Motorola MPC8260 - Manual (Page 808)

29-28 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
Table 29-9 lists pre-assigned header values at the network-node interface (NNI).
29.6.2 Virtual Path (F4) Flow Mechanism
The F4 ßow is designated by pre-assigned virtual channel identiÞers within the virtual path.
The following two kinds of F4 ßows can exist simultaneously:
¥ End-to-end (identiÞed as VCI 4)ÑThis ßow is used for end-to-end VPC operations
communications. Cells inserted into this ßow can be removed only by the endpoints
of the virtual path.
¥ Segment (identiÞed as VCI 3)ÑThis ßow 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 ßow can
be removed only by the segment endpoints, which must remove these cells to
prevent confusion in adjacent segments.
29.6.3 Virtual Channel (F5) Flow Mechanism
The F5 ßow is designated by pre-assigned payload type identiÞers. The following two kinds
of F5 ßow can exist simultaneously:
¥ End-to-end (identiÞed by PTI = 5)ÑThis ßow is used for end-to-end VCC
operations communications. Cells inserted into this ßow can be removed only by VC
endpoints.
¥ Segment (identiÞed by PTI = 4)ÑThis ßow 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.
29.6.4 Receiving OAM F4 or F5 Cells
OAM F4/F5 ßow cells are received using the raw cell queue, described in Section 29.4.4,
ÒReceive Raw Cell Queue.Ó An F4/F5 OAM cell which does not appear in the CAM or
address compression tables is considered a misinserted cell.
Table 29-9. Pre-Assigned Header Values at the NNI
Use VPI VCI PTI CLP
Segment OAM F4 ßow cell aaaa_aaaa_aaaa 0000_0000_0000_0011 0a0 a
End-to-end OAM F4 ßow cell aaaa_aaaa_aaaa 0000_0000_0000_0100 0a0 a
Segment OAM F5 ßow cell aaaa_aaaa_aaaa aaaa_aaaa_aaaa_aaaa 100 a
End-to-end OAM F5 ßow cell aaaa_aaaa_aaaa aaaa_aaaa_aaaa_aaaa 101 a
a= available for use by the appropriate ATM layer function