Using Ethernet Operations Administration and Maintenance

Ethernet Operations, Administration, and Maintenance (OAM) is a protocol for installing, monitoring, and troubleshooting Ethernet metropolitan-area networks (MANs) and Ethernet WANs. It relies on a new, optional sublayer in the data link layer of the Open Systems Interconnection (OSI) model. The OAM features covered by this protocol are Discovery, Link Monitoring, Remote Fault Detection, Remote Loopback, and Cisco Proprietary Extensions.

The advent of Ethernet as a MAN and WAN technology has emphasized the necessity for integrated management for larger deployments. For Ethernet to extend into public MANs and WANs, it must be equipped with a new set of requirements on Ethernet’s traditional operations, which had been centered on enterprise networks only. The expansion of Ethernet technology into the domain of service providers, where networks are substantially larger and more complex than enterprise networks and the user-base is wider, makes operational management of link uptime crucial.

Information About Using Ethernet Operations Administration and Maintenance

Ethernet OAM

Ethernet OAM is a protocol for installing, monitoring, and troubleshooting metro Ethernet networks and Ethernet WANs. It relies on a new, optional sublayer in the data link layer of the OSI model. Ethernet OAM can be implemented on any full-duplex point-to-point or emulated point-to-point Ethernet link. A system-wide implementation is not required; OAM can be deployed for part of a system; that is, on particular interfaces.

Normal link operation does not require Ethernet OAM. OAM frames, called OAM protocol data units (PDUs), use the slow protocol destination MAC address 0180.c200.0002. They are intercepted by the MAC sublayer and cannot propagate beyond a single hop within an Ethernet network.

Ethernet OAM is a relatively slow protocol with modest bandwidth requirements. The frame transmission rate is limited to a maximum of 10 frames per second; therefore, the impact of OAM on normal operations is negligible. However, when link monitoring is enabled, the CPU must poll error counters frequently. In this case, the required CPU cycles will be proportional to the number of interfaces that have to be polled.

Two major components, the OAM client and the OAM sublayer, make up Ethernet OAM. The following two sections describe these components.

OAM Client

The OAM client is responsible for establishing and managing Ethernet OAM on a link. The OAM client also enables and configures the OAM sublayer. During the OAM discovery phase, the OAM client monitors OAM PDUs received from the remote peer and enables OAM functionality on the link based on local and remote state as well as configuration settings. Beyond the discovery phase (at steady state), the OAM client is responsible for managing the rules of response to OAM PDUs and managing the OAM remote loopback mode.

OAM Sublayer

The OAM sublayer presents two standard IEEE 802.3 MAC service interfaces: one facing toward the superior sublayers, which include the MAC client (or link aggregation), and the other interface facing toward the subordinate MAC control sublayer. The OAM sublayer provides a dedicated interface for passing OAM control information and OAM PDUs to and from a client.

The OAM sublayer is made up of three components: control block, multiplexer, and packet parser (p-parser). Each component is described in the following sections.

Control Block

The control block provides the interface between the OAM client and other blocks internal to the OAM sublayer. The control block incorporates the discovery process, which detects the existence and capabilities of remote OAM peers. It also includes the transmit process that governs the transmission of OAM PDUs to the multiplexer and a set of rules that govern the receipt of OAM PDUs from the p-parser.

Multiplexer

The multiplexer manages frames generated (or relayed) from the MAC client, control block, and p-parser. The multiplexer passes through frames generated by the MAC client untouched. It passes OAM PDUs generated by the control block to the subordinate sublayer; for example, the MAC sublayer. Similarly, the multiplexer passes loopback frames from the p-parser to the same subordinate sublayer when the interface is in OAM remote loopback mode.

P-Parser

The p-parser classifies frames as OAM PDUs, MAC client frames, or loopback frames and then dispatches each class to the appropriate entity. OAM PDUs are sent to the control block. MAC client frames are passed to the superior sublayer. Loopback frames are dispatched to the multiplexer.

Benefits of Ethernet OAM

Ethernet OAM provides the following benefits:

  • Competitive advantage for service providers.

  • Standardized mechanism to monitor the health of a link and perform diagnostics.


Note

REP traps are prioritized when both Ethernet OAM and REP traps are configured on the same port. If you want to view Ethernet OAM logs, then you must disable REP configurations.

Cisco Implementation of Ethernet OAM

The Cisco implementation of Ethernet OAM consists of the Ethernet OAM shim and the Ethernet OAM module.

The Ethernet OAM shim is a thin layer that connects the Ethernet OAM module and the platform code. It is implemented in the platform code (driver). The shim also communicates port state and error conditions to the Ethernet OAM module via control signals.

The Ethernet OAM module, implemented within the control plane, handles the OAM client as well as control block functionality of the OAM sublayer. This module interacts with the CLI and Simple Network Management Protocol (SNMP)/programmatic interface via control signals. In addition, this module interacts with the Ethernet OAM shim through OAM PDU flows.

OAM Features

The OAM features as defined by IEEE 802.3ah, Ethernet in the First Mile, are discovery, Link Monitoring, Remote Fault Detection, Remote Loopback, and Cisco Proprietary Extensions.

Discovery

Discovery is the first phase of Ethernet OAM and it identifies the devices in the network and their OAM capabilities. Discovery uses information OAM PDUs. During the discovery phase, the following information is advertised within periodic information OAM PDUs:

  • OAM mode—Conveyed to the remote OAM entity. The mode can be either active or passive and can be used to determine device functionality.

  • OAM configuration (capabilities)—Advertises the capabilities of the local OAM entity. With this information a peer can determine what functions are supported and accessible; for example, loopback capability.

  • OAM PDU configuration—Includes the maximum OAM PDU size for receipt and delivery. This information along with the rate limiting of 10 frames per second can be used to limit the bandwidth allocated to OAM traffic.

  • Platform identity—A combination of an organization unique identifier (OUI) and 32-bits of vendor-specific information. OUI allocation, controlled by the IEEE, is typically the first three bytes of a MAC address.

Discovery includes an optional phase in which the local station can accept or reject the configuration of the peer OAM entity. For example, a node may require that its partner support loopback capability to be accepted into the management network. These policy decisions may be implemented as vendor-specific extensions.

Link Monitoring

Link monitoring in Ethernet OAM detects and indicates link faults under a variety of conditions. Link monitoring uses the event notification OAM PDU and sends events to the remote OAM entity when there are problems detected on the link. The error events include the following:

  • Error Symbol Period (error symbols per second)—The number of symbol errors that occurred during a specified period exceeded a threshold. These errors are coding symbol errors.

  • Error Frame (error frames per second)—The number of frame errors detected during a specified period exceeded a threshold.

  • Error Frame Period (error frames per n frames)—The number of frame errors within the last n frames has exceeded a threshold.

  • Error Frame Seconds Summary (error seconds per m seconds)—The number of error seconds (1-second intervals with at least one frame error) within the last m seconds has exceeded a threshold.

Since IEEE 802.3ah OAM does not provide a guaranteed delivery of any OAM PDU, the event notification OAM PDU may be sent multiple times to reduce the probability of a lost notification. A sequence number is used to recognize duplicate events.

Remote Failure Indication

Faults in Ethernet connectivity that are caused by slowly deteriorating quality are difficult to detect. Ethernet OAM provides a mechanism for an OAM entity to convey these failure conditions to its peer via specific flags in the OAM PDU. The following failure conditions can be communicated:

  • Link Fault—Loss of signal is detected by the receiver; for instance, the peer’s laser is malfunctioning. A link fault is sent once per second in the information OAM PDU. Link fault applies only when the physical sublayer is capable of independently transmitting and receiving signals.

  • Dying Gasp—An unrecoverable condition has occurred; for example, when an interface is shut down. This type of condition is vendor specific. A notification about the condition may be sent immediately and continuously.

    For more information on Dying Gasp, see the Dying Gasp Support for Loss of Power Supply Through SNMP, Syslog and Ethernet OAM chapter in the Cisco NCS 520 Series Router Configuration Guide.

  • Critical Event—An unspecified critical event has occurred. This type of event is vendor specific. A critical event may be sent immediately and continuously.

Remote Loopback

An OAM entity can put its remote peer into loopback mode using the loopback control OAM PDU. Loopback mode helps an administrator ensure the quality of links during installation or when troubleshooting. In loopback mode, every frame received is transmitted back on the same port except for OAM PDUs and pause frames. The periodic exchange of OAM PDUs must continue during the loopback state to maintain the OAM session.

The loopback command is acknowledged by responding with an information OAM PDU with the loopback state indicated in the state field. This acknowledgement allows an administrator, for example, to estimate if a network segment can satisfy a service-level agreement. Acknowledgement makes it possible to test delay, jitter, and throughput.

When an interface is set to the remote loopback mode the interface no longer participates in any other Layer 2 or Layer 3 protocols; for example Spanning Tree Protocol (STP) or Open Shortest Path First (OSPF). The reason is that when two connected ports are in a loopback session, no frames other than the OAM PDUs are sent to the CPU for software processing. The non-OAM PDU frames are either looped back at the MAC level or discarded at the MAC level.

From a user’s perspective, an interface in loopback mode is in a link-up state.

Cisco Vendor-Specific Extensions

Ethernet OAM allows vendors to extend the protocol by allowing them to create their own type-length-value (TLV) fields.

OAM Messages

Ethernet OAM messages or OAM PDUs are standard length, untagged Ethernet frames within the normal frame length bounds of 64 to 1518 bytes. The maximum OAM PDU frame size exchanged between two peers is negotiated during the discovery phase.

OAM PDUs always have the destination address of slow protocols (0180.c200.0002) and an Ethertype of 8809. OAM PDUs do not go beyond a single hop and have a hard-set maximum transmission rate of 10 OAM PDUs per second. Some OAM PDU types may be transmitted multiple times to increase the likelihood that they will be successfully received on a deteriorating link.

Four types of OAM messages are supported:

  • Information OAM PDU--A variable-length OAM PDU that is used for discovery. This OAM PDU includes local, remote, and organization-specific information.

  • Event notification OAM PDU--A variable-length OAM PDU that is used for link monitoring. This type of OAM PDU may be transmitted multiple times to increase the chance of a successful receipt; for example, in the case of high-bit errors. Event notification OAM PDUs also may include a time stamp when generated.

  • Loopback control OAM PDU--An OAM PDU fixed at 64 bytes in length that is used to enable or disable the remote loopback command.

  • Vendor-specific OAM PDU--A variable-length OAM PDU that allows the addition of vendor-specific extensions to OAM.

IEEE 802.3ah Link Fault RFI Support

The IEEE 802.3ah Link Fault RFI Support feature provides a per-port configurable option that moves a port into a blocking state when an OAM PDU control request packet is received with the Link Fault Status flag set. In the blocking state, the port can continue to receive OAM PDUs, detect remote link status, and automatically recover when the remote link becomes operational. When an OAM PDU is received with the Link Fault Status flag set to zero or FALSE, the port is enabled and all VLANs configured on the port are set to “forwarding.”


Note

If you configure the Ethernet OAM timeout period to be the minimum allowable value of 2 seconds, the Ethernet OAM session may be dropped briefly when the port transitions from blocked to unblocked. This action will not occur by default; the default timeout value is 5 seconds.

Before the release of the IEEE 802.3ah Link Fault RFI Support feature, when an OAM PDU control request packet was received with the Link Fault Status flag set, one of three actions was taken:

  • A warning message was displayed or logged, and the port remained operational.

  • The Link Fault Status flag was ignored.

Ethernet Connectivity Fault Management

Ethernet connectivity fault management (CFM) is an end-to-end per-service-instance Ethernet layer OAM protocol that includes proactive connectivity monitoring, fault verification, and fault isolation. End to end can be provider edge (PE) to PE or customer edge (CE) to CE. Per service instance means per VLAN.

For more information about Ethernet CFM, see Ethernet Connectivity Fault Management .

High Availability Features Supported by 802.3ah

In access and service provider networks using Ethernet technology, High Availability (HA) is a requirement, especially on Ethernet OAM components that manage Ethernet virtual circuit (EVC) connectivity. End-to-end connectivity status information is critical and must be maintained on a hot standby Route Switch Processor (RSP) (a standby RSP that has the same software image as the active RSP and supports synchronization of line card, protocol, and application state information between RSPs for supported features and protocols). End-to-end connectivity status is maintained on the CE, PE, and access aggregation PE (uPE) network nodes based on information received by protocols such as CFM and 802.3ah. This status information is used to either stop traffic or switch to backup paths when an EVC is down. Metro Ethernet clients (for example, CFM and 802.3ah) maintain configuration data and dynamic data, which is learned through protocols. Every transaction involves either accessing or updating data among the various databases. If the databases are synchronized across active and standby modules, the RSPs are transparent to clients.

Cisco infrastructure provides various component application program interfaces (APIs) for clients that are helpful in maintaining a hot standby RSP. Metro Ethernet HA clients (such as, HA/ISSU, CFM HA/ISSU, 802.3ah HA/ISSU) interact with these components, update the databases, and trigger necessary events to other components.

Benefits of 802.3ah HA

  • Elimination of network downtime for Cisco software image upgrades, resulting in higher availability

  • Elimination of resource scheduling challenges associated with planned outages and late night maintenance windows

  • Accelerated deployment of new services and applications and faster implementation of new features, hardware, and fixes due to the elimination of network downtime during upgrades

  • Reduced operating costs due to outages while delivering higher service levels due to the elimination of network downtime during upgrades

NSF SSO Support in 802.3ah OAM

The redundancy configurations Stateful Switchover (SSO) and Nonstop Forwarding (NSF) are both supported in Ethernet OAM and are automatically enabled. A switchover from an active to a standby Route Switch Processor (RSP) occurs when the active RSP fails, is removed from the networking device, or is manually taken down for maintenance. NSF interoperates with the SSO feature to minimize network downtime following a switchover. The primary function of Cisco NSF is to continue forwarding IP packets following an RSP switchover.

For detailed information about the SSO feature, see the “Configuring Stateful Switchover” module of the High Availability Configuration Guide. For detailed information about the NSF feature, see the “Configuring Cisco Nonstop Forwarding” module of the High Availability Configuration Guide.

ISSU Support in 802.3ah OAM

Cisco In-Service Software Upgrades (ISSUs) allow you to perform a Cisco software upgrade or downgrade without disrupting packet flow. ISSU is automatically enabled in 802.3ah. OAM performs a bulk update and a runtime update of the continuity check database to the standby Route Switch Processor (RSP), including adding, deleting, or updating a row. This checkpoint data requires ISSU capability to transform messages from one release to another. All the components that perform active RSP to standby RSP updates using messages require ISSU support.

ISSU lowers the impact that planned maintenance activities have on network availability by allowing software changes while the system is in service. For detailed information about ISSU, see the “Performing an In Service Software Upgrade” module of the High Availability Configuration Guide.

How to Set Up and Configure Ethernet Operations Administration and Maintenance

Enabling Ethernet OAM on an Interface

Ethernet OAM is by default disabled on an interface.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ethernet oam [max-rate oampdus | min-rate num-seconds | mode {active | passive } | timeout seconds ]
  5. exit

DETAILED STEPS

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Specifies an interface and enters interface configuration mode.

Step 4

ethernet oam [max-rate oampdus | min-rate num-seconds | mode {active | passive } | timeout seconds ]

Example:


Device(config-if)# ethernet oam

Enables Ethernet OAM.

Step 5

exit

Example:


Device(config-if)# exit

Returns to global configuration mode.

Disabling and Enabling a Link Monitoring Session

Link monitoring is enabled by default when you enable Ethernet OAM. Perform these tasks to disable and enable link monitoring sessions:

Disabling a Link Monitoring Session

Perform this task to disable a link monitoring session.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ethernet oam [max-rate oampdus | min-rate num-seconds | mode {active | passive } | timeout seconds ]
  5. no ethernet oam link-monitor supported
  6. exit

DETAILED STEPS

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Specifies an interface and enters interface configuration mode.

Step 4

ethernet oam [max-rate oampdus | min-rate num-seconds | mode {active | passive } | timeout seconds ]

Example:

Device(config-if)# ethernet oam

Enables Ethernet OAM.

Step 5

no ethernet oam link-monitor supported

Example:

Device(config-if)# no ethernet oam link-monitor supported

Disables link monitoring on the interface.

Step 6

exit

Example:

Device(config-if)# exit

Returns to global configuration mode.

Enabling a Link Monitoring Session

Perform this task to reenable a link monitoring session after it was previously disabled.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ethernet oam link-monitor supported
  5. exit

DETAILED STEPS

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Specifies an interface and enters interface configuration mode.

Step 4

ethernet oam link-monitor supported

Example:

Device(config-if)# ethernet oam link-monitor supported

Enables link monitoring on the interface.

Step 5

exit

Example:

Device(config-if)# exit

Returns to global configuration mode.

Stopping and Starting Link Monitoring Operations

Link monitoring operations start automatically when Ethernet OAM is enabled on an interface. When link monitoring operations are stopped, the interface does not actively send or receive event notification OAM PDUs. The tasks in this section describe how to stop and start link monitoring operations.

Stopping Link Monitoring Operations

Perform this task to stop link monitoring operations.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ethernet oam [max-rate oampdus | min-rate num-seconds | mode {active | passive } | timeout seconds ]
  5. no ethernet oam link-monitor on
  6. exit

DETAILED STEPS

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Specifies an interface and enters interface configuration mode.

Step 4

ethernet oam [max-rate oampdus | min-rate num-seconds | mode {active | passive } | timeout seconds ]

Example:

Device(config-if)# ethernet oam

Enables Ethernet OAM.

Step 5

no ethernet oam link-monitor on

Example:

Device(config-if)# no ethernet oam link-monitor on

Stops link monitoring operations.

Step 6

exit

Example:

Device(config-if)# exit

Returns to global configuration mode.

Starting Link Monitoring Operations

Perform this task to start link monitoring operations.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ethernet oam link-monitor on
  5. exit

DETAILED STEPS

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Specifies an interface and enters interface configuration mode.

Step 4

ethernet oam link-monitor on

Example:

Device(config-if)# ethernet oam link-monitor on

Starts link monitoring operations.

Step 5

exit

Example:

Device(config-if)# exit

Returns to global configuration mode.

Configuring Link Monitoring Options

Perform this optional task to specify link monitoring options. Steps 4 through 10 can be performed in any sequence.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ethernet oam [max-rate oampdus | min-rate num-seconds | mode {active | passive } | timeout seconds ]
  5. ethernet oam link-monitor frame {threshold {high {none | high-frames } | low low-frames } | window milliseconds }
  6. ethernet oam link-monitor frame-period {threshold {high {none | high-frames } | low low-frames } | window frames }
  7. ethernet oam link-monitor frame-seconds {threshold {high {none | high-frames } | low low-frames } | window milliseconds }
  8. ethernet oam link-monitor receive-crc {threshold {high {high-frames | none } | low low-frames } | window milliseconds }
  9. ethernet oam link-monitor transmit-crc {threshold {high {high-frames | none } | low low-frames } | window milliseconds }
  10. ethernet oam link-monitor symbol-period {threshold {high {none | high-symbols } | low low-symbols } | window symbols }
  11. exit

DETAILED STEPS

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Identifies the interface and enters interface configuration mode.

Step 4

ethernet oam [max-rate oampdus | min-rate num-seconds | mode {active | passive } | timeout seconds ]

Example:


Device(config-if)# ethernet oam

Enables Ethernet OAM.

Step 5

ethernet oam link-monitor frame {threshold {high {none | high-frames } | low low-frames } | window milliseconds }

Example:


Device(config-if)# ethernet oam link-monitor frame window 399

Configures a number for error frames that when reached triggers an action.

Step 6

ethernet oam link-monitor frame-period {threshold {high {none | high-frames } | low low-frames } | window frames }

Example:


Device(config-if)# ethernet oam link-monitor frame-period threshold high 599

Configures a number of frames to be polled.

Frame period is a user-defined parameter.

Step 7

ethernet oam link-monitor frame-seconds {threshold {high {none | high-frames } | low low-frames } | window milliseconds }

Example:


Device(config-if)# ethernet oam link-monitor frame-seconds window 699

Configures a period of time in which error frames are counted.

Step 8

ethernet oam link-monitor receive-crc {threshold {high {high-frames | none } | low low-frames } | window milliseconds }

Example:


Device(config-if)# ethernet oam link-monitor receive-crc window 99

Configures an Ethernet OAM interface to monitor ingress frames with cyclic redundancy check (CRC) errors for a period of time.

Step 9

ethernet oam link-monitor transmit-crc {threshold {high {high-frames | none } | low low-frames } | window milliseconds }

Example:


Device(config-if)# ethernet oam link-monitor transmit-crc threshold low 199

Configures an Ethernet OAM interface to monitor egress frames with CRC errors for a period of time.

Step 10

ethernet oam link-monitor symbol-period {threshold {high {none | high-symbols } | low low-symbols } | window symbols }

Example:


Device(config-if)# ethernet oam link-monitor symbol-period threshold high 299

Configures a threshold or window for error symbols, in number of symbols.

Step 11

exit

Example:


Device(config-if)# exit

Returns to global configuration mode.

Example

Configuring Global Ethernet OAM Options Using a Template

Perform this task to create a template to use for configuring a common set of options on multiple Ethernet OAM interfaces. Steps 4 through 10 are optional and can be performed in any sequence. These steps may also be repeated to configure different options.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. template template-name
  4. ethernet oam link-monitor receive-crc {threshold {high {high-frames | none } | low low-frames } | window milliseconds }
  5. ethernet oam link-monitor transmit-crc {threshold {high {high-frames | none } | low low-frames } | window milliseconds }
  6. ethernet oam link-monitor symbol-period {threshold {high {none | high-symbols } | low low-symbols } | window symbols }
  7. ethernet oam link-monitor frame {threshold {high {none | high-frames } | low low-frames } | window milliseconds }
  8. ethernet oam link-monitor frame-period {threshold {high {none | high-frames } | low low-frames } | window frames }
  9. ethernet oam link-monitor frame-seconds {threshold {high {none | high-frames } | low low-frames } | window milliseconds }
  10. exit
  11. interface type number
  12. source template template-name
  13. exit
  14. exit
  15. show running-config

DETAILED STEPS

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

template template-name

Example:


Device(config)# template oam-temp

Configures a template and enters template configuration mode.

Step 4

ethernet oam link-monitor receive-crc {threshold {high {high-frames | none } | low low-frames } | window milliseconds }

Example:


Device(config-template)# ethernet oam link-monitor receive-crc window 99

Configures an Ethernet OAM interface to monitor ingress frames with CRC errors for a period of time.

Step 5

ethernet oam link-monitor transmit-crc {threshold {high {high-frames | none } | low low-frames } | window milliseconds }

Example:


Device(config-template)# ethernet oam link-monitor transmit-crc threshold low 199

Configures an Ethernet OAM interface to monitor egress frames with CRC errors for a period of time.

Step 6

ethernet oam link-monitor symbol-period {threshold {high {none | high-symbols } | low low-symbols } | window symbols }

Example:


Device(config-template)# ethernet oam link-monitor symbol-period threshold high 299

Configures a threshold or window for error symbols, in number of symbols.

Step 7

ethernet oam link-monitor frame {threshold {high {none | high-frames } | low low-frames } | window milliseconds }

Example:


Device(config-template)# ethernet oam link-monitor frame window 399

Configures a number for error frames that when reached triggers an action.

Step 8

ethernet oam link-monitor frame-period {threshold {high {none | high-frames } | low low-frames } | window frames }

Example:


Device(config-template)# ethernet oam link-monitor frame-period threshold high 599

Configures a number of frames to be polled.

Frame period is a user-defined parameter.

Step 9

ethernet oam link-monitor frame-seconds {threshold {high {none | high-frames } | low low-frames } | window milliseconds }

Example:


Device(config-template)# ethernet oam link-monitor frame-seconds window 699

Configures a period of time in which error frames are counted.

Step 10

exit

Example:


Device(config-template)# exit

Returns to global configuration mode.

Step 11

interface type number

Example:

Identifies the interface on which to use the template and enters interface configuration mode.

Step 12

source template template-name

Example:


Device(config-if)# source template oam-temp

Applies to the interface the options configured in the template.

Step 13

exit

Example:


Device(config-if)# exit

Returns to global configuration mode.

Step 14

exit

Example:


Device(config)# exit

Returns to privileged EXEC mode.

Step 15

show running-config

Example:


Device# show running-config

Displays the updated running configuration.

Configuring a Port for Link Fault RFI Support

Perform this task to put a port into a blocking state when an OAM PDU control request packet is received with the Link Fault Status flag set.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ethernet oam remote-failure {critical-event | dying-gasp | link-fault } action { }
  5. exit

DETAILED STEPS

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:

Enters interface configuration mode.

Step 4

ethernet oam remote-failure {critical-event | dying-gasp | link-fault } action { }

Example:

Sets the interface to the blocking state when a critical event occurs.

Step 5

exit

Example:


Device(config-if)# exit

Returns to global configuration mode.

Configuration Examples for Ethernet Operations Administration and Maintenance

The following example shows how to configure Ethernet OAM options using a template and overriding that configuration by configuring an interface. In this example, the network supports a Gigabit Ethernet interface between the customer edge device and provider edge device. 


! Configure a global OAM template for both PE and CE configuration.
!
Device(config)# template oam
Device(config-template)# ethernet oam link-monitor symbol-period threshold low 10
Device(config-template)# ethernet oam link-monitor symbol-period threshold high 100
Device(config-template)# ethernet oam link-monitor frame window 100
Device(config-template)# ethernet oam link-monitor frame threshold low 10
Device(config-template)# ethernet oam link-monitor frame threshold high 100
Device(config-template)# ethernet oam link-monitor frame-period window 100
Device(config-template)# ethernet oam link-monitor frame-period threshold low 10
Device(config-template)# ethernet oam link-monitor frame-period threshold high 100
Device(config-template)# ethernet oam link-monitor frame-seconds window 1000
Device(config-template)# ethernet oam link-monitor frame-seconds threshold low 10
Device(config-template)# ethernet oam link-monitor frame-seconds threshold high 100
Device(config-template)# ethernet oam link-monitor receive-crc window 100
Device(config-template)# ethernet oam link-monitor receive-crc threshold high 100
Device(config-template)# ethernet oam link-monitor transmit-crc window 100
Device(config-template)# ethernet oam link-monitor transmit-crc threshold high 100

Device(config-template)# exit
!
! Enable Ethernet OAM on the CE interface
!
Device(config)# 
Device(config-if)# ethernet oam
!
! Apply the global OAM template named "oam" to the interface.
!
Device(config-if)# source template oam
!
! Configure any interface-specific link monitoring commands to override the template configuration. The following example disables the high threshold link monitoring for receive CRC errors.
!
Device(config-if)# ethernet oam link-monitor receive-crc threshold high none
!
! Enable Ethernet OAM on the PE interface
!
Device(config)# 
Device(config-if)# ethernet oam
!
! Apply the global OAM template named "oam" to the interface.
!
Device(config-if)# source template oam

The following examples show how to verify various Ethernet OAM configurations and activities.

Verifying an OAM Session

The following example shows that the local OAM client, Gigabit Ethernet interface , is in session with a remote client with MAC address 0012.7fa6.a700 and OUI 00000C, which is the OUI for Cisco. The remote client is in active mode and has established capabilities for link monitoring and remote loopback for the OAM session. 


Device# show ethernet oam summary
Symbols:          * - Master Loopback State,  # - Slave Loopback State
Capability codes: L - Link Monitor,  R - Remote Loopback
                  U - Unidirection,  V - Variable Retrieval
  Local                       Remote
Interface       MAC Address    OUI    Mode    Capability
 Gi6/1/1       0012.7fa6.a700 00000C active      L R

Verifying OAM Discovery Status

The following example shows how to verify OAM discovery status of a local client and a remote peer: 


Device# 

Local client
------------
  Administrative configurations:
    Mode:              active
    Unidirection:      not supported
    Link monitor:      supported (on)
    Remote loopback:   not supported
    MIB retrieval:     not supported
    Mtu size:          1500
  Operational status:
Port status:       operational
    Loopback status:   no loopback
    PDU permission:    any
    PDU revision:      1
Remote client
-------------
  MAC address: 0030.96fd.6bfa
  Vendor(oui): 0x00 0x00 0x0C (cisco)
  Administrative configurations:
   
   Mode:              active
   Unidirection:      not supported
   Link monitor:      supported
   Remote loopback:   not supported
   MIB retrieval:     not supported
   Mtu size:          1500

Verifying Information OAMPDU and Fault Statistics

The following example shows how to verify statistics for information OAM PDUs and local and remote faults: 


Device# 

Counters:
---------
Information OAMPDU Tx                   : 588806
Information OAMPDU Rx                   : 988
Unique Event Notification OAMPDU Tx     : 0
Unique Event Notification OAMPDU Rx     : 0
Duplicate Event Notification OAMPDU TX  : 0
Duplicate Event Notification OAMPDU RX  : 0
Loopback Control OAMPDU Tx              : 1
Loopback Control OAMPDU Rx              : 0
Variable Request OAMPDU Tx              : 0
Variable Request OAMPDU Rx              : 0
Variable Response OAMPDU Tx             : 0
Variable Response OAMPDU Rx             : 0
Cisco OAMPDU Tx                         : 4
Cisco OAMPDU Rx                         : 0
Unsupported OAMPDU Tx                   : 0
Unsupported OAMPDU Rx                   : 0
Frames Lost due to OAM                  : 0
Local Faults:
-------------
0 Link Fault records
2 Dying Gasp records
Total dying gasps       : 4
Time stamp              : 00:30:39
Total dying gasps       : 3
Time stamp              : 00:32:39
0 Critical Event records
Remote Faults:
--------------
0 Link Fault records
0 Dying Gasp records
0 Critical Event records
Local event logs:
-----------------
0 Errored Symbol Period records
0 Errored Frame records
0 Errored Frame Period records
0 Errored Frame Second records
Remote event logs:
------------------
0 Errored Symbol Period records
0 Errored Frame records
0 Errored Frame Period records
0 Errored Frame Second records

Verifying Link Monitoring Configuration and Status

The following example shows how to verify link monitoring configuration and status on the local client. The highlighted Status field in the example shows that link monitoring status is supported and enabled (on). 


Device# 

General
-------
  Mode:                  active
  PDU max rate:          10 packets per second
  PDU min rate:          1 packet per 1 second
  Link timeout:          5 seconds
  High threshold action: no action
Link Monitoring
---------------
  Status: supported (on)
  Symbol Period Error
    Window:              1 million symbols
    Low threshold:       1 error symbol(s)
    High threshold:      none
  Frame Error
    Window:              10 x 100 milliseconds
    Low threshold:       1 error frame(s)
    High threshold:      none
Frame Period Error
    Window:              1 x 100,000 frames
    Low threshold:       1 error frame(s)
    High threshold:      none
  Frame Seconds Error
    Window:              600 x 100 milliseconds
    Low threshold:       1 error second(s)
    High threshold:      none

Verifying Status of a Remote OAM Client

The following example shows that the local client interface Gi6/1/1 is connected to a remote client. Note the values in the Mode and Capability fields. 


Device# show ethernet oam summary
Symbols:          * - Master Loopback State,  # - Slave Loopback State
Capability codes: L - Link Monitor,  R - Remote Loopback
                  U - Unidirection,  V - Variable Retrieval
  Local                       Remote
Interface       MAC Address    OUI    Mode    Capability
 Gi6/1/1       0012.7fa6.a700 00000C active      L R

Additional References

Related Documents

Related Topic

Document Title

Ethernet CFM

“Configuring Ethernet Connectivity Fault Management in a Service Provider Network” module in the Carrier Ethernet Configuration Guide

NSF SSO Support in 802.3ah OAM

“Configuring Stateful Switchover” module in the High Availability Configuration Guide and “Configuring Nonstop Forwarding” in the High Availability Configuration Guide

ISSU Support in 802.3ah OAM

“Configuring In Service Software Upgrades" module in the High Availability Configuration Guide

Carrier Ethernet commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS Carrier Ethernet Command Reference

Configuring CFM over an EFP Interface with the Cross Connect feature on the Cisco ASR 903 Router

Configuring the CFM over EFP Interface with Cross Connect Feature

Configuring Ethernet Virtual Connections on the Cisco ASR 903 Router

Configuring Ethernet Virtual Connections on the Cisco ASR 903 Router

Standards

Standard

Title

IEEE Draft P802.3ah/D3.3

Ethernet in the First Mile - Amendment

IETF VPLS OAM

L2VPN OAM Requirements and Framework

ITU-T

ITU-T Y.1731 OAM Mechanisms for Ethernet-Based Networks

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for Using Ethernet Operations Administration and Maintenance

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1. Feature Information for Using Ethernet Operations, Administration, and Maintenance

Feature Name

Releases

Feature Information

Ethernet Operations, Administration, and Maintenance

12.4(15)T

Ethernet OAM is a protocol for installing, monitoring, and troubleshooting metro Ethernet networks and Ethernet WANs. It relies on a new, optional sublayer in the data link layer of the OSI model. The OAM features covered by this protocol are Discovery, Link Monitoring, Remote Fault Detection, Remote Loopback, and Cisco Proprietary Extensions.

The Ethernet Operations, Administration, and Maintenance feature was integrated into Cisco IOS Release 12.4(15)T.

The following commands were introduced or modified: clear ethernet oam statistics, debug ethernet oam, ethernet oam, ethernet oam link-monitor frame, ethernet oam link-monitor frame-period, ethernet oam link-monitor frame-seconds, ethernet oam link-monitor high-threshold action, ethernet oam link-monitor on, ethernet oam link-monitor receive-crc, ethernet oam link-monitor supported, ethernet oam link-monitor symbol-period, ethernet oam link-monitor transmit-crc, ethernet oam remote-loopback, ethernet oam remote-loopback (interface), show ethernet oam discovery, show ethernet oam statistics, show ethernet oam status, show ethernet oam summary, source template (eoam), template (eoam) .