Administrator Guide

Figure 72. Configuring LLDP
Storing and Viewing Unrecognized LLDP TLVs
Dell EMC Networking OS provides support to store unrecognized (reserved and organizational specific) LLDP TLVs. Also, support is
extended to retrieve the stored unrecognized TLVs using SNMP.
When the incoming TLV from LLDP neighbors is not recognized, the TLV is categorized as unrecognized TLV. The unrecognized TLVs is
categorized into two types:
1. Reserved unrecognized LLDP TLV
2. Organizational specific unrecognized LLDP TLV
Reserved Unrecognized LLDP TLVs
The type value for reserved TLV ranging from 9 to 126.
The system processes each LLDP frame to retrieve the type and length, and stores the retrieved data of reserved unrecognized LLDP
TLVs in a list. The stored list of unrecognized TLVs is removed when subsequent LLDP neighbor frame is received, neighbor is lost, or
neighbor ages out. If there are multiple unrecognized TLVs with the same TLV type, only the information of first unrecognized TLV is
stored and the TLV discard counter is incremented for the successive TLVs.
Organizational Specific Unrecognized LLDP TLVs
The type value for organizational specific TLV is 127.
The system processes each LLDP frame to retrieve the OUI, subtype, and data length, and stores the retrieved data of organizational
specific unrecognized LLDP TLVs in a list. The stored list of organizational TLVs is removed when the neighbor is lost or neighbor ages
out. The software assigns a temporary identification index for each unrecognized organizational specific LLDP TLVs upon receiving more
than one TLV with the same OUI and subtype, but with different organizationally defined information strings.
NOTE:
The system increments the TLV discard counter and does not store unrecognized LLDP TLV information in following
scenarios:
• If there are multiple TLVs with the same information is received
• If DCBX is down on the receiving interface
The organizational specific TLV list is limited to store 256 entries per neighbor. If TLV entries are more than 256, then the oldest entry (of
that neighbor) in the list is replaced. A syslog message appears when the organization specific unrecognized TLV list exceeds more than
205 entries (80 percent of 256) for you to take action. Following shows the syslog message:
Nov 14 03:01:53 %STKUNIT2-M:CP %LLDP-5-LLDP_ORG_UNRECOGNISED_TLV_MAX: Received Organizational
Specific unrecognised TLVs exceeds threshold (205) from Remote Chassis ID: 4c:76:25:f4:ab:00,
Remote Port ID: fortyGigE 1/2/8/1 on interface: Te 2/31/1
Link Layer Discovery Protocol (LLDP)
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