Motorola MPC8260 - Manual (Page 807)

29-27 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
29.5.3 ABR Flow Control Setup
Follow these steps to setup ABR ßow control:
1. Initialize the ABR data structure: RCT, TCT, RCT-ABR protocol-speciÞc, TCTE-
ABR protocol-speciÞc.
2. Initialize ABR global parameters in the parameter RAM. See Section 29.10.1,
ÒParameter RAM.Ó
3. Program the AAL-type in the RCT and TCT to AAL5 and set TCT[ABRF]. Note
that the ABR ßow control is available only with AAL5.
4. The time stamp timer generates the RM cellÕs time stamp, which the ABR ßow
control monitors to maintain source behavior in steps #3 and #7 of Section 29.5.1.1,
ÒABR Flow Control Source End-System Behavior.Ó Enable the time stamp timer by
writing to the RTSCR; see Section 13.3.7, ÒRISC Time-Stamp Control Register
(RTSCR).Ó
5. Initialize the ABR parameters (CPS_ABR and LINE_RATE_ABR) in the APCT;
see Section 29.10.4.1, ÒAPC Parameter Tables.Ó Note that when using ABR, the CPS
(cells per slot) parameter in the APCPT should be a power of two.
6. Finally, send the ATM TRANSMIT command to restart channel transmission.
29.6 OAM Support
This section describes the MPC8260Õs support for ATM-layer (F4 out-of-band, and F5 in-
band) operations and maintenance (OAM) of connections. Alarm surveillance, continuity
checking, remote defect indication, and loopback cells are supported using OAM receive
and transmit AAL0 cell queues. Using dedicated support, performance management block
tests can be performed on up to 64 connections simultaneously. The CP automatically
inserts forward monitoring cells (FMC) and generates backward-reporting cells (BRC) as
recommended by ITU I.610.
29.6.1 ATM-Layer OAM DeÞnitions
Table 29-8 lists pre-assigned header values at the user-network interface (UNI).
Table 29-8. Pre-Assigned Header Values at the UNI
Use GFC VPI VCI PTI CLP
Segment OAM F4 ßow cell xxxx aaaa_aaaa 0000_0000_0000_0011 0a0 a
End-to-end OAM F4 ßow cell xxxx aaaa_aaaa 0000_0000_0000_0100 0a0 a
Segment OAM F5 ßow cell xxxx aaaa_aaaa aaaa_aaaa_aaaa_aaaa 100 a
End-to-end OAM F5 ßow cell xxxx aaaa_aaaa aaaa_aaaa_aaaa_aaaa 101 a
a = available for use by the appropriate ATM layer function