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This chapter describes how to configure the basic interface parameters or the parameters that are shared by multiple interfaces.
This chapter includes the following sections:
•Information About the Basic Interface Parameters
•Configuring the Basic Interface Parameters
•Verifying the Basic Interface Parameters
•Feature History for Basic Interface Parameters
Note To configure Layer 2 access or trunking interfaces, see Chapter 2 "Configuring Interface Parameters."
This section includes the following topics:
For the vEthernet, 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.
By default, the description for vEthernet interfaces is auto-formatted to contain information about the device connected. The description for a VNIC, for example, contains the VM name and network adapter number. You keep this default description or can also override it with a description of your choosing.
For information about setting the description parameter for port channel interfaces, see the "Adding a Description to a Port Channel Interface" section.
For information about configuring this parameter for other interfaces, see the "Configuring a Description" section.
The speed and duplex modes are interrelated for each Ethernet and management interface. By default, each of these interfaces autonegotiates its speed and duplex modes with the other interface, but you can change these settings. If you change the settings, be sure to use the same speed and duplex mode settings on both interfaces, or use autonegotiation for at least one of the interfaces.
For information about setting the speed and duplex modes for port channel interfaces, see the "Configuring the Speed and Duplex Settings for a Port Channel Interface" section.
For information about setting the speed and duplex modes for other interfaces, see the "Configuring the Interface Speed and Duplex Modes" section.
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 MTU size for each port is 1500 bytes, which is the IEEE 802.3 standard for Ethernet frames. Larger MTU sizes are possible for more efficient processing of data with less overhead. The larger frames, called jumbo frames, can be up to 9000 bytes in size, which is also the fixed system jumbo MTU size in the Cisco Nexus 1000V.
For a Layer 2 port, you can configure an MTU size as the system default of 1500 bytes or the system default jumbo MTU size of 9000 bytes.
For information about setting the MTU size, see the "Configuring the MTU Size for an Ethernet Interface" section.
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 more information, see the following sections:
•Shutting Down and Restarting a Port Channel Interface.
•Shutting Down and Activating an Interface.
The Cisco Discovery Protocol (CDP) is a Layer 2 protocol that enables two devices that run CDP to learn about each other. You can use CDP to troubleshoot the network by displaying information about the neighboring devices that are linked through each interface. By default, CDP is enabled.
To configure CDP, see the "Enabling or Disabling CDP" section.
A port channel is an aggregation of physical interfaces that comprise a logical interface. You can bundle up to eight 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.
Any configuration changes that you apply to the port channel are applied to each interface member of that port channel.
To configure port channels, see the "Configuring Port Channels" section.
Interface parameters have the following guidelines and limitations:
•You usually configure Ethernet port speed and duplex mode parameters to auto to allow negotiation of the speed and duplex modes between ports. If you decide to configure the port speed and duplex modes manually for these ports, consider the following:
–If you set the Ethernet port speed to auto, the device automatically sets the duplex mode to auto.
–If you enter the no speed command, the device automatically sets both the speed and duplex parameters to auto (the no speed command produces the same results as the speed auto command).
–If you configure an Ethernet port speed to a value other than auto (for example, 10, 100, or 1000 Mbps), you must configure the connecting port to match. Do not configure the connecting port to negotiate the speed.
Note The device cannot automatically negotiate the Ethernet port speed and duplex modes if the connecting port is configured to a value other than auto.
Note Changing the Ethernet port speed and duplex mode configuration might shut down and reenable the interface.
•To specify an interface in the CLI, use the following guidelines:
–For an Ethernet port— use ethernet slot/port, where slot is the module slot number and port is the port number.
–For the management interface—use mgmt 0 or mgmt0.
–For a vEthernet port— use vethernet number, where number is a number from 1 to 1048575.
–A space is not required between the interface type and the slot/port or interface number. For example, for the Ethernet slot 4, port 5 interface, you can specify either of the following:
ethernet 4/5
ethernet4/5
•Jumbo frames are only supported on the vmxnet3 driver. Attempts to change the MTU appear to succeed but the adapter always drops frames larger than 1500 bytes.For more information see the VMware KB article 1015556.
This section includes the following topics:
•Specifying an Interface to Configure
•Configuring the Interface Speed and Duplex Modes
•Configuring the MTU Size for an Ethernet Interface
•Shutting Down and Activating an Interface
You can use this procedure to specify an interface to configure.
Before beginning this procedure, you must know or do the following:
•You are logged in to the CLI in EXEC mode.
1. config t
2. interface interface
3. show interface interface
You can use this procedure to add a description to av Ethernet, vEthernet, or management interface.
Before beginning this procedure, you must know or do the following:
•You are logged in to the CLI in EXEC mode.
•A description is case-sensitive and can be up to 80 alphanumeric characters in length.
1. config t
2. interface interface
3. description string
4. show interface interface
5. copy running-config startup-config
The following example shows how to set the interface description to Ethernet port 24 on module 3:
n1000v# config t
n1000v(config)# interface ethernet 3/24
n1000v(config-if)# description server1
n1000v(config-if)#
You can use this procedure to configure the interface speed and duplex modes.
Before beginning this procedure, you must know or do the following:
•The interface speed and duplex modes are interrelated, so you should configure both at the same time. To see the speeds and duplex modes that you can configure together for Ethernet and management interfaces, see the "Speed and Duplex Modes" section.
Note The interface speed that you specify can affect the duplex mode used for an interface, so you should set the speed before setting the duplex mode. If you set the speed for autonegotiation, the duplex mode is automatically set to be autonegotiated. If you specify a speed of 10 Mbps or 100 Mbps, the port is automatically configured to use half-duplex mode, but you can specify full-duplex mode instead. If you specify a speed of 1000 Mbps (1 Gbps) or faster, full duplex is automatically used.
•Make sure that the remote port has a speed setting that supports your changes for the local port. If you want to set the local port to use a specific speed, you must set the remote port for the same speed or set the local port to autonegotiate the speed.
1. config t
2. interface interface
3. speed {{10 | 100 | 1000 | {auto [10 100 [1000]]}} | {10000 | auto}}
4. duplex {full | half | auto}
5. show interface interface
6. copy running-config startup-config
The following example shows how to set the speed of Ethernet port 1 on the 48-port 10/100/1000 module in slot 3 to 1000 Mbps and full-duplex mode:
n1000v# config t
n1000v(config)# interface ethernet 3/1
n1000v(config-if)# speed 1000
n1000v(config-if)# duplex full
n1000v(config-if)#
You can use this procedure to configure the size of the maximum transmission unit (MTU) for a Layer 2 Ethernet interface.
Before beginning this procedure, you must know or do the following:
•You are logged in to the CLI in EXEC mode.
•You can specify an MTU size between 1500 and 9000 bytes for an Ethernet interface.
•Make sure the MTU value you set is supported by the VEM physical NIC. See your VMware documentation for more information about supported MTU for physical NICs.
•Jumbo frames are only supported on the vmxnet3 driver. Attempts to change the MTU appear to succeed but the adapter always drops frames larger than 1500 bytes.For more information see the VMware KB article 1015556.
1. config t
2. interface ethernet slot/port
3. mtu size
4. show interface ethernet slot/port
5. copy running-config startup-config
The following example shows how to configure the Ethernet interface 3/1 with the default MTU size of 1500 bytes:
n1000v# config t
n1000v(config)# interface ethernet 3/1
n1000v(config-if)# mtu 1500
n1000v(config-if)#
You can use this procedure to shut down and restart Ethernet or management interfaces.
Before beginning this procedure, you must know or do the following:
•You are logged in to the CLI in EXEC mode.
•When you shut down an interface, it becomes disabled and the output of monitoring commands show it as being down.
•To activate an interface that has been shut down, you must restart the device.
1. config t
2. interface interface
3. shutdown
4. show interface interface
5. no shutdown
6. show interface interface
7. copy running-config startup-config
The following example shows how to change the administrative status for Ethernet port 3/1 from disabled to enabled:
n1000v# config t
n1000v(config)# interface ethernet 3/1
n1000v(config-if)# shutdown
n1000v(config-if)# no shutdown
n1000v(config-if)#
You can use this procedure to enable or disable the Cisco Discovery Protocol (CDP) for Ethernet and management interfaces.
Before beginning this procedure, you must know or do the following:
•You are logged in to the CLI in EXEC mode.
•Make sure that CDP is enabled at both ends of the link.
1. config t
2. interface interface
3. cdp enable
no cdp enable
4. show cdp interface interface
5. copy running-config startup-config
The following example shows how to enable CDP for Ethernet port 3/1:
n1000v# config t
n1000v(config)# interface ethernet 3/1
n1000v(config-if)# cdp enable
n1000v(config-if)#
The following example shows how to disable CDP for Ethernet port 3/1:
n1000v# config t
n1000v(config)# interface ethernet 3/1
n1000v(config-if)# no cdp enable
n1000v(config-if)#
You can use this procedure to clear the Ethernet, vEthernet, and management interface counters.
Before beginning this procedure, you must know or do the following:
•You are logged in to the CLI in EXEC mode, configuration mode, or interface configuration mode.
1. clear counters interface-type interface-id
2. show interface interface
The following example shows how to clear and reset the counters on Ethernet port 5/5:
n1000v# clear counters ethernet 5/5
n1000v#
Use the commands listed here to display and verify the basic interface parameters.
This section provides the feature history for basic interface parameters.