Configuration Guide User guide

456 FastIron Configuration Guide
53-1002494-02
General LLDP operating principles
Port ID
The Port ID identifies the port from which LLDP packets were sent.
There are several ways in which a port may be identified, as shown in Figure 82. A port ID subtype,
included in the TLV, indicates how the port is being referenced in the Port ID field.
Brocade 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): 0012.f233.e2d3
The LLDPDU format is shown in “LLDPDU packet format” on page 453.
The Port ID TLV format is shown below.
FIGURE 37 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.
TABLE 82 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