Juniper JUNOSE 11.1.X - LINK LAYER CONFIGURATION 4-7-2010, Руководство по настройке

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The Flags field is used to inform the local state to the peer. This state is used in
discovery and in remote failure detection. The Code field denotes the type of OAM
packet. The format of the OAM Data/Pad field consists of TLV elements.
Four types of OAM messages are supported:
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Information OAM PDU—A variable-length OAM PDU that is used for the discovery
process. This OAM PDU contains local, remote, and organization-specific
information.
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Event notification OAM PDU—A variable-length OAM PDU that is used for link
monitoring. This type of OAM PDU might be transmitted multiple times to
improve the probability of a successful receipt, such as in environments that
result in high-bit errors. Event notification OAM PDUs also include a timestamp
to signify the time at which they are triggered.
■
Loopback control OAM PDU—An OAM PDU predefined with a length of 64 bytes
to enable or disable the remote loopback command.
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Vendor-specific OAM PDU—A variable-length OAM PDU that enables the addition
of vendor-specific extensions to OAM.
Related Topics
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OAM Feature Overview on page 234
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Configuring 802.3ah OAM Link-Fault Management on page 242
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ethernet oam lfm
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ethernet oam lfm remote-loopback
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ethernet oam lfm remote-loopback supported
OAM Elements Overview
IEEE 802.3ah defines OAM procedures for a single point-to-point Ethernet link.
Ethernet OAM is a slow protocol with limited bandwidth requirements. The frame
transmission rate is limited to a maximum of 10 frames per second. As a result, the
impact of OAM on normal operations is negligible. However, when link monitoring
is enabled, the CPU must poll error counters frequently. In this case, the required
processor memory and usage are proportional to the number of interfaces that have
to be polled.
Two major elements, the OAM client and the OAM sublayer, make up the Ethernet
OAM. The OAM sublayer resides above the MAC layer and below the logical link
control (LLC) layer. The OAM sublayer presents a MAC data interface to MAC clients
and an OAM client interface to OAM clients. Figure 31 on page 232 shows the OAM
sublayer interfaces. For effective interoperation and enhanced collaboration with
802.3ad link aggregation, the OAM sublayer exists below the LAG bundle. The LAG
bundle is present between the OAM sublayer and the MAC client.
OAM Elements Overview
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Chapter 7: Configuring IEEE 802.3ah OAM Link-Fault Management