Link Layer Oam Operational Modes; Link Layer Oam Discovery - Dell Force10 C150 Configuration Manual

Link Layer OAM Operational Modes

When participating in EFM OAM, system may operate in active or passive mode.
• Active mode—Active mode systems initiate discovery. Once the Discovery process completes, they
can send any OAMPDU while connected to a peer in Active mode, and a subset of OAMPDUs if the
peer is in Passive mode (see
• Passive mode—Passive mode systems wait for an active mode system to initiate discovery, and do not
send Variable Request or Loopback Control OAMPDUs.
Taken from IEEE 802.3ah,
Table 6-1. Active Mode and Passive Mode Behaviors
Capability
Initiates OAM Discovery process
Reacts to OAM Discovery process initiation
Required to send Information OAMPDUs
Permitted to send Event Notification OAMPDUs
Permitted to send Variable Request OAMPDUs
Permitted to send Variable Response OAMPDUs (the peer must be in Active mode)
Permitted to send Loopback Control OAMPDUs
Reacts to Loopback Control OAMPDUs (the peer must be in Active mode)
Permitted to send Organization Specific OAMPDUs

Link Layer OAM Discovery

OAM Discovery is the mechanism a Link Layer OAM-capable system uses to determine if the remote
system on the link has OAM functionality enabled. OAM Discovery ascertains OAM parameters, such as
maximum allowable OAMPDU size, and supported functions such as OAM remote loopback.
The discovery process is as follows:
1. If the link is not in Fault state, Active mode systems send Information OAMPDUs that contain (only)
the Local Information TLV.
2. Once a system receives an Information OAMPDU, it responds with an Information OAMPDU that
contains the Local and Remote Information TLV. Negotiation is complete when both systems have
received their peer's information and are satisfied with it; to be satisfied, both peers on the link must be
have link performance event monitoring enabled.
3. When negotiation is complete, both peers may send any type of OAMPDU.
Table 6-1).
Table 6-1 summarizes the permitted actions in each role.
Active Passive
Yes No
Yes Yes
Yes Yes
Yes Yes
Yes No
Yes Yes
Yes No
Yes Yes
Yes Yes
802.3ah | 95