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 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 Enabled
1
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.
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.
Chapter 8 Configuring for Network Management Applications 203
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