Brocade Multi-Service IronWare Administration Guide (Supporting R05.6.00) - Manual (Page 208)

190 Multi-Service IronWare Administration Guide
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IEEE 802.3ah EFM-OAM
6
Timers
• Two configurable timers control the protocol, one determining the rate at which OAMPDUs are
to be sent, and the second controlling the rate at which OAMPDUs are to be received to
maintain the adjacency between devices.
• An additional 1-second non-configurable timer is used for error aggregation, which is
necessary for the Link Monitoring Process to generate link quality events.
• The timer should generate PDUs in the range of 1s - 10sec. The default value is 1sec.
• The Hold timer should assume the peer is dead if no packet is received for a period of 1s to
10s. The default value is 5 seconds.
Flags
• Included in every OAMPDU is a flags field, which contains, besides other information, the
status of the discovery process. There are three possible values for the status:
• Discovering: Discovery is in progress.
• Stable: Discovery is completed. Once aware of this, the remote OAM entity can start sending
any type of OAMPDU.
• Unsatisfied: When there are mismatches in the OAM configuration that prevent OAM from
completing the discovery, the discovery process is considered unsatisfactory and cannot
continue.
Process overvi ew
The discovery process allows a local Data Terminating Entity (DTE) to detect OAM on a remote DTE.
Once OAM support is detected, both ends of the link exchange state and configuration information
(such as mode, PDU size, loopback support, etc.). If both DTEs are satisfied with the settings, OAM
is enabled on the link. However, the loss of a link or a failure to receive OAMPDUs for five seconds
may cause the discovery process the start over again.
DTEs may either be in active or passive mode. Active mode DTEs instigate OAM communications
and can issue queries and commands to a remote device. Passive mode DTEs generally wait for the
peer device to instigate OAM communications and respond to, but do not instigate, commands and
queries. Rules of what DTEs in active or passive mode can do are discussed in the following
sections.
Rules for active mode
A DTE in Active mode:
• Initiates the OAM Discovery process
• Sends Information PDUs
• May send Event Notification PDUs
• May send Variable Request/Response PDUs.
• May send Loopback Control PDUs.
Exceptions:
• Does not respond to Variable Request PDUs from DTEs in Passive mode.
• Does not react to Loopback Control PDUs from DTEs in Passive mode.