Fault Information Advertisement Between EFM and Other Modules

Between EFM and Detection Modules

The OAMMGR module associates EFM with detection modules, such as EFM, CFM, and BFD modules. Fault information advertisement between EFM and detection modules enables a device to delete MAC address entries once a fault is detected. Figure 1 shows the network on which fault information is advertised between EFM and detection modules.

Figure 1 Fault information advertisement between EFM and detection modules

The following example illustrates fault information advertisement between EFM and detection modules over a path CE5 -> CE4 -> CE1-> PE2 -> PE4 on the network shown in Table 1.

**Table 1** Fault information advertisement between EFM and detection modules
Function Deployment	Issue to Be Resolved	Solution
EFM is used to monitor the direct link between CE1 and PE2, and CFM is used to monitor the link between PE2 and PE6.	Although EFM detects a fault, EFM cannot notify PE6 of the fault. As a result, PE6 still forwards network traffic to PE2, causing a traffic interruption. Although CFM detects a fault, CFM cannot notify CE1 of the fault. As a result, CE1 still forwards user traffic to PE2, causing a traffic interruption.	The EFM module can be associated with the CFM module. If the EFM module detects a fault, it instructs the OAMMGR module to notify the CFM module of the fault. If the CFM module detects a fault, it instructs the OAMMGR module to notify the EFM module of the fault. The association allows a module to notify another associated module of a fault and to send an alarm to a network management system (NMS). A network administrator analyzes alarm information and takes measures to rectify the fault.
EFM is used to monitor the direct link between CE1 and PE2, and BFD is used to monitor the link between PE2 and PE6.	Although EFM detects a fault, EFM cannot notify PE6 of the fault. As a result, PE6 still forwards network traffic to PE2, causing a traffic interruption. Although BFD detects a fault, EFM cannot notify CE1 of the fault. As a result, CE1 still forwards user traffic to PE2, causing a traffic interruption.	The EFM module can be associated with the BFD module. If the EFM module detects a fault, it instructs the OAMMGR module to notify the BFD module of the fault. If the BFD module detects a fault, it instructs the OAMMGR module to notify the EFM module of the fault. If EFM on CE1 detects a fault or receives fault information sent by PE2, the association between EFM and BFD works and deletes the MAC entry, which switches traffic to a backup link. The association allows a module to notify another associated module of a fault and to send an alarm to an NMS. A network administrator analyzes alarm information and takes measures to rectify the fault.

Fault Information Advertisement Between EFM and Application Modules

The OAMMGR module associates an EFM module with application modules, such as a Virtual Router Redundancy Protocol (VRRP) module. Figure 2 shows the network on which a user-side device is dual-homed to network-side devices, improving telecom service reliability.

Figure 2 Fault information advertisement between EFM and application modules

Table 2 describes fault information advertisement between EFM and VRRP modules.

**Table 2** Fault information advertisement between EFM and VRRP modules
Function Deployment	Issue to Be Resolved	Solution
A VRRP group is configured to determine the master/backup status of provider edges-aggregation (PE-AGGs). EFM is used to monitor links between the UPE and PE-AGGs.	If links connected to a VRRP group fail, VRRP packets cannot be sent to negotiate the master/backup status. A backup VRRP device preempts the Master state after a period of three times the interval at which VRRP packets are sent. As a result, data loss occurs.	To help prevent data loss, the VRRP module can be associated with the EFM module. If a fault occurs, the EFM module notifies the VRRP module of the fault. After receiving the notification, the VRRP module triggers a master/backup VRRP switchover.