Brocade Multi-Service IronWare Administration Guide (Supporting R05.6.00) - Manual (Page 207)

Multi-Service IronWare Administration Guide 189
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IEEE 802.3ah EFM-OAM
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The IEEE 802.3ah EFM standard offers an opportunity to create the operations, OAM sub-layer
within the data-link layer of the OSI protocol stack. The data-link layer provides utilities for
monitoring and troubleshooting Ethernet links.
Possible applications
The data-link layer OAM is targeted at last-mile applications and service providers can use it for
demarcation point OAM services.
Ethernet Last Mile applications require robust infrastructure that is both passive and active.
802.3ah OAM aims to solve validation and testing problems in such an infrastructure.
Using the Ethernet demarcation service providers can additionally manage the remote device
without utilizing an IP layer. This can be done by using link-layer SNMP counters, request and reply,
loopback testing and other techniques.
EFM- OAM protocol
The functionality of the OAM-EFM can be summarized under the following categories:
Discovery: Discovery is the mechanism to detect the presence of an OAM sublayer on the remote
device. During the discovery process, information about OAM entities, capabilities and
configuration are exchanged.
Link monitoring: This process is used to detect link faults and to provide information about the
number of frame errors and coding symbol errors.
Remote fault detection: Provides a mechanism for an OAM entity to convey error conditions to its
peer via a flag in the OAMPDUs.
Remote loopback: This mechanism is used to troubleshoot networks and to isolate problem
segments in a large network by sending test segments.
Discovery
This is the first phase of the EFM-OAM. At this phase, EFM-OAM identifies network devices along
with their OAM capabilities. The Discovery process relies on the Information OAMPDUs (discussed
below). During discovery, the following information is advertised through the TLVs within periodic
Information OAMPDUs:
• OAM configuration (capabilities): Advertises the capabilities of the local OAM entity. Using this
information, a peer can determine what functions are supported and accessible (e.g. loopback
capability).
• OAM mode: This is conveyed to the remote OAM entity. The mode can be either active or
passive, and can also be used to determine device’s functionality.
• OAMPDU configuration: This includes maximum OAMPDU size to delivery. In combination with
the limited rate of ten frames/sec this information can be used to limit the bandwidth allocated
to OAM traffic.