АМАТЕК AN-SGM28P24-400 [298/322] Cfm profile

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26.1 CFM profile

CFM is the abbreviation of Connectivity Fault Management (connected error

management). The CFM of this switch mainly refers to connected error detection, which follows

the CFM protocol defined by IEEE 802.1ag. It is a two layer link based on end to end OAM

VLAN (Operations Administration, and Maintenance, operation, management and maintenance)

mechanism, mainly used in the two layer of the network detection link connectivity, confirm the

fault and determine the fault position。

26.1.1 Basic concepts of CFM

1 Maintenance domain

The Maintenance Domain (MD) points out the network covered by the connectivity error

detection, whose boundaries are defined by a series of maintenance endpoints configured on the

port. The maintenance domain is marked by "domain name maintenance"。

In order to locate the fault point accurately, the concept of level (hierarchy) is introduced into

the maintenance domain. Maintenance domain is divided into eight levels, represented by integer

0~7, the larger the number, the higher the level, the greater the scope of the maintenance domain.

Different maintenance domains can be adjacent or nested, but can not cross, and nested can only

be embedded by high-level maintenance domain to low-level maintenance domain, that is to say,

low level maintenance domain must be included in the high-level maintenance domain. The CFM

PDU of the low-level maintenance domain will be discarded after entering the high-level

maintenance domain; the CFM PDU of the high-level maintenance domain can cross the low level

maintenance domain; the CFM PDU of the same level maintenance domain can not cross each

other。

Figure 1-1

In practical application, to rational planning of maintenance domain: as shown in Figure 1-1,

MD_B nested in the maintenance domain maintenance domain MD_A, to connectivity detection

in MD_A, MD_A CFM PDU is required to cross the MD_B, it needs to be MD_A better than

MD_B high level configuration. In this way, MD_A CFM PDU can pass through MD_B, so as to

achieve the whole MD_A connectivity fault management, and the MD_B CFM PDU will not

spread to MD_A。

Maintenance domain classification makes fault location more convenient and accurate, as

shown in Figure 1-1, MD_B embedded in the maintenance domain maintenance domain MD_A, if

it is found that the link is on the border of MD_A indicates that the domain of equipment

malfunction, failure may occur in Device A ~ Device E five device. At this time, if not found in