Basic concepts
DLDP neighbor states
If port A can receive link-layer packets from port B on the same link, port B is a DLDP neighbor of port A. Two ports that can exchange packets are neighbors.
Table 3: DLDP neighbor states
DLDP timer | Description |
|---|---|
Confirmed | The link to a DLDP neighbor is bidirectional. |
Unconfirmed | The state of the link to a newly discovered neighbor is not determined. |
DLDP port states
A DLDP-enabled port is called a DLDP port. A DLDP port can have multiple neighbors, and its state varies by the DLDP neighbor state.
Table 4: DLDP port states
State | Description |
|---|---|
Initial | DLDP is enabled on the port, but is disabled globally. |
Inactive | DLDP is enabled on the port and globally, and the link is physically down. |
Bidirectional | DLDP is enabled on the port and globally, and at least one neighbor in Confirmed state exists. |
Unidirectional | DLDP is enabled on the port and globally, and no neighbor in Confirmed state exists. In this state, a port does not send or receive packets other than DLDP packets any more. |
DLDP timers
Table 5: DLDP timers
DLDP timer | Description |
|---|---|
Advertisement timer | Advertisement packet sending interval (the default is 5 seconds and is configurable). |
Probe timer | Probe packet sending interval. This timer is set to 1 second. |
Echo timer | The Echo timer is triggered when a probe is launched for a new neighbor. This timer is set to 10 seconds. |
Entry timer | When a new neighbor joins, a neighbor entry is created and the corresponding entry timer is triggered if the neighbor is in Confirmed state. When an Advertisement is received, the device updates the corresponding neighbor entry and the Entry timer. The setting of an Entry timer is three times that of the Advertisement timer. |
Enhanced timer | The Enhanced timer is triggered, together with the Echo timer, when the Entry timer expires. The Enhanced timer is set to 1 second. |
DelayDown timer | If a port is physically down, the device triggers the DelayDown timer, rather than removing the corresponding neighbor entry. The default DelayDown timer is 1 second and is configurable. When the DelayDown timer expires, the device removes the corresponding DLDP neighbor information if the port is down, and does not perform any operation if the port is up. |
RecoverProbe timer | This timer is set to 2 seconds. A port in unidirectional state regularly sends RecoverProbe packets to detect whether a unidirectional link has been restored to bidirectional. |
DLDP authentication mode
You can use DLDP authentication to prevent network attacks and illegal detecting.
Table 6: DLDP authentication mode
Authentication mode | Processing at the DLDP packet sending side | Processing at the DLDP packet receiving side |
|---|---|---|
Non-authentication | The sending side sets the Authentication field of DLDP packets to 0. | The receiving side examines the authentication information of received DLDP packets and drops packets where the authentication information conflicts with the local configuration. |
Plaintext authentication | The sending side sets the Authentication field to the password configured in plain text. | |
MD5 authentication | The sending side encrypts the user configured password by using MD5 algorithm, and assigns the digest to the Authentication field. |