LLDP
To standardize device discovery on all HPE switches, LLDP will be implemented while offering limited read-only support for CDP, as documented in this manual. For the latest information on your switch model, consult the Release Notes (available on the HPE Networking website). If LLDP has not yet been implemented (or if you are running an older version of software), consult a previous version of the Management and Configuration Guide for device discovery details.
LLDP (Link Layer Discovery Protocol): provides a standards-based method for enabling the switches covered in this guide to advertise themselves to adjacent devices and to learn about adjacent LLDP devices.
LLDP-MED (LLDP Media Endpoint Discovery): Provides an extension to LLDP and is designed to support VoIP deployments.
![[NOTE: ]](images/note.gif) | NOTE: LLDP-MED is an extension for LLDP, and the switch requires that LLDP be enabled as a prerequisite to LLDP-MED operation. |
An SNMP utility can progressively discover LLDP devices in a network by:
Reading a given device's Neighbors table (in the Management Information Base, or MIB) to learn about other, neighboring LLDP devices.
Using the information learned in step 1 to find and read the neighbor devices' Neighbors tables to learn about additional devices, and so on.
Also, by using show commands
to access the switch's neighbor database for information collected
by an individual switch, system administrators can learn about other
devices connected to the switch, including device type (capability)
and some configuration information. In VoIP deployments using LLDP-MED
on the switches, additional support unique to VoIP applications is
also available. See LLDP-MED (media-endpoint-discovery).
General LLDP operation
An LLDP packet contains data about the transmitting switch and port. The switch advertises itself to adjacent (neighbor) devices by transmitting LLDP data packets out all ports on which outbound LLDP is enabled and by reading LLDP advertisements from neighbor devices on ports that are inbound LLDP-enabled. (LLDP is a one-way protocol and does not include any acknowledgement mechanism.) An LLDP-enabled port receiving LLDP packets inbound from neighbor devices stores the packet data in a Neighbor database (MIB).
LLDP-MED
This capability is an extension to LLDP and is available on the switches. See LLDP-MED (media-endpoint-discovery).
Packet boundaries in a network topology
Where multiple LLDP devices are directly connected, an outbound LLDP packet travels only to the next LLDP device. An LLDP-capable device does not forward LLDP packets to any other devices, regardless of whether they are LLDP-enabled.
An intervening hub or repeater forwards the LLDP packets it receives in the same manner as any other multicast packets it receives. Thus, two LLDP switches joined by a hub or repeater handle LLDP traffic in the same way that they would if directly connected.
Any intervening 802.1D device or Layer-3 device that is either LLDP-unaware or has disabled LLDP operation drops the packet.
LLDP operation configuration options
In the default configuration, LLDP is enabled and in both transmit and receive mode on all active ports. The LLDP configuration includes global settings, which apply to all active ports on the switch, and per-port settings, which affect only the operation of the specified ports.
The commands in the LLDP sections affect both LLDP and LLDP-MED operation. For information on operation and configuration unique to LLDP-MED, see LLDP-MED (media-endpoint-discovery).
Enable or disable LLDP on the switch
In the default configuration, LLDP is globally enabled on the switch. To prevent transmission or receipt of LLDP traffic, you can disable LLDP operation.
Enable or disable LLDP-MED
In the default configuration for the switches, LLDP-MED is enabled by default. (Requires that LLDP is also enabled.) For more information, see LLDP-MED (media-endpoint-discovery).
Change the frequency of LLDP packet transmission to neighbor devices
On a global basis, you can increase or decrease the frequency of outbound LLDP advertisements.
Change the Time-To-Live for LLDP packets sent to neighbors
On a global basis, you can increase or decrease the time that the information in an LLDP packet outbound from the switch will be maintained in a neighbor LLDP device.
Transmit and receive mode
With LLDP enabled, the switch periodically transmits an LLDP advertisement (packet) out each active port enabled for outbound LLDP transmissions and receives LLDP advertisements on each active port enabled to receive LLDP traffic (Configuring per-port transmit and receive modes (CLI)). Per-port configuration options include four modes:
Transmit and receive (
tx_rx): This is the default setting on all ports. It enables a given port to both transmit and receive LLDP packets and to store the data from received (inbound) LLDP packets in the switch's MIB.Transmit only (
txonly): This setting enables a port to transmit LLDP packets that can be read by LLDP neighbors. However, the port drops inbound LLDP packets from LLDP neighbors without reading them. This prevents the switch from learning about LLDP neighbors on that port.Receive only (
rxonly): This setting enables a port to receive and read LLDP packets from LLDP neighbors and to store the packet data in the switch's MIB. However, the port does not transmit outbound LLDP packets. This prevents LLDP neighbors from learning about the switch through that port.Disable (
disable): This setting disables LLDP packet transmissions and reception on a port. In this state, the switch does not use the port for either learning about LLDP neighbors or informing LLDP neighbors of its presence.
SNMP notification
You can enable the switch to send a notification to any configured SNMP trap receiver(s) when the switch detects a remote LLDP data change on an LLDP-enabled port (Configuring SNMP notification support).
Per-port (outbound) data options
The following table lists the information the switch can include in the per-port, outbound LLDP packets it generates. In the default configuration, all outbound LLDP packets include this information in the TLVs transmitted to neighbor devices. However, you can configure LLDP advertisements on a per-port basis to omit some of this information (Configuring a remote management address for outbound LLDP advertisements (CLI)).
Data available for basic LLDP advertisements
| Data type | Configuration options | Default | Description |
|---|---|---|---|
Time-to-Live |
[1] |
120 Seconds |
The length of time an LLDP neighbor retains the advertised data before discarding it. |
N/A |
Always Enabled |
Indicates the type of identifier used for Chassis ID. | |
Chassis ID[6] |
N/A |
Always Enabled |
Uses base MAC address of the switch. |
N/A |
Always Enabled |
Uses "Local," meaning assigned locally by LLDP. | |
Port Id[6] |
N/A |
Always Enabled |
Uses port number of the physical port. This is an internal number reflecting the reserved slot/port position in the chassis. For more information on this numbering scheme, see the appendix "MAC Address Management". |
Remote Management Address | |||
N/A |
Always Enabled |
Shows the network address type. | |
Address[4] |
Default or Configured |
Uses a default address selection method unless an optional address is configured. See Remote management address. | |
System Name[6] |
Enable/Disable |
Enabled |
Uses the switch's assigned name. |
System Description[6] |
Enable/Disable |
Enabled |
Includes switch model name and running software version, and ROM version. |
Port Description[6] |
Enable/Disable |
Enabled |
Uses the physical port identifier. |
Enable/Disable |
Enabled |
Identifies the switch's primary capabilities (bridge, router). | |
Enable/Disable |
Enabled |
Identifies the primary switch functions that are enabled, such as routing. | |
[2] Subelement of the Chassis ID TLV. [6] Populated with data captured internally by the switch. For more on these data types, refer to the IEEE P802.1AB Standard. [3] Subelement of the Port ID TLV. [4] Subelement of the Remote-Management-Address TLV. [5] Subelement of the System Capability TLV. | |||
Remote management address
The switch always includes an IP address in its LLDP advertisements. This can be either an address selected by a default process or an address configured for inclusion in advertisements. See IP address advertisements.
Debug logging
You can enable LLDP debug logging to a configured
debug destination (Syslog server, a terminal device, or both) by executing
the debug lldp command. (For more information on
Debug and Syslog, see the "Troubleshooting" appendix in
this guide.) Note that the switch's Event Log does not record usual
LLDP update messages.
Options for reading LLDP information collected by the switch
You can extract LLDP information from the switch to identify adjacent LLDP devices. Options include:
Using the switch's
show lldp info command options to display data collected on adjacent LLDP devices—as well as the local data the switch is transmitting to adjacent LLDP devices (Displaying the global LLDP, port admin, and SNMP notification status (CLI)).Using an SNMP application that is designed to query the Neighbors MIB for LLDP data to use in device discovery and topology mapping.
Using the
walkmibcommand to display a listing of the LLDP MIB objects
LLDP and LLDP-MED standards compatibility
The operation covered by this section is compatible with these standards:
LLDP operating rules
For additional information specific to LLDP-MED operation, see LLDP-MED (media-endpoint-discovery).
Port trunking
LLDP manages trunked ports individually. That is, trunked ports are configured individually for LLDP operation, in the same manner as non-trunked ports. Also, LLDP sends separate advertisements on each port in a trunk, and not on a per-trunk basis. Similarly, LLDP data received through trunked ports is stored individually, per-port.
IP address advertisements
In the default operation, if a port belongs to only one static VLAN, the port advertises the lowest-order IP address configured on that VLAN. If a port belongs to multiple VLANs, the port advertises the lowest-order IP address configured on the VLAN with the lowest VID. If the qualifying VLAN does not have an IP address, the port advertises 127.0.0.1 as its IP address. For example, if the port is a member of the default VLAN (VID=1), and there is an IP address configured for the default VLAN, the port advertises this IP address. In the default operation, the IP address that LLDP uses can be an address acquired by DHCP or Bootp.
You can override the default operation by configuring the port to advertise any IP address that is manually configured on the switch, even if the port does not belong to the VLAN configured with the selected IP address (Configuring a remote management address for outbound LLDP advertisements (CLI)). (Note that LLDP cannot be configured through the CLI to advertise an addresses acquired through DHCP or Bootp. However, as mentioned above, in the default LLDP configuration, if the lowest-order IP address on the VLAN with the lowest VID for a given port is a DHCP or Bootp address, the switch includes this address in its LLDP advertisements unless another address is configured for advertisements on that port.) Also, although LLDP allows configuring multiple remote management addresses on a port, only the lowest-order address configured on the port will be included in outbound advertisements. Attempting to use the CLI to configure LLDP with an IP address that is either not configured on a VLAN or has been acquired by DHCP or Bootp results in the following error message.
xxx.xxx.xxx.xxx: This IP address is not configured or is a DHCP address.
Configuring LLDP operation
Displaying the global LLDP, port admin, and SNMP notification status (CLI)
In the default configuration, LLDP is enabled and in both transmit and receive mode on all active ports. The LLDP configuration includes global settings that apply to all active ports on the switch, and per-port settings that affect only the operation of the specified ports.
The commands in this section affect both LLDP and LLDP-MED operation. for information on operation and configuration unique to LLDP-MED, refer to “LLDP-MED (Media-Endpoint-Discovery)”.
Syntax:
show lldp configDisplays the LLDP global configuration, LLDP port status, and SNMP notification status. For information on port admin status, see Configuring per-port transmit and receive modes (CLI).
show lldp config produces
the following display when the switch is in the default LLDP configuration:
Viewing the general LLDP configuration
HP Switch(config)# show lldp config LLDP Global Configuration LLDP Enabled [Yes] : Yes LLDP Transmit Interval [30] : 30 LLDP Hold time Multiplier [4] : 4 LLDP Delay Interval [2] : 2 LLDP Reinit Interval [2] : 2 LLDP Notification Interval [5] : 5 LLDP Fast Start Count [5] : 5 LLDP Port Configuration Port | AdminStatus NotificationEnabled Med Topology Trap Enabled ---- + ----------- ------------------- ------------------------- A1 | Tx_Rx False False A2 | Tx_Rx False False A3 | Tx_Rx False False A4 | Tx_Rx False False A5 | Tx_Rx False False A6 | Tx_Rx False False A7 | Tx_Rx False False A8 | Tx_Rx False False
| NOTE: The values displayed in the LLDP column correspond
to the |
Viewing port configuration details (CLI)
Syntax:
show lldp config <port-list>Displays the LLDP port-specific configuration for all ports in <
port-list>, including which optional TLVs and any non-default IP address that are included in the port's outbound advertisements.
For information on the notification setting, see Configuring SNMP notification support. For information on the other configurable settings displayed by this command, see Configuring per-port transmit and receive modes (CLI).
Configuring Global LLDP Packet Controls
The commands in this section configure the aspects of LLDP operation that apply the same to all ports in the switch.
LLDP operation on the switch
Enabling LLDP operation (the default) causes the switch to:
Use active, LLDP-enabled ports to transmit LLDP packets describing itself to neighbor devices.
Add entries to its neighbors table based on data read from incoming LLDP advertisements.
Enabling or disabling LLDP operation on the switch (CLI)
For more information, see LLDP operation on the switch.
Syntax:
[no]
lldp runEnables or disables LLDP operation on the switch.
The
noform of the command, regardless of individual LLDP port configurations, prevents the switch from transmitting outbound LLDP advertisements and causes the switch to drop all LLDP advertisements received from other devices.The switch preserves the current LLDP configuration when LLDP is disabled. After LLDP is disabled, the information in the LLDP neighbors database remains until it times-out.
(Default: Enabled)
Changing the packet transmission interval (CLI)
This interval controls how often active ports retransmit advertisements to their neighbors.
Syntax:
lldp refresh-interval<5-32768>Changes the interval between consecutive transmissions of LLDP advertisements on any given port.
(Default: 30 seconds)
| NOTE: The |
Time-to-Live for transmitted advertisements
The Time-to-Live value (in seconds) for all LLDP
advertisements transmitted from a switch is controlled by the switch
that generates the advertisement and determines how long an LLDP neighbor
retains the advertised data before discarding it. The Time-to-Live
value is the result of multiplying the refresh-interval by
the holdtime-multiplier.
Changing the time-to-live for transmitted advertisements (CLI)
For more information, see Time-to-Live for transmitted advertisements.
lldp holdtime-multiplier <2-10>Changes the multiplier an LLDP switch uses to calculate the Time-to-Live for the LLDP advertisements it generates and transmits to LLDP neighbors. When the Time-to-Live for a given advertisement expires, the advertised data is deleted from the neighbor switch's MIB.
(Default: 4; Range 2–10)
If the refresh-interval on the switch is 15 seconds
and the holdtime-multiplier is at the default,
the Time-to-Live for advertisements transmitted from the switch is
60 seconds (4 x 15).
To reduce the Time-to-Live, you could lower the holdtime-interval to
2, which would result in a Time-to-Live of 30 seconds.
HP Switch(config)# lldp holdtime-multiplier 2
Delay interval between advertisements generated by value or status changes to the LLDP MIB
The switch uses a delay-interval setting
to delay transmitting successive advertisements resulting from these
LLDP MIB changes. If a switch is subject to frequent changes to its
LLDP MIB, lengthening this interval can reduce the frequency of successive
advertisements. You can change the delay-interval by using either
an SNMP network management application or the CLI setmib command.
Changing the delay interval between advertisements generated by value or status changes to the LLDP MIB (CLI)
setmib lldpTxDelay.0 -i <1-8192>Uses
setmibto change the minimum time (delay-interval) any LLDP port will delay advertising successive LLDP advertisements because of a change in LLDP MIB content.(Default: 2; Range 1–8192)
| NOTE: The LLDP refresh-interval (transmit interval)
must be greater than or equal to (4 x delay-interval). The switch
does not allow increasing the delay interval to a value that conflicts
with this relationship. That is, the switch displays |
To change the delay-interval from 2 seconds to 8 seconds when the refresh-interval is at the default 30 seconds, you must first set the refresh-interval to a minimum of 32 seconds (32 = 4 x 8). (See Changing the transmit-delay interval.)
Reinitialization delay interval
In the default configuration, a port receiving
a disable command followed immediately by a txonly, rxonly,
or tx_rx command delays reinitializing for two
seconds, during which LLDP operation remains disabled. If an active
port is subjected to frequent toggling between the LLDP disabled and
enabled states, LLDP advertisements are more frequently transmitted
to the neighbor device. Also, the neighbor table in the adjacent device
changes more frequently as it deletes, then replaces LLDP data for
the affected port which, in turn, generates SNMP traps (if trap receivers
and SNMP notification are configured). All of this can unnecessarily
increase network traffic. Extending the reinitialization-delay interval
delays the ability of the port to reinitialize and generate LLDP traffic
following an LLDP disable/enable cycle.
Changing the reinitialization delay interval (CLI)
For more information, see Reinitialization delay interval.
setmib lldpReinitDelay.0 -i <1-10> Uses
setmibto change the minimum time (reinitialization delay interval) an LLDP port will wait before reinitializing after receiving an LLDP disable command followed closely by a txonly or tx_rx command. The delay interval commences with execution of thelldp admin-statuscommand.port-listdisable(Default: 2 seconds; Range 1–10 seconds)
The following command changes the reinitialization delay interval to five seconds:
HP Switch(config)# setmib lldpreinitdelay.0 -i 5
Configuring SNMP notification support
You can enable SNMP trap notification of LLDP data changes detected on advertisements received from neighbor devices, and control the interval between successive notifications of data changes on the same neighbor.
Enabling LLDP data change notification for SNMP trap receivers (CLI)
For more information, see Section 1.67.3.2.
Syntax:
[no]
lldp enable-notification <port-list>Enables or disables each port in
port-listfor sending notification to configured SNMP trap receivers if an LLDP data change is detected in an advertisement received on the port from an LLDP neighbor.(Default: Disabled)
For information on configuring trap receivers in the switch, see SNMP notifications.
Example:
This command enables SNMP notification on ports 1 - 5:
HP Switch(config)# lldp enable-notification 1-5
Changing the minimum interval for successive data change notifications for the same neighbor
If LLDP trap notification is enabled on a port, a rapid succession of changes in LLDP information received in advertisements from one or more neighbors can generate a high number of traps. To reduce this effect, you can globally change the interval between successive notifications of neighbor data change.
Syntax:
setmib lldpnotificationinterval.0 -i <1-3600>Globally changes the interval between successive traps generated by the switch. If multiple traps are generated in the specified interval, only the first trap is sent. The remaining traps are suppressed. (A network management application can periodically check the switch MIB to detect any missed change notification traps. See IEEE P802.1AB or later for more information.)
(Default: 5 seconds)
Example:
The following command limits change notification traps from a particular switch to one per minute.
HP Switch(config)# setmib lldpnotificationinterval.0 -i 60 lldpNotificationInterval.0=60
Configuring per-port transmit and receive modes (CLI)
Syntax:
lldp admin-status <port-list><txonly|rxonly|tx_rx|disable>With LLDP enabled on the switch in the default configuration, each port is configured to transmit and receive LLDP packets. These options enable you to control which ports participate in LLDP traffic and whether the participating ports allow LLDP traffic in only one direction or in both directions.
txonlyConfigures the specified ports to transmit LLDP packets, but block inbound LLDP packets from neighbor devices.
rxonlyConfigures the specified ports to receive LLDP packets from neighbors, but block outbound packets to neighbors.
tx_rxConfigures the specified ports to both transmit and receive LLDP packets. (This is the default setting.)
disableDisables LLDP packet transmit and receive on the specified ports.
Basic LLDP per-port advertisement content
In the default LLDP configuration, outbound advertisements from each port on the switch include both mandatory and optional data.
Mandatory Data
An active LLDP port on the switch always includes the mandatory data in its outbound advertisements. LLDP collects the mandatory data, and, except for the Remote Management Address, you cannot use LLDP commands to configure the actual data.
Configuring a remote management address for outbound LLDP advertisements (CLI)
This is an optional command you can use to include a specific IP address in the outbound LLDP advertisements for specific ports. For more information, see Basic LLDP per-port advertisement content.
Syntax:
[no]
lldp config <port-list> ipAddrEnable <ip-address>Replaces the default IP address for the port with an IP address you specify. This can be any IP address configured in a static VLAN on the switch, even if the port does not belong to the VLAN configured with the selected IP address.
The
noform of the command deletes the specified IP address.If there are no IP addresses configured as management addresses, the IP address selection method returns to the default operation.
Default: The port advertises the IP address of the lowest-numbered VLAN (VID) to which it belongs. If there is no IP address configured on the VLANs to which the port belongs, and if the port is not configured to advertise an IP address from any other (static) VLAN on the switch, the port advertises an address of 127.0.0.1.)
| NOTE: This command does not accept either IP addresses acquired through DHCP or Bootp, or IP addresses that are not configured in a static VLAN on the switch. |
Example:
If port 3 belongs to a subnetted VLAN that includes an IP address of 10.10.10.100 and you want port 3 to use this secondary address in LLDP advertisements, you need to execute the following command:
HP Switch(config)# lldp config 3 ipAddrEnable 10.10.10.100
Syntax:
[no]
lldp config <port-list> basicTlvEnable <TLV-Type>
port_descrFor outbound LLDP advertisements, this TLV includes an alphanumeric string describing the port.
(Default: Enabled)
system_nameFor outbound LLDP advertisements, this TLV includes an alphanumeric string showing the assigned name of the system.
(Default: Enabled)
system_descrFor outbound LLDP advertisements, this TLV includes an alphanumeric string describing the full name and version identification for the hardware type, software version, and networking application of the system.
(Default: Enabled)
system_capFor outbound advertisements, this TLV includes a bitmask of supported system capabilities (device functions). Also includes information on whether the capabilities are enabled.
(Default: Enabled)
Example:
If you want to exclude the system name TLV from the outbound LLDP advertisements for all ports on a switch, use this command:
HP Switch(config)# no lldp config 1-24 basicTlvEnable system_name
If you later decide to reinstate the system name TLV on ports 1-5, use this command:
HP Switch(config)# lldp config 1-5 basicTlvEnable system_name
Optional Data
You can configure an individual port or group of ports to exclude one or more of the following data types from outbound LLDP advertisements.
Optional data types, when enabled, are populated with data internal to the switch; that is, you cannot use LLDP commands to configure their actual content.
Support for port speed and duplex advertisements
This feature is optional for LLDP operation, but is required for LLDP-MED operation.
Port speed and duplex advertisements are supported on the switches to inform an LLDP endpoint and the switch port of each other's port speed and duplex configuration and capabilities. Configuration mismatches between a switch port and an LLDP endpoint can result in excessive collisions and voice quality degradation. LLDP enables discovery of such mismatches by supporting SNMP access to the switch MIB for comparing the current switch port and endpoint settings. (Changing a current device configuration to eliminate a mismatch requires intervention by the system operator.)
An SNMP network management application can be used to compare the port speed and duplex data configured in the switch and advertised by the LLDP endpoint. You can also use the CLI to display this information. For more information on using the CLI to display port speed and duplex information, seeViewing the current port speed and duplex configuration on a switch port.
Configuring support for port speed and duplex advertisements (CLI)
For more information, see Support for port speed and duplex advertisements.
Syntax:
[no]
lldp config <port-list> dot3TlvEnable macphy_configFor outbound advertisements, this TLV includes the (local) switch port's current speed and duplex settings, the range of speed and duplex settings the port supports, and the method required for reconfiguring the speed and duplex settings on the device (autonegotiation during link initialization, or manual configuration).
Using SNMP to compare local and remote information can help in locating configuration mismatches.
(Default: Enabled)
| NOTE: For LLDP operation, this TLV is optional. For LLDP-MED operation, this TLV is mandatory. |
Port VLAN ID TLV support on LLDP
The port-vlan-id option enables
advertisement of the port VLAN ID TLV as part of the regularly advertised
TLVs. This allows discovery of a mismatch in the configured native
VLAN ID between LLDP peers. The information is visible using show commands
and is logged to the Syslog server.
Configuring the VLAN ID TLV
This TLV advertisement is enabled by default. To enable or disable the TLV, use this command. For more information, see Port VLAN ID TLV support on LLDP.
Syntax:
Viewing the TLVs advertised
The show commands display the configuration of
the TLVs. The command show lldp config lists the
TLVs advertised for each port, as shown in Displaying the TLVs for a port through Remote device LLDP information.
Displaying the TLVs for a port
HP Switch(config)# show lldp config a1 LLDP Port Configuration Detail Port : A1 AdminStatus [Tx_Rx] : Tx_Rx NotificationEnabled [False] : False Med Topology Trap Enabled [False] : False TLVS Advertised: * port_descr * system_name * system_descr * system_cap * capabilities * network_policy * location_id * poe * macphy_config * port_vlan_id IpAddress Advertised: : :
Local device LLDP information
HP Switch(config)# show lldp config info local-device a1 LLDP Port Configuration Information Detail Port : A1 PortType : local PortId : 1 PortDesc : A1 Port VLAN ID : 1
Remote device LLDP information
HP Switch(config)# show lldp info remote-device a1
LLDP Remote Device Information Detail
Local Port : A1
ChassisType : mac-address
ChassisId : 00 16 35 22 ca 40
PortType : local
PortID : 1
SysName : esp-dback
System Descr : HP J8693A Switch 3500yl-48G, revision XX.13.03, ROM...
PortDescr : A1
System Capabilities Supported : bridge, router
System Capabilities Enabled : bridge, router
Port VLAN ID : 200
Remote Management Address
Type : ipv4
Address : 192.168.1.1
SNMP support
The LLDP-EXT-DOT1-MIB has the corresponding MIB
variables for the Port VLAN ID TLV. The TLV advertisement can be enabled
or disabled using the MIB object lldpXdot1ConfigPortVlanTxEnable in
the lldpXdot1ConfigPortVlanTable.
The port VLAN ID TLV local information can be
obtained from the MIB object lldpXdot1LocPortVlanId in
the local information table lldpXdot1LocTable.
The port VLAN ID TLV information about all the
connected peer devices can be obtained from the MIB object lldpXdot1RemPortVlanId in
the remote information table lldpXdot1RemTable.
LLDP-MED (media-endpoint-discovery)
LLDP-MED (ANSI/TIA-1057/D6) extends the LLDP
(IEEE 802.1AB) industry standard to support advanced features on the
network edge for Voice Over IP (VoIP) endpoint
devices with specialized capabilities and LLDP-MED standards-based
functionality. LLDP-MED in the switches uses the standard LLDP commands
described earlier in this section, with some extensions, and also
introduces new commands unique to LLDP-MED operation. The show commands
described elsewhere in this section are applicable to both LLDP and
LLDP-MED operation. LLDP-MED benefits include:
Plug-and-play provisioning for MED-capable, VoIP endpoint devices
Simplified, vendor-independent management enabling different IP telephony systems to interoperate on one network
Automatic deployment of convergence network policies (voice VLANs, Layer 2/CoS priority, and Layer 3/QoS priority)
Configurable endpoint location data to support the Emergency Call Service (ECS) (such as Enhanced 911 service, 999, 112)
Detailed VoIP endpoint data inventory readable via SNMP from the switch
Power over Ethernet (PoE) status and troubleshooting support via SNMP
support for IP telephony network troubleshooting of call quality issues via SNMP
This section describes how to configure and use LLDP-MED features in the switches to support VoIP network edge devices (media endpoint devices) such as:
IP phones
Voice/media gateways
Media servers
IP communications controllers
Other VoIP devices or servers
LLDP-MED endpoint support
LLDP-MED interoperates with directly connected IP telephony (endpoint) clients having these features and services:
Autonegotiate speed and duplex configuration with the switch
Use the following network policy elements configured on the client port
Voice VLAN ID
802.1p (Layer 2) QoS
Diffserv codepoint (DSCP) (Layer 3) QoS
Discover and advertise device location data learned from the switch
Support ECS (such as E911, 999, and 112)
Advertise device information for the device data inventory collected by the switch, including:
Hardware revision
Firmware revision
Software revision
Serial number
Manufacturer name
Model name
Asset ID
Provide information on network connectivity capabilities (For example, a multi-port VoIP phone with Layer 2 switch capability)
Support the fast-start capability
| NOTE: LLDP-MED is intended for use with VoIP endpoints and is not designed to support links between network infrastructure devices, such as switch-to-switch or switch-to-router links. |
LLDP-MED endpoint device classes
LLDP-MED endpoint devices are, by definition, located at the network edge and communicate using the LLDP-MED framework. Any LLDP-MED endpoint device belongs to one of the following three classes:
Class 1 (generic endpoint devices): These devices offer the basic LLDP discovery services, network policy advertisement (VLAN ID, Layer 2/802.1p priority, and Layer 3/DSCP priority), and PoE management. This class includes such devices as IP call controllers and communication-related servers.
Class 2 (media endpoint devices): These devices offer all Class 1 features plus media-streaming capability, and include such devices as voice/media gateways, conference bridges, and media servers.
Class 3 (communication devices): These devices are typically IP phones or end-user devices that otherwise support IP media and offer all Class 1 and Class 2 features, plus location identification and emergency 911 capability, Layer 2 switch support, and device information management.
LLDP-MED operational support
The switches offer two configurable TLVs supporting MED-specific capabilities:
medTlvEnable (for per-port enabling or disabling of LLDP-MED operation)
medPortLocation (for configuring per-port location or emergency call data)
| NOTE: LLDP-MED operation also requires the port speed and duplex TLV (dot3TlvEnable), which is enabled in the default configuration. Topology change notifications provide one method for monitoring system activity. However, because SNMP normally employs UDP, which does not guarantee datagram delivery, topology change notification should not be relied upon as the sole method for monitoring critical endpoint device connectivity. |
LLDP-MED fast start control
Syntax:
lldp fast-start-count <1-10>An LLDP-MED device connecting to a switch port may use the data contained in the MED TLVs from the switch to configure itself. However, the
lldp refresh-intervalsetting (default: 30 seconds) for transmitting advertisements can cause an unacceptable delay in MED device configuration.To support rapid LLDP-MED device configuration, the
lldp fast-start-countcommand temporarily overrides therefresh-intervalsetting for thefast-start-countadvertisement interval. This results in the port initially advertising LLDP-MED at a faster rate for a limited time. Thus, when the switch detects a new LLDP-MED device on a port, it transmits one LLDP-MED advertisement per second out the port for the duration of thefast-start-countinterval. In most cases, the default setting should provide an adequatefast-start-countinterval.(Default: 5 seconds)
| NOTE: This global command applies only to ports on
which a new LLDP-MED device is detected. It does not override the |
Advertising device capability, network policy, PoE status and location data
The medTlvEnable option on the switch is enabled in the default configuration and supports the following LLDP-MED TLVs:
LLDP-MED capabilities: This TLV enables the switch to determine:
Whether a connected endpoint device supports LLDP-MED
Which specific LLDP-MED TLVs the endpoint supports
The device class (1, 2, or 3) for the connected endpoint
This TLV also enables an LLDP-MED endpoint to discover what LLDP-MED TLVs the switch port currently supports.
Network policy operating on the port to which the endpoint is connected (VLAN, Layer 2 QoS, Layer 3 QoS)
PoE (MED Power-over-Ethernet)
Physical location data (see Configuring location data for LLDP-MED devices)
| NOTE: LLDP-MED operation requires the macphy_config
TLV subelement (enabled by default) that is optional for IEEE 802.1AB
LLDP operation. For more information, see the |
Network policy advertisements
Network policy advertisements are intended for real-time voice and video applications, and include these TLV subelements:
Layer 2 (802.1p) QoS
Layer 3 DSCP (diffserv code point) QoS
Voice VLAN ID (VID)
VLAN operating rules
These rules affect advertisements of VLANs in network policy TLVs:
The VLAN ID TLV subelement applies only to a VLAN configured for voice operation (
vlan <).vid> voiceIf there are multiple voice VLANs configured on a port, LLDP-MED advertises the voice VLAN having the lowest VID.
The voice VLAN port membership configured on the switch can be tagged or untagged. However, if the LLDP-MED endpoint expects a tagged membership when the switch port is configured for untagged, or the reverse, a configuration mismatch results. (Typically, the endpoint expects the switch port to have a tagged voice VLAN membership.)
If a given port does not belong to a voice VLAN, the switch does not advertise the VLAN ID TLV through this port.
Policy elements
These policy elements may be statically configured on the switch or dynamically imposed during an authenticated session on the switch using a RADIUS server and 802.1X or MAC authentication. (Web authentication does not apply to VoIP telephones and other telecommunications devices that are not capable of accessing the switch through a Web browser.) The QoS and voice VLAN policy elements can be statically configured with the following CLI commands:
vlan <vid> voice
vlan <<tagged | untagged>vid><port-list>
int <port-list> qos priority <0-7>
vlan <vid> qos dscp <codepoint>
| NOTE: A codepoint must have an 802.1p priority before
you can configure it for use in prioritizing packets by VLAN-ID. If
a codepoint you want to use shows |
Enabling or Disabling medTlvEnable
In the default LLDP-MED configuration, the TLVs controlled by medTlvEnable are enabled. For more information, see Advertising device capability, network policy, PoE status and location data.
Syntax:
[no]
lldp config <port-list> medTlvEnable <medTlv>Enables or disables advertisement of the following TLVs on the specified ports:
Device capability TLV
Configured network policy TLV
Configured location data TLV (see Configuring location data for LLDP-MED devices.)
Current PoE status TLV
(Default: All of the above TLVs are enabled.)
Helps to locate configuration mismatches by allowing use of an SNMP application to compare the LLDP-MED configuration on a port with the LLDP-MED TLVs advertised by a neighbor connected to that port.
capabilitiesThis TLV enables the switch to determine:
Which LLDP-MED TLVs a connected endpoint can discover
The device class (1, 2, or 3) for the connected endpoint
This TLV also enables an LLDP-MED endpoint to discover what LLDP-MED TLVs the switch port currently supports.
(Default: enabled)
NOTE: This TLV cannot be disabled unless the
network_policy,poe, andlocation_idTLVs are already disabled.network-policyThis TLV enables the switch port to advertise its configured network policies (voice VLAN, Layer 2 QoS, Layer 3 QoS), and allows LLDP-MED endpoint devices to autoconfigure the voice network policy advertised by the switch. This also enables the use of SNMP applications to troubleshoot statically configured endpoint network policy mismatches.
(Default: Enabled)
NOTE: Network policy is advertised only for ports that are configured as members of the voice VLAN. If the port belongs to more than one voice VLAN, the voice VLAN with the lowest-numbered VID is selected as the VLAN for voice traffic. Also, this TLV cannot be enabled unless the
capabilityTLV is already enabled.For more information, see Network policy advertisements.
location_idThis TLV enables the switch port to advertise its configured location data (if any). For more information on configuring location data, see Configuring location data for LLDP-MED devices.
(Default: Enabled)
NOTE: When disabled, this TLV cannot be enabled unless the capability TLV is already enabled.
poeThis TLV enables the switch port to advertise its current PoE state and to read the PoE requirements advertised by the LLDP-MED endpoint device connected to the port.
(Default: Enabled)
NOTE: When disabled, this TLV cannot be enabled unless the
capabilityTLV is already enabled.For more on this topic, see PoE advertisements.
PoE advertisements
These advertisements inform an LLDP-MED endpoint of the power (PoE) configuration on switch ports. Similar advertisements from an LLDP-MED endpoint inform the switch of the endpoint's power needs and provide information that can be used to identify power priority mismatches.
PoE TLVs include the following power data:
Power type: indicates whether the device is a power-sourcing entity (PSE) or a PD. Ports on the J8702A PoE zl module are PSE devices. A MED-capable VoIP telephone is a PD.
Power source: indicates the source of power in use by the device. Power sources for PDs include PSE, local (internal), and PSE/local. The switches advertise Unknown.
Power priority: indicates the power priority configured on the switch (PSE) port or the power priority configured on the MED-capable endpoint.
Power value: indicates the total power in watts that a switch port (PSE) can deliver at a particular time, or the total power in watts that the MED endpoint (PD) requires to operate.
Viewing PoE advertisements
To display the current power data for an LLDP-MED device connected to a port, use the following command:
show lldp info remote-device <port-list>
For more information on this command, see page A-60.
To display the current PoE configuration on the switch, use the following commands:
show power brief <port-list>
show power <port-list>
For more information on PoE configuration and operation, see Chapter 11, "Power Over Ethernet (PoE/PoE+) Operation".
Location data for LLDP-MED devices
You can configure a switch port to advertise location data for the switch itself, the physical wall-jack location of the endpoint (recommended), or the location of a DHCP server supporting the switch, endpoint, or both. You also have the option of configuring these different address types:
Civic address: physical address data such as city, street number, and building information
ELIN (Emergency Location Identification Number): an emergency number typically assigned to MLTS (Multiline Telephone System) Operators in North America
Coordinate-based location: attitude, longitude, and altitude information (Requires configuration via an SNMP application.)
Configuring location data for LLDP-MED devices
For more information, see Location data for LLDP-MED devices.
Syntax:
[no]
lldp config <port-list> medPortLocation <Address-Type>Configures location of emergency call data the switch advertises per port in the
location_idTLV. This TLV is for use by LLDP-MED endpoints employing location-based applications.
| NOTE: The switch allows one medPortLocation entry per port (without regard to type). Configuring a new medPortLocation entry of any type on a port replaces any previously configured entry on that port. |
civic-addr < [ <COUNTRY-STR>
<WHAT> <CA-TYPE>
<CA-VALUE> …CA-TYPE>
<CA-VALUE> ]… [ <CA-TYPE>
<CA-VALUE> ]
Enables configuration of a physical address on a switch port and allows up to 75 characters of address information.
|
A two-character country code, as defined
by ISO 3166. Some examples include | ||||||
|
A single-digit number specifying the type of device to which the location data applies:
This field is required in a | ||||||
|
A series of data pairs,
each composed of a location data "type" specifier and the
corresponding location data for that type. That is, the first value
in a pair is expected to be the civic address "type" number
( For
example, if the Multiple type/value pairs can
be entered in any order, although Hewlett Packard Enterprise recommends
that multiple pairs be entered in ascending order of the When an emergency call is placed from a properly configured class 3 endpoint device to an appropriate PSAP, the country code, device type, and type/value pairs configured on the switch port are included in the transmission. The "type" specifiers are used by the PSAP to identify and organize the location data components in an understandable format for response personnel to interpret. A
(Range: 0 - 255) For a sample listing
of
Strings are delimited by either blank spaces, single quotes (' … '), or double quotes ("… "). Each string should represent
a specific data type in a set of unique type/value pairs comprising
the description of a location, and each string must be preceded by
a
| ||||||
|
This feature is intended for use in ECS applications to support class 3 LLDP-MED VoIP telephones connected to a switch in an MLTS infrastructure. An ELIN is a valid NANP format telephone number assigned to MLTS operators in North America by the appropriate authority. The ELIN is used to route emergency (E911) calls to a PSAP. (Range: 1-15 numeric characters) |
Configuring coordinate-based locations
Latitude, longitude, and altitude data can be configured per switch port using an SNMP management application. For more information, see the documentation provided with the application. A further source of information on this topic is RFC 3825-Dynamic host configuration protocol option for coordinate-based location configuration information.
| NOTE: Endpoint use of data from a medPortLocation TLV sent by the switch is device-dependent. See the documentation provided with the endpoint device. |
Some location codes used in CA-TYPE fields[*]
Location element |
Code |
Location element |
Code |
|---|---|---|---|
national subdivision |
1 |
street number |
19 |
regional subdivision |
2 |
additional location data |
22 |
city or township |
3 |
unit or apartment |
26 |
city subdivision |
4 |
floor |
27 |
street |
6 |
room number |
28 |
street suffix |
18 |
|
|
Example:
Suppose a system operator wants to configure the following information as the civic address for a telephone connected to her company's network through port A2 of a switch at the following location:
CA-type |
CA-type |
CA-VALUE |
national subdivision |
1 |
CA |
city |
3 |
Widgitville |
street |
6 |
Main |
street number |
19 |
1433 |
unit |
26 |
Suite 4-N |
floor |
27 |
4 |
room number |
28 |
N4-3 |
A civic address configuration shows the commands for configuring and displaying the above data.
A civic address configuration
HP Switch(config)# lldp config 2 medportlocation civic-addr US 2 1 CA 3 Widgitville 6 Main 19 1433 26 Suite_4—N 27 4 28 N4—3 HP Switch(config)# show lldp config 2 LLDP Port Configuration Detail Port : A2 AdminStatus [Tx_Rx] : Tx_Rx NotificationEnabled [False] : False Med Topology Trap Enabled [False] : False Country Name : US What : 2 Ca-Type : 1 Ca-Length : 2 Ca-Value : CA Ca-Type : 3 Ca-Length : 11 Ca-Value : Widgitville Ca-Type : 6 Ca-Length : 4 Ca-Value : Main Ca-Type : 19 Ca-Length : 4 Ca-Value : 1433 Ca-Type : 26 Ca-Length : 9 Ca-Value : Suite_4-N Ca-Type : 27 Ca-Length : 1 Ca-Value : 4 Ca-Type : 28 Ca-Length : 4 Ca-Value : N4-3
Viewing switch information available for outbound advertisements
Syntax:
show lldp info local-device[port-list]Without the
[option, displays the global switch information and the per-port information currently available for populating outbound LLDP advertisements.port-list]With the
[option, displays only the following port-specific information that is currently available for outbound LLDP advertisements on the specified ports:port-list]
PortType
PortId
PortDesc
| NOTE: This command displays the information available
on the switch. Use the |
In the default configuration, the switch information currently available for outbound LLDP advertisements appears similar to the display in Displaying the global and per-port information available for outbound advertisements.
Displaying the global and per-port information available for outbound advertisements
HP Switch(config)# show lldp info local-device LLDP Local Device Information Chassis Type : mac-address Chassis Id : 00 23 47 4b 68 DD System Name : HP Switch1 System Description : HP J9091A Switch 3500yl, revision XX.15.06... System Capabilities Supported:bridge System Capabilities Enabled:bridge Management Address
The Management Address field displays only the LLDP-configurable IP addresses on the switch. (Only manually-configured IP addresses are LLDP-configurable.) If the switch has only an IP address from a DHCP or Bootp server, then the Management Address field is empty (because there are no LLDP-configurable IP addresses available. |
The default per-port information content for ports 1 and 2
HP Switch(config)# show lldp info local 1-2 LLDP Local Port Information Detail Port : 1 PortType : local PortId : 1 PortDesc : 1 ---------------------------------------- Port : 2 PortType : local PortId : 2 PortDesc : 2
Displaying the current port speed and duplex configuration on a switch port
You can compare port speed and duplex information
for a switch port and a connected LLDP-MED endpoint for configuration
mismatches by using an SNMP application. You can also use the switch
CLI to display this information, if necessary. The show interfaces
brief < and port-list>show
lldp info remote-device [ (Remote power information) commands provide methods for displaying speed
and duplex information for switch ports. For information on displaying
the currently configured port speed and duplex on an LLDP-MED endpoint,
see Viewing the current port speed and duplex configuration on
a switch port.port-list]
Viewing advertisements currently in the neighbors MIB
Syntax:
show lldp info remote-device[port-list]Without the
[option, provides a global list of the individual devices it has detected by reading LLDP advertisements. Discovered devices are listed by the inbound port on which they were discovered.port-list]Multiple devices listed for a single port indicates that such devices are connected to the switch through a hub.
Discovering the same device on multiple ports indicates that the remote device may be connected to the switch in one of the following ways:
Through different VLANS using separate links. (This applies to switches that use the same MAC address for all configured VLANs.)
Through different links in the same trunk.
Through different links using the same VLAN. (In this case, spanning-tree should be invoked to prevent a network topology loop. Note that LLDP packets travel on links that spanning-tree blocks for other traffic types.)
With the
[option, provides a listing of the LLDP data that the switch has detected in advertisements received on the specified ports.port-list]For descriptions of the various types of information displayed by these commands, see Data available for basic LLDP advertisements.
A global listing of discovered devices
HP Switch(config)# show lldp info remote LLDP Remote Devices Information LocalPort | ChassisId PortId PortDescr SysName --------- + ------------------------- ------ --------- ------------- 1 | 00 11 85 35 3b 80 6 6 HP Switch 2 | 00 11 85 cf 66 60 8 8 HP Switch
An LLLDP-MED listing of an advertisement received from an LLDP-MED (VoIP telephone) source
HP Switch(config)# show lldp info remote-device 1 LLDP Remote Device Information Detail Local Port : A2 ChassisType : network-address ChassisId : 0f ff 7a 5c PortType : mac-address PortId : 08 00 0f 14 de f2 SysName : HP Switch System Descr : HP Switch, revision xx.15.06.0000x PortDescr : LAN Port System Capabilities Supported : bridge, telephone System Capabilities Enabled : bridge, telephone Remote Management Address MED Information Detail
Displaying LLDP statistics
LLDP statistics are available on both a global and a per-port levels. Rebooting the switch resets the LLDP statistics counters to zero. Disabling the transmit and/or receive capability on a port "freezes" the related port counters at their current values.
Viewing LLDP statistics
For more information, see Displaying LLDP statistics.
Syntax:
show lldp stats[port-list]The global LLDP statistics command displays an overview of neighbor detection activity on the switch, plus data on the number of frames sent, received, and discarded per-port.
The per-port LLDP statistics command enhances the list of per-port statistics provided by the global statistics command with some additional per-port LLDP statistics.
|
The elapsed time since a neighbor was last added or deleted. |
|
The total of new LLDP neighbors detected since the last switch reboot. Disconnecting, and then reconnecting a neighbor increments this counter. |
|
The number of neighbor deletions from the MIB for AgeOut Count and forced drops for all ports. For
example, if the admin status for port on a neighbor device changes
from The device receiving the shutdown packet deletes all information about the neighbor received on the applicable inbound port and increments the counter. |
|
The number of valid LLDP neighbors the switch detected, but could not add. This can occur, For example, when a new neighbor is detected when the switch is already supporting the maximum number of neighbors. See Neighbor maximum. |
|
The number of LLDP neighbors dropped on all ports because of Time-to-Live expiring. |
Per-Port LLDP Counters:
|
The total number of valid, inbound LLDP
advertisements received from any neighbors on Where multiple neighbors are connected to a port through a hub, this value is the total number of LLDP advertisements received from all sources. |
|
The total number of LLDP advertisements
sent from |
|
The total number of inbound LLDP advertisements
discarded by This can occur, For example, when a new neighbor is detected on the port, but the switch is already supporting the maximum number of neighbors. See Neighbor maximum. This can also be an indication of advertisement formatting problems in the neighbor device. |
|
The total number of invalid LLDP advertisements received on the port. An invalid advertisement can be caused by header formatting problems in the neighbor device. |
|
The total number of LLDP TLVs received on a port with a type value in the reserved range. This can be caused by a basic management TLV from a later LLDP version than the one currently running on the switch. |
|
The total number of LLDP TLVs discarded for any reason. In this case, the advertisement carrying the TLV may be accepted, but the individual TLV is not usable. |
|
The number of LLDP neighbors dropped on the port because of Time-to-Live expiring. |
Examples:
A global LLDP statistics display
HP Switch(config)# show lldp stats LLDP Device Statistics Neighbor Entries List Last Updated : 2 hours New Neighbor Entries Count : 20 Neighbor Entries Deleted Count : 20 Neighbor Entries Dropped Count : 0 Neighbor Entries AgeOut Count : 20 LLDP Port Statistics Port | NumFramesRecvd NumFramesSent NumFramesDiscarded ------ + -------------- ------------- ------------------ A1 | 97317 97843 0 A2 | 21 12 0 A3 | 0 0 0 A4 | 446 252 0 A5 | 0 0 0 A6 | 0 0 0 A7 | 0 0 0 A8 | 0 0 0
LLDP Operating Notes
Neighbor maximum
The neighbors table in the switch supports as many neighbors as there are ports on the switch. The switch can support multiple neighbors connected through a hub on a given port, but if the switch neighbor maximum is reached, advertisements from additional neighbors on the same or other ports will not be stored in the neighbors table unless some existing neighbors time-out or are removed.
LLDP packet forwarding
An 802.1D-compliant switch does not forward LLDP packets, regardless of whether LLDP is globally enabled or disabled on the switch.
One IP address advertisement per port
LLDP advertises only one IP address per port,
even if multiple IP addresses are configured by lldp config on
a given port. port-list ipAddrEnable
802.1Q VLAN Information
LLDP packets do not include 802.1Q header information and are always handled as untagged packets.
Effect of 802.1X Operation
If 802.1X port security is enabled on a port, and a connected device is not authorized, LLDP packets are not transmitted or received on that port. Any neighbor data stored in the neighbor MIB for that port prior to the unauthorized device connection remains in the MIB until it ages out. If an unauthorized device later becomes authorized, LLDP transmit and receive operation resumes.
Neighbor data can remain in the neighbor database after the neighbor is disconnected
After disconnecting a neighbor LLDP device from
the switch, the neighbor can continue to appear in the switch's neighbor
database for an extended period if the neighbor's holdtime-multiplier is
high; especially if the refresh-interval is large.
See Changing the time-to-live for transmitted advertisements (CLI).
LLDP and CDP data management
This section describes points to note regarding LLDP and CDP (Cisco Discovery Protocol) data received by the switch from other devices. LLDP operation includes both transmitting LLDP packets to neighbor devices and reading LLDP packets received from neighbor devices. CDP operation is limited to reading incoming CDP packets from neighbor devices. (HPE switches do not generate CDP packets.)
Incoming CDP and LLDP packets tagged for VLAN 1 are processed even if VLAN 1 does not contain any ports. VLAN 1 must be present, but it is typically present as the default VLAN for the switch.
| NOTE: The switch may pick up CDP and LLDP multicast packets from VLAN 1 even when CDP- and /or LLDP-enabled ports are not members of VLAN 1. |
LLDP and CDP neighbor data
With both LLDP and (read-only) CDP enabled on
a switch port, the port can read both LLDP and CDP advertisements,
and stores the data from both types of advertisements in its neighbor
database. (The switch stores only CDP data that
has a corresponding field in the LLDP neighbor database.) The neighbor
database itself can be read by either LLDP or CDP methods or by using
the show lldp commands. Take note of the following
rules and conditions:
If the switch receives both LLDP and CDP advertisements on the same port from the same neighbor, the switch stores this information as two separate entries if the advertisements have different chassis ID and port ID information.
If the chassis and port ID information are the same, the switch stores this information as a single entry. That is, LLDP data overwrites the corresponding CDP data in the neighbor database if the chassis and port ID information in the LLDP and CDP advertisements received from the same device is the same.
Data read from a CDP packet does not support some LLDP fields, such as "System Descr," "SystemCapSupported," and "ChassisType." For such fields, LLDP assigns relevant default values. Also:
The LLDP "System Descr" field maps to CDP's "Version" and "Platform" fields.
The switch assigns "ChassisType" and "PortType" fields as "local" for both the LLDP and the CDP advertisements it receives.
Both LLDP and CDP support the "System Capability" TLV. However, LLDP differentiates between what a device is capable of supporting and what it is actually supporting, and separates the two types of information into subelements of the System Capability TLV. CDP has only a single field for this data. Thus, when CDP System Capability data is mapped to LLDP, the same value appears in both LLDP System Capability fields.
System Name and Port Descr are not communicated by CDP, and thus are not included in the switch's Neighbors database.
| NOTE: Because HPE switches do not generate CDP packets, they are not represented in the CDP data collected by any neighbor devices running CDP. A switch with CDP disabled forwards the CDP packets it receives from other devices, but does not store the CDP information from these packets in its own MIB. |
LLDP data transmission/collection and CDP data collection are both enabled in the switch's default configuration. In this state, an SNMP network management application designed to discover devices running either CDP or LLDP can retrieve neighbor information from the switch regardless of whether LLDP or CDP is used to collect the device-specific information.
Protocol state |
Packet generation |
Inbound data management |
Inbound packet forwarding |
|---|---|---|---|
CDP Enabled[1] |
N/A |
Store inbound CDP data. |
No forwarding of inbound CDP packets. |
CDP Disabled |
N/A |
No storage of CDP data from neighbor devices. |
Floods inbound CDP packets from connected devices to outbound ports. |
LLDP Enabled1 |
Generates and transmits LLDP packets out all ports on the switch. |
Store inbound LLDP data. |
No forwarding of inbound LLDP packets. |
LLDP Disabled |
No packet generation. |
No storage of LLDP data from neighbor devices. |
No forwarding of inbound LLDP packets. |
[1] Both CDP data collection and LLDP transmit/receive are enabled in the default configuration. If a switch receives CDP packets and LLDP packets from the same neighbor device on the same port, it stores and displays the two types of information separately if the chassis and port ID information in the two types of advertisements is different. In this case, if you want to use only one type of data from a neighbor sending both types, disable the unwanted protocol on either the neighbor device or on the switch. However, if the chassis and port ID information in the two types of advertisements is the same, the LLDP information overwrites the CDP data for the same neighbor device on the same port. | |||
CDP operation and commands
By default the switches have CDP enabled on each port. This is a read-only capability, meaning that the switch can receive and store information about adjacent CDP devices but does not generate CDP packets.
When a CDP-enabled switch receives a CDP packet from another CDP device, it enters that device's data in the CDP Neighbors table, along with the port number where the data was received—and does not forward the packet. The switch also periodically purges the table of any entries that have expired. (The hold time for any data entry in the switch's CDP Neighbors table is configured in the device transmitting the CDP packet and cannot be controlled in the switch receiving the packet.) A switch reviews the list of CDP neighbor entries every three seconds and purges any expired entries.
| NOTE: For details on how to use an SNMP utility to retrieve information from the switch's CDP Neighbors table maintained in the switch's MIB, see the documentation provided with the particular SNMP utility. |
Viewing the current CDP configuration of the switch
CDP is shown as enabled/disabled both globally on the switch and on a per-port basis.
Syntax:
Default CDP configuration shows the default CDP configuration.
Viewing the current CDP neighbors table of the switch
Devices are listed by the port on which they were detected.
Syntax:
show cdp neighborsLists the neighboring CDP devices the switch detects, with a subset of the information collected from the device's CDP packet.
[ [e] port-numb [ detail ] ]
Lists the CDP device connected to the specified port. (Allows only one port at a time.)
Using
detailprovides a longer list of details on the CDP device the switch detects on the specified port.[ detail [[e] port-numb] ]
Provides a list of the details for all of the CDP devices the switch detects.
Using
port-numproduces a list of details for the selected port.
CDP neighbors table listing displays the CDP devices that the switch has detected by receiving their CDP packets.
CDP neighbors table listing
HP Switch(config)# show cdp neighbors CDP neighbors information Port Device ID | Platform Capability ---- ----------------------------- + ---------------------------- ----------- 1 Accounting (0030c1-7fcc40) | J4812A HP Switch. . . S 2 Resear¢1-1 (0060b0-889e43) | J4121A HP Switch. . . S 4 Support (0060b0_761a45) | J4121A HP Switch. . . S 7 Marketing (0030c5_33dc59) | J4313A HP Switch. . . S 12 Mgmt NIC(099a05-09df9b | NIC Model X666 H 12 Mgmt NIC(099a05-09df11 | NIC Model X666 H
Enabling and Disabling CDP Operation
Enabling CDP operation (the default) on the switch causes the switch to add entries to its CDP Neighbors table for any CDP packets it receives from other neighboring CDP devices.
Disabling CDP operation clears the switch's CDP Neighbors table and causes the switch to drop inbound CDP packets from other devices without entering the data in the CDP Neighbors table.
Syntax:
Example:
To disable CDP read-only on the switch:
HP Switch(config)# no cdp run
When CDP is disabled:
show cdp neighborsdisplays an empty CDP Neighbors tableshow cdpdisplaysGlobal CDP information
Enable CDP [Yes]: No
Enabling or disabling CDP operation on individual ports
In the factory-default configuration, the switch has all ports enabled to receive CDP packets. Disabling CDP on a port causes it to drop inbound CDP packets without recording their data in the CDP Neighbors table.
Syntax:
Example:
To disable CDP on port A1:
HP Switch(config)# no cdp enable a1
Filtering CDP information
In some environments it is desirable to be able to configure a switch to handle CDP packets by filtering out the MAC address learns from untagged VLAN traffic from IP phones. This means that normal protocol processing occurs for the packets, but the addresses associated with these packets is not learned or reported by the software address management components. This enhancement also filters out the MAC address learns from LLDP and 802.1x EAPOL packets on untagged VLANs.
The feature is configured per-port.
Configuring the switch to filter untagged traffic
Enter this command to configure the switch not to learn CDP, LLDP, or EAPOL traffic for a set of interfaces.
Syntax:
Displaying the configuration
Enter the show running-config command
to display information about the configuration.
Configuration showing interfaces to ignore packet MAC address learns
HP Switch(config) show running-config Running configuration: ; J9627 Configuration Editor; Created on release XX.15.XX ; Ver #03:03.1f.ef:f0 hostname “HP Switch” interface 1 ignore-untagged-mac exit interface 2 ignore-untagged-mac exit . . . vlan 1 name “DEFAULT_VLAN” untagged 1-24 ip address dhcp-bootp exit . . .
Filtering PVID mismatch log messages
This enhancement filters out PVID mismatch log messages on a per-port basis. PVID mismatches are logged when there is a difference in the PVID advertised by a neighboring switch and the PVID of the switch port which receives the LLDP advertisement. Logging is an LLDP feature that allows detection of possible vlan leakage between adjacent switches. However, if these events are logged too frequently, they can overwhelm the log buffer and push relevant logging data out of log memory, making it difficult to troubleshoot another issue.
Logging is disabled and enabled with the support of CLI commands.
This enhancement also includes displaying the Mac-Address in the PVID mismatch log message when the port ID is Mac-Address instead of displaying garbage characters in the peer device port ID field.
Use the following command to disable the logging of the PVID mismatch log messages: