OAM Configuration OAM Configuration I OAM Configuration Table of Contents Chapter 1 OAM Configuration...............................................................................................................1 1.1 OAM Overview......................................................................................................................... 1 1.1.1 OAM Protocol’s Attributes...........................................................................................1 1.1.2 OAM Mode.................................................................................................................... 2 1.1.3 Components of the OAM Packet............................................................................... 3 1.2 OAM Configuration Task List..................................................................................................4 1.3 OAM Configuration Tasks.......................................................................................................5 1.3.1 Enabling OAM on an Interface...................................................................................5 1.3.2 Configuring OAM Link Monitoring..............................................................................5 1.3.3 Configuring the Trouble Notification from Remote OAM Entity.............................7 1.3.4 Displaying the Information about OAM Protocol..................................................... 8 1.4 Configuration Example............................................................................................................9 1.4.1 Network Environment Requirements........................................................................ 9 1.4.2 Network Topology.........................................................................................................9 1.4.3 Configuration Procedure............................................................................................. 9 II OAM Configuration Chapter 1 OAM Configuration 1.1 OAM Overview EFM OAM of IEEE 802.3ah provides point-to-point link trouble/performance detection on the single link. However, EFM OAM cannot be applied to EVC and so terminal-to-terminal Ethernet monitoring cannot be realized. OAM PDU cannot be forwarded to other interfaces. Ethernet OAM regulated by IEEE 802.3ah is a relatively slow protocol. The maximum transmission rate is 10 frames per second and the minimum transmission rate is 1 frame per second. 1.1.1 OAM Protocol’s Attributes  Support Ethernet OAM devices and OAM attributes The Ethernet OAM connection process is called as the Discovery phase when the OAM entity finds the OAM entity of the remote device and a stable session will be established. During the phase, the connected Ethernet OAM entities report their OAM mode, Ethernet OAM configuration information and local-node-supported Ethernet OAM capacity to each other by interacting the information OAM PDU. If the loopback configuration, unidirectional link detection configuration and link-event configuration have been passed on the Ethernet OAM of the two terminals, the Ethernet OAM protocol will start working on the link layer.  Link monitoring The Ethernet OAM conducts the link monitoring through Event Notification OAM PDU. If the link has troubles and the local link monitors the troubles, the local link will transmits Event Notification OAM PDU to the peer Ethernet OAM to report the normal link event. The administrator can dynamically know the network conditions through link monitoring. The definition of a normal link event is shown in table 1. Table 1 Definition of the normal link event Normal Link Event Definition Period event of error Specifies the signal number N as the period. The number of signal error signals exceeds the defined threshold when N signals are received. Error frame event The number of error frames exceeds the defined threshold during the unit time. Period event of error Specifies the frame number N as the period. The number of frame error frames exceeds the defined threshold when N frames are received. Second frame of error Specifies that the number of seconds of the error frame frame exceeds the defined threshold in the designated M second. 1 OAM Configuration  Remote trouble indication It is difficult to check troubles in the Ethernet, especially the case that the network performance slows down while physical network communication continues. OAM PDU defines a flag domain to allow Ethernet OAM entity to transmit the trouble information to the peer. The flag can stand for the following emergent link events:  Link Fault: The physical layer detects that the reception direction of the local DTE has no effect. If troubles occur, some devices at the physical layer support unidirectional operations and allows trouble notification from remote OAM.  Dying Gasp: If an irrecoverable local error occurs, such as OAM shutdown, the interface enters the error-disabled state and then is shut down.  Critical Event: Uncertain critical events occur (critical events are specified by the manufacturer). Information OAM PDU is continuously transmitted during Ethernet OAM connection. The local OAM entity can report local critical link events to remote OAM entity through Information OAM PDU. The administrator thus can dynamically know the link’s state and handle corresponding errors in time.  Remote loopback OAM provides an optional link-layer-level loopback mode and conducts error location and link performance testing through non-OAM-PDU loopback. The remote loopback realizes only after OAM connection is created. After the OAM connection is created, the OAM entity in active mode triggers the remote loopback command and the peer entity responses the command. If the remote terminal is in loopback mode, all packets except OAM PDU packets and Pause packets will be sent back through the previous paths. Error location and link performance testing thus can be conducted. When remote DTE is in remote loopback mode, the local or remote statistics data can be queried and compared randomly. The query operation can be conducted before, when or after the loopback frame is transmitted to the remote DTE. Regular loopback check can promptly detect network errors, while segmental loopback check can help locating these network errors and then remove these errors.  Round query of any MIB variables described in chapter 30 of 802.3. 1.1.2 OAM Mode The device can conduct the OAM connection through two modes: active mode and passive mode. The device capacity in different mode is compared in table 2. Only OAM entity in active mode can trigger the connection process, while the OAM entity in passive mode has to wait for the connection request from the peer OAM entity. After the remote OAM discovery process is done, the local entity in active mode can transmit any OAM PDU packet if the remote entity is in active mode, while the local entity’s operation in active mode will be limited if the remote entity is in passive mode. This is because the device in active mode does not react on remote loopback commands and variable requests transmitted by the passive remote entity. Table 2 Comparing device capacity in active and passive modes 2 OAM Configuration Capacity Active Mode Passive Mode Initializing the Ethernet OAM discovery process Yes No Responding to the OAM discovery initialization Yes Yes process Transmitting the Information OAM PDU packet Yes Yes Permitting to transmit the Event Notification OAM Yes Yes PDU packet Allowing to transmit the Variable Request OAM Yes No PDU packet Allowing to transmit Variable Response OAM PDU Yes Yes packet Allowing to transmit the Loopback Control OAM Yes No PDU packet Responding to Loopback Control OAM PDU Yes, but there is a Yes request that the peer must be in ACTIVE mode. Allowing to transmit specified OAM PDU Yes Yes After the Ethernet OAM connection is established, the OAM entities at two terminals maintain connection by transmitting the Information OAM PDU packets. If the Information OAM PDU packet from the peer OAM entity is not received in five seconds, the connection times out and a new OAM connection then requires to be established. 1.1.3 Components of the OAM Packet Figure 1 Components of the OAM packet The following are the meanings of the fields of the OAM packet: 3 OAM Configuration  Destination address: means the destination MAC address of the Ethernet OAM packet.  Source address: Source MAC address of the Ethernet OAM packet
It is the MAC address of the transmitter terminal's port and also a unicast MAC address.  Length/Type: Always adopts the Type encoding. The protocol type of the Ethernet OAM packet is 0x8809.  Subtype: The subtype of the protocol for Ethernet OAM packets is 0x03.  Flags: a domain where the state of Ethernet OAM entity is shown  Code: a domain where the type of the OAMPDU packet is shown  Data/Pad: a domain including the OAMPDU data and pad values  checksum of the frame Table 3 Type of the CODE domain CODE OAMPDU 00 Information 01 Event Notification 02 Variable Request 03 Variable Response 04 Loopback Control 05-FD Reserved FE Organization Specific FF Reserved The Information OAM PDU packet is used to transmit the information about the state of the OAM entity to the remote OAM entity to maintain the OAM connection. The Event Notification OAMPDU packet is used to monitor the link and report the troubles occurred on the link between the local and remote OAM entities. The Loopback control OAMPDU packet is mainly used to control the remote loopback, including the state of the OAM loopback from the remote device. The packet contains the information to enable or disable the loopback function. You can open or shut down the remote loopback according to the contained information. 1.2 OAM Configuration Task List  Enabling OAM on an Interface  Enabling Remote OAM Loopback 4 OAM Configuration  Configuring OAM Link Monitoring  Configuring the Trouble Notification From Remote OAM Entity  Displaying the Information About OAM Protocol 1.3 OAM Configuration Tasks 1.3.1 Enabling OAM on an Interface Run the following command to enable OAM: Proced ure Command Purpose Step1 config Enters the GLOBAL configuration mode. Step2 interface intf-type intf-id Enters the interface configuration mode. Step3 ethernet oam Enables Ethernet OAM on an interface. Step4 ethernet oam [max-rate oampdus | Configures optional OAM parameters: min-rate seconds | mode {active |  The max-rate parameter is used to configure passive} | timeout seconds] the maximum number of OAMPDUs transmitted per second. It ranges between 1 and 10 and its default value is 10.  The min-rate parameter is used to configure the minimum transmission rate of OAMPDU. Its unit is second. It ranges between 1 and 10 and its default value is 1.  The mode {active | passive} parameter is used to set the mode of OAM. The OAM connection can be established between two interfaces only when at least one interface is in active mode.  The timeout parameter is used to set the timeout time of the OAM connection. It ranges between 2 and 30 seconds and its default value is 5 seconds. You can run no Ethernet OAM to shut down the OAM function. The remote OAM loopback cannot be enabled on the physical interface that belongs to the aggregation interface. 1.3.2 Configuring OAM Link Monitoring You can configure the low threshold and the high threshold of OAM link monitoring. The procedure to configure the remote OAM trouble indication on an interface is shown in the following table: Proced ure Command Purpose 5 OAM Configuration Step1 config Enters the GLOBAL configuration mode. Step2 interface intf-type intf-id Enters the interface configuration mode. Step3 ethernet oam link-monitor Enables link monitoring on an interface. The link negotiation-supported monitoring is supported by default. Step4 ethernet oam link-monitor Sets the high and low threshold of the periodical symbol-period {threshold {high event of the error signal, which triggers the error link { symbols |none} | low {symbols}} | events. window symbols} The threshold high parameter is used to configure the high threshold. Its unit is signal number. It ranges between 1 and 65535 and its default value is none. The threshold high parameter is used to configure the low threshold. Its unit is signal number. It ranges between 0 and 65535 and its default value is 1. The window parameter is used to configure the window size of the round-query period. The unit of the window size is the number of the 100M signal. The window size ranges between 10 and 600 on a 1000M Ethernet interface and its default value is 10 in this case, while the window size ranges between 1 and 60 on a 100M Ethernet interface and its default value is 1 in this case. Step5 ethernet oam link-monitor frame Sets the high and low thresholds of the error frame {threshold {high { symbols |none} | event, which triggers the link events of error frame. low {symbols}} | window symbols} The threshold high parameter is used to configure the high threshold. Its unit is signal number. It ranges between 1 and 65535 and its default value is none. The threshold high parameter is used to configure the low threshold. Its unit is signal number. It ranges between 0 and 65535 and its default value is 1. The window parameter is used to configure the window size of the round-query period. Its unit is second. It ranges between 1 and 60 and its default value is 1. Step6 ethernet oam link-monitor Sets the high and low thresholds of the period event frame-period {threshold {high of error frame, which triggers the link events of error { symbols |none} | low {symbols}} | frame period. window symbols} The threshold high parameter is used to configure the high threshold. Its unit is signal number. It ranges between 1 and 65535 and its default value is none. The threshold high parameter is used to configure the low threshold. Its unit is signal number. It ranges between 0 and 65535 and its default value is 1. The window parameter is used to configure the window size of the round-query period. The unit of 6 OAM Configuration the window size is the number of the 14881 frames. The window size ranges between 100 and 6000 on a 1000M Ethernet interface and its default value is 100 in this case, while the window size ranges between 10 and 600 on a 100M Ethernet interface and its default value is 10 in this case. Step7 ethernet oam link-monitor Sets the high and low thresholds of the second frame-seconds {threshold {high event of error frame, which triggers the link events of { symbols |none} | low {symbols}} | error frame’s second. window symbols} The threshold high parameter is used to configure the high threshold. Its unit is signal number. It ranges between 1 and 900 and its default value is none. The threshold high parameter is used to configure the low threshold. Its unit is second. It ranges between 0 and 900 and its default value is 1. The window parameter is used to configure the window size of the round-query period. Its unit is second. It ranges between 10 and 900 and its default value is 60. Step8 ethernet oam link-monitor Sets the high and low thresholds of the error CRC receive-crc {threshold {high frame event, which triggers the link events of CRC { symbols |none} | low {symbols}} | checksum error. window symbols} The threshold high parameter is used to configure the high threshold. Its unit is signal number. It ranges between 1 and 65535 and its default value is none. The threshold high parameter is used to configure the low threshold. Its unit is signal number. It ranges between 0 and 65535 and its default value is 1. The window parameter is used to configure the window size of the round-query period. Its unit is second. It ranges between 1 and 180 and its default value is 10. 1.3.3 Configuring the Trouble Notification from Remote OAM Entity You can configure an error-disable action on an interface. The local interface will enter the errdisabled state in the following cases: 1.The high threshold of a normal link event on a local interface is exceeded.
2. The remote interface which connects the local interface enters the errdisabled state.
3. The OAM function on the remote interface which connects the local interface is shut down by the administrator. The procedure to configure the remote OAM trouble indication on an interface is shown in the following table: Proced ure Command Purpose Step1 config Enters the GLOBAL configuration mode. 7 OAM Configuration Step2 interface intf-type intf-id Enters the interface configuration mode. Step3 ethernet oam remote-failure Configures the trigger action of a remote OAM {critical-event | dying-gasp | trouble on an interface: link-fault} action  The critical-event parameter is used to enable error-disable-interface an interface to enter the errdisabled state when an undesignated critical event occurs.  The dying-gasp parameter is used to enable the local interface to enter the errdisabled state if the high threshold of a normal link event on a local interface is exceeded or if the remote interface which connects the local interface enters the errdisabled state or if the OAM function on the remote interface which connects the local interface is shut down by the administrator.  The link-fault parameter is used to enable an interface to enter the errdisabled state when the receiver detects signal loss. The switch cannot generate the LINK FAULT packets and the Critical Event packets. However, these packets will be handled if they are received from the remote terminal. router can transmit and receive the Dying Gasp packet. When the local port enters the err disabled state or is closed by the administrator or the OAM function of the local port is closed by the manager, the Dying Gasp packet will be transmitted to the remote terminal that connects the local port. 1.3.4 Displaying the Information about OAM Protocol Table 4 Displaying the information about OAM protocol Command Purpose show ethernet oam discovery Displays the OAM discovery information on all interface [intf-type intf-id] interfaces or a designated interface. show ethernet oam statistics {pdu | Displays the OAM statistics information on all link-monitor | remote-failure} interface interfaces or a designated interface. [intf-type intf-id]  The pdu parameter is used to classify and count the OAM packets according to the code-domain value of the OAM packet.  The link-monitor parameter is used to display the detailed statistics information of normal link events.  The remote-failure parameter is to display the detailed statistics information about the remote trouble. show ethernet oam configuration Displays the OAM configuration information on all interface [intf-type intf-id] interfaces or a designated interface. show ethernet oam runtime interface Displays the OAM running information on all [intf-type intf-id] interfaces or a designated interface. The OAM running information includes the control variables in some 8 OAM Configuration protocols and the latest 10 times status changing records. 1.4 Configuration Example 1.4.1 Network Environment Requirements You need configure the OAM protocol on the interface where two switches connect for capturing the information about the switch receiving error frames on user access side. 1.4.2 Network Topology Figure 2 Network Topology 1.4.3 Configuration Procedure Configuring switch S1: Switch_config_g0/1#ethernet oam Switch_config_g0/1#ethernet oam mode passive Switch_config_g0/1#ethernet oam link-monitor frame threshold low 10 Switch_config_g0/1#ethernet oam link-monitor frame window 30 Switch_config_g0/1#show ethernet oam configuration int g0/1 GigaEthernet0/1 General ------- Admin state : enabled Mode : passive PDU max rate : 10 packets/second PDU min rate : 1 seconds/packet Link timeout : 1 seconds High threshold action: no action Remote Failure -------------- Link fault action : no action Dying gasp action : no action Critical event action: no action Remote Loopback --------------- 9 OAM Configuration Is supported : not supported Loopback timeout : 2 Link Monitoring --------------- Negotiation : supported Status : on Errored Symbol Period Event Window : 10 * 100M symbols Low threshold : 1 error symbol(s) High threshold : none Errored Frame Event Window : 30 seconds Low threshold : 10 error frame(s) High threshold : none Errored Frame Period Event Window : 100 * 14881 frames Low threshold : 1 error frame(s) High threshold : none Errored Frame Seconds Summary Event Window : 60 seconds Low threshold : 1 error second(s) High threshold : none Errored CRC Frames Event Window : 1 seconds Low threshold : 10 error frame(s) High threshold : none Configuring switch S2: Switch_config_g0/1#ethernet oam Switch_config_g0/1#show ethernet oam statistics link-monitor int g0/1 GigaEthernet0/1 Local Link Events: ------------- Errored Symbol Period Event: No errored symbol period event happened yet. 10 OAM Configuration Errored Frame Event: No errored frame event happened yet. Errored Frame Period Event: No errored frame period event happened yet. Errored Frame Seconds Summary Event: No errored frame seconds summary event happened yet. Errored CRC Frames Event: No errored CRC frame event happened yet. Remote Link Events: ------------------- Errored Symbol Period Event: No errored symbol period event happened yet. Errored Frame Event: No errored frame event happened yet. Errored Frame Period Event: No errored frame period event happened yet. Errored Frame Seconds Summary Event: No errored frame seconds summary event happened yet. Errored CRC Frames Event: No errored CRC frame event happened yet. 11