For the Ethernet and management interfaces, you can configure the description parameter to provide a recognizable name for the interface. Using a unique name for each interface allows you to quickly identify the interface when you are looking at a listing of multiple interfaces.

For information about setting the description parameter for port-channel interfaces, see the “Configuring a Port-Channel Description” section. For information about configuring this parameter for other interfaces, see the “Configuring the Description” section.

The beacon mode allows you to identify a physical port by flashing its link state LED with a green light. By default, this mode is disabled. To identify the physical port for an interface, you can activate the beacon parameter for the interface.

For information about configuring the beacon parameter, see the “Configuring the Beacon Mode” section.

A port is in the error-disabled (err-disabled) state when the port is enabled administratively (using the no shutdown command) but disabled at runtime by any process. For example, if UDLD detects a unidirectional link, the port is shut down at runtime. However, because the port is administratively enabled, the port status displays as err-disable. Once a port goes into the err-disable state, you must manually reenable it or you can configure a timeout value that provides an automatic recovery. By default, the automatic recovery is not configured, and by default, the err-disable detection is enabled for all causes.

When an interface is in the err-disabled state, use the show interface status err-disabled command to find information about the error.

You can configure the automatic error-disabled recovery timeout for a particular error-disabled cause and configure the recovery period.

The errdisable recovery cause command provides an automatic recovery after 300 seconds.

You can use the errdisable recovery interval command to change the recovery period within a range of 30 to 65535 seconds. You can also configure the recovery timeout for a particular err-disable cause.

If you do not enable the error-disabled recovery for the cause, the interface stays in the error-disabled state until you enter the shutdown and no shutdown commands. If the recovery is enabled for a cause, the interface is brought out of the error-disabled state and allowed to retry operation once all the causes have timed out.

The medium dependent interface crossover (MDIX) parameter enables or disables the detection of a crossover connection between devices. This parameter applies only to copper interfaces. By default, this parameter is enabled. The no mdix auto command is supported only on N9K-C93108TC-EX, N9K-C93108TC-FX, N9K-X9788TC-FX, and N9K-C9348GC-FXP devices.

For information about configuring the MDIX parameter, see the Configuring the MDIX Parameter section.

Cisco NX-OS policy servers such as Access Control List (ACL) Manager and Quality of Service (QoS) Manager, maintain a policy database. A policy is defined through the command-line interface.

Policies are pushed when you configure a policy on an interface to ensure that policies that are pushed are consistent with the hardware policies. To clear the errors and to allow the policy programming to proceed with the running configuration, enter the no shutdown command. If the policy programming succeeds, the port is allowed to come up. If the policy programming fails, the configuration is inconsistent with the hardware policies and the port is placed in an error-disabled policy state. The error-disabled policy state remains and the information is stored to prevent the same port from being brought up in the future. This process helps to avoid unnecessary disruption to the system.

The maximum transmission unit (MTU) size specifies the maximum frame size that an Ethernet port can process. For transmissions to occur between two ports, you must configure the same MTU size for both ports. A port drops any frames that exceed its MTU size.

By default, the Cloud-Scale ASIC NX-OS system always allows an extra 166B in the MTU on top of the configured value in order to fully support/accept different types of encapsulations in the hardware.

Cisco NX-OS allows you to configure MTU on an interface, with options to configure it on different level in the protocol stack. By default, each interface has an MTU of 1500 bytes, which is the IEEE 802.3 standard for Ethernet frames. Larger MTU sizes are possible for more efficient processing of data to allow different application requirements. The larger frames, are also called jumbo frames, can be up to 9216 bytes in size.

MTU is configured per interface, where an interface can be a Layer 2 or a Layer 3 interface. For a Layer 2 interface, you can configure the MTU size with one of two values, the value system default MTU value or the system jumbo MTU value. The system default MTU value is 1500 bytes. Every Layer 2 interface is configured with this value by default. You can configure an interface with the default system jumbo MTU value, that is 9216 bytes. To allow an MTU value from 1500 through 9216, you must adjust the system jumbo MTU to an appropriate value where interface can be configured with the same value.

Note	You can change the system jumbo MTU size. When the value is changed, the Layer 2 interfaces that use the system jumbo MTU value, will automatically changes to the new system jumbo MTU value.

A Layer 3 interface, can be Layer 3 physical interface (configure with no switchport), switch virtual interface (SVI), and sub-interface, you can configure an MTU size between 576 and 9216 bytes.

For information about setting the MTU size, see the Configuring the MTU Size section.

Note	On Cisco Nexus 9300-FX2 and 9300-GX devices, if ingress interface is configured with an MTU less than 9216, FTE does not capture input errors and does not display any events. However, if the ingress interface is configured with an MTU of 9216, FTE displays all the events.

Ethernet ports have a fixed bandwidth of 1,000,000 Kb at the physical layer. Layer 3 protocols use a bandwidth value that you can set for calculating their internal metrics. The value that you set is used for informational purposes only by the Layer 3 protocols—it does not change the fixed bandwidth at the physical layer. For example, the Enhanced Interior Gateway Routing Protocol (EIGRP) uses the minimum path bandwidth to determine a routing metric, but the bandwidth at the physical layer remains at 1,000,000 Kb.

For information about configuring the bandwidth parameter, see the Configuring the Bandwidth.

Specifying a value for the throughput-delay parameter provides a value used by Layer 3 protocols; it does not change the actual throughput delay of an interface. The Layer 3 protocols can use this value to make operating decisions. For example, the Enhanced Interior Gateway Routing Protocol (EIGRP) can use the delay setting to set a preference for one Ethernet link over another, if other parameters such as link speed are equal. The delay value that you set is in the tens of microseconds.

For information on configuring the throughput-delay parameter for other interfaces, see Configuring the Throughput Delay.

The administrative-status parameter determines whether an interface is up or down. When an interface is administratively down, it is disabled and unable to transmit data. When an interface is administratively up, it is enabled and able to transmit data.

For information about configuring the administrative status parameter for port-channel interfaces, see the “Shutting Down and Restarting the Port-Channel Interface” section. For information about configuring the administrative-status parameter for other interfaces, see the “Shutting Down and Activating the Interface” section.

A port channel is an aggregation of physical interfaces that comprise a logical interface. You can bundle up to 32 individual interfaces into a port channel to provide increased bandwidth and redundancy. Port channeling also load balances traffic across these physical interfaces. The port channel stays operational if at least one physical interface within the port channel is operational.

You can create Layer 3 port channels by bundling compatible Layer 3 interfaces.

Any configuration changes that you apply to the port channel are applied to each interface member of that port channel.

For information about port channels and for information about configuring port channels, see Chapter 6, “Configuring Port Channels.”

On Cisco Nexus 9300 Series switches, you can create a port profile that contains many interface commands and apply that port profile to a range of interfaces. Each port profile can be applied only to a specific type of interface; the choices are as follows:

• Ethernet

• VLAN network interface

• Port channel

When you choose Ethernet or port channel as the interface type, the port profile is in the default mode which is Layer 3. Enter the switchport command to change the port profile to Layer 2 mode.

You inherit the port profile when you attach the port profile to an interface or range of interfaces. When you attach, or inherit, a port profile to an interface or range of interfaces, the system applies all the commands in that port profile to the interfaces. Additionally, you can have one port profile inherit the settings from another port profile. Inheriting another port profile allows the initial port profile to assume all of the commands of the second, inherited, port profile that do not conflict with the initial port profile. Four levels of inheritance are supported. The same port profile can be inherited by any number of port profiles.

The system applies the commands inherited by the interface or range of interfaces according to the following guidelines:

• Commands that you enter under the interface mode take precedence over the port profile’s commands if there is a conflict. However, the port profile retains that command in the port profile.

• The port profile’s commands take precedence over the default commands on the interface, unless the port-profile command is explicitly overridden by the default command.

• When a range of interfaces inherits a second port profile, the commands of the initial port profile override the commands of the second port profile if there is a conflict.

• After you inherit a port profile onto an interface or range of interfaces, you can override individual configuration values by entering the new value at the interface configuration level. If you remove the individual configuration values at the interface configuration level, the interface uses the values in the port profile again.

• There are no default configurations associated with a port profile.

A subset of commands are available under the port-profile configuration mode, depending on which interface type you specify.

Note	You cannot use port profiles with Session Manager. See the Cisco Nexus 9000 Series NX-OS System Management Configuration Guide for information about Session Manager.

To apply the port-profile configurations to the interfaces, you must enable the specific port profile. You can configure and inherit a port profile onto a range of interfaces prior to enabling the port profile. You would then enable that port profile for the configurations to take effect on the specified interfaces.

If you inherit one or more port profiles onto an original port profile, only the last inherited port profile must be enabled; the system assumes that the underlying port profiles are enabled.

When you remove a port profile from a range of interfaces, the system undoes the configuration from the interfaces first and then removes the port-profile link itself. Also, when you remove a port profile, the system checks the interface configuration and either skips the port-profile commands that have been overridden by directly entered interface commands or returns the command to the default value.

If you want to delete a port profile that has been inherited by other port profiles, you must remove the inheritance before you can delete the port profile.

You can also choose a subset of interfaces from which to remove a port profile from among that group of interfaces that you originally applied the profile. For example, if you configured a port profile and configured ten interfaces to inherit that port profile, you can remove the port profile from just some of the specified ten interfaces. The port profile continues to operate on the remaining interfaces to which it is applied.

If you delete a specific configuration for a specified range of interfaces using the interface configuration mode, that configuration is also deleted from the port profile for that range of interfaces only. For example, if you have a channel group inside a port profile and you are in the interface configuration mode and you delete that port channel, the specified port channel is also deleted from the port profile as well.

Just as in the device, you can enter a configuration for an object in port profiles without that object being applied to interfaces yet. For example, you can configure a virtual routing and forward (VRF) instance without it being applied to the system. If you then delete that VRF and related configurations from the port profile, the system is unaffected.

After you inherit a port profile on an interface or range of interfaces and you delete a specific configuration value, that port-profile configuration is not operative on the specified interfaces.

If you attempt to apply a port profile to the wrong type of interface, the system returns an error.

When you attempt to enable, inherit, or modify a port profile, the system creates a checkpoint. If the port-profile configuration fails, the system rolls back to the prior configuration and returns an error. A port profile is never only partially applied.

The Cisco QSFP+ to SFP+ Adapter (QSA) module provides 10G support for the 40G uplink ports that are a part of the Cisco Nexus M6PQ and Cisco Nexus M12PQ uplink modules of specific Cisco Nexus 9300 devices.

A group of six consecutive ports in the M6PQ or M12PQ uplink module must be operating at the same speed (40G or 10G) to use the QSA/QSFP modules.

• For Cisco Nexus 9396PX devices, 2/1-6 ports form the first port speed group and the remaining 2/7-12 ports form the second port speed group.

• For Cisco Nexus 93128PX/TX devices, 2/1-6 ports form the first port speed group and the remaining 2/7-8 ports form the second port speed group.

• For Cisco Nexus 937xPX/TX devices, 1/49-54 ports form the only port speed group.

• For Cisco Nexus 93120TX devices, 1/97-102 ports form the only port speed group.

• For Cisco Nexus 9332PQ devices, 1/27-32 ports form the only port speed group.

Use the speed-group 10000 command to configure the first port of a port speed group for the QSA. This command specifies the administrator speed preference for the port group. (The default port speed is 40G.)

• The speed-group 10000 command specifies a speed of 10G.

• The no speed-group 10000 command specifies a speed of 40G.

• Uplink modules should not be removed from a Cisco Nexus 9300 platform switch that is running Cisco NX-OS Release 7.0(3)I7(5). The ports on uplink modules should be used only for uplinks.

• Beginning with Cisco NX-OS Release 9.2(2), CWDM4 is supported on the 36-port 100-Gigabit Ethernet QSFP28 line cards (N9K-X9636C-R), the 36-port 40-Gigabit Ethernet QSFP+ line cards (N9K-X9636Q-R), the 36-port 100-Gigabit QSFP28 line cards (N9K-X9636C-RX) and the 52-port 100-Gigabit QSFP28 line cards (N9K-X96136YC-R).

After the speed has been configured, the compatible transceiver modules are enabled. The remaining transceiver modules in the port group (incompatible transceiver modules) become error disabled with a reason of "check speed-group config".

Note	The Cisco QSFP+ to SFP+ Adapter (QSA) module does not provide 10G support for the 40G line cards for Cisco Nexus 9500 devices. You can use a QSFP-to-SFP adapter on Cisco Nexus 9200 and 9300-EX Series switches and Cisco Nexus 3232C and 3264Q Series switches.

You can use the CVR-2QSFP28-8SFP adapter for 25-Gigabit optics support on 100-Gigabit ports of the Cisco Nexus 9236C switch.

The interface breakout module command can be used to split this switch's 100G interfaces into four 25G interfaces. After you enter this command, you must copy the running configuration to the startup configuration.

Beginning with Cisco NX-OS Release 9.2(3), 10/25 LR is supported on N9K-C93180YC-EX, N9K-X97160YC-EX, N9K-C93180YC-FX, N9K-C93240YC-FX2 and N3K-C34180YC switches. This dual speed optical transceiver operates at 25G by default and it seamlessly interoperates with other 25G LR transceivers. Because auto speed sensing is not supported on this device, to interoperate with a 10G transceiver, you must manually configure it to use 10G speed.

Beginning with Cisco NX-OS Release 9.3(5), 10G BASE-T SFP+ (RJ-45) is supported on N9K-C93240YC-FX2, N9K-C93180YC-EX, N9K-C93180YC-FX and N9K-C93360YC-FX2 devices. This copper transceiver operates at 10G by default.

Note	When you connect a SFP-10G-T-X device into a port, all the neighboring ports of this device must be either empty, or be connected to passive copper links only.

Note

On Cisco Nexus 9000 Series Switches, the show interface and show interface capability commands may display 100 Mbps as a supported speed for certain ports. However, this speed is only supported when using the SFP-10G-T-X transceiver. For ports using GLC-TE transceivers, the lowest supported speed is 1 Gbps.

Note	Interface configured with media-type 10G-TX while in admin up state will remain errdisabled under Unsupported media-type. To remove this condition, use the following commands on the interface: shutdown no shutdown

You can view the reason that an interface moves to the error-disabled state and configure automatic recovery.

This example shows how to verify the media-type configuration:

Note	The ports that support SFP-10G-T-X may vary in different devices. This example displays the port numbers that support SFP-10G-T-X on a Cisco Nexus N9K-C93240YC-FX2 switch.

switch# sh running-config interface ethernet 1/2
 
!Command: show running-config interface Ethernet1/2
!Running configuration last done at: Mon Jun  1 10:16:46 2020
!Time: Mon Jun  1 10:16:54 2020
 
version 9.3(5) Bios:version 05.41
 
interface Ethernet1/2
  switchport
  switchport access vlan 10
  mtu 9216
  media-type 10g-tx
  no shutdown
 
Supported ports in Switch 01:
switch# sh interface status | i i SFP-10
Eth1/2        --                 connected 10        full    10G     SFP-10G-T-X
Eth1/6        --                 connected 11        full    10G     SFP-10G-T-X
Eth1/8        --                 connected 11        full    10G     SFP-10G-T-X
Eth1/12       --                 connected 12        full    10G     SFP-10G-T-X
Eth1/14       --                 connected 12        full    10G     SFP-10G-T-X
Eth1/18       --                 connected 13        full    10G     SFP-10G-T-X
Eth1/20       --                 connected 13        full    10G     SFP-10G-T-X
Eth1/24       --                 connected 14        full    10G     SFP-10G-T-X
Eth1/26       --                 connected 14        full    10G     SFP-10G-T-X
Eth1/30       --                 connected 15        full    10G     SFP-10G-T-X
Eth1/32       --                 connected 15        full    10G     SFP-10G-T-X
Eth1/36       --                 connected 16        full    10G     SFP-10G-T-X
Eth1/38       --                 connected 16        full    10G     SFP-10G-T-X
Eth1/42       --                 connected 20        full    10G     SFP-10G-T-X
Eth1/44       Connect_to_Sw_01   connected 202       full    10G     SFP-10G-T-X
Eth1/48       Connect_to_Sw_02   connected 202       full    10G     SFP-10G-T-X
 



switch# sh mod
Mod Ports             Module-Type                       Model          Status
--- ----- ------------------------------------- --------------------- ---------
1    60   48x10/25G + 12x40/100G Ethernet Modul N9K-C93240YC-FX2      active *
 
Mod  Sw                       Hw    Slot
---  ----------------------- ------ ----
1    9.3(4.104)               0.3020 NA
 
 
Mod  MAC-Address(es)                         Serial-Num
---  --------------------------------------  ----------
1    b4-de-31-94-4e-c8 to b4-de-31-94-4f-0f  FDO2143306S
 
Mod  Online Diag Status
---  ------------------
1    Pass

MTU is configured per interface, where the interface can be a Layer 2 or a Layer 3 interface. Every interface has default MTU of 1500 bytes. This value is called system default MTU. You can configure a Layer 2 interface, with a a value of 9216 bytes, which is the default value of the system jumbo MTU. To allow an MTU value that is between 1500 and 9216, system jumbo MTU needs to be adjusted to appropriate value where interface can be configured with the same value.

Note	You can change the system jumbo MTU size. When the value is changed, the Layer 2 interfaces that use the system jumbo MTU value, will automatically changes to the new system jumbo MTU value.

A Layer 3 interface, can be Layer 3 physical interface switch virtual interface (SVI), and subinterface, you can configure an MTU size between 576–9216 bytes.

You can apply several configuration parameters to a range of interfaces simultaneously. All the interfaces in the range must be the same type. You can also inherit the configurations from one port profile into another port profile. The system supports four levels of inheritance.

Autonegotiation allows devices to advertise enhanced modes of operation it possesses via the link segment and to detect corresponding enhanced operational modes that the other devices may be advertising. Autonegotiation provides the means to exchange information between two devices that share a link segment and to automatically configure both devices to take maximum advantage of their abilities.