This article describes Operations, Administration and Maintenance (OAM) Connectivity Fault Management (CFM). It includes an example configuration.

For more information, see Related Links (below).

OAM protocols and mechanisms help the operator achieve fault management for a service provider.

• fault indication
• performance monitoring
• security management
• diagnostic functions
• configuration & service provisioning

The IEEE 802.1ag: Connectivity Fault Management (CFM) family of protocols provides capabilities to detect, verify, isolate, and report end-to-end ethernet connectivity faults.

CFM frames are distinguishable by Ether-Type (0x8902) and dMAC address (for multicast messages).

An example OAM CFM is below.

Topology

Cheese -------------- Transmission Device ---------------- Hamburgerkid

- interval: Interval between continuity-check messages
- loss-threshold: Number of continuity-check messages lost before marking endpoint as down

lab@tendonman-re0# set protocols oam ethernet connectivity-fault-management maintenance-domain 1 maintenance-association 1 mep 1 lowest-priority-defect ?
Possible completions:
all-defects Allows all defects
err-xcon Allows only erroneous CCM and cross connect CCM defects
mac-rem-err-xcon Allows only MAC, not receiving CCM, erroneous CCM and cross connect defects
no-defect Allows no defect
rem-err-xcon Allows only not receiving CCM, erroneous CCM and cross connect CCM defects
xcon Allows only cross connect CCM defect
[edit]
lab@tendonman-re0# set protocols oam ethernet connectivity-fault-management maintenance-domain 1 maintenance-association 1 mep 1 lowest-priority-defect err-xcon ?
Possible completions:
<[Enter]> Execute this command
+ apply-groups Groups from which to inherit configuration data
+ apply-groups-except Don't inherit configuration data from these groups
auto-discovery Accept continuity-check messages from all remote MEPs
direction Direction of maintenance endpoint
> interface Name of interface
priority 802.1p priority of continuity-check and link-trace packet (0..7)
> remote-mep Remote maintenance association endpoint configuration
| Pipe through a command
[edit]
lab@tendonman-re0# set protocols oam ethernet connectivity-fault-management maintenance-domain 1 maintenance-association 1 mep 1 lowest-priority-defect err-xcon


maintenance-domain APACI {
level 5;
maintenance-association E104582270 {
continuity-check {
interval 10s;
loss-threshold 3;
}
mep 1 {
interface ae1.2020;
direction down;
remote-mep 2 {
action-profile IFD;
}
lowest-priority-defect rem-err-xcon;
}
}


Jun 28 21:01:54 HamburgerKid mgd[1352]: UI_CMDLINE_READ_LINE: User 'lab', command 'rename protocols oam ethernet connectivity-fault-management maintenance-domain jsnoh to maintenance-domain Incorrect-MAID '
Jun 28 21:01:54 HamburgerKid mgd[1352]: UI_CFG_AUDIT_NEW: User 'lab' rename: [protocols oam ethernet conne`ctivity-fault-management maintenance-domain jsnoh] to "Incorrect-MAID"
Jun 28 21:01:57 HamburgerKid mgd[1352]: UI_COMMIT_PROGRESS: Commit operation in progress: signaling 'Alarm control process', pid 1208, signal 30, status 0 with notification errors enabled

Jun 28 21:05:06 cheese cfmd[1365]: CFMD_CCM_DEFECT_RMEP: CFM defect: Remote CCM timeout detected by MEP on Level: 0 MD: jsnoh MA: jsnoh-1 Interface: xe-0/0/0.0
Jun 28 21:05:06 cheese rpd[1353]: EVENT <UpDown> xe-0/0/0.0 index 2684275512 <Broadcast Multicast> address #0 80.71.1f.c2.66.0
Jun 28 21:05:06 cheese /kernel: cheese cfmd[1365]: CFMD_CCM_DEFECT_RMEP: CFM defect: Remote CCM timeout detected by MEP on Level: 0 MD: jsnoh MA: jsnoh-1 Interface: xe-0/0/0.0
Jun 28 21:05:06 cheese rpd[1353]: EVENT <UpDown> index 156 <Broadcast Multicast> address #0 80.71.1f.c2.66.0
Jun 28 21:05:06 cheese mib2d[1378]: SNMP_TRAP_LINK_DOWN: ifIndex 512, ifAdminStatus up(1), ifOperStatus down(2), ifName xe-0/0/0
Jun 28 21:05:06 cheese /kernel: cheese mib2d[1378]: SNMP_TRAP_LINK_DOWN: ifIndex 512, ifAdminStatus up(1), ifOperStatus down(2), ifName xe-0/0/0

19-11-2025: Minor, non-technical edit

• Configuring Ethernet CFM on Physical Interfaces