Extreme Networks ExtremeWare XOS 11.3, Manual

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Link Layer Discovery Protocol
ExtremeWare XOS 11.3 Concepts Guide
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Managing LLDP
LLDP can work in tandem with EDP. LLDP is disabled by default, and EDP is enabled by default. LLDP
information is transmitted periodically and stored for a finite period. You access the information using
SNMP. A port configured to receive LLDP messages can store information for up to four neighbors.
You manage LLDP using the CLI and SNMP. (Refer to ExtremeWare XOS Command Reference Guide for
complete information on configuring, managing, and displaying LLDP.)
LLDP information is transmitted periodically and stored for a finite period. Once you enable LLDP, you
can set a variety of time periods for the transmission and storage of the LLDP messages (or you can use
the default values), as follows:
●
Reinitialization period (default is 2 seconds)
●
Delay between LLDP transmissions (default is 2 seconds)—applies to triggered updates, or updates
that are initiated by a change in the topology
●
Transmit interval (default is 30 seconds)—applies to messages sent periodically as part of protocol
●
Time-to-live (TTL) value (default is 2 minutes)—time that the information remains in the recipient’s
LLDP database
Each time a device receives an LLDP advertisement packet, the device stores the information and
initializes a timer that is compared to the TTL value of the packet. If the timer reaches the TTL value,
the LLDP agent deletes the stored information. This action ensures that only valid information is stored
in the LLDP agent.
Once you enable LLDP, you can enable the LLDP-specific SNMP traps; the traps are disabled by default.
You configure the period between the system sending SNMP notifications; the default interval is 5
seconds. LLDP configurations are saved across reboots when you issue the
save configuration
command.
The system logs EMS messages regarding LLDP when:
●
Configured optional TLVs that exceed the 1500-byte limit and are dropped.
●
More than 4 neighbors are detected on a port.
When both IEEE 802.1x and LLDP are enabled on the same port, LLDP packets are not sent until one or
more clients authenticate a port. Also, incoming LLDP packets are only accepted if one or more clients
are authenticated.
You can configure an optional TLV to advertise or not to advertise the device’s management address
information to the port’s neighbors. With ExtremeWare XOS, when enabled, this TLV sends out the IPv4
address configured on the management VLAN. If you have not configured an IPv4 address on the
management VLAN, the software advertises the system’s MAC address. LLDP does not send out IPv6
addresses in this field.
Supported TLVs
The TLVs are contained in the LLDPDU portion of the LLDP packet, and the LLDPDU cannot exceed
1500 bytes. Some TLVs are mandatory according to the 802.1ab standard, and the rest are optional. The
mandatory TLVs are included by default as soon as you enable LLDP, as is the system description TLV.
One other TLV, system description, is enabled by default on the ExtremeWare XOS LLDP
implementation. Additionally some TLVs can be repeated in one LLDP.