Freescale Semiconductor MPC8260 - Manual (Page 948)

ATM Controller and AAL0, AAL1, and AAL5
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
30-28 Freescale Semiconductor
30.6.2 Virtual Path (F4) Flow Mechanism
The F4 flow is designated by pre-assigned virtual channel identifiers within the virtual path. The following
two kinds of F4 flows can exist simultaneously:
• End-to-end (identified as VCI 4)—This flow is used for end-to-end VPC operations
communications. Cells inserted into this flow can be removed only by the endpoints of the virtual
path.
• Segment (identified as VCI 3)—This flow is used for communicating operations information
within one VPC link or among multiple interconnected VPC links. The concatenation of VPC links
is called a VPC segment. Cells inserted into this flow can be removed only by the segment
endpoints, which must remove these cells to prevent confusion in adjacent segments.
30.6.3 Virtual Channel (F5) Flow Mechanism
The F5 flow is designated by pre-assigned payload type identifiers. The following two kinds of F5 flow
can exist simultaneously:
• End-to-end (identified by PTI = 5)—This flow is used for end-to-end VCC operations
communications. Cells inserted into this flow can be removed only by VC endpoints.
• Segment (identified by PTI = 4)—This flow is used for communicating operations information
with the bound of one VCC link or multiple interconnected VCC links. A concatenation of VCC
links is called a VCC segment. Segment endpoints must remove these cells to prevent confusion
in adjacent segments.
30.6.4 Receiving OAM F4 or F5 Cells
OAM F4/F5 flow cells are received using the raw cell queue, described in Section 30.4.4, “Receive Raw
Cell Queue.” An F4/F5 OAM cell which does not appear in the CAM or address compression tables is
considered a misinserted cell.
30.6.5 Transmitting OAM F4 or F5 Cells
OAM F4/F5 flow cells are sent using the usual AAL0 transmit flow. For OAM F4/F5 cell transmission,
program channel one in the TCT to operate in AAL0 mode. Enable the CR10 (CRC-10 insertion) mode as
described in
Section 30.10.2.3.3, “AAL0 Protocol-Specific TCT.” Prepare the OAM F4/F5 flow cell and
Table 30-9. Pre-Assigned Header Values at the NNI
Use VPI VCI PTI CLP
Segment OAM F4 flow cell aaaa_aaaa_aaaa 0000_0000_0000_0011 0a0 a
End-to-end OAM F4 flow cell aaaa_aaaa_aaaa 0000_0000_0000_0100 0a0 a
Segment OAM F5 flow cell aaaa_aaaa_aaaa aaaa_aaaa_aaaa_aaaa 100 a
End-to-end OAM F5 flow cell aaaa_aaaa_aaaa aaaa_aaaa_aaaa_aaaa 101 a
a= available for use by the appropriate ATM layer function