NX-OS Nexus 9000 Series Switches
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Specifications
Product Name: Cisco Nexus 9000 Series NX-OS
Protocol: Link Layer Discovery Protocol
(LLDP)
Support: Virtualization Support for one
instance of LLDP
Default Settings: LLDP Hold Time: 120 seconds,
LLDP Reinitialization Delay: 2 seconds, LLDP Timer: 30 seconds
Product Usage Instructions
About LLDP
The Link Layer Discovery Protocol (LLDP) is used to discover
other devices on the local network.
Configuring LLDP
To configure LLDP, follow these steps:
- Enter global configuration mode by using the command:
configure terminal - Enable LLDP globally with the command:
feature
lldp - To verify the global LLDP configuration, you can use the
command:show running-config lldp
Enabling or Disabling LLDP on an Interface
To enable or disable LLDP on an interface:
- If needed, copy the running configuration to the startup
configuration using:copy running-config
startup-config - Ensure that LLDP is globally enabled on the device
- You can individually enable or disable LLDP on interfaces or
configure them to send or receive LLDP packets only
FAQ
A: DCBXP is enabled by default when LLDP is
enabled. It can be enabled or disabled using the [no] lldp
tlv-select dcbxp command. DCBXP is disabled on ports where LLDP
transmit or receive is disabled.
Q: How does LLDP support high availability?
A: The LLDP feature supports stateless and
stateful restarts. After a reboot or supervisor switchover, the
running configuration is applied. For more information on high
availability, refer to the Cisco Nexus 9000 Series NX-OS High
Availability and Redundancy Guide.
Q: What are the guidelines and limitations for LLDP?
A: Only front-panel fixed ports are supported
with DCBXP. FEX ports are not supported. The priority-flow-control
mode is set to auto at the interface level.
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Configuring LLDP
This chapter describes how to configure the Link Layer Discovery Protocol (LLDP) in order to discover other devices on the local network. This chapter includes the following sections:
· About LLDP, on page 1 · Guidelines and Limitations for LLDP, on page 3 · Default Settings for LLDP, on page 3 · Configuring LLDP, on page 4 · Verifying the LLDP Configuration, on page 11 · Configuration Example for LLDP, on page 11
About LLDP
The Cisco Discovery Protocol (CDP) is a device discovery protocol that allows network management applications to automatically discover and learn about other Cisco devices that are connected to the network. To permit the discovery of non-Cisco devices, the switch also supports the Link Layer Discovery Protocol (LLDP), a vendor-neutral device discovery protocol that is defined in the IEEE 802.1ab standard. LLDP allows network devices to advertise information about themselves to other devices on the network. This protocol runs over the data-link layer, which allows two systems running different network layer protocols to learn about each other. LLDP is a one-way protocol that transmits information about the capabilities and current status of a device and its interfaces. LLDP devices use the protocol to solicit information only from other LLDP devices. LLDP supports a set of attributes that it uses to discover other devices. These attributes contain type, length, and value (TLV) descriptions. LLDP devices can use TLVs to send and receive information to other devices on the network. Details such as configuration information, device capabilities, and device identity can be advertised using this protocol. LLDP advertises the following TLVs by default:
· DCBXP · Management address · Port description · Port VLAN
Configuring LLDP 1
About DCBXP
Configuring LLDP
· System capabilities
· System description
· System name
About DCBXP
The Data Center Bridging Exchange Protocol (DCBXP) is an extension of LLDP. It is used to announce, exchange, and negotiate node parameters between peers. DCBXP parameters are packaged as DCBXP TLVs in the LLDP packet. If CEE is used, DCBXP will use an acknowledgment mechanism over LLDP. When the port comes up, DCBX TLVs are sent and any DCBX TLVs received are processed. By default, the DCBX protocol is set to auto-detect, and the latest protocol version supported by both the peers is used. Features that need to exchange and negotiate parameters with peer nodes using DCBXP are as follows:
· Priority-based Flow Control (PFC)–PFC is an enhancement to the existing Pause mechanism in Ethernet. It enables Pause based on user priorities or classes of service. A physical link that is divided into eight virtual links with PFC provides the capability to use Pause on a single virtual link without affecting traffic on the other virtual links. Enabling Pause on a per-user-priority basis allows administrators to create lossless links for traffic requiring no-drop service while retaining packet-drop congestion management for IP traffic.
· Enhanced Transmission Selection (ETS)–ETS enables optimal bandwidth management of virtual links. ETS is also called priority grouping. It enables differentiated treatments within the same priority classes of PFC. ETS provides prioritized processing based on bandwidth allocation, low latency, or best effort, resulting in per-group traffic class allocation. For example, an Ethernet class of traffic may have a high-priority designation and a best effort within that same class. ETS allows differentiation between traffic of the same priority class, thus creating priority groups.
· Application Priority Configuration–Carries information about the priorities that are assigned to specific protocols.
· Priority to DSCP Mapping–The mapping of the DSCP and COS values configured in the QoS policy are sent in the Application Priority TLV.
Note For information on the quality of service (QoS) features, see the Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide.
DCBXP is enabled by default, provided LLDP is enabled. When LLDP is enabled, DCBXP can be enabled or disabled using the [no] lldp tlv-select dcbxp command. DCBXP is disabled on ports where LLDP transmit or receive is disabled.
High Availability
The LLDP feature supports stateless and stateful restarts. After a reboot or supervisor switchover, the running configuration is applied. For more information on high availability, see the Cisco Nexus 9000 Series NX-OS High Availability and Redundancy Guide.
Configuring LLDP 2
Configuring LLDP
Virtualization Support
Virtualization Support
One instance of LLDP is supported.
Guidelines and Limitations for LLDP
LLDP has the following configuration guidelines and limitations: · The LLDP feature must be enabled on the device before you can enable or disable the LLDP protocol on any interfaces. · LLDP is supported only on physical interfaces. · LLDP can discover up to one device per port. · LLDP can discover Linux servers, provided they are not using a converged network adapter (CNA). LLDP cannot discover other types of servers. · DCBXP is not supported for LLDP until Cisco NX-OS Release 7.0(3)I3(1). · DCBXP is supported on the following platforms: · Cisco Nexus 9200 and 9300-EX Series switches, beginning with Cisco NX-OS Release 7.0(3)I5(1) · Cisco Nexus 9332PQ, 9372PX, 9372PX-E, and 9396PX switches · Cisco Nexus 9504 and 9508 switches with X9432PQ, X9464PX, X9536PQ, X9564PX, and X9636PQ line cards
Note Only front-panel fixed ports are supported with DCBXP. FEX ports are not supported.
· DCBXP incompatibility messages might appear when you change the network QoS policy on a switch, if a physical cable loopback connection is present on the device. The incompatibility exists for only a short time and then resolves on its own.
· The Cisco Nexus 3232C and 3264Q switches do not support DCBXP. · DCBX TLVs are sent only when the input queuing is configured and applied at the system level. · The mapping of the DSCP and COS values configured in the QOS policy are sent in the Application
TLV. · PFC TLVs are sent when pause is enabled for at least one COS value in a network-qos policy and the
priority-flow-control mode is set to auto at the interface level.
Default Settings for LLDP
This table lists the LLDP default settings.
Configuring LLDP 3
Configuring LLDP
Configuring LLDP
Parameters Global LLDP LLDP on interfaces LLDP hold time (before discarding) LLDP reinitialization delay LLDP timer (packet update frequency) LLDP TLVs LLDP receive LLDP transmit DCBXP DCBXP version
Configuring LLDP
Default Disabled Enabled, after LLDP is enabled globally 120 seconds 2 seconds 30 seconds Enabled Enabled, after LLDP is enabled globally Enabled, after LLDP is enabled globally Enabled, provided LLDP is enabled Auto-detect
Note Cisco NX-OS commands for this feature may differ from Cisco IOS commands for a similar feature.
Enabling or Disabling LLDP Globally
You can enable or disable LLDP globally on a device. You must enable LLDP globally to allow a device to send and receive LLDP packets.
Procedure
Step 1 Step 2 Step 3
Command or Action
configure terminal
Example:
switch# configure terminal switch(config)#
Purpose Enters global configuration mode.
[no] feature lldp Example:switch(config)# feature lldp
Enables or disables LLDP on the device. LLDP is disabled by default.
(Optional) show running-config lldp
Displays the global LLDP configuration. If
Example:
LLDP is enabled, it shows “feature lldp.” If LLDP is disabled, it shows an “Invalid
switch(config)# show running-config lldp command” error.
Configuring LLDP 4
Configuring LLDP
Enabling or Disabling LLDP on an Interface
Step 4
Command or Action
(Optional) copy running-config startup-config
Example:
switch(config)# copy running-config startup-config
Purpose
Copies the running configuration to the startup configuration.
Enabling or Disabling LLDP on an Interface
After you globally enable LLDP, it is enabled on all supported interfaces by default. However, you can enable or disable LLDP on individual interfaces or selectively configure an interface to only send or only receive LLDP packets.
Before you begin Make sure that you have globally enabled LLDP on the device.
Procedure
Step 1 Step 2 Step 3 Step 4 Step 5
Command or Action
configure terminal
Example:
switch# configure terminal switch(config)#
Purpose Enters global configuration mode.
interface interface slot/port
Example:
switch(config)# interface ethernet 7/1 switch(config-if)#
Specifies the interface on which you are enabling LLDP and enters the interface configuration mode.
[no] lldp transmit Example:switch(config-if)# lldp transmit
Enables or disables the transmission of LLDP packets on an interface. After you globally enable LLDP, it is enabled on all supported interfaces by default.
[no] lldp receive Example:switch(config-if)# lldp receive
Enables or disables the reception of LLDP packets on an interface. After you globally enable LLDP, it is enabled on all supported interfaces by default.
(Optional) show lldp interface interface Displays the LLDP configuration on the
slot/port
interface.
Example:
switch(config-if)# show lldp interface ethernet 7/1
Configuring LLDP 5
Multiple LLDP Neighbors Per Physical Interface
Configuring LLDP
Step 6
Command or Action
(Optional) copy running-config startup-config
Example:
switch(config)# copy running-config startup-config
Purpose
Copies the running configuration to the startup configuration.
Multiple LLDP Neighbors Per Physical Interface
Often times a network device sends multiple LLDP packets, out of which one is from the actual host. If a Cisco Nexus switch is communicating with the device but can only manage a single LLDP neighbor per interface, there is a good chance that becoming a neighbor with the actual required host will fail. To minimize this, Cisco Nexus switch interfaces can support multiple LLDP neighbors creating a better opportunity of becoming an LLDP neighbor with the correct device.
Support for multiple LLDP neighbors over the same interface requires LLDP multi-neighbor support to be configured globally.
Note You must disable DCBX globally before configuring LLDP multi-neighbor support. Failure to do so invokes an error message.
Enabling or Disabling LLDP Multi-Neighbor Support
Before you begin Consider the following before enabling LLDP multi-neighbor support on the interfaces:
· Make sure that you have globally enabled LLDP on the device (global configuration command feature lldp).
Procedure
Note After you globally enable LLDP, it is enabled on all supported interfaces by default.
· A maximum of three (3) neighbors are supported on an interface. · LLDP multi-neighbor is not supported on FEX interfaces.
Step 1
Command or Action
configure terminal
Example:
switch# configure terminal switch(config)#
Purpose Enters global configuration mode.
Configuring LLDP 6
Configuring LLDP
Enabling or Disabling LLDP Multi-Neighbor Support
Step 2 Step 3 Step 4 Step 5
Step 6
Step 7 Step 8
Command or Action
Purpose
Required: no lldp tlv-select dcbxp
Disables DCBXP TLVs globally.
Example:
Note
switch(config)# no lldp tlv-select dcbxp This command must be entered to avoid
switch(config)#
invoking an error message once LLDP
multi-neighbor support is configured.
Required: [no] lldp multi-neighbor Example:
switch(config)# lldp multi-neighbor switch(config)#
interface port / slot
Example:
switch(config)# interface 1/1 switch(config-if)#
(Optional) [no] lldp transmit Example:
switch(config-if)# lldp transmit
Enables or disables LLDP multi-neighbor support for all interfaces globally.
Specifies the interface on which you are enabling LLDP and enters the interface configuration mode.
Disables (or enables) the transmission of LLDP packets on the interface. Note The transmission of LLDP packets on this interface was enabled using the global feature lldp command. This option is to disable the feature for this specific interface.
(Optional) [no] lldp receive Example:
switch(config-if)# lldp receive
Disables (or enables) the reception of LLDP packets on the interface.
Note The reception of LLDP packets on this interface was enabled using the global feature lldp command. This option is to disable the feature for this specific interface.
(Optional) show lldp interface port / slot
Example:
switch(config-if)# show lldp interface 1/1
Displays the LLDP configuration on the interface.
(Optional) copy running-config startup-config
Example:
switch(config)# copy running-config startup-config
Copies the running configuration to the startup configuration.
Configuring LLDP 7
Enabling or Disabling LLDP Support on Port-Channel Interfaces
Configuring LLDP
Enabling or Disabling LLDP Support on Port-Channel Interfaces
Before you begin Consider the following before enabling LLDP support on port-channels:
· Make sure that you have globally enabled LLDP on the device (global configuration command feature lldp).
Note After you globally enable LLDP, it is enabled on all supported interfaces by default.
· Applying the lldp transmit and lldp receive configuration commands to a port-channel does not affect the configuration for the members of the port-channel.
· LLDP neighbors form between the port-channels only when LLDP transmit and receive is configured on both sides of the port-channel.
· The LLDP transmit and receive commands do not work on MCT, VPC, fex-fabric, FEX port-channels, and port-channel sub-interfaces.
Note If you enable the LLDP port-channel feature globally, the LLDP configuration is not applied to any of these port types. If the configuration is removed from the port-channels or the port type feature is disabled globally, you cannot use the lldp port-channel command to enable it on the newly supported port-channels. The command was already issued. To enable LLDP port-channel on the port-channels in question, configure lldp transmit and lldp receive for each port-channel (see steps 4, 5, and 6 in the following procedure).
Procedure
Step 1 Step 2 Step 3
Command or Action
configure terminal
Example:
switch# configure terminal switch(config)#
Purpose Enters global configuration mode.
Required: no lldp tlv-select dcbxp
Disables DCBXP TLVs globally. You must
Example:
enter this command before configuring LLDP on port-channels.
switch(config)# no lldp tlv-select dcbxp
switch(config)#
Required: [no] lldp port-channel Example:
Enables or disables LLDP transmit and receive for all port channels globally.
Configuring LLDP 8
Configuring LLDP
Enabling or Disabling LLDP Support on Port-Channel Interfaces
Step 4
Step 5 Step 6 Step 7 Step 8
Command or Action
switch(config)# lldp port-channel switch(config)#
Purpose
interface port-channel [port-channel-number Specifies the interface port-channel on which
| port-channel-range]
you are enabling LLDP and enters the interface
Example:
configuration mode.
switch(config)# interface port-channel Specifies the interface port-channel range on
3
which you are enabling LLDP and enters the
switch(config-if)#
interface range configuration mode.
Example:
Enter a range of port-channel numbers if you are configuring LLDP over more than one port-channel:
switch(config)# interface port-channel 1-3 switch(config-if-range)#
(Optional) [no] lldp transmit Example:
switch(config-if)# lldp transmit
Disables (or enables) the transmission of LLDP packets on the port-channel or range of port-channels.
Note The transmission of LLDP packets on this port-channel was enabled using the global lldp port-channel command in step 3. This option is to disable the feature for this specific port-channel.
(Optional) [no] lldp receive Example:
switch(config-if)# lldp receive
Disables (or enables) the reception of LLDP packets on the port-channel or range of port-channels.
Note The reception of LLDP packets on this port-channel was enabled using the global lldp port-channel command in step 3. This option is to disable the feature for this specific port-channel.
(Optional) show lldp interface port-channell Displays the LLDP configuration on the
port-channel-number
port-channel.
Example:
switch(config-if)# show lldp interface port-channel 3
(Optional) copy running-config startup-config
Example:
Copies the running configuration to the startup configuration.
Configuring LLDP 9
Configuring Optional LLDP Parameters
Configuring LLDP
Command or Action
switch(config)# copy running-config startup-config
Purpose
Configuring Optional LLDP Parameters
You can configure the frequency of LLDP updates, the amount of time for a receiving device to hold the information before discarding it, and the initialization delay time. You can also select the TLVs to include in LLDP packets.
Procedure
Step 1 Step 2
Command or Action
configure terminal Example:
switch# configure terminal switch(config)#
(Optional) [no] lldp holdtime seconds Example:
switch(config)# lldp holdtime 200
Step 3
(Optional) [no] lldp reinit seconds Example:
switch(config)# lldp reinit 5
Step 4
(Optional) [no] lldp timer seconds Example:
switch(config)# lldp timer 50
Step 5 Step 6
(Optional) show lldp timers Example:
switch(config)# show lldp timers
(Optional) [no] lldp tlv-select tlv Example:
switch(config)# lldp tlv-select system-name
Step 7
(Optional) show lldp tlv-select Example:
Purpose Enters global configuration mode.
Specifies the amount of time in seconds that a receiving device should hold the information that is sent by your device before discarding it. The range is 10 to 255 seconds; the default is 120 seconds.
Specifies the delay time in seconds for LLDP to initialize on any interface. The range is 1 to 10 seconds; the default is 2 seconds.
Specifies the transmission frequency of LLDP updates in seconds. The range is 5 to 254 seconds; the default is 30 seconds.
Displays the LLDP hold time, delay time, and update frequency configuration.
Specifies the TLVs to send and receive in LLDP packets. The available TLVs are dcbxp, management-address, port-description, port-vlan, system-capabilities, system-description, and system-name. All available TLVs are enabled by default.
Displays the LLDP TLV configuration.
Configuring LLDP 10
Configuring LLDP
Verifying the LLDP Configuration
Step 8
Command or Action
switch(config)# show lldp tlv-select
(Optional) copy running-config startup-config
Example:
switch(config)# copy running-config startup-config
Purpose
Copies the running configuration to the startup configuration.
Verifying the LLDP Configuration
To display the LLDP configuration, perform one of the following tasks:
Command show running-config lldp show lldp all
show lldp interface interface slot/port show lldp timers
show lldp tlv-select show lldp dcbx interface interface slot/port
show lldp neighbors {detail | interface interface slot/port} show lldp traffic
show lldp traffic interface interface slot/port
Purpose
Displays the global LLDP configuration.
Displays the LLDP DCBXP, transmit and receive configuration for all interfaces.
Displays the LLDP interface configuration.
Displays the LLDP hold time, delay time, and update frequency configuration.
Displays the LLDP TLV configuration.
Displays DCBXP TLV information for a specific interface.
Displays the LLDP neighbor device status.
Displays the LLDP counters, including the number of LLDP packets sent and received by the device, the number of discarded packets, and the number of unrecognized TLVs.
Displays the number of LLDP packets sent and received on the interface.
Use the clear lldp counters command to clear the LLDP statistics.
Configuration Example for LLDP
This example shows how to enable LLDP on a device; disable LLDP on some interfaces; configure optional parameters such as hold time, delay time, and update frequency; and disable several LLDP TLVs:
switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. switch(config)# feature lldp switch(config)# interface ethernet 7/9 switch(config-if)# no lldp transmit
Configuring LLDP 11
Configuration Example for LLDP
switch(config-if)# no lldp receive switch(config-if)# exit switch(config)# interface ethernet 7/10 switch(config-if)# no lldp transmit switch(config-if)# no lldp receive switch(config-if)# exit switch(config)# lldp holdtime 200 switch(config)# lldp reinit 5 switch(config)# lldp timer 50 switch(config)# no lldp tlv-select port-vlan switch(config)# no lldp tlv-select system-name
Configuring LLDP
Configuring LLDP 12
Documents / Resources
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CISCO NX-OS Nexus 9000 Series Switches [pdf] User Guide NX-OS, NX-OS Nexus 9000 Series Switches, Nexus 9000 Series Switches, Switches |