RLDP (Ring Light Detection and Protection) of Simplified Optical 3.0-Configure basic RLDP functions

4.1.1 Networking Requirements
The aggregation and access form a loop network topology. Each device in the loop network enables STP to prevent loops and provide redundancy protection.
To prevent a unidirectional or bidirectional link fault in the loop from causing STP protocol failure, RLDP unidirectional and bidirectional detection are enabled between aggregation devices, between aggregation and access devices. To prevent the aggregation device from being incorrectly connected to the loop, the downstream ports of the aggregation device and the access device are both enabled with RLDP loop detection. The downstream ports of the access device are also enabled with RLDP loop detection to prevent incorrect connections and loops.
4.1.2 Network topology diagram

Figure 4-1

4.1.3 Key points of configuration
Device A and Device B act as aggregation devices, and Device C acts as an access device. User devices can be connected to Device C in downstream. The three devices form a ring network topology. Each device enables STP (Spanning Tree Protocol), and the STP configuration can refer to the relevant configuration guide.
Device A enables RLDP. Two ports need to be configured for unidirectional and bidirectional link detection, and the downstream port needs to be configured to enable loop detection.

Device B enables RLDP, and both ports need to be configured for unidirectional and bidirectional link detection. The downstream port needs to be configured to enable loop detection.

When Device C enables RLDP, the two upstream ports need to be configured for one-way and two-way link detection, and the two downstream ports need to be configured to enable loop detection.

4.1.4 Configuration Steps

# Configure on Device A.

Device A# configure terminal

Device A(config)# rldp enable

Device A(config)# interfaceGigabitEthernet 2/0/1

Device A(config-if-GigabitEthernet2/0/1)# rldp port unidirection-detect shutdown-port

Device A(config-if-GigabitEthernet2/0/1)# rldp port bidirection-detect shutdown-port.

Device A (config-if-GigabitEthernet2/0/1)# exit

Device A(config)# interfaceGigabitEthernet 2/0/9

Device A(config-if-GigabitEthernet2/0/1)# rldp port unidirection-detect shutdown-port

Device A(config-if-GigabitEthernet2/0/1)# rldp port bidirection-detect shutdown-port

Device A(config-if-GigabitEthernet2/0/1)# rldp port loop-detect shutdown-port

# Configure on Device B.

Device B# configure terminal

Device B(config)# rldp enable

Device B(config)# interfaceGigabitEthernet 2/0/1

Device B(config-if-GigabitEthernet2/0/1)# rldp port unidirection-detect shutdown-port

Device B(config-if-GigabitEthernet2/0/1)# rldp port bidirection-detect shutdown-port

Device B(config-if-GigabitEthernet2/0/1)# exit

Device B(config)# interfaceGigabitEthernet 2/0/9

Device B(config-if-GigabitEthernet2/0/1)# rldp port unidirection-detect shutdown-port

Device B(config-if-GigabitEthernet2/0/1)# rldp port bidirection-detect shutdown-port

Device B(config-if-GigabitEthernet2/0/1)# rldp port loop-detect shutdown-port

# Configure on Device C.

Device C# configure terminal

Device C(config)# rldp enable

Device C(config)# interfaceGigabitEthernet 0/49

Device C(config-if-GigabitEthernet0/49)# rldp port unidirection-detect shutdown-port

Device C(config-if-GigabitEthernet 0/49)#rldp port bidirection-detect shutdown-port

Device C(config-if-GigabitEthernet0/49)# exit

Device C(config)# interfaceGigabitEthernet 0/50

Device C(config-if-GigabitEthernet0/50)# rldp port unidirection-detect shutdown-port

Device C(config-if-GigabitEthernet0/50)# rldp port bidirection-detect shutdown-port

Device C(config-if-GigabitEthernet0/50)# exit

Device C(config)# interfaceGigabitEthernet 0/1

Device C(config-if-GigabitEthernet0/1)# rldp port loop-detect shutdown-port

Device C(config-if-GigabitEthernet0/1)# exit

Device C(config)# interfaceGigabitEthernet 0/2

Device C(config-if-GigabitEthernet0/2)# rldp port loop-detect shutdown-port

4.1.5 Verification Configuration Result
Check the RLDP status information of Device A, Device B, and Device C devices. Take Device A as an example. Use "show rldp" to verify if the configuration is correct.

Device A# show rldp
rldp state        : enable
rldp hello interval: 3
rldp max hello    : 2
rldp local bridge :  00d0.f822.33aa

-----------------------------------

Interface GigabitEthernet  2/0/1
port state     : normal
neighbor bridge : 00d0.f800.51b1
neighbor port  : GigabitEthernet  2/0/1
unidirection detect information:
     action:shutdown-port
     state :normal
bidirection detect information:
     action:shutdown-port
     state :normal

Interface GigabitEthernet  2/0/9
port state     : normal
neighbor bridge : 00d0.f800.41b0
neighbor port  : GigabitEthernet  0/49
unidirection detect information:
     action:shutdown-port
     state :normal
bidirection detect information:
     action:shutdown-port
     state :normal
loop detect information:
     action:shutdown-port
     state :normal

4.1.6 Common errors
(1) The functions of loopback and private multicast address authentication or TPP cannot be enabled at the same time.
(2) When configuring bidirectional detection, if neighbor negotiation is not specified, it is required that the neighboring devices enable RLDP under global and interface settings, otherwise it will be detected as unidirectional or bidirectional failure.
(3) If you specify negotiating with neighbors before starting detection when configuring for bidirectional detection, in the case of an existing failure, you cannot detect normally because you cannot learn the neighbors. It is recommended to restore the link error status first.
(4) In the three-layer interface, itis not recommended to specify the fault handling method as Shutdown SVI.
(5) In the case where the loop protection protocol, such as STP, is enabled, it is not recommended to specify the failure handling method as Block for the ports.