PXB4340E Datasheet, PDF (27/185 Pages) Infineon Technologies AG – ICs for Communications

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There are two groups of applications for OAM functions: alarms and measurements. Alarm
functions inform users and network operators about network failures. These include the OAM
functions
• Alarm Indication Signal (AIS)
• Remote Defect Indication (RDI)
• Continuity Check (CC).
AIS and RDI are used to convey transmission line failure information to subscriber and network
operator; CC detects ATM layer failures.
As failure events are unpredictable the alarm supervising HW is always running. When a failure
occurs the notification process starts automatically.
Measurements are initiated for diagnosis purposes by the network operator. Therefore these
functions do not need to be active permanently for all connections. The respective OAM
functions are:
• Loopback LB
• Performance Monitoring PM
LB checks the connectivity of a connection by sending a single cell which is looped back at
predefined points. LB is used e.g. immediately after connection set-up or periodically to check
all permanent connections of a network using end-to-end or segment LB. A network operator
could also use intra-domain LB to localize a failed link. Another option for loopback are
subscriber initiated loops either end-to-end to the partner or access line LB to the first node in
the network.
PM is a more precise tool than LB. It checks not only the connectivity, but the real performance
of a connection in terms of bit failures and cell losses. As it requires complex HW support and
SW performance PM will not be activated permanently for all connections. E.g. VPCs or
permanent VCCs could be monitored if a subscriber pays for this service. Also a network
operator would use PM to check the quality of a connection if a subscriber complains about it.
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There are two types of failures detected by the alarm functions: transmission line failures and
ATM layer failures. Transmission line failures are e.g. line brakes, failures of lasers or failures of
reception diodes. Typical ATM layer failures are the misrouting of cells in the switching fabric or
a falsified entry in a routing table. In this case all cells of a connection are forwarded to a wrong
destination.
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Transmission line failures are recognized by the receiving PHY and conveyed to the PXB 4340
AOP by the on-board control processor. It is sufficient to set one single bit for the respective PHY
to initiate the periodic insertion of AIS cells for all affected connections. In the external RAM entry
a bit CARIEN exists for F5-AIS and a bit PARIEN for F4-AIS ( for CARIEN see VHFWLRQ 
page 100, for upstream and VHFWLRQ  page 112, for downstream; for PARIEN see
VHFWLRQ  page 107, for upstream and VHFWLRQ  page 118, for downstream). When
these bits are set to ’1’, the insertion of AIS cells is enabled. Note, that no F4 OAM/User-Flow is
supported if the LCI-Mode "10" in register UTCONF1 is selected (see VHFWLRQ  page 88).
Further the bit DISF4 and DISF5 in the external RAM entries have to be set to ’0’ to enable the
Data Sheet
2-27
04.2000