Example for Configuring DLDP to Detect Intersected Fibers

Networking Requirements

As shown in Figure 1, SwitchA and SwitchB are connected through a pair of optical fibers. On an optical fiber, Rx indicates the receive end, and Tx indicates the transmit end. Optical fibers may be cross connected, as shown in Figure 2. The requirement is to detect unidirectional links caused by cross connections of optical fibers.

Figure 1 Correct optical fiber connections

Figure 2 Intersected fibers

Configuration Roadmap

The configuration roadmap is as follows:

Configure the interfaces on both ends to work in non-auto-negotiation mode.
Enable DLDP to detect unidirectional links between SwitchA and SwitchB.
Adjust DLDP parameters to detect unidirectional links more efficiently.

Procedure

Configure the interfaces on SwitchA to work in non-auto negotiation mode.

<HUAWEI> system-view
[HUAWEI] sysname SwitchA
[SwitchA] interface gigabitethernet 0/0/1
[SwitchA-GigabitEthernet0/0/1] undo negotiation auto
[SwitchA-GigabitEthernet0/0/1] quit
[SwitchA] interface gigabitethernet 0/0/2
[SwitchA-GigabitEthernet0/0/2] undo negotiation auto
[SwitchA-GigabitEthernet0/0/2] quit

Enable DLDP globally on SwitchA.
```
[SwitchA] dldp enable
```

Enable DLDP on an interface of SwitchA.

[SwitchA] interface gigabitethernet 0/0/1
[SwitchA-GigabitEthernet0/0/1] dldp enable
[SwitchA-GigabitEthernet0/0/1] quit
[SwitchA] interface gigabitethernet 0/0/2
[SwitchA-GigabitEthernet0/0/2] dldp enable
[SwitchA-GigabitEthernet0/0/2] quit

Set the interval for sending Advertisement packets to 10 seconds on SwitchA.
```
[SwitchA] dldp interval 10
```
Set the timeout value of the DelayDown timer to 4 seconds on SwitchA.
```
[SwitchA] dldp delaydown-timer 4
```
Set the authentication mode of DLDPDUs to sha password authentication and set the password to 12345 on SwitchA.
```
[SwitchA] dldp authentication-mode sha 12345
```
Perform steps 1 to 6 on SwitchB.

Verify the configuration.

After the configuration is complete, run the display dldp command in the interface view. The command output shows that the DLDP status of the interface is advertisement.

[SwitchA] display dldp interface gigabitethernet 0/0/1
Interface GigabitEthernet0/0/1
 DLDP port state: advertisement                                                 
 DLDP link state: up                                                            
 The neighbor number of the port is: 1.                                         
   Neighbor mac address:0001-0001-0001                                          
   Neighbor port index:26                                                       
   Neighbor state:two way                                                       
   Neighbor aged time(s):206

[SwitchA] display dldp interface gigabitethernet 0/0/2
Interface GigabitEthernet0/0/2
 DLDP port state: advertisement                                                 
 DLDP link state: up                                                            
 The neighbor number of the port is: 1.                                         
   Neighbor mac address:0001-0001-0001                                          
   Neighbor port index:28                                                       
   Neighbor state:two way                                                       
   Neighbor aged time(s):188

[SwitchB] display dldp interface gigabitethernet 0/0/1
Interface GigabitEthernet0/0/1
 DLDP port state: advertisement                                                 
 DLDP link state: up                                                            
 The neighbor number of the port is: 1.                                         
   Neighbor mac address:781d-ba57-c24a                                          
   Neighbor port index:51                                                       
   Neighbor state:two way                                                       
   Neighbor aged time(s):235

[SwitchB] display dldp interface gigabitethernet 0/0/2
Interface GigabitEthernet0/0/2
 DLDP port state: advertisement                                                 
 DLDP link state: up                                                            
 The neighbor number of the port is: 1.                                         
   Neighbor mac address:781d-ba57-c24a                                          
   Neighbor port index:53                                                       
   Neighbor state:two way                                                       
   Neighbor aged time(s):214

As shown in Figure 2, if a unidirectional link occurs between the interfaces on SwitchA and SwitchB due to cross connections of optical fibers, DLDP will shut down the interfaces.

Run the display dldp command on SwitchA and SwitchB. The command output shows that the DLDP status of interfaces on SwitchA and SwitchB is disable.

[SwitchA] display dldp interface gigabitethernet 0/0/1
Interface GigabitEthernet0/0/1
 DLDP port state: disable
 DLDP link state: up
 The neighbor number of the port is: 0.
[SwitchA] display dldp interface gigabitethernet 0/0/2
Interface GigabitEthernet0/0/2
 DLDP port state: disable
 DLDP link state: up
 The neighbor number of the port is: 0.

[SwitchB] display dldp interface gigabitethernet 0/0/1
Interface GigabitEthernet0/0/1
 DLDP port state: disable
 DLDP link state: up
 The neighbor number of the port is: 0.
[SwitchB] display dldp interface gigabitethernet 0/0/2
Interface GigabitEthernet0/0/2
 DLDP port state: disable
 DLDP link state: up
 The neighbor number of the port is: 0.

Configuration Files

SwitchA configuration file

#
sysname SwitchA
#
dldp enable
dldp interval 10
dldp delaydown-timer 4
dldp authentication-mode sha %#%#x=4::bbwY1`:YhJ/e*kK_I:ONJ|CYMO/=^0QyZXEfr0xL'5Md,<4Dl:`za$9%#%# 
#
interface GigabitEthernet0/0/1
 undo negotiation auto
 dldp enable
#
interface GigabitEthernet0/0/2
 undo negotiation auto
 dldp enable
#
return

SwitchB configuration file

#
sysname SwitchB
#
dldp enable
dldp interval 10
dldp delaydown-timer 4
dldp authentication-mode sha %#%#|I<VLDbQrWDa"<!e'7WVN,l%(t0ga;&{$r,Mrq*<!,}(C|oZXAz1!gIH}*x:%#%#
#
interface GigabitEthernet0/0/1
 undo negotiation auto
 dldp enable
#
interface GigabitEthernet0/0/2
 undo negotiation auto
 dldp enable
#
return