Configuring Layer 2 Interfaces

This chapter contains the following sections:

Licensing Requirements

For a complete explanation of Cisco NX-OS licensing recommendations and how to obtain and apply licenses, see the Cisco NX-OS Licensing Guide.

Information About Ethernet Interfaces

The Ethernet ports can operate as standard Ethernet interfaces connected to servers or to a LAN.

The Ethernet interfaces are enabled by default.

Interface Command

You can enable the various capabilities of the Ethernet interfaces on a per-interface basis using the interface command. When you enter the interface command, you specify the following information:

  • Interface type—All physical Ethernet interfaces use the ethernet keyword.

  • Slot number:

    • Slot 1 includes all the fixed ports.

    • Slot 2 includes the ports on the upper expansion module (if populated).

    • Slot 3 includes the ports on the lower expansion module (if populated).

    • Slot 4 includes the ports on the lower expansion module (if populated).

  • Port number— Port number within the group.

The interface numbering convention is extended to support use with a Cisco Nexus Fabric Extender as follows:

switch(config)# interface ethernet [chassis/]slot/port

  • The chassis ID is an optional entry that you can use to address the ports of a connected Fabric Extender. The chassis ID is configured on a physical Ethernet or EtherChannel interface on the switch to identify the Fabric Extender discovered through the interface. The chassis ID ranges from 100 to 199.

Unidirectional Link Detection Parameter

The Cisco-proprietary Unidirectional Link Detection (UDLD) protocol allows ports that are connected through fiber optics or copper (for example, Category 5 cabling) Ethernet cables to monitor the physical configuration of the cables and detect when a unidirectional link exists. When the switch detects a unidirectional link, UDLD shuts down the affected LAN port and alerts the user. Unidirectional links can cause a variety of problems, including spanning tree topology loops.

UDLD is a Layer 2 protocol that works with the Layer 1 protocols to determine the physical status of a link. At Layer 1, autonegotiation takes care of physical signaling and fault detection. UDLD performs tasks that autonegotiation cannot perform, such as detecting the identities of neighbors and shutting down misconnected LAN ports. When you enable both autonegotiation and UDLD, Layer 1 and Layer 2 detections work together to prevent physical and logical unidirectional connections and the malfunctioning of other protocols.

A unidirectional link occurs whenever traffic transmitted by the local device over a link is received by the neighbor but traffic transmitted from the neighbor is not received by the local device. If one of the fiber strands in a pair is disconnected, and if autonegotiation is active, the link does not stay up. In this case, the logical link is undetermined, and UDLD does not take any action. If both fibers are working normally at Layer 1, then UDLD at Layer 2 determines whether those fibers are connected correctly and whether traffic is flowing bidirectionally between the correct neighbors. This check cannot be performed by autonegotiation, because autonegotiation operates at Layer 1.

A Cisco Nexus device periodically transmits UDLD frames to neighbor devices on LAN ports with UDLD enabled. If the frames are echoed back within a specific time frame and they lack a specific acknowledgment (echo), the link is flagged as unidirectional and the LAN port is shut down. Devices on both ends of the link must support UDLD in order for the protocol to successfully identify and disable unidirectional links.

The following figure shows an example of a unidirectional link condition. Device B successfully receives traffic from Device A on the port. However, Device A does not receive traffic from Device B on the same port. UDLD detects the problem and disables the port.

Figure 1. Unidirectional Link

Default UDLD Configuration

The following table shows the default UDLD configuration.

Table 1. UDLD Default Configuration

Feature

Default Value

UDLD global enable state

Globally disabled

UDLD aggressive mode

Disabled

UDLD per-port enable state for fiber-optic media

Enabled on all Ethernet fiber-optic LAN ports

UDLD per-port enable state for twisted-pair (copper) media

Disabled on all Ethernet 10/100 and 1000BASE-TX LAN ports

UDLD Aggressive and Nonaggressive Modes

UDLD aggressive mode is disabled by default. You can configure UDLD aggressive mode only on point-to-point links between network devices that support UDLD aggressive mode. If UDLD aggressive mode is enabled, when a port on a bidirectional link that has a UDLD neighbor relationship established stops receiving UDLD frames, UDLD tries to reestablish the connection with the neighbor. After eight failed retries, the port is disabled.

To prevent spanning tree loops, nonaggressive UDLD with the default interval of 15 seconds is fast enough to shut down a unidirectional link before a blocking port transitions to the forwarding state (with default spanning tree parameters).

When you enable the UDLD aggressive mode, the following occurs:

  • One side of a link has a port stuck (both transmission and receive)

  • One side of a link remains up while the other side of the link is down

In these cases, the UDLD aggressive mode disables one of the ports on the link, which prevents traffic from being discarded.

Interface Speed

Cisco Nexus 3000 Series switches have a number of fixed 10-Gigabit ports; each is equipped with SFP+ interface adapters. Cisco Nexus 3100 Series switches have 32 Quad Same Factor Pluggable (QSFP) ports and 4 SFP+ interface adapters. The default speed for these 32 ports is 40 Gbps.


Note

If you set a port configuration that does not use all of the ports, the unused ports are left in the removed state. For example, if you configure 96 x 25G + 32 x 100G on a Cisco Nexus 3264C-E platform switch, the configuration uses 56 ports and leaves 8 ports in the removed state. 

switch(config)# hardware profile portmode ?
  128x25g         128x25G port mode        
  64x100g         64 100G ports with 2x50G, 1x100G, 1x40G capability   
  96x25g+32x100g  96x25G+32x100G port mode

Where:

  • 128x25g: Only 32 QSFP ports are usable

  • 64x100g: All 64 ports are usable (default port mode)

  • 96x25g+32x100g: Only 56 ports are usable

40-Gigabit Ethernet Interface Speed

You can operate QSFP ports as either 40-Gigabit Ethernet or 4 x10-Gigabit Ethernet modes on Cisco Nexus 3132 and Cisco Nexus 3172 switches. By default, there are 32 ports in the 40-Gigabit Ethernet mode. These 40-Gigabit Ethernet ports are numbered in a 2-tuple naming convention. For example, the second 40-Gigabit Ethernet port is numbered as 1/2. The process of changing the configuration from 40-Gigabit Ethernet to 10-Gigabit Ethernet is called breakout and the process of changing the configuration from 10-Gigabit Ethernet to Gigabit Ethernet is called breakin. When you break out a 40-Gigabit Ethernet port into 10-Gigabit Ethernet ports, the resulting ports are numbered using a 3-tuple naming convention. For example, the break-out ports of the second 40-Gigabit Ethernet port are numbered as 1/2/1, 1/2/2, 1/2/3, 1/2/4.

You can break out the 40-Gigabit Ethernet port into four 10-Gigabit Ethernet ports by using the speed 10000 command and using a splitter cable to connect to multiple peer switches. You can break in four 10-Gigabit Ethernet ports to a 40-Gigabit Ethernet port by using the speed 40000 command. The configuration change from 40-Gigabit Ethernet to 10-Gigabit Ethernet and from 10-Gigabit Ethernet to 40-Gigabit Ethernet takes effect immediately. You do not need to reload the switch. A QSFP transceiver security check is also performed.


Note
When you break out from 40-Gigabit Ethernet to 10-Gigabit Ethernet, or break in from 10-Gigabit Ethernet to 40-Gigabit Ethernet, all interface configurations are reset, and the affected ports are administratively unavailable. To make these ports available, use the no shut command.

Note

Starting with Release 6.0(2)U5(1), a new QSFP+ 40-Gb transceiver is now supported on the Cisco Nexus 3000 Series switches. The new QSFP+ (40-Gb) transceiver has a cable that splits into four 10Gb SFP-10G-LR transceivers. To use it, you need the port to be in 4x10G mode. If you are using the breakout cable, you need to run that 40G port in 4x10G mode.

The ability to break out a 40-Gigabit Ethernet port into four 10-Gigabit Ethernet ports and break in four 10-Gigabit Ethernet ports into a 40-Gigabit Ethernet port dynamically allows you to use any of the breakout-capable ports to work in the 40-Gigabit Ethernet or 10-Gigabit Ethernet modes without permanently defining them.

For Cisco Nexus 3132Q switches, when the Ethernet interface 1/1 is in the 40-Gigabit Ethernet mode, the first QSFP port is active. After breakout, when the Ethernet interface 1/1/1-4 is in the 10-Gigabit Ethernet mode, you can choose to use either QSFP ports or SFP+ ports. However, both the first QSFP port and the four SFP+ ports cannot be active at the same time.

When using a QSFP-40G-CR4 on Cisco Nexus 3000 switches, you must configure the default speed as 40G in the auto-negotiation parameters. Otherwise, the interface may not be able to bring the link up.

Port Modes

Nexus 3100 Series Switches Ports Port Modes
Cisco Nexus 3132Q 32 x QSFP ports and 4 SFP+ ports
The following port modes support breakout:
  • 32x40G—This is an oversubscribed port mode. All 32 ports are oversubscribed and the first 24 QSFP ports are break-out capable. You cannot enter the speed 10000 command on ports 25 through 32. 32x40G breakout mode is the default port mode.
  • 26x40G—This is an oversubscribed port mode. Of the 26 ports, 12 ports are nonoversubscribed (cut-through). These ports are 2,4 to 8,14,and 16 to 20. The remaining 14 ports are oversubscribed. All available QSFP ports are break-out capable.
  • 24x40G—This is the only nonoversubscribed (cut-through) mode. All available QSFP ports are break-out capable.

The Fixed32x40G port mode does not support breakout.

Cisco Nexus 3132Q-V 32 x 40G QSFP ports
  • 32x40G—This is the default port mode. Of the 32 ports, first 24 QSFP ports are 10Gx4 break-out capable and the last 8 QSFP ports has a fixed speed of 40G. The maximum port counts are: 96x10G + 8x40G. All ports are oversubscribed equally. The 10G ports does not support cut-through switching.
  • 26x40G—This port mode supports the maximum number of 10G ports. The first 26 QSFP ports are 10Gx4 break-out capable and the last 6 QSFP ports are not usable. The maximum port counts are: 104x10G. All available QSFP ports are break-out capable. Of the 26 ports, 12 ports are non-oversubscribed (cut-through). These ports are 2,4 to 8,14,and 16 to 20. The remaining 14 ports are oversubscribed.
  • 24x40G—This is a non-oversubscribed, line rate port mode. Of the 32 ports, first 24 QSFP ports are 10Gx4 break-out capable. The maximum port counts can be 96x10G. The 10G ports support cut-through switching.
Cisco Nexus 31108PC-V 48 x 10G SFP+ ports and 6 x 100G QSFP ports

The following two port modes are supported:

  • 48x10G SFP+ ports + 6x100G QSFP ports.
  • 48x10G SFP+ ports + 4x100G QSFP ports + 2x40G QSFP ports.

The following features are specific to port mode-1:

  • SFP+ Ports 1 through 8 always delivers at line-rate.
  • SFP+ Ports 9 through 48 are always over subscribed.
  • QSFP Ports 49 through 52 are capable of 100G and/or 40G and 10Gx4 breakout.
  • QSFP Ports 53 through 54 are capable of 100G and/or 40G. These ports do not support 10Gx4 breakout.
  • The maximum supported port count is 64x10G + 2x40G/100G.

The following features are specific to port mode-2:

  • SFP+ Ports 1 through 48 always delivers at line-rate and support cut-through switching.
  • Line-rate SFP+ ports support cut-through switching and because of that it will have less latency.
  • QSFP Ports 49 through 52 are capable of 100G/40G and 10Gx4 breakout.
  • QSFP Ports 53 through 54 are capable of 40G and 10Gx4 breakout. These ports do not support 100G.
  • The maximum supported port count is 72x10G.
Cisco Nexus 31108TC-V 48 x 10GBase-T and 6 x 100G ports

The following two port modes are supported:

  • 48x10GBASE-T ports + 6x100G QSFP ports.
  • 48x10GBASE-T ports + 4x100G QSFP ports + 2x40G QSFP ports.

The following features are specific to port mode-1:

  • 10GBASE-T Ports 1 through 8 always delivers at line-rate.
  • 10GBASE-T Ports 9 through 48 are always over subscribed.
  • QSFP Ports 49 through 52 are capable of 100G and/or 40G and 10Gx4 breakout.
  • QSFP Ports 53 through 54 are capable of 100G and/or 40G. These ports do not support 10Gx4 breakout.
  • The maximum supported port count is 64x10G + 2x40G/100G.

The following features are specific to port mode-2:

  • 10GBASE-T Ports 1 through 48 always delivers at line-rate and support cut-through switching.
  • Line-rate SFP+ ports support cut-through switching and because of that it will have less latency.
  • QSFP Ports 49 through 52 are capable of 100G/40G and 10Gx4 breakout.
  • QSFP Ports 53 through 54 are capable of 40G and 10Gx4 breakout. These ports do not support 100G.
  • The maximum supported port count is 72x10G.
Cisco Nexus 3172PQ 6 x QSFP ports and 48 SFP+ ports
The following is the default port mode and supports breakout:
  • 48x10G+breakout6x40G
The following are the fixed port modes that do not support breakout:
  • 48x10G+6x40G
  • 72x10G

SVI Autostate

The Switch Virtual Interface (SVI) represents a logical interface between the bridging function and the routing function of a VLAN in the device. By default, when a VLAN interface has multiple ports in the VLAN, the SVI goes to the down state when all the ports in the VLAN go down.

Autostate behavior is the operational state of an interface that is governed by the state of the various ports in its corresponding VLAN. An SVI interface on a VLAN comes up when there is at least one port in that vlan that is in STP forwarding state. Similarly, this interface goes down when the last STP forwarding port goes down or goes to another STP state.

By default, Autostate calculation is enabled. You can disable Autostate calculation for an SVI interface and change the default value.


Note

Nexus 3000 Series switches do not support bridging between two VLANs when an SVI for one VLAN exists on the same device as the bridging link. Traffic coming into the device and bound for the SVI is dropped as a IPv4 discard. This is because the BIA MAC address is shared across VLANs/SVIs with no option to modify the MAC of the SVI.

Cisco Discovery Protocol

The Cisco Discovery Protocol (CDP) is a device discovery protocol that runs over Layer 2 (the data link layer) on all Cisco-manufactured devices (routers, bridges, access servers, and switches) and allows network management applications to discover Cisco devices that are neighbors of already known devices. With CDP, network management applications can learn the device type and the Simple Network Management Protocol (SNMP) agent address of neighboring devices that are running lower-layer, transparent protocols. This feature enables applications to send SNMP queries to neighboring devices.

CDP runs on all media that support Subnetwork Access Protocol (SNAP). Because CDP runs over the data-link layer only, two systems that support different network-layer protocols can learn about each other.

Each CDP-configured device sends periodic messages to a multicast address, advertising at least one address at which it can receive SNMP messages. The advertisements also contain time-to-live, or holdtime information, which is the length of time a receiving device holds CDP information before discarding it. Each device also listens to the messages sent by other devices to learn about neighboring devices.

The switch supports both CDP Version 1 and Version 2.

Default CDP Configuration

The following table shows the default CDP configuration.

Table 2. Default CDP Configuration

Feature

Default Setting

CDP interface state

Enabled

CDP timer (packet update frequency)

60 seconds

CDP holdtime (before discarding)

180 seconds

CDP Version-2 advertisements

Enabled

Error-Disabled State

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

When an interface is in the err-disabled state, use the errdisable detect cause command to find information about the error.

You can configure the automatic err-disabled recovery timeout for a particular err-disabled cause by changing the time variable.

The errdisable recovery cause command provides automatic recovery after 300 seconds. To change the recovery period, use the errdisable recovery interval command to specify the timeout period. You can specify 30 to 65535 seconds.

To disable recovery of an interface from the err-disabled state, use the no errdisable recovery cause command.

The various options for the errdisable recover cause command are as follows:

  • all—Enables a timer to recover from all causes.

  • bpduguard—Enables a timer to recover from the bridge protocol data unit (BPDU) Guard error-disabled state.

  • failed-port-state—Enables a timer to recover from a Spanning Tree Protocol (STP) set port state failure.

  • link-flap—Enables a timer to recover from linkstate flapping.

  • pause-rate-limit—Enables a timer to recover from the pause rate limit error-disabled state.

  • udld—Enables a timer to recover from the Unidirectional Link Detection (UDLD) error-disabled state.

  • loopback—Enables a timer to recover from the loopback error-disabled state.

If you do not enable the err-disabled recovery for the cause, the interface stays in the err-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 err-disabled state and allowed to retry operation once all the causes have timed out. Use the show interface status err-disabled command to display the reason behind the error.

Default Interfaces

You can use the default interface feature to clear the configured parameters for both physical and logical interfaces such as the Ethernet, loopback, management, VLAN, and the port-channel interface.

Debounce Timer Parameters

The debounce timer delays notification of a link change, which can decrease traffic loss due to network reconfiguration. You can configure the debounce timer separately for each Ethernet port and specify the delay time in milliseconds. The delay time can range from 0 milliseconds to 5000 milliseconds. By default, this parameter is set for 100 milliseconds, which results in the debounce timer not running. When this parameter is set to 0 milliseconds, the debounce timer is disabled.


Caution
Enabling the debounce timer causes the link-down detections to be delayed, which results in a loss of traffic during the debounce period. This situation might affect the convergence and reconvergence of some Layer 2 and Layer 3 protocols.

MTU Configuration

The switch does not fragment frames. As a result, the switch cannot have two ports in the same Layer 2 domain with different maximum transmission units (MTUs). A per-physical Ethernet interface MTU is not supported. Instead, the MTU is set according to the QoS classes. You modify the MTU by setting class and policy maps.


Note

When you show the interface settings, a default MTU of 1500 is displayed for physical Ethernet interfaces.

Counter Values

See the following information on the configuration, packet size, incremented counter values, and traffic.

Configuration

Packet Size

Incremented Counters

Traffic

L2 port – without any MTU configuration

6400 and 10000

Jumbo, giant, and input error

Dropped

L2 port – with jumbo MTU 9216 in network-qos configuration

6400

Jumbo

Forwarded

L2 port – with jumbo MTU 9216 in network-qos configuration

10000

Jumbo, giant, and input error

Dropped

Layer 3 port with default Layer 3 MTU and jumbo MTU 9216 in network-qos configuration

6400

Jumbo

Packets are punted to the CPU (subjected to CoPP configs), get fragmented, and then they are forwarded by the software.

Layer 3 port with default Layer 3 MTU and jumbo MTU 9216 in network-qos configuration

6400

Jumbo

Packets are punted to the CPU (subjected to CoPP configs), get fragmented, and then they are forwarded by the software.

Layer 3 port with default Layer 3 MTU and jumbo MTU 9216 in network-qos configuration

10000

Jumbo, giant, and input error

Dropped

Layer 3 port with jumbo Layer 3 MTU and jumbo MTU 9216 in network-qos configuration

6400

Jumbo

Forwarded without any fragmentation.

Layer 3 port with jumbo Layer 3 MTU and jumbo MTU 9216 in network-qos configuration

10000

Jumbo, giant, and input error

Dropped

Layer 3 port with jumbo Layer 3 MTU and default L2 MTU configuration

6400 and 10000

Jumbo, giant, and input error

Dropped


Note

  • Under 64 bytes packet with good CRC–The short frame counter increments.

  • Under 64 bytes packet with bad CRC–The runts counter increments.

  • Greater than 64 bytes packet with bad CRC–The CRC counter increments.

Downlink Delay

You can operationally enable uplink SFP+ ports before downlink RJ-45 ports after a reload on a Cisco Nexus 3048 switch. You must delay enabling the RJ-45 ports in the hardware until the SFP+ ports are enabled.

You can configure a timer that during reload enables the downlink RJ-45 ports in hardware only after the specified timeout. This process allows the uplink SFP+ ports to be operational first. The timer is enabled in the hardware for only those ports that are admin-enable.

Downlink delay is disabled by default and must be explicitly enabled. When enabled, if the delay timer is not specified, it is set for a default delay of 20 seconds.

Default Physical Ethernet Settings

The following table lists the default settings for all physical Ethernet interfaces:

Parameter

Default Setting

Duplex

Auto (full-duplex)

Encapsulation

ARPA

MTU1

1500 bytes

Port Mode

Access

Speed

Auto (10000)

1 MTU cannot be changed per-physical Ethernet interface. You modify MTU by selecting maps of QoS classes.

Configuring Ethernet Interfaces

Guidelines for Configuring Ethernet Interfaces

Configuring the UDLD Mode

You can configure normal or aggressive unidirectional link detection (UDLD) modes for Ethernet interfaces on devices configured to run UDLD. Before you can enable a UDLD mode for an interface, you must make sure that UDLD is already enabled on the device that includes the interface. UDLD must also be enabled on the other linked interface and its device.

To use the normal UDLD mode, you must configure one of the ports for normal mode and configure the other port for the normal or aggressive mode. To use the aggressive UDLD mode, you must configure both ports for the aggressive mode.


Note

Before you begin, UDLD must be enabled for the other linked port and its device.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# feature udld

Enables UDLD for the device.

Step 3

switch(config)# no feature udld

Disables UDLD for the device.

Step 4

switch(config)# show udld global

Displays the UDLD status for the device.

Step 5

switch(config)# interface type slot/port

Specifies an interface to configure, and enters interface configuration mode.

Step 6

switch(config-if)# udld {enable | disable | aggressive}

Enables the normal UDLD mode, disables UDLD, or enables the aggressive UDLD mode.

Step 7

switch(config-if)# show udld interface

Displays the UDLD status for the interface.

Example

This example shows how to enable UDLD for the switch: 

 
switch# configure terminal
switch(config)# feature udld

This example shows how to enable the normal UDLD mode for an Ethernet port: 

 
switch# configure terminal
switch(config)# interface ethernet 1/4
switch(config-if)# udld enable

This example shows how to enable the aggressive UDLD mode for an Ethernet port: 


switch# configure terminal
switch(config)# interface ethernet 1/4
switch(config-if)# udld aggressive

This example shows how to disable UDLD for an Ethernet port: 

 
switch# configure terminal
switch(config)# interface ethernet 1/4
switch(config-if)# udld disable

This example shows how to disable UDLD for the switch: 


switch# configure terminal
switch(config)# no feature udld

Triggering the Link State Consistency Checker

You can manually trigger the link state consistency checker to compare the hardware and software link status of an interface and display the results. To manually trigger the link state consistency checker and display the results, use the following command in any mode:

Procedure

Command or Action Purpose

switch# show consistency-checker link-state module slot

Starts a link state consistency check on the specified module and displays its results.

Example

This example shows how to trigger a Link State consistency check and display its results: 

switch# show consistency-checker link-state module 1
Link State Checks: Link state only
Consistency Check: FAILED
No inconsistencies found for:
   Ethernet1/1
   Ethernet1/2
   Ethernet1/3
   Ethernet1/4
   Ethernet1/5
   Ethernet1/6
   Ethernet1/7
   Ethernet1/8
   Ethernet1/9
   Ethernet1/10
   Ethernet1/12
   Ethernet1/13
   Ethernet1/14
   Ethernet1/15   
Inconsistencies found for following interfaces:
   Ethernet1/11

Changing an Interface Port Mode

You can configure a Quad small form-factor pluggable (QSFP+) port by using the hardware profile portmode command. To restore the defaults, use the no form of these commands. The Cisco Nexus 3172PQ switch has 48x10g+breakout6x40g as the default port mode.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# copy running-config bootflash: my-config.cfg

Copies the running configuration to the bootflash. You can use this file to configure your device later.

Step 3

switch(config)# write erase

Removes all the interface configurations.

Step 4

switch(config)# reload

Reloads the Cisco NX-OS software.

Step 5

switch(config)# [no] hardware profile portmode portmode

Changes the interface port mode.

Step 6

(Optional) switch(config)# hardware profile portmode portmode 2-tuple

(Optional)

Displays the port names in 2-tuple mode instead of the default 3-tuple convention mode.

Step 7

(Optional) switch(config)# copy running-config startup-config

(Optional)

Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Step 8

switch(config)# reload

Reloads the Cisco NX-OS software.

Manually apply all the interface configuration. You can refer to the configuration file that you saved earlier.

Note 

The interface numbering changes if the ports are changed from 40G mode to 4x10G mode or vice versa.

Example

This example shows how to change the port mode to 48x10g+breakout6x40g for QSFP+ ports: 

switch# configure terminal
switch(config)# copy running-config bootflash:my-config.cfg
switch(config)# write erase
switch(config)# reload
WARNING: This command will reboot the system
Do you want to continue? (y/n) [n] y
switch(config)# hardware profile portmode 48x10g+breakout6x40g
Warning: This command will take effect only after saving the configuration and reload!
Port configurations could get lost when port mode is changed!
switch(config)# copy running-config startup-config
switch(config)# reload
WARNING: This command will reboot the system
Do you want to continue? (y/n) [n] y

This example shows how to change the port mode to 48x10g+4x40g for QSFP+ ports: 

switch# configure terminal
switch(config)# copy running-config bootflash:my-config.cfg
switch(config)# write erase
switch(config)# reload
WARNING: This command will reboot the system
Do you want to continue? (y/n) [n] y
switch(config)# hardware profile portmode 48x10g+4x40g
Warning: This command will take effect only after saving the configuration and reload!
Port configurations could get lost when port mode is changed!
switch(config)# copy running-config startup-config
switch(config)# reload
WARNING: This command will reboot the system
Do you want to continue? (y/n) [n] y

This example shows how to change the port mode to 48x10g+4x40g for QSFP+ ports and verify the changes: 

switch# configure terminal
switch(config)# hardware profile portmode 48x10g+4x40g
Warning: This command will take effect only after saving the configuration and r
eload! Port configurations could get lost when port mode is changed!
switch(config)# show running-config
!Command: show running-config
!Time: Thu Aug 25 07:39:37 2011
version 5.0(3)U2(1)
feature telnet
no feature ssh
feature lldp
username admin password 5 $1$OOV4MdOM$BAB5RkD22YanT4empqqSM0 role network-admin
ip domain-lookup
switchname BLR-QG-5
ip access-list my-acl
10 deny ip any 10.0.0.1/32
20 deny ip 10.1.1.1/32 any
class-map type control-plane match-any copp-arp
class-map type control-plane match-any copp-bpdu
:
:
control-plane
service-policy input copp-system-policy
hardware profile tcam region arpacl 128
hardware profile tcam region ifacl 256
hardware profile tcam region racl 256
hardware profile tcam region vacl 512
hardware profile portmode 48x10G+4x40G
snmp-server user admin network-admin auth md5 0xdd1d21ee42e93106836cdefd1a60e062
<--Output truncated-->
switch#

This example shows how to restore the default port mode for QSFP+ ports: 

switch# configure terminal
switch(config)# no hardware profile portmode
Warning: This command will take effect only after saving the configuration and r
eload! Port configurations could get lost when port mode is changed!
switch(config)#

Configuring the Interface Speed


Note

If the interface and transceiver speed is mismatched, the SFP validation failed message is displayed when you enter the show interface ethernet slot/port command. For example, if you insert a 1-Gigabit SFP transceiver into a port without configuring the speed 1000 command, you will get this error. By default, all ports are 10 Gbps.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface type slot/port

Enters interface configuration mode for the specified interface. This interface must have a 1-Gigabit Ethernet SFP transceiver inserted into it.

Step 3

switch(config-if)# speed speed

Sets the speed on the interface.

This command can only be applied to a physical Ethernet interface. The speed argument can be set to one of the following:

  • 10 Mbps

  • 100 Mbps

  • 1 Gbps

  • 10 Gbps

  • automatic

Example

This example shows how to set the speed for a 1-Gigabit Ethernet port: 

switch# configure terminal
switch(config)# interface ethernet 1/4
switch(config-if)# speed 1000

Configuring Break-Out 10-Gigabit Interface Speed Ports

By default, all ports on Cisco Nexus 3132 switches are 40-Gigabit Ethernet. You can break out a 40-Gigabit Ethernet port to four x10-Gigabit Ethernet ports.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface type slot/port-range

Enters interface configuration mode for the specified interface.
Note 
Interface range is not supported for 40-Gigabit Ethernet interfaces. For example, Eth 1/2-5 is not supported.
Step 3

switch(config-if)# speed 10000

Sets the speed on the interface to 10-Gigabit per second.

Note 

Configuring breakout on QSFP ports using speed 10000 adds interface breakout module <module number> port <port range> map 10g-4x in the running-config output.

Example

This example shows how to set the speed to 10-Gigabit per second on Ethernet interface 1/2: 

switch# configure terminal
switch(config)# interface ethernet 1/49
switch(config-if)# speed 10000

switch(config-if)# sh running-config | grep port
  limit-resource port-channel minimum 0 maximum 511
interface breakout module 1 port 49 map 10g-4x ------------------------------------------> interface breakout is added on "speed" config
hardware profile portmode 48x10g+breakout6x40g
(config-if)#

(config)# int ethernet 1/49/1
(config-if)#no speed 10000 ------------------------------------> on "no speed", the interface breakout cmd is removed.

(config-if)#  sh running-config | grep port
  limit-resource port-channel minimum 0 maximum 511
hardware profile portmode 48x10g+breakout6x40g

Configuring Break-In 40-Gigabit Ethernet Interface Speed Ports

You can break in four x 10-Gigabit Ethernet ports to a 40-Gigabit Ethernet port.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface type slot/port

Enters interface configuration mode for the specified interface.
Note 
The Interface range is supported for 10-Gigabit Ethernet interfaces. For example, Eth 1/2/1-4 is supported.
Step 3

switch(config-if)# speed 40000

Sets the speed on the interface to 40 Gbps.

Example

This example shows how to set the speed to 40 Gbps on Ethernet interface 1/2/1: 

switch# configure terminal 
switch(config)# interface ethernet 1/2/1
switch(config-if)# speed 40000

Switching Between QSFP and SFP+ Ports

When you break out ports into the 10-GbE mode, you can switch between the first QSFP port and SFP+ ports 1 to 4. Either the first QSFP port or the four SFP+ ports can be active at any time. QSFP is the default port with an interface speed of 40 Gbps.

When the first QSFP port is in the 40-GbE mode, you cannot switch the port to four SFP+ ports and the first QSFP port will be active until you break out the port into the 10-GbE mode. This is because SFP+ ports do not support the 40-GbE mode.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# [no] hardware profile front portmode qsfp | sfp-plus

Activates the specified port mode.
  • qsfp —The front panel QSFP port is active
  • sfp-plus —The front panel SFP+ ports 1 to 4 are active

The no form of this command activates the QSFP port.

Note 
If the first QSFP port speed is 40 Gbps, this command will run, but the SFP+ ports will not become active until after the speed is changed to 10 Gbps.
Step 3

switch(config)# interface breakout module module number port port rangemap 10g-4x

Enables you to configure the module in 10g mode. When you are changing the portmode from QSFP to SFP+, the hardware profile front portmode command takes effect only after breaking out the first QSFP port as displayed in this command.

Step 4

(Optional) switch(config)# copy running-config startup-config

(Optional)

Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Example

This example shows how to change the portmode from QSFP to SFP+: 

switch# show int e1/1 tranceiver
Ethernet1/1
transceiver is present
type is QSFP-40G-SR
name is CISCO
part number is AFBR-79EIPZ-CS1
revision is 02
serial number is AVP1645S1QT
nominal bitrate is 10300 MBit/sec per channel
Link length supported for 50/125um fiber is 30 m
Link length supported for 50/125um fiber is 100 m
cisco id is --
cisco extended id number is 16

switch# show running-config | inc portmode
hardware profile portmode 32X40G
hardware profile front portmode qsfp

switch# configure terminal
switch(config)# hardware profile front portmode sfp-plus
switch(config)# interface breakout module 1 port 1 map 10g-4x
switch(config)# copy running-config startup-config

This example shows how to make the QSFP port active: 

switch# configure terminal
switch(config)# hardware profile front portmode qsfp
switch(config)# copy running-config startup-config

Disabling Link Negotiation

By default, auto-negotiation is enabled on all 1G SFP+ and 40G QSFP ports and it is disabled on 10G SFP+ ports. Auto-negotiation is by default enabled on all 1G and 10G Base-T ports. It cannot be disabled on 1G and 10G Base-T ports.

This command is equivalent to the Cisco IOS speed non-negotiate command.


Note
The auto-negotiation configuration is not applicable on 10-Gigabit Ethernet ports. When auto-negotiation is configured on a 10-Gigabit port, the following error message is displayed: 
ERROR: Ethernet1/40: Configuration does not match the port capability

Note

You usually configure Ethernet port speed and duplex mode parameters to auto to allow the system to negotiate the speed and duplex mode between ports. If you decide to configure the port speed and duplex modes manually for these ports, consider the following:

  • If you configure an Ethernet port speed to a value other than auto (for example, 1G, 10G, or 40G), you must configure the connecting port to match. Do not configure the connecting port to negotiate the speed.

  • The device cannot automatically negotiate the Ethernet port speed and duplex mode if the connecting port is configured to a value other than auto.


Note

For 1G SFP with autonegotiation enabled, Auto Speed mode is not compatible to linkup with a peer having 100M speed.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface ethernet slot/port

Selects the interface and enters interface mode.

Step 3

switch(config-if)# no negotiate auto

Disables link negotiation on the selected Ethernet interface (1-Gigabit port).

Step 4

(Optional) switch(config-if)# negotiate auto

(Optional)

Enables link negotiation on the selected Ethernet interface. The default for 1-Gigabit Ethernet ports is enabled.

Note 

This command is not applicable for 10GBASE-T ports. It should not be used on 10-GBASE-T ports.

Example

This example shows how to disable auto-negotiation on a specified Ethernet interface (1-Gigabit port): 

switch# configure terminal
switch(config)# interface ethernet 1/1
switch(config-if)# no negotiate auto
switch(config-if)#

This example shows how to enable auto-negotiation on a specified Ethernet interface (1-Gigabit port): 

switch# configure terminal
switch(config)# interface ethernet 1/5
switch(config-if)# negotiate auto
switch(config-if)#

Disabling SVI Autostate

You can configure a SVI to remain active even if no interfaces are up in the corresponding VLAN. This enhancement is called Autostate Disable.

When you enable or disable autostate behavior, it is applied to all the SVIs in the switch unless you configure autostate per SVI .


Note

Autostate behavior is enabled by default.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# feature interface-vlan

Enables the interface-vlan feature.
Step 3

switch(config)# system default interface-vlan [no] autostate

Configures the system to enable or disable the Autostate default behavior.
Step 4

(Optional) switch(config)# interface vlan interface-vlan-number

(Optional)

Creates a VLAN interface. The number range is from 1 to 4094.
Step 5

(Optional) switch(config-if)# [no] autostate

(Optional)

Enables or disables Autostate behavior per SVI.
Step 6

(Optional) switch(config)# show interface-vlan interface-vlan

(Optional)

Displays the enabled or disabled Autostate behavior of the SVI.
Step 7

(Optional) switch(config)# copy running-config startup-config

(Optional)

Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Example

This example shows how to disable the systems Autostate default for all the SVIs on the switch:

switch# configure terminal
switch(config)# feature interface-vlan
switch(config)# system default interface-vlan no autostate
switch(config)# interface vlan 50
switch(config-if)# no autostate
switch(config)# copy running-config startup-config

This example shows how to enable the systems autostate configuration:

switch(config)# show interface-vlan 2
Vlan2 is down, line protocol is down, autostate enabled
Hardware is EtherSVI, address is 547f.ee40.a17c
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec

Configuring a Default Interface

The default interface feature allows you to clear the existing configuration of multiple interfaces such as Ethernet, loopback, management, VLAN, and port-channel interfaces. All user configuration under a specified interface will be deleted. On a Cisco Nexus C3408-S switch, the number of interfaces you can configure using the default interface ethernet command, at a time, is limited to a maximum of 64 ports.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# default interface type interface number

Deletes the configuration of the interface and restores the default configuration. The following are the supported interfaces:
  • ethernet
  • loopback
  • mgmt
  • port-channel
  • vlan
Step 3

switch(config)# exit

Exits global configuration mode.

Example

This example shows how to delete the configuration of an Ethernet interface and revert it to its default configuration: 

switch# configure terminal
switch(config)# default interface ethernet 1/3
.......Done
switch(config)# exit

Configuring the CDP Characteristics

You can configure the frequency of Cisco Discovery Protocol (CDP) updates, the amount of time to hold the information before discarding it, and whether or not to send Version-2 advertisements.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

(Optional) switch(config)# [no] cdp advertise {v1 | v2 }

(Optional)

Configures the version to use to send CDP advertisements. Version-2 is the default state.

Use the no form of the command to return to its default setting.

Step 3

(Optional) switch(config)# [no] cdp format device-id {mac-address | serial-number | system-name}

(Optional)

Configures the format of the CDP device ID. The default is the system name, which can be expressed as a fully qualified domain name.

Use the no form of the command to return to its default setting.

Step 4

(Optional) switch(config)# [no] cdp holdtime seconds

(Optional)

Specifies the amount of time a receiving device should hold the information sent by your device before discarding it. The range is 10 to 255 seconds; the default is 180 seconds.

Use the no form of the command to return to its default setting.

Step 5

(Optional) switch(config)# [no] cdp timer seconds

(Optional)

Sets the transmission frequency of CDP updates in seconds. The range is 5 to 254; the default is 60 seconds.

Use the no form of the command to return to its default setting.

Example

This example shows how to configure CDP characteristics: 

switch# configure terminal
switch(config)# cdp timer 50
switch(config)# cdp holdtime 120
switch(config)# cdp advertise v2

Enabling or Disabling CDP

You can enable or disable CDP for Ethernet interfaces. This protocol works only when you have it enabled on both interfaces on the same link.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface type slot/port

Enters interface configuration mode for the specified interface.

Step 3

switch(config-if)# cdp enable

Enables CDP for the interface.

To work correctly, this parameter must be enabled for both interfaces on the same link.

Step 4

switch(config-if)# no cdp enable

Disables CDP for the interface.

Example

This example shows how to enable CDP for an Ethernet port: 

switch# configure terminal
switch(config)# interface ethernet 1/4
switch(config-if)# cdp enable

This command can only be applied to a physical Ethernet interface.

Enabling the Error-Disabled Detection

You can enable error-disable (err-disabled) detection in an application. As a result, when a cause is detected on an interface, the interface is placed in an err-disabled state, which is an operational state that is similar to the link-down state.


Note

Base ports in Cisco Nexus 5500 never get error disabled due to pause rate-limit like in the Cisco Nexus 5020 or 5010 switch.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# errdisable detect cause {all | link-flap | loopback}

Specifies a condition under which to place the interface in an err-disabled state. The default is enabled.

Step 3

switch(config)# shutdown

Brings the interface down administratively. To manually recover the interface from the err-disabled state, enter this command first.

Step 4

switch(config)# no shutdown

Brings the interface up administratively and enables the interface to recover manually from the err-disabled state.

Step 5

switch(config)# show interface status err-disabled

Displays information about err-disabled interfaces.

Step 6

(Optional) switch(config)# copy running-config startup-config

(Optional)

Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Example

This example shows how to enable the err-disabled detection in all cases: 

switch# configure terminal
switch(config)# errdisable detect cause all
switch(config)# shutdown
switch(config)# no shutdown
switch(config)# show interface status err-disabled
switch(config)# copy running-config startup-config

Enabling the Error-Disabled Recovery

You can specify the application to bring the interface out of the error-disabled (err-disabled) state and retry coming up. It retries after 300 seconds, unless you configure the recovery timer (see the errdisable recovery interval command).

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# errdisable recovery cause {all | udld | bpduguard | link-flap | failed-port-state | pause-rate-limit | loopback}

Specifies a condition under which the interface automatically recovers from the err-disabled state, and the device retries bringing the interface up. The device waits 300 seconds to retry. The default is disabled.
Step 3

switch(config)# show interface status err-disabled

Displays information about err-disabled interfaces.
Step 4

(Optional) switch(config)# copy running-config startup-config

(Optional)

Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Example

This example shows how to enable err-disabled recovery under all conditions:

switch# configure terminal
switch(config)# errdisable recovery cause loopback
switch(config)# show interface status err-disabled
switch(config)# copy running-config startup-config

Configuring the Error-Disabled Recovery Interval

You can use this procedure to configure the err-disabled recovery timer value. The range is from 30 to 65535 seconds. The default is 300 seconds.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# errdisable recovery interval interval

Specifies the interval for the interface to recover from the err-disabled state. The range is from 30 to 65535 seconds. The default is 300 seconds.

Step 3

switch(config)# show interface status err-disabled

Displays information about err-disabled interfaces.

Step 4

(Optional) switch(config)# copy running-config startup-config

(Optional)

Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Example

This example shows how to enable err-disabled recovery under all conditions: 

switch# configure terminal
switch(config)# errdisable recovery interval 32
switch(config)# show interface status err-disabled
switch(config)# copy running-config startup-config

Disabling the Error-Disabled Recovery

You can disable recovery of an interface from the err-disabled state.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# no errdisable recovery cause {all | udld | bpduguard | link-flap | failed-port-state | pause-rate-limit | loopback}

Specifies a condition under which the interface reverts back to the default err-disabled state.
Step 3

(Optional) switch(config)# show interface status err-disabled

(Optional)

Displays information about err-disabled interfaces.
Step 4

(Optional) switch(config)# copy running-config startup-config

(Optional)

Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration.

Example

This example shows how to disable err-disabled recovery:

switch# configure terminal
switch(config)# no errdisable recovery cause loopback
switch(config)# show interface status err-disabled
switch(config)# copy running-config startup-config

Configuring the Debounce Timer

You can enable the debounce timer for Ethernet ports by specifying a debounce time, in milliseconds (ms), or disable the timer by specifying a debounce time of 0. By default, the debounce timer is set to 100 ms, which results in the debounce timer not running.


Note

The link state of 10G and 100G ports may change repeatedly when connected to service provider network. As a part of link reset or break-link functionality, it is expected that the Tx power light on the SFP to change to N/A state, at an event of link state change.

However, to prevent this behavior during the link state change, you may increase the link debounce timer to start from 500ms and increase it in 500ms intervals until the link stabilizes. On the DWDM, UVN, and WAN network, it is recommended to disable automatic link suspension (ALS) whenever possible. ALS suspends the link on the WAN when the Nexus turn off the link.

You can show the debounce times for all of the Ethernet ports by using the show interface debounce command.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface type slot/port

Enters interface configuration mode for the specified interface.

Step 3

switch(config-if)# link debounce time milliseconds

Enables the debounce timer for the amount of time (1 to 5000 ms) specified.

Disables the debounce timer if you specify 0 milliseconds.

Example

This example shows how to enable the debounce timer and set the debounce time to 1000 ms for an Ethernet interface: 

switch# configure terminal
switch(config)# interface ethernet 3/1
switch(config-if)# link debounce time 1000

This example shows how to disable the debounce timer for an Ethernet interface: 

switch# configure terminal
switch(config)# interface ethernet 3/1
switch(config-if)# link debounce time 0

Configuring the Description Parameter

You can provide textual interface descriptions for the Ethernet ports.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface type slot/port

Enters interface configuration mode for the specified interface.

Step 3

switch(config-if)# description test

Specifies the description for the interface.

Example

This example shows how to set the interface description to Server 3 interface: 

switch# configure terminal
switch(config)# interface ethernet 1/3
switch(config-if)# description Server 3 Interface

Disabling and Restarting Ethernet Interfaces

You can shut down and restart an Ethernet interface. This action disables all of the interface functions and marks the interface as being down on all monitoring displays.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface type slot/port

Enters interface configuration mode for the specified interface.

Step 3

switch(config-if)# shutdown

Disables the interface.

Step 4

switch(config-if)# no shutdown

Restarts the interface.

Example

This example shows how to disable an Ethernet port: 

switch# configure terminal
switch(config)# interface ethernet 1/4
switch(config-if)# shutdown

This example shows how to restart an Ethernet interface: 

switch# configure terminal
switch(config)# interface ethernet 1/4
switch(config-if)# no shutdown

Configuring Downlink Delay

You can operationally enable uplink SFP+ ports before downlink RJ-45 ports after a reload on a Cisco Nexus 3048 switch by delaying enabling the RJ-45 ports in the hardware until the SFP+ ports are enabled.

Procedure

  Command or Action Purpose
Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# downlink delay enable | disable [timeout time-out]

Enables or disables downlink delay and configures the timeout.

Example

This example shows how to enable downlink delay and configure the delay timeout on the switch: 

switch# configure terminal
switch(config)# downlink delay enable timeout 45

Displaying Interface Information

To view configuration information about the defined interfaces, perform one of these tasks:

Command

Purpose

switch# show interface type slot/port

Displays the detailed configuration of the specified interface.

switch# show interface type slot/port capabilities

Displays detailed information about the capabilities of the specified interface. This option is available only for physical interfaces.

switch# show interface type slot/port transceiver

Displays detailed information about the transceiver connected to the specified interface. This option is available only for physical interfaces.

switch# show interface brief

Displays the status of all interfaces.

switch# show interface flowcontrol

Displays the detailed listing of the flow control settings on all interfaces.

The show interface command is invoked from EXEC mode and displays the interface configurations. Without any arguments, this command displays the information for all the configured interfaces in the switch.

This example shows how to display the physical Ethernet interface: 


switch# show interface ethernet 1/1
  Ethernet1/1 is up
  Hardware is 1000/10000 Ethernet, address is 000d.eca3.5f08 (bia 000d.eca3.5f08)
  MTU 1500 bytes, BW 10000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 190/255, rxload 192/255
  Encapsulation ARPA
  Port mode is trunk
  full-duplex, 10 Gb/s, media type is 1/10g
  Input flow-control is off, output flow-control is off
  Auto-mdix is turned on
  Rate mode is dedicated
  Switchport monitor is off
  Last clearing of "show interface" counters never
  5 minute input rate 942201806 bytes/sec, 14721892 packets/sec
  5 minute output rate 935840313 bytes/sec, 14622492 packets/sec
  Rx
    129141483840 input packets 0 unicast packets 129141483847 multicast packets
    0 broadcast packets 0 jumbo packets 0 storm suppression packets
    8265054965824 bytes
    0 No buffer 0 runt 0 Overrun
    0 crc 0 Ignored 0 Bad etype drop
    0 Bad proto drop
  Tx
    119038487241 output packets 119038487245 multicast packets
   0 broadcast packets 0 jumbo packets
    7618463256471 bytes
    0 output CRC 0 ecc
    0 underrun 0 if down drop     0 output error 0 collision 0 deferred
    0 late collision 0 lost carrier 0 no carrier
    0 babble
    0 Rx pause 8031547972 Tx pause 0 reset

This example shows how to display the physical Ethernet capabilities: 

switch# show interface ethernet 1/1 capabilities
Ethernet1/1
  Model:                 734510033
  Type:                  10Gbase-(unknown)
  Speed:                 1000,10000
  Duplex:                full
  Trunk encap. type:     802.1Q
  Channel:               yes
  Broadcast suppression: percentage(0-100)
  Flowcontrol:											rx-(off/on),tx-(off/on)
  Rate mode:             none
  QOS scheduling:        rx-(6q1t),tx-(1p6q0t)
  CoS rewrite:           no
  ToS rewrite:           no
  SPAN:                  yes
  UDLD:                  yes

  MDIX:                  no
  FEX Fabric:            yes

This example shows how to display the physical Ethernet transceiver: 

switch# show interface ethernet 1/1 transceiver
Ethernet1/1
    sfp is present
    name is CISCO-EXCELIGHT
    part number is SPP5101SR-C1
    revision is A
    serial number is ECL120901AV
    nominal bitrate is 10300 MBits/sec
    Link length supported for 50/125mm fiber is 82 m(s)
    Link length supported for 62.5/125mm fiber is 26 m(s)
    cisco id is --
    cisco extended id number is 4

This example shows how to display a brief interface status (some of the output has been removed for brevity): 

switch# show interface brief

--------------------------------------------------------------------------------
Ethernet      VLAN   Type Mode   Status  Reason                   Speed     Port
Interface                                                                   Ch #
--------------------------------------------------------------------------------
Eth1/1        200    eth  trunk  up      none                        10G(D) --
Eth1/2        1      eth  trunk  up      none                        10G(D) --
Eth1/3        300    eth  access down    SFP not inserted            10G(D) --
Eth1/4        300    eth  access down    SFP not inserted            10G(D) --
Eth1/5        300    eth  access down    Link not connected         1000(D) --
Eth1/6        20     eth  access down    Link not connected          10G(D) --
Eth1/7        300    eth  access down    SFP not inserted            10G(D) --
...

This example shows how to display the CDP neighbors: 


switch# show cdp neighbors
Capability Codes: R - Router, T - Trans-Bridge, B - Source-Route-Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater,
                  V - VoIP-Phone, D - Remotely-Managed-Device,
                  s - Supports-STP-Dispute
Device ID              Local Intrfce   Hldtme  Capability  Platform      Port ID
d13-dist-1               mgmt0           148     S I      WS-C2960-24TC  Fas0/9
n5k(FLC12080012)         Eth1/5          8       S I s    N5K-C5020P-BA  Eth1/5

MIBs for Layer 2 Interfaces

MIB

MIB Link

IF-MIB

To locate and download MIBs, go to the following URL:

http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

MAU-MIB

Limited support includes only the following MIB Objects:

  • ifMauType (Read-only) GET

  • ifMauAutoNegSupported (Read-only) GET

  • ifMauTypeListBits (Read-only) GET

  • ifMauDefaultType (Read-write) GET-SET

  • ifMauAutoNegAdminStatus (Read-write) GET-SET

  • ifMauAutoNegCapabilityBits (Read-only) GET

  • ifMauAutoNegAdvertisedBits (Read-write) GET-SET