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12-31
Configuring for Network Management Applications
LLDP (Link-Layer Discovery Protocol)
LLDP 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)
LLDP Operating Rules
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, then the port advertises the lowest-order IP address
configured on that VLAN. If a port belongs to multiple VLANs, then 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, then 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 (page 12-40).
(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, then 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.