User's Manual

50 ALFOplus 24GHz (North America) - Release 01.05.0x - MN.00395.E - 004
7.6 ETHERNET OAM (OPERATION ADMINISTRATION AND MAINTE-
NANCE)
This protocol can be used in any point-to-point Ethernet link. The aim of this protocol is to check and mon-
itor the functionality of the service that the provider guarantees on the network.
7.6.1 Service layer OAM
The Service Layer OAM fully monitors a customer End-to-End Ethernet Service. Two main standards cover
this topic, the IEEE 802.1ag and ITU-T Y.1731.
The IEEE 802.1ag provides CFM (Connectivity Fault Management) useful for detecting, isolating and re-
porting connectivity faults. The ITU-T Y.1731 Standard comprehends the CFM plus some additional fea-
tures, like RDI (Remote Defect Indicator) that allows to report back to the start of the chain the Alarm
message.
SIAE equipment support CFM according to both standards ITU-T Y.1731 and 802.1ag.
The IEEE 802.1ag and the ITU-T Y.1731 are End-to-End service, i.e. provide the tools to monitor the Ether-
net Service regardless of the layers, Network Path and operators. Since the spectrum of application can
include many applications a more hierarchical structure is needed.
The Standards define:
• Maintenance Domains (MD)
: these specify the Domains of operators, users and service providers.
Levels from 0 to 7 are possible depending on the type of service to be monitored. Customer Domain
is the higher which includes both ends of the Ethernet service (from one End user to the other End
user), Standard Default values for Customer Domain are 7, 6 and 5. Service Provider Domains
should have a MD lower than the Customer Domain since include the whole network except the End
Users. Standard default values for Provider Domains are 3 and 4. Operator Domains are lower than
Service Provider Domains since just a part of the network is included. Standard Default values for
operator domains are 0, 1 and 2. Here follows a picture explaining the hierarchical structure of Main-
tenance Domains.
•ALFOplus
: in SIAE equipment one Maintenance Domain can be specified. At each end of the Main-
tenance Domain two MEPs (Maintenance End Point) will be specified. The MEPs are “markers” that
define the end of a domain and are in charge of originating OAM frames. In a domain also MIPs
(Maintenance Intermediate Points) can be specified. The MIPs are passive check-points. The MEPs
and MIPs configuration are discussed in details in the following points. The choice of the domain and
the Domain Label (name) is left to the user. Particular attenuation must be paid to use the same
MD label in each equipment where the MD is specified, i.e. different equipment with same value of
MD domain but different MD labels belongs to different Domains.