Operations, administration and maintenance (OAM) is a Layer 2 protocol, used to monitor and solve network problems. OAM can report the network state at the data link layer so that a network administrator can manage the network effectively. Currently, OAM is used to solve OAM problems on Ethernet equipment in the last mile. It can monitor link performance, monitor faults and generate alarms, perform loopback test, and send remote MIB variable requests.

OAM serves as a universal mechanism of interoperation and inter-maintenance between Ethernet equipment. The basic operations include establishing OAM connection, monitoring links, diagnosing remote faults, performing a remote loopback, and sending remote MIB variable requests.

& Note:

Table 1-1 lists the cards that support unidirectional link fault events and remote loopback defined by OAM.

Table 1-1 Cards supporting OAM features

Name	Description	Support the link fault event or not (packet delivery ratio when a unidirectional link presents)	Support remote loopback or not
LSB1GP12	12-port Gigabit Ethernet optical interface card	Yes (1%)	No
LSB1GT12	12-port Gigabit Ethernet electrical interface card	No	Yes
LSB1GT24	24-port Gigabit Ethernet electrical interface card	No	Yes
LSB1GP24	24-port Gigabit Ethernet optical interface card	Yes (1%)	No
LSB1GV48	48-port Gigabit Ethernet electrical interface card-1:4-POE	No	Yes
LSB1GP48	48-port Gigabit Ethernet optical interface card-1:4	Yes (1%)	No
LSB1XK1	1-port 10GE optical interface card	Yes (100%)	No
LSB1XP2	2-port 10GE optical interface card	Yes (100%)	No
LSB1XP4L	4-port 10GE optical interface card	Yes (100%)	No
LSB1AHP4G	2-port OC-3-ATM + 2-port OC-3/12-ATM + 8-port Gigabit optical interface card	Yes (1%)	No
LSB1CLP4G	4-port channelized OC-3-POS + 4-port Gigabit interface card	Yes (1%)	No
LSB1ET32G	32-port channelized E1/T1 electrical interface + 4-port Gigabit optical interface card	Yes (1%)	No
LSB1F32G	32-port fast Ethernet electrical interface + 4-port Gigabit Ethernet optical interface card	Yes (1%)	No
LSB1P4G8	4-port OC-3c POS optical interface + 8-port Gigabit optical interface card	Yes (1%)	No
LSB1GT8P	8-port Gigabit electrical interface + 4-port Gigabit optical interface card (B)	Yes (1%)	Yes
LSB1FW8	Firewall card with eight Gigabit optical interfaces	Yes (1%)	No
LSB1IPSEC8	IPSec card with eight Gigabit optical interfaces	Yes (1%)	No
LSB1XP4	4-port 10 GE optical interface card-1:2	No	No
LSB1FP20	20-port 100 Mbps optical Ethernet interface board	Yes (100%)	No

1.1.1 Establishing OAM Connection

OAM connection is established in the OAM discovery phase. Through OAM connection, interconnected equipment can exchange OAM configuration information and announce the OAM capabilities supported by a local node.

The equipment can establish OAM connection in the active mode or in the passive mode. Table 1-2 compares the processing capabilities of data terminal entity (DTE) in the passive and active mode.

Table 1-2 Comparison between processing capabilities of active DTE and passive DTE

Processing capability	Active DTE	Passive DTE
Initialize OAM discovery	Yes	No
Respond to the initialization of OAM discovery	Yes	Yes
Send information OAM protocol data unit (OAMPDU)	Yes	Yes
Send event notification PDUs	Yes	Yes
Send loopback OAMPDUs	Yes	No
Send information OAMPDUs without TLV	Yes	Yes
Send variable request OAMPDUs	Yes	No
Send variable response OAMPDUs	Yes, but the peer DTE is required to be in the active mode.	Yes
Send loopback control OAMPDUs	Yes	No
Respond to loopback control OAMPDUs	Yes, but the peer DTE is required to be in the active mode.	Yes
Send organization specific OAMPDUs	Yes	Yes

If OAM configurations at both ends are consistent, OAM operation begins at the data link layer.

1.1.2 Link Monitor

Through link monitor, you can detect and find faults in various environments at the data link layer. Link monitor uses event notification PDUs. When a link fault occurs, the local link notifies the OAM entity of the fault after detecting the fault. The following table defines standard link events.

Table 1-3 Standard link events

Standard link events	Definition
Error signal event	The number of error signals within a fixed period of time exceeds the defined threshold.
Errored frame event	The number of errored frames within a fixed period of time exceeds the defined threshold.
Errored frame period event	The number of errored frames received within the period of N frames exceeds the defined threshold.
Errored frame seconds event	The number of error seconds within M seconds exceeds the defined threshold.

802.3ah does not guarantee that all OAMPDUs can be sent successfully. An event notification OAMPDU should be sent multiple times to handle the packet loss situation and a counting sequence number is used to identify each OAMPDU to be sent.

1.1.3 Diagnosing Remote Faults

Ethernet faults are difficult to diagnose, especially when physical communication is still maintained but network performance is decreasing gradually. OAMPDU defines a flag to allow an OAM entity to send information to the peer. The flag defines an emergency link event supported by OAM. Currently, OAM defines the link fault event, which occurs when the local end can send data, but cannot receive data. In this case, OAMPDUs are sent once every second.

1.1.4 Remote Loopback

A local OAM entity can send a remote loopback OAMPDU to the remote OAM entity, requesting the remote OAM entity to perform loopback. This function can provide necessary help for troubleshooting.

In the loopback mode, all packets except OAMPDUs and pause packets are returned along the way they are sent. Periodical loopback detection can guarantee that current links are smooth. Loopback detection in phases can help you locate specific areas where faults occur.

1.1.5 Remote MIB Variable Request

A local OAM entity can send a remote MIB request OAMPDU to the remote OAM entity, requesting the remote OAM entity to notify the local end of the current MIB variable. This function can be used to periodically monitor the link state of the remote port.

1.1.6 OAMPDU

The formats of OAMPDUs are as follows.

Figure 1-1 OAMPDU formats

This document involves the following packets:

I. Information OAMPDU

The information OAMPDU is used to send state information, such as local information, remote information, and user-defined information, to the remote OAM entity for maintaining OAM connection.

II. Event notification OAMPDU

The event notification OAMPDU is used for link monitoring and is used to notify the remote OAM entity that a fault has occurred to the link.

III. Var request OAMPDU

The Var request OAMPDU is used for variable request, primarily for MIB variables request.

IV. Var response OAMPDU

The Var response OAMPDU is used for responding to variable requests. This packet is used for returning MIB values.

V. Loopback control OAMPDU

The loopback control OAMPDU is used for remote loopback control. The device can determine whether to send the packet. To implement loopback control, the local DTE sends the loopback control command to the remote DTE. If loopback control is enabled on the remote DTE, the remote DTE returns the packet to the sending entity directly.

1.2 Configuring OAM

Complete the following tasks to configure OAM:

l Setting OAM Mode

l Enabling OAM

l Configuring the Error Signal Detection Interval and Error Threshold

l Configuring the Error Frame Detection Interval and Error Threshold

l Configuring the Error Frame Period Detection Interval and Error Threshold

l Configuring the Error Frame Second Detection Interval and Error Threshold

l Enabling/Disabling OAM Remote Loopback

l Setting the Interval for Sending OAM Hello PDUs

l Setting the OAM Link Timeout Time

1.2.1 Setting OAM Mode

Follow these steps to configure the OAM mode for the current port:

To do …	Use the command …	Remarks
Enter system view	system-view	—
Enter Ethernet port view	interface interface-type interface-number	—
Set OAM mode	oam ethernet mode { active \| passive }	Optional By default, OAM is set to the passive mode.

& Note:

l The OAM entity in the active mode can initiate an OAM connection, while the OAM entity in the passive mode can only wait for the connection request sent from the opposite OAM entity.

l You cannot establish an OAM connection between two OAM entities in the passive mode.

l After the OAM function is enabled by entering the oam ethernet enable command, you are not allowed to change the OAM mode. If needed, you can first disable the OAM, then change the OAM mode, and finally enable OAM again.

1.2.2 Enabling OAM

Follow these steps to enable OAM on an Ethernet port:

To do …	Use the command …	Remarks
Enter system view	system-view	—
Enter Ethernet port view	interface interface-type interface-number	—
Enable OAM on the current port	oam ethernet enable	Required After OAM is enabled, the current Ethernet port starts to establish OAM connection with the peer entity in the preset mode. OAM is disabled by default.

1.2.3 Configuring the Error Signal Detection Interval and Error Threshold

Follow these steps to configure the error signal detection interval and the error threshold for creating an error signal event:

To do …	Use the command …	Remarks
Enter system view	system-view	—
Configure the error signal detection interval	oam ethernet errored-symbol period period-value	Optional The default is 1 second.
Configure the error threshold for creating an error signal event	oam ethernet errored-symbol threshold threshold-value	Optional The default is 1.
Display the configuration information	display oam ethernet configuration	Available in any view

& Note:

l If the number of error signals detected on a port over a detection interval is equal to or greater than the error threshold, an error signal event is created.

l After the OAM connection is established, the configured values take effect on all the Ethernet ports automatically.

1.2.4 Configuring the Error Frame Detection Interval and Error Threshold

Follow these steps to configure the error frame detection interval and the threshold for creating an error frame event:

To do …	Use the command …	Remarks
Enter system view	system-view	—
Configure the error frame detection interval	oam ethernet errored-frame period period-value	Optional The default is 1 second.
Configure the error threshold for creating an error frame event	oam ethernet errored-frame threshold threshold-value	Optional The default is 1.
Display the configuration information	display oam ethernet configuration	Available in any view

& Note:

l If the number of error frames detected on a port over a detection interval is equal to or greater than the error threshold, an error frame event is created.

l After the OAM connection is established, the configured values take effect on all the Ethernet ports automatically.

1.2.5 Configuring the Error Frame Period Detection Interval and Error Threshold

Follow these steps to configure the error frame period detection interval and the error threshold for creating an error frame period event:

To do …	Use the command …	Remarks
Enter system view	system-view	—
Configure the error frame period detection interval	oam ethernet errored-frame-period period period-value	Optional The default is 1 second.
Configure the error threshold for creating an error frame period event	oam ethernet errored-frame-period threshold threshold-value	Optional The default is 1.
Display the configuration information	display oam ethernet configuration	Available in any view

& Note:

l The system converts the configured interval to the maximum number of packets that a port can send over this interval, that is, the maximum number of packets sent serves as the interval.

l If the number of error frames detected on a port over a detection interval is equal to or greater than the error threshold, an error frame period event is created.

l After the OAM connection is established, the configured values take effect on all the Ethernet ports automatically.

1.2.6 Configuring the Error Frame Second Detection Interval and Error Threshold

Follow these steps to configure the error frame second detection interval and the error threshold for creating an error frame second event:

To do …	Use the command …	Remarks
Enter system view	system-view	—
Configure the error frame second detection interval	oam ethernet errored-frame-seconds period period-value	Optional The default is 60 seconds.
Configure the error threshold for creating an error frame second event	oam ethernet errored-frame-seconds threshold threshold-value	Optional The default is 1.
Display the configuration information	display oam ethernet configuration	Available in any view

& Note:

l Error frame seconds are the seconds within which error frames are detected.

l The threshold value should not be greater than the corresponding interval; otherwise, no error frame second event can be created.

l If the number of error frame seconds detected on a port over a detection interval is equal to or greater than the error threshold, an error frame second event is created.

l After the OAM connection is established, the configured values take effect on all the Ethernet ports automatically.

1.2.7 Enabling/Disabling OAM Remote Loopback

Follow these steps to perform or remove an OAM remote loopback:

To do …	Use the command …	Remarks
Enter system view	system-view	—
Enter Ethernet port view	interface interface-type interface-number	—
Enable OAM remote loopback	oam ethernet loopback	Optional OAM remote loopback is disabled by default.
Disable OAM remote loopback	undo oam ethernet loopback	Optional OAM remote loopback is disabled by default.
Display the configuration information	display oam ethernet loopback status	Available in any view

& Note:

l The oam ethernet loopback command just triggers loopback, and buildrun is not performed.

l You can perform remote loopback only after establishing the OAM connection; otherwise the system will give an error prompt.

l Remote loopback needs the support of remote hardware. If the remote hardware does not support remote loopback, the system gives a prompt message.

l OAM remote loopback is used to test a single link. It is not supported on aggregated ports. Ports in remote loopback are not allowed to join aggregation.

1.2.8 Setting the Interval for Sending OAM Hello PDUs

Follow these steps to set the interval for sending OAM hello PDUs:

To do …	Use the command …	Remarks
Enter system view	system-view	—
Set the interval for sending OAM hello PDUs	oam ethernet timer hello interval	Optional By default, the interval for sending OAM hello PDUs is 1,000 ms.
Display the configuration information	display oam ethernet local	Available in any view.

1.2.9 Setting the OAM Link Timeout Time

Follow these steps to set the OAM link timeout time:

To do …	Use the command …	Remarks
Enter system view	system-view	—
Set the OAM link timeout time	oam ethernet timer keepalive interval	Optional By default, the OAM link timeout time is 5000 ms.
Display the configuration information	display oam ethernet local	Available in any view.

& Note:

After an OAM link times out, the local end of the Ethernet OAM will age out its connection to the remote OAM entity, resulting in disconnection of the OAM link. In normal conditions, you are recommended to set the timeout time to be longer than the interval for sending Ethernet OAM hello PDUs. Otherwise, a link may disconnect before Ethernet OAM hello PDUs are received, thus causing link instability.

1.3 Displaying and Maintaining OAM

To do …	Use the command …	Remarks
Display global configuration information of OAM	display oam ethernet configuration	Available in any view
Display the statistics about the link events after an OAM sub-layer reset or clear of the statistics	display oam ethernet link-event { local \| remote } [ interface interface-type interface-number ]	Available in any view
Display the statistics about link events after the establishment of the OAM connection	display oam ethernet critical-event [ interface interface-type interface-number ]	Available in any view
Display the information of the OAM connection	display oam ethernet { local \| remote } [ interface interface-type interface-number ]	Available in any view
Clear the statistics about Ethernet OAMPDUs and link events	reset oam ethernet [ interface interface-type interface-number ]	Available in user view
Display the variable information on the peer entity	display oam ethernet remote variable interface interface-type interface-number	Available in any view

& Note:

When specifying a port in any of the commands in this section, note that the interface-type argument must be Ethernet or GigabitEthernet and the interface-number argument must take the form of slot number/port number.

1.4 OAM Configuration Example

I. Network requirements

l Enable the OAM protocol on switches to manage the data link layer.

l Verify link performance by observing error frames received by the switches.

II. Network diagram

Figure 1-2 Network diagram for OAM configuration

III. Configuration procedure

1) Configure Switch A

# Set Ethernet 1/1/1 in the Passive mode, and then enable OAM.

<H3C>system-view

[H3C] interface ethernet 1/1/1

[H3C-Ethernet1/1/1] oam ethernet mode passive

[H3C-Ethernet1/1/1] oam ethernet enable

[H3C-Ethernet1/1/1] quit

# Configure the error frame detection interval.

[H3C] oam ethernet errored-frame period 20

# Configure the error threshold for creating an error frame event.

[H3C] oam ethernet errored frame threshold 10

# Display the global configuration information of OAM

[H3C] display oam ethernet configuration

Configuration of the link event window/threshold : (s = seconds, f = frames, ms= milliseconds)

--------------------------------------------------------------------------

Errored-symbol Event period : 1(s)

Errored-symbol Event threshold : 1(f)

Errored-frame Event period : 20(s)

Errored-frame Event threshold : 10(f)

Errored-frame-period Event period : 1000(ms)

Errored-frame-period Event threshold : 1(f)

Errored-frame-seconds Event period : 60(s)

Errored-frame-seconds Event threshold : 1(s)

2) Configure Switch B

# Enable OAM on Ethernet 1/1/1. The default OAM mode is Active.

<H3C> system-view

[H3C] interface ethernet 1/1/1

[H3C-Ethernet1/1/1] oam ethernet enable

[H3C-Ethernet1/1/1] quit

# Display the statistics about link events.

[H3C] display oam ethernet link-event remote

Port : Ethernet1/1/1

Link Status : Up

OAMRemoteErrFrameEvent : (s = seconds, f = frames, t = times)

--------------------------------------------------------------------------

Event Time Stamp : 5619(s) Errored Frame Window : 20(s)

Errored Frame Threshold : 10(f) Errored Frame : 1243635(f)

Error Running Total : 85887789(f) Event Running Total : 57(t)

H3C S9500 Operation Manual-Release1648[v1.24]-01 Access Volume

Chapter 1 Ethernet OAM Configuration

I. Information OAMPDU

II. Event notification OAMPDU

III. Var request OAMPDU

IV. Var response OAMPDU

V. Loopback control OAMPDU

1.2.1 Setting OAM Mode

I. Network requirements

II. Network diagram

III. Configuration procedure

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