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Note: Ethernet running on top of a Layer 2 protocol, such as Ethernet over ATM, is not supported in OAM configurations. |
Ethernet interfaces on M-series, and T-series routing platforms support the IEEE 802.3ah standard for operation, administration, and management (OAM). You can configure 802.3ah OAM on Ethernet point-to-point direct links or links across Ethernet repeaters. The 802.3ah standard solves the OAM requirement as Ethernet moves from being solely an enterprise technology into being a WAN and access technology, as well as being backward compatible with existing Ethernet technology. JUNOS software supports 802.3ah discovery and monitoring, remote fault detection, and remote loopback.
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Note: Ethernet running on top of a Layer 2 protocol, such as Ethernet over ATM, is not supported in OAM configurations. |
When you include the interface statement at the [edit protocols oam ethernetlink-fault-management] hierarchy level, 802.3ah is enabled on a physical interface, and the discovery process is automatically triggered. The discovery process permits Ethernet interfaces to discover and monitor the peer on the link if it also supports the 802.3ah standard. Periodic OAM PDUs are sent to perform link monitoring.
Fault detection is based on either flags or fault event threshold limit values (TLVs) in OAM Protocol Data Units (PDUs). Flags that trigger a link fault are:
The link event TLVs are sent by the remote DTE by means of event notification PDUs. Link errors that trigger the sending of link event TLVs are:
You can configure threshold values for the fault events that trigger a link fault. To set threshold values for fault events, use the statements at the [edit protocols oam ethernet link-fault-management interface event-thresholds] hierarchy level.
Remote loopback is supported on IQ2 Gigabit Ethernet interfaces, 10-Gigabit Ethernet interfaces, and all Ethernet interfaces on the MX-series routers. When you configure remote loopback, the JUNOS software can place a remote DTE into loopback mode (if remote-loopback mode is supported by the remote DTE). Local interfaces react to the remote-loopback request sent by the remote DTE and put the interface into remote-loopback mode. When the peer is in remote-loopback mode, all frames except OAM PDUs are looped back without any changes to the frames. OAM PDUs continue to be sent to the management plane and processed. By default, remote loopback is not enabled. You can enable the remote loopback feature, using the statement allow-remote-loopback at the [edit protocols oam ethernet link-fault-management interface negotiation-options]hierarchy level.
You can disable monitoring of link event TLVs in periodic PDUs, using the statement no-allow-link-events at the [edit protocols oam ethernet link-fault-management interface negotiation-options] hierarchy level.
To view OAM statistics, use the operational mode command show oam ethernet link-fault-management. To clear OAM statistics, use the operational mode command clear oam ethernet link-fault-management statistics. To clear link fault management state information and restart the link discovery process on Ethernet interfaces, use the operational mode command clear oam ethernet link-fault-management state. For more information about these commands, see the JUNOS Interfaces Command Reference.
You can configure the following 802.3ah OAM properties: