Tp-Link T2600G-28MPS (TL-SG3424P) — обзор Ethernet OAM: Мониторинг и Управление Сетями [134/379]

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Chapter 8 Ethernet OAM

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OAM Overview

Ethernet OAM (Operation, Administration, and Maintenance) is a Layer 2 protocol for

monitoring and troubleshooting Ethernet networks. It can report the network status to network

administrators through the OAMPDUs exchanged between two OAM entities, facilitating

network management.

Ethernet OAM is a slow protocol with very limited bandwidth requirement. The frame

transmission rate is limited to a maximum of 10 frames per second; therefore, the impact of

OAM on data traffic is negligible.

On a point-to-point link between two OAM-enabled devices, OAM helps to monitor the link

status from the following three points.

1. Link performance monitoring, for detecting link errors.

2. Fault detection and alarm, for reporting link errors to the administrators.

3. Loopback testing, for detecting link errors through non-OAMPDUs.

Currently, Ethernet OAM is mainly used to monitor the data link in the “last mile”.



OAMPDUs

There are six types of OAMPDUs. The following figure shows the details of the most commonly

used OAMPDUs, namely, Information OAMPDU, Event Notification OAMPDU and Loopback

Control OAMPDU.

Figure 8-1 OAMPDUs

As Figure 8-1 shows, OAMPDUs are standard length Ethernet frames. They must be untagged

and range from 64 to 1518 bytes.

(1) Dest addr: The Dest addr (Destination MAC address) of an OAMPDU is the

Slow_Protocols_Multicast address (01:80:c2:00:00:02).

(2) Source addr: The Source addr is the MAC address associated with the port through which

the OAMPDU is transmitted.

(3) Type: The type field is fixed to 0x8809.

(4) Sub-type: The Sub-type field is fixed to 0x03.

(5) Flags: The flags field contains status bits of an OAM entity.

(6) Code: The code field identifies the specific type of OAMPDU. As mentioned above,

Information OAMPDU, Event Notification OAMPDU and Loopback control OAMPDU are

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