(2), all modules keep operating in the same bandwidth fairness configuration prior to the downgrade. After the downgrade, any new module that is inserted has bandwidth fairness disabled.
Note After the downgrade, any insertion of a module or module reload will have bandwidth fairness disabled.
Taking Interfaces Out of Service
You can take interfaces out of service on Generation 2 and Generation 3 switching modules. When an interface is out of service, all the shared resources for the interface are released as well as the configuration associated with those resources.
Note The interface must be disabled using a shutdown command before it can be taken out of service.
Taking interfaces out of service releases all the shared resources to ensure that they are available to other interfaces. This causes the configuration in the shared resources to revert to default when the interface is brought back into service. Also, an interface cannot come back into service unless the default shared resources for the port are available. The operation to free up shared resources from another port is disruptive.
Note The interface cannot be a member of a PortChannel.
To take an interface out of service, follow these steps:
Use the show port-resources module command to verify the out-of-service configuration for interfaces on a Generation 2 and Generation 3 switching module.
This example shows a 24-port 4-Gbps module:
Releasing Shared Resources in a Port Group
When you want to reconfigure the interfaces in a port group on a Generation 2 or Generation 3 module, you can return the port group to the default configuration to avoid problems with allocating shared resources.
Note The interface cannot be a member of a PortChannel.
Releasing shared resources disrupts traffic on the port. Traffic on other ports in the port group is not affected.
To release the shared resources for a port group, follow these steps:
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Selects the interface and enters interface configuration submode. |
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switch(config-if)# out-of-service Putting an interface into out-of-service will cause its shared resource configuration to revert to default |
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Makes the interface available for service. Repeat Step 2 through Step 6 for all the interfaces in the port group. |
Disabling ACL Adjacency Sharing for System Image Downgrade
Fibre Channel ACL adjacency sharing is enabled by default on the switches with an active Generation 2 switching module as of Cisco MDS SAN-OS Release 3.0(3), and with an active Generation 3 module as of MDS NX-OS Release 4.1(1). Fibre Channel ACL adjacency sharing improves the performance for zoning and inter-VSAN routing (IVR) network address translation (NAT). To prevent disruptions when downgrading the system image on your switch to a release prior to Cisco SAN-OS Release 3.0(3), enter the following command in EXEC mode:
To reenable Fibre Channel ACL adjacency sharing on your switch, enter the following command in EXEC mode:
Displaying SFP Diagnostic Information
You can use the show interface transceiver command to display small form-factor pluggable (SFP) diagnostic information for Generation 2 switching modules.
Example Configurations
This section describes example configurations and includes the following sections:
- Configuring a 48-Port 8-Gbps Fibre Channel Switching Module Example
- Configuring a 24-Port 8-Gbps Fibre Channel Switching Module Example
- Configuring a 4/44-Port 8-Gbps Fibre Channel Switching Module Example
- Configuring a 24-Port 4-Gbps Fibre Channel Switching Module Example
- Configuring a 48-Port 4-Gbps Fibre Channel Switching Module Example
Configuring a 48-Port 8-Gbps Fibre Channel Switching Module Example
These steps describe how to configure the 48-port 8-Gbps module interfaces module:
Step 1 Select the interfaces fc 4/1 through fc 4/2.
Step 2 Configure the port speed, rate mode, and port mode on the interfaces.
Step 3 Enable the interfaces and return to configuration mode.
Step 4 Select the interfaces fc 4/3 through fc 4/4.
Step 5 Configure the port speed, rate mode, and port mode on the interfaces.
Step 6 Enable the interfaces and return to configuration mode.
Step 7 Select the interfaces fc 4/5 through fc 4/6.
Step 8 Configure the port speed, rate mode, and port mode on the interfaces.
Step 9 Enable the interfaces and return to configuration mode.
Configuring a 24-Port 8-Gbps Fibre Channel Switching Module Example
These steps describe how to configure the 24-port 8-Gbps module interfaces:
Step 1 Select interfaces fc 3/1.
Step 2 Configure the port speed, rate mode, and port mode on the interfaces.
Step 3 Enable the interfaces and return to configuration mode.
Step 4 Select the interfaces fc 3/2 through fc 3/3.
Step 5 Configure the port speed, rate mode, and port mode on the interfaces.
Step 6 Enable the interfaces and return to configuration mode.
Configuring a 4/44-Port 8-Gbps Fibre Channel Switching Module Example
These steps describe how to configure the 4/44-port 8-Gbps module interfaces:
Step 1 Select interfaces fc 4/11 through fc 4/12.
Step 2 Disable the interfaces and take them out of service.
Step 3 Return to configuration mode.
Step 4 Select the interfaces fc 4/1.
Step 5 Configure the port speed, rate mode, and port mode on the interfaces.
Step 6 Enable the interfaces and return to configuration mode.
Step 7 Select the interfaces fc 4/2 through fc 4/10.
Step 8 Configure the port speed, rate mode, and port mode on the interfaces.
Step 9 Enable the interfaces and return to configuration mode.
Configuring a 24-Port 4-Gbps Fibre Channel Switching Module Example
These steps describe how to configure the example shown in Figure 1-8:
Step 1 Select interfaces fc 3/1 through fc 3/3.
Step 2 Configure the port speed, rate mode, and port mode on the interfaces.
Step 3 Enable the interfaces and return to configuration mode.
Step 4 Select the interfaces fc 3/4 through fc 3/6.
Step 5 Configure the port speed, rate mode, and port mode on the interfaces.
Step 6 Enable the interfaces and return to configuration mode.
Configuring a 48-Port 4-Gbps Fibre Channel Switching Module Example
These steps describe how to configure the example shown in Figure 1-6:
Step 1 Select interfaces fc 4/11 through fc 4/12.
Step 2 Disable the interfaces and take them out of service.
Step 3 Return to configuration mode.
Step 4 Select the interfaces fc 4/1 through fc 4/6.
Step 5 Configure the port speed, rate mode, and port mode on the interfaces.
Step 6 Enable the interfaces and return to configuration mode.
Step 7 Select the interfaces fc 4/7 through fc 4/10.
Step 8 Configure the port speed, rate mode, and port mode on the interfaces.
Step 9 Enable the interfaces and return to configuration mode.
Default Settings
Table 1-10 lists the default settings for Generation 2 interface parameters.
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auto8 |
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auto9 |
auto 10 |
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145 11 |
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Table 1-11 lists the default settings for Generation 3 interface parameters.
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auto_max_4G12 |
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12.Auto_max_4G speed mode on the 4/44-port 8-Gbps switching module negotiates to a maximum speed of |
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