Interfaces and Hardware Component Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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Interfaces and Hardware Component Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

Ethernet Link OAM configuration

Updated: July 31, 2026

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This topic describes how Ethernet Link OAM (IEEE 802.3ah) operates on a single physical link so that service providers can monitor connection quality, watch for specific events, and take actions on those events.

Ethernet as a Metro Area Network (MAN) or a Wide Area Network (WAN) technology benefits greatly from the implementation of Operations, Administration and Maintenance (OAM) features. The Ethernet Link OAM is a management mechanism that

  • allows Service Providers to monitor connection quality on MANs or WANs

  • tracks specific events, and

  • enables event-based actions.

Table 1. Feature History Table

Feature Name

Release Information

Feature Description

Ethernet Link OAM on Physical Interface— (802.3ah) Link Monitoring

 Release 26.1.1

Introduced in this release on: Centralized Systems (8400 [ASIC:K100]) )(select variants only*)

*This feature is now supported on Cisco 8404-SYS-D routers.

Ethernet Link OAM on Physical Interface— (802.3ah) Link Monitoring

 Release 25.4.1

Introduced in this release on: Fixed Systems (8010 [ASIC: A100], 8700 [ASIC: K100])(select variants only*)

*This feature is now supported on:

  • 8011-32Y8L2H2FH

  • 8011-12G12X4Y-A/D

  • 8711-48Z-M

Ethernet Link OAM support

 Release 25.2.1

Introduced in this release on: Fixed Systems (8700 [ASIC:K100]) )(select variants only*)

This release supports:

  • Ethernet Link OAM on physical interface— (802.3ah) link monitoring.

*This feature is now supported on Cisco 8712-MOD-M routers.

Ethernet Link OAM on Physical Interface— (802.3ah) Link Monitoring

 Release 25.1.1

Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only*)

*This feature is now supported on Cisco 8011-4G24Y4H-I routers.

Ethernet Link OAM on Physical Interface— (802.3ah) Link Monitoring

Release 24.4.1

Introduced in this release on: Fixed Systems (8200 [ASIC: P100], 8700 [ASIC: P100, K100])(select variants only*); Modular Systems (8800 [LC ASIC: P100])(select variants only*)

Ethernet link OAM operates on a single, physical link and it can be configured to monitor either side or both sides of that link.

Ethernet OAM supports link monitoring:

*This feature is now supported on:

  • 8212-48FH-M

  • 8711-32FH-M

  • 8712-MOD-M

  • 88-LC1-12TH24FH-E

  • 88-LC1-36EH

  • 88-LC1-52Y8H-EM

Ethernet Link OAM

Release 7.3.1

This feature allows service providers to monitor the quality of the connections on a MAN or WAN. Service providers can monitor specific events, and take actions on events. Ethernet link OAM operates on a single, physical link and it can be configured to monitor either side or both sides of that link.

You can configure Ethernet link OAM in these ways:

  • A Link OAM profile can be configured, and this profile can be used to set the parameters for multiple interfaces.

  • Link OAM can be configured directly on an interface.

    When an interface is also using a link OAM profile, specific parameters that are set in the profile can be overridden by configuring a different value directly on the interface.

An Ethernet Link OAM profile simplifies the configuration process for EOAM features across multiple interfaces. An Ethernet OAM profile and its features allow other interfaces to reference and inherit the defined settings. You can configure individual Ethernet link OAM features on specific interfaces without using a profile, and these individual configurations always override the profile features. The preferred method for configuring custom EOAM settings involves creating an EOAM profile in Ethernet configuration mode and attaching it to one or more interfaces. These standard Ethernet Link OAM features are supported on the router.

These standard Ethernet Link OAM features are supported on the router:

  • Neighbor Discovery

  • Ethernet Fault Detection

  • MIB Retrieval

  • Miswiring Detection

  • SNMP Traps

  • Link Monitoring

  • Remote Loopback

Neighbor discovery

The Neighbor discovery is an OAM process that

  • enables each end of a link to learn the OAM capabilities of the other end

  • establishes an OAM peer relationship, and

  • enforces specific capability requirements before the initiation of a session.

You can configure certain actions to be taken if there is a capabilities conflict or if a discovery process times out by using the action capabilities-conflict or action discovery-timeout commands.

Ethernet Fault Detection

Ethernet Fault Detection (EFD) is a mechanism that

  • allows Ethernet OAM protocols to control the line protocol state of an interface

  • enables EOAM to shut down an interface when it detects a defect with an expected peer MEP, and

  • triggers higher-level protocols to react and reconverge around the problem.

How EFD works

Unlike many other interface types, Ethernet interfaces do not have an independent line protocol; the physical-layer Ethernet protocol itself determines whether the interface is available. EFD lets EOAM act as the line protocol for Ethernet interfaces, so that EOAM defects such as Alarm Indication Signal (AIS) or loss of continuity can shut down the interface and trigger higher-level protocols to reconverge.

  • EFD can only be used for down MEPs.

  • When EFD shuts down the interface, EOAM frames continue to flow so that EOAM can detect when the problem is resolved and bring the interface back up automatically.

Summary

The following actors and components participate in this process:

  • EOAM: Detects defects on its sessions with the expected peer MEP, and signals EFD when a defect is detected or cleared.

  • EFD: Controls the line protocol state of the Ethernet interface based on signals from EOAM.

  • MAC layer: Transitions to the down state when EFD signals an error, and back to the up state when EFD signals recovery.

  • Higher-level protocols: Layer 2 pseudowires, IP protocols, MSTP, IGP, and similar protocols that react to the MAC state change and reconverge around the fault.

When EOAM detects an error on one of its sessions, EFD signals the MAC layer to go down. This triggers higher-level protocols to reconverge. When EOAM detects that the fault is cleared, EFD reverses the signal and all protocols become active again.

Workflow

Figure 1. EOAM Error Detection and EFD Trigger

These stages describe how EFD reacts to an EOAM defect and to its subsequent recovery:

  1. Stage 1 — EOAM detects a defect. EOAM identifies a defect (such as AIS or loss of continuity) on one of its sessions with an expected peer MEP.
  2. Stage 2 — EFD signals the MAC layer. EFD receives the defect notification from EOAM and signals the error to the corresponding MAC layer for the interface.
  3. Stage 3 — MAC goes down and higher-level protocols reconverge. The MAC transitions to the down state, which triggers higher-level protocols to go down and reconverge where possible.
    • For Layer 2 interfaces, the MAC table is cleared and MSTP reconverges.
    • For Layer 3 interfaces, the ARP cache is cleared and, potentially, the IGP reconverges.
  4. Stage 4 — EOAM detects clearance and EFD reactivates the interface. Because EOAM frames continue to flow while the interface is shut down, EOAM can detect when the defect is resolved. EOAM signals EFD, and all protocols become active again.

MIB retrieval

MIB retrieval enables an OAM peer on one side of an interface to get the MIB variables from the remote side of the link. The MIB variables that are retrieved from the remote OAM peer are READ ONLY.

Miswiring detection (Cisco-proprietary)

Miswiring Detection is a Cisco-proprietary feature that uses the 32-bit vendor field in every Information OAMPDU to identify potential miswiring cases.

SNMP traps

SNMP traps can be enabled or disabled on an Ethernet Operations, Administration, and Maintenance (OAM) interface.

Link monitoring enables an OAM peer to monitor faults that cause the quality of a link to deteriorate over time. When you enable link monitoring, an OAM peer can be configured to take action when the configured thresholds are exceeded.

Remote loopback

Remote loopback enables one side of a link to put the remote side of the link into loopback mode for testing. When remote loopback is enabled, all packets initiated by the primary side of the link are looped back to the primary side, unaltered by the remote side. In remote loopback mode, the remote side is not allowed to inject any data into the packets.