10-High Availability Configuration Guide

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01-Ethernet OAM configuration
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Configuring Ethernet OAM

Overview

Ethernet Operation, Administration and Maintenance (OAM) is a tool that monitors Layer 2 link status and addresses common link-related issues on the "last mile." Ethernet OAM improves Ethernet management and maintainability. You can use it to monitor the status of the point-to-point link between two directly connected devices.

Major functions of Ethernet OAM

Ethernet OAM provides the following functions:

·          Link performance monitoring—Monitors the performance indices of a link, including packet loss, delay, and jitter, and collects traffic statistics of various types.

·          Fault detection and alarm—Checks the connectivity of a link by sending OAM protocol data units (OAMPDUs) and reports to the network administrators when a link error occurs.

Ethernet OAMPDUs

Ethernet OAM operates on the data link layer. Ethernet OAM reports the link status by periodically exchanging OAMPDUs between devices, so that the administrator can effectively manage the network.

Ethernet OAMPDUs include the following types shown in Table 1.

Table 1 Functions of different types of OAMPDUs

OAMPDU type

Function

Information OAMPDU

Used for transmitting state information of an Ethernet OAM entity, including the information about the local device and remote devices, and customized information, to the remote Ethernet OAM entity, and maintaining OAM connections.

Event Notification OAMPDU

Used by link monitoring to notify the remote OAM entity when it detects problems on the link in between.

 

 

NOTE:

Throughout this document, an Ethernet OAM-enabled port is called an "Ethernet OAM entity" or an "OAM entity."

 

How Ethernet OAM works

This section describes the working procedures of Ethernet OAM.

Ethernet OAM connection establishment

Ethernet OAM connection is the basis of all the other Ethernet OAM functions. OAM connection establishment is also known as the "Discovery phase," where an Ethernet OAM entity discovers the remote OAM entity to establish a session.

In this phase, two connected OAM entities exchange Information OAMPDUs to advertise their OAM configuration and capabilities to each other for a comparison. If their link detection and link event settings match, the OAM entities establish an OAM connection.

An OAM entity operates in active mode or passive mode. OAM entities in active mode initiate OAM connections, and OAM entities in passive mode wait and respond to the OAM connection requests. To set up an OAM connection between two OAM entities, you must set at least one entity to operate in active mode.

Table 2 shows the actions that a device can perform in different modes.

Table 2 Active Ethernet OAM mode and passive Ethernet OAM mode

Item

Active Ethernet OAM mode

Passive Ethernet OAM mode

Initiating OAM Discovery

Available

Unavailable

Responding to OAM Discovery

Available

Available

Transmitting Information OAMPDUs

Available

Available

Transmitting Event Notification OAMPDUs

Available

Available

Transmitting Information OAMPDUs without any TLV

Available

Available

 

After an Ethernet OAM connection is established, the Ethernet OAM entities exchange Information OAMPDUs at the handshake packet transmission interval to detect the availability of the Ethernet OAM connection. If an Ethernet OAM entity receives no Information OAMPDU within the Ethernet OAM connection timeout time, the Ethernet OAM connection is considered disconnected.

Link monitoring

Error detection in an Ethernet is difficult, especially when the physical connection in the network is not disconnected, but network performance is degrading gradually.

Link monitoring detects link faults in various environments. Ethernet OAM entities monitor link status by exchanging Event Notification OAMPDUs. When detecting one of the link error events listed in Table 3, an OAM entity sends an Event Notification OAMPDU to its peer OAM entity. The network administrator can keep track of network status changes by retrieving the log.

Table 3 Ethernet OAM link error events

Ethernet OAM link events

Description

Errored symbol event

An errored symbol event occurs when the number of detected symbol errors in the detection window (specified number of received symbols) exceeds the predefined threshold.

Errored frame event

An errored frame event occurs when the number of detected error frames in the detection window (specified detection interval) exceeds the predefined threshold.

Errored frame period event

An errored frame period event occurs when the number of frame errors in the detection window (specified number of received frames) exceeds the predefined threshold.

Errored frame seconds event

An errored frame seconds event occurs when the number of errored frame seconds (the second in which an errored frame appears is called an "errored frame second") detected on a port in the detection window (specified detection interval) reaches the predefined threshold.

 

Remote fault detection

Information OAMPDUs are exchanged periodically among Ethernet OAM entities across established OAM connections. In a network where traffic is interrupted due to device failures or unavailability, the flag field defined in Information OAMPDUs allows an Ethernet OAM entity to send error information (any critical link event type shown in Table 4) to its peer. You can use the log information to track ongoing link status and troubleshoot problems promptly.

Table 4 Critical link events

Type

Description

OAMPDU transmission frequencies

Link Fault

Peer link signal is lost.

Once per second.

Dying Gasp

An unexpected fault, such as power failure, occurred.

Non-stop.

Critical Event

An undetermined critical event happened.

Non-stop.

 

Support of this switch series for the sending and receiving of Information OAMPDUs carrying critical link events is as follows:

·          Able to receive Information OAMPDUs carrying the critical link events listed in Table 4.

·          Unable to send Information OAMPDUs carrying Link Fault events.

·          Able to send Information OAMPDUs carrying Dying Gasp events when the device is rebooted or relevant ports are manually shut down. Physical IRF ports, but unable to send this type of OAMPDUs.

·          Unable to send Information OAMPDUs carrying Critical Events.

Protocols and standards

IEEE 802.3ah, Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications

Ethernet OAM configuration task list

Tasks at a glance

(Required.) Configuring basic Ethernet OAM functions

(Optional.) Configuring the Ethernet OAM connection detection timers

1.        (Optional.) Configuring link monitoring

·         Configuring errored symbol event detection

·         Configuring errored frame event detection

·         Configuring errored frame period event detection

·         Configuring errored frame seconds event detection

(Optional.) Configuring the action a port takes after it receives an Ethernet OAM event from the remote end

 

Configuring basic Ethernet OAM functions

To set up an Ethernet OAM connection between two Ethernet OAM entities, you must set at least one entity to operate in active mode. An Ethernet OAM entity can initiate OAM connection only in active mode.

To change the Ethernet OAM mode on an Ethernet OAM-enabled port, first disable Ethernet OAM on the port.

To configure basic Ethernet OAM functions:

 

Step

Command

Remarks

1.       Enter system view.

System-view

N/A

2.       Enter Layer 2 Ethernet port view.

interface interface-type interface-number

N/A

3.       Set the Ethernet OAM mode.

oam mode { active | passive }

The default is active Ethernet OAM mode.

4.       Enable Ethernet OAM.

oam enable

Ethernet OAM is disabled by default.

 

Configuring the Ethernet OAM connection detection timers

After an Ethernet OAM connection is established, the Ethernet OAM entities exchange Information OAMPDUs at the handshake packet transmission interval to detect the availability of the Ethernet OAM connection. If an Ethernet OAM entity receives no Information OAMPDU within the Ethernet OAM connection timeout time, the Ethernet OAM connection is considered disconnected.

By adjusting the handshake packet transmission interval and the connection timeout timer, you can change the detection time resolution for Ethernet OAM connections.

You can configure this command in system view or port view. The configuration in system view takes effect on all ports, and the configuration in port view takes effect on the specified port. For a port, the configuration in port view takes precedence.

After the timeout timer of an Ethernet OAM connection expires, the local OAM entity ages out its connection with the peer OAM entity, causing the OAM connection to disconnect. As a best practice to keep the Ethernet OAM connections stable, set the connection timeout timer to be at least five times the handshake packet transmission interval.

To configure the Ethernet OAM connection detection timers globally:

 

Step

Command

Remarks

1.       Enter system view.

System-view

N/A

2.       Configure the Ethernet OAM handshake packet transmission interval.

oam global timer hello interval

The default is 1000 milliseconds.

3.       Configure the Ethernet OAM connection timeout timer.

oam global timer keepalive interval

The default is 5000 milliseconds.

 

To configure the Ethernet OAM connection detection timers on a port:

 

Step

Command

Remarks

1.       Enter system view.

System-view

N/A

2.       Enter Layer 2/Layer 3 Ethernet port view.

interface interface-type interface-number

N/A

3.       Configure the Ethernet OAM handshake packet transmission interval.

oam timer hello interval

By default, an interface uses the value configured globally.

4.       Configure the Ethernet OAM connection timeout timer.

oam timer keepalive interval

By default, an interface uses the value configured globally.

 

Configuring link monitoring

After Ethernet OAM connections are established, the link monitoring periods and thresholds configured in this section automatically take effect on all Ethernet ports.

Configuring errored symbol event detection

An errored symbol event occurs when the number of detected symbol errors in the detection window (specified number of received symbols) exceeds the predefined threshold.

You can configure this command in system view or port view. The configuration in system view takes effect on all ports, and the configuration in port view takes effect on the specified port. For a port, the configuration in port view takes precedence.

To configure errored symbol event detection globally:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

2.       Configure the errored symbol event detection window.

oam global errored-symbol-period window window-value

By default, the errored symbol event detection window is 100000000.

3.       Configure the errored symbol event triggering threshold.

oam global errored-symbol-period threshold threshold-value

By default, the errored symbol event triggering threshold is 1.

 

To configure errored symbol event detection on a port:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

2.       Enter Layer 2/Layer 3 Ethernet port view.

interface interface-type interface-number

N/A

3.       Configure the errored symbol event detection window.

oam errored-symbol-period window window-value

By default, an interface uses the value configured globally.

4.       Configure the errored symbol event triggering threshold.

oam errored-symbol-period threshold threshold-value

By default, an interface uses the value configured globally.

 

Configuring errored frame event detection

An errored frame event occurs when the number of times that error frames in the detection window (specified detection interval) are detected exceeds the predefined threshold.

You can configure this command in system view or port view. The configuration in system view takes effect on all ports, and the configuration in port view takes effect on the specified port. For a port, the configuration in port view takes precedence.

To configure errored frame event detection globally:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

2.       Configure the errored frame event detection window.

oam global errored-frame window window-value

By default, the errored frame event detection window is 1000 milliseconds.

3.       Configure the errored frame event triggering threshold.

oam global errored-frame threshold threshold-value

By default, the errored frame event triggering threshold is 1.

 

To configure errored frame event detection on a port:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

2.       Enter Layer 2/Layer 3 Ethernet port view.

interface interface-type interface-number

N/A

3.       Configure the errored frame event detection window.

oam errored-frame window window-value

By default, an interface uses the value configured globally.

4.       Configure the errored frame event triggering threshold.

oam errored-frame threshold threshold-value

By default, an interface uses the value configured globally.

 

Configuring errored frame period event detection

An errored frame period event occurs when the number of times that frame errors in the detection window (specified number of received frames) are detected exceeds the predefined threshold.

You can configure this command in system view or port view. The configuration in system view takes effect on all ports, and the configuration in port view takes effect on the specified port. For a port, the configuration in port view takes precedence.

To configure errored frame period event detection globally:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

2.       Configure the errored frame period event detection window.

oam global errored-frame-period window window-value

By default, the errored frame period event detection window is 10000000.

3.       Configure the errored frame period event triggering threshold.

oam global errored-frame-period threshold threshold-value

By default, the errored frame period event triggering threshold is 1.

 

To configure errored frame period event detection on a port:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

2.       Enter Layer 2/Layer 3 Ethernet port view.

interface interface-type interface-number

N/A

3.       Configure the errored frame period event detection window.

oam errored-frame-period window window-value

By default, an interface uses the value configured globally.

4.       Configure the errored frame period event triggering threshold.

oam errored-frame-period threshold threshold-value

By default, an interface uses the value configured globally.

 

Configuring errored frame seconds event detection

CAUTION

CAUTION:

Make sure the errored frame seconds triggering threshold is less than the errored frame seconds detection window. Otherwise, no errored frame seconds event can be generated.

 

An errored frame seconds event occurs when the number of times that errored frame seconds are detected on a port in the detection window (specified detection interval) exceeds the predefined threshold.

You can configure this command in system view or port view. The configuration in system view takes effect on all ports, and the configuration in port view takes effect on the specified port. For a port, the configuration in port view takes precedence.

To configure errored frame seconds event detection globally:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

2.       Configure the errored frame seconds event detection window.

oam global errored-frame-seconds window window-value

By default, the errored frame seconds event detection window is 60000 milliseconds.

3.       Configure the errored frame seconds event triggering threshold.

oam global errored-frame-seconds threshold threshold-value

By default, the errored frame seconds event triggering threshold is 1.

 

To configure errored frame seconds event detection on a port:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

2.       Enter Layer 2/Layer 3 Ethernet port view.

interface interface-type interface-number

N/A

3.       Configure the errored frame seconds event detection window.

oam errored-frame-seconds window window-value

By default, an interface uses the value configured globally.

4.       Configure the errored frame seconds event triggering threshold.

oam errored-frame-seconds threshold threshold-value

By default, an interface uses the value configured globally.

 

Configuring the action a port takes after it receives an Ethernet OAM event from the remote end

This feature enables a port to log events and automatically terminate the OAM connection and set the link state to down.

To configure the action the port takes after it receives an Ethernet OAM event from the remote end:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

2.       Enter Layer 2/Layer 3 Ethernet port view.

interface interface-type interface-number

N/A

3.       Configure the action the port takes after it receives an Ethernet OAM event from the remote end.

oam remote-failure { connection-expired | critical-event | dying-gasp | link-fault } action error-link-down

By default, the port only logs the Ethernet OAM event it receives from the remote end.

 

Displaying and maintaining Ethernet OAM

Execute display commands in any view and reset commands in user view:

 

Purpose

Command

Display information about an Ethernet OAM connection.

display oam { local | remote } [ interface interface-type interface-number ]

Display Ethernet OAM configuration.

display oam configuration [ interface interface-type interface-number ]

Display the statistics on critical events after an Ethernet OAM connection is established.

display oam critical-event [ interface interface-type interface-number ]

Display the statistics on Ethernet OAM link error events after an Ethernet OAM connection is established.

display oam link-event { local | remote } [ interface interface-type interface-number ]

Clear statistics on Ethernet OAM packets and Ethernet OAM link error events.

reset oam [ interface interface-type interface-number ]

 

Ethernet OAM configuration example

Network requirements

On the network shown in Figure 1, perform the following operations:

·          Enable Ethernet OAM on Device A and Device B to auto-detect link errors between the two devices

·          Determine the performance of the link between Device A and Device B by collecting statistics about the error frames received by Device A

Figure 1 Network diagram

 

Configuration procedure

1.        Configure Device A:

# Configure FortyGigE 1/0/1 to operate in active Ethernet OAM mode, and enable Ethernet OAM for it.

<DeviceA> system-view

[DeviceA] interface fortygige 1/0/1

[DeviceA-FortyGigE1/0/1] oam mode active

[DeviceA-FortyGigE1/0/1] oam enable

# Set the errored frame event detection window to 20000 milliseconds, and set the errored frame event triggering threshold to 10.

[DeviceA-FortyGigE1/0/1] oam errored-frame window 200

[DeviceA-FortyGigE1/0/1] oam errored-frame threshold 10

[DeviceA-FortyGigE1/0/1] quit

2.        Configure Device B:

# Configure FortyGigE 1/0/1 to operate in passive Ethernet OAM mode (the default), and enable Ethernet OAM for it.

<DeviceB> system-view

[DeviceB] interface fortygige 1/0/1

[DeviceB-FortyGigE1/0/1] oam mode passive

[DeviceB-FortyGigE1/0/1] oam enable

[DeviceB-FortyGigE1/0/1] quit

3.        Verify the configuration:

Use the display oam critical-event command to display the statistics of Ethernet OAM critical link events. For example:

# Display the statistics of Ethernet OAM critical link events on all the ports of Device A.

[DeviceA] display oam critical-event

-----------[FortyGigE1/0/1] -----------

 Local link status   : UP

 Event statistics

   Link fault        : Not occurred

   Dying gasp        : Not occurred

   Critical event    : Not occurred

The output shows that no critical link event occurred on the link between Device A and Device B.

Use the display oam link-event command to display the statistics of Ethernet OAM link events. For example:

# Display Ethernet OAM link event statistics of the local end of Device A.

[DeviceA] display oam link-event local

------------ [FortyGigE1/0/1] -----------

 Link status: UP

 OAM local errored frame event

   Event time stamp        : 5789 x 100 milliseconds

   Errored frame window    : 200 x 100 milliseconds

   Errored frame threshold : 10 error frames

   Errored frame           : 13 error frames

   Error running total     : 350 error frames

   Event running total     : 17 events

The output shows that 350 errors occurred after Ethernet OAM is enabled on Device A, 17 of which were caused by error frames. The link is instable.

 

 

 

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