190 Brocade ICX 6650 Administration Guide
53-1002600-01
General LLDP operating principles
8
There are several ways in which a port may be identified, as shown in Figure43. A port ID subtype,
included in the TLV, indicates how the port is being referenced in the Port ID field.
Brocade ICX 6650 devices use port ID subtype 3, the permanent MAC address associated with the
port. Other third party devices may use a port ID subtype other than 3. The port ID appears similar
to the following on the remote device, and in the CLI display output on the Brocade device (show
lldp local-info).
Port ID (MAC address): 748e.f80c.5f40
The LLDPDU format is shown in “LLDPDU packet format” on page187.
The Port ID TLV format is shown below.
FIGURE 14 Port ID TLV packet format
TTL value
The Time to Live (TTL) Value is the length of time the receiving device should maintain the
information acquired by LLDP in its MIB.
The TTL value is automatically computed based on the LLDP configuration settings. The TTL value
will appear similar to the following on the remote device, and in the CLI display output on the
Brocade device (show lldp local-info).
Time to live: 40 seconds
If the TTL field has a value other than zero, the receiving LLDP agent is notified to completely
replace all information associated with the LLDP agent/port with the information in the received
LLDPDU.
If the TTL field value is zero, the receiving LLDP agent is notified that all system information
associated with the LLDP agent/port is to be deleted. This TLV may be used, for example, to signal
that the sending port has initiated a port shutdown procedure.
The LLDPDU format is shown in “LLDPDU packet format” on page187.
TABLE 43 Port ID subtypes
ID subtype Description
0Reserved
1Interface alias
2Port component
3MAC address
4Network address
5Interface name
6 Agent circuit ID
7 Locally assigned
8 – 255 Reserved
TLV Type = 3 TLV Information
String Length = 2 Time to Live (TTL)
7 bits 9 bits 2 octets