Troubleshooting Ethernet Service Troubleshooting
802.3ah Ethernet OAM Tools
The 802.3ah standard or OAM for Ethernet in the First Mile is limited to managing and
troubleshooting the single-hop from the closest access platform to the customer's premise,
improving service reliability in this part of the network that often is problematic. As a link
level standard operating on a port by port basis, this standard cannot monitor an end-to-end
link or EVC or a particular application.
To enable and configure 802.3ah
802.3ah is enabled and configured on CO and CPE Ethernet Port Configuration dialog on
either side of the link (by default, the option is disabled on all ports).
Since EFM OAM can only monitor a single hop (i.e. from CO to CPE), messages are
contained in the link. OAM information is not passed to other network elements and alarms
and info messages are extracted from or sent to the operators access platform.
Key functions include:
EFM OAM Discovery. Enables ML device systems to identify the OAM capability of
other ML device systems (such as CPE) and exchange state and configuration
information such as Mode, Vendor, Unit ID, loopback support, and more. The MAX
OAM MFS size =1518 bytes. The transmit OAM size is optimized to the content
(minimum 64 bytes).
Remote Loopback (on page 15-22) with timeout test - a simple port-level end-to-end test
function to check traffic transmission performance.
Remote Failure Indication (RFI) - provides indication of loss of signal (LOS). On ETH
Optical Ports (100FX and 1000FX) with 802.3ah option enabled, when a loss of signal is
detected by the receiver, LOS alarm is raised on a local port and OAMPDU frames with
"link failure" bit set to 1 are transmitted back towards the opposite port. When OAMPDU
frames with "link failure" bit set to 1 are received from a peer port, the RFI alarm is
raised on a local port.
NOTE: RFI origination is unsupported on port configured in MODE=AUTO (auto-
negotiation) or HALF-DUPLEX, as specified in IEEE 802.3ah clause 22.2.4.1.12.
Performing Remote Loopback
This OAM option is used for link level testing between 802.3ah OAM-capable devices. This
test is used to compare TX/RX on the local port and ensure quality (frame loss) and
throughput (speed and duplex) of the link between two ports (local and remote). The process
is performed as follows:
Configuration is applied on the local port (the port that will forward through test traffic).
The local port will automatically (by special OAM PDU) configure the remote port (the
port that will perform a loopback of test traffic).
After configuration is completed, every Ethernet frame received on the remote port will
be transmitted back to the local port, without frame modification.
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