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Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
OL-23826-09
Chapter 28 Configuring Link Layer Discovery Protocol
Restrictions for LLDP
Restrictions for LLDP
The following are the restrictions for LLDP:
• The memory available on a given end network device dictates the number of neighbor entries
recorded. However, under most operating conditions, end devices such as printers, IP phones,
workstations and so on, are typically operated in the receive mode only.
• If Entity MIB are used for LLDP broadcast, such as to create a sender ID. LLDP can be configured
only when these MIBs are available.
Overview of LLDP
It is an optional element of a protocol stack in the 802 LAN station. LLDP uses the logical link control
(LLC) services to transmit and receive information to and from other LLDP agents. LLC provides a Link
Service Access Point (LSAP) for access to LLDP. Each LLDP frame is transmitted as a single MAC
service request. Each incoming LLDP frame is received at the MAC Service Access Point (MSAP) by
the LLC entity as a MAC service indication.
The LLDP protocol operates through the LLDP agent. The tasks of the LLDP agent are to:
• Collect information from the LLDP local system MIB and transmit it periodically.
• Receive LLDP frames from neighbors and populate LLDP remote devices MIBs.
LLDP supports a set of attributes used to find the neighbor devices. These attributes are type, length, and
value descriptions of devices, and are referred to as Type Length Value (TLV). LLDP supported devices
use TLVs to send and receive information from their neighbors. Details such as configuration
information, device capabilities, and device identity are also advertised using this protocol.
How to Configure LLDP
This section contains the following procedures:
• Configuring LLDP
• Verifying LLDP
Configuring LLDP
Complete the following steps to configure LLDP on the Cisco ASR 901 platform:
SUMMARY STEPS
1. enable
2. configure terminal
3. lldp {run | holdtime seconds | reinit | timer rate | tlv-select}
4. end