SNR S2940-8G-v2 Switch Configuration Guide
CFM-OAM Configuration
• ITU-Y.1731: OAM functions and mechanisms for Ethernet based network
• MEF E-LMI: Ethernet Local Management Interface
EFM OAM and CFM as the constitute to set the IEEE, EFM OAM working data link layer, as
shown in Figure 15.1, can discover and manage the lower layer's data links effectively. Also, we
can use EFM OAM technology to increase the management and maintenance ability, in order to
maintain the stability of operation. CFM is the network level of Ethernet OAM technology, mainly
use for the connect pool layer and responds for inspecting the connectedness of the network,
orientating the failure of network connectedness. Y.1731 is establish by the ITU, the international
telecom union, it's function is much bigger than CFM. Can also say that the function which perform
by CFM is the subset of Y.1731. E-LMI is established by the MEF; only apply for UNI (the user
boundary and the provider boundary that is faced by the user).
15.2 CFM OAM Basic Concept
802.1ag divide the whole network (customer, provider, operator) into different MD (Maintenance
Domain). In each of the maintenance domains, it wills contrapose the MD provided service for
maintenance management. On these services, there will have a lot of node point facilities. The
core idea of the service of 802.1ag is inspecting the involved or all node points, so that it can dis-
cover the failure parts. The point that participates in maintenance inspection is called MP (Main-
tenance Point), the bridge of port that configure on the maintenance point.
15.2.1 Maintenance Domain
The network can be logically divided into different layers from internal to external; it is called MD
(Maintenance Domain). The maintenance domain can be nesting but not across. Each of the
vindicator can only see it own maintenance domain. The lower level of maintenance can provide
the service to the border upon upper layer. Then, it can separate the vindicator e.g. operator and
the user clearly. It can orientate the network problem more convenient.
In the network can contains of multi maintenance domain, each of the maintenance domain
locates in particular level, totally there are 8 levels. The higher the level, the range of maintenance
is higher. The higher level can nesting into lower level of domain. In the reality, CFM usually
applies for the following situation. At this moment, it will divide into customer domain, service
provider domain, operator domain etc.
Except the level, each of the MD has the global unique MD Name, which uses for label that
MD.
15.2.2 Maintenance Set
Each of the service instances in the maintenance domain is a MA (Maintenance Association).
One MD usually provide several service instances externally, 802.1ag is one to one management
maintenance and inspect the failure of MA. Each of the MA will have a unique name in the MD.
In the network, service instance usually mark by vlanId. And MA is corresponding to the services
instances. Therefore, there is a linkage between MA and vlanId. One MA corresponds to one
vlanId, at the same time, protocol allows many vlanId manage and maintain by one MA. In these
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