Management and Configuration Guide K/KA/KB.15.15

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
(“Viewing the global LLDP, port admin, and SNMP notification status” (page 219).)
• 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 walkmib command 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:
• IEEE P802.1AB
• RFC 2922 (PTOPO, or Physical Topology MIB)
• RFC 2737 (Entity MIB)
• RFC 2863 (Interfaces MIB)
• ANSI/TIA-1057/D6 (LLDP-MED; refer to “LLDP-MED” (page 258).)
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 (Section (page 223).) (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.
Spanning-tree blocking
Spanning tree does not prevent LLDP packet transmission or receipt on STP-blocked links.
LLDP 255