Datasheet

____________________________________________________ DS34S101, DS34S102, DS34S104, DS34S108
Rev: 032609 55 of 198
Figure 10-36. AAL1 Mapping, General
The structure of the AAL1 header is shown in Table 10-21 below.
Table 10-21. AAL1 Header Fields
Field
Length
(bits)
Description
C
1
Indicates if there is a pointer in the second octet of the AAL1 SAR PDU. When set, a pointer exists.
SN
3
AAL1 SAR PDU sequence number
CRC
3
Cyclic redundancy code on C and SN
P
1
Even parity bit on C, SN and CRC or the even byte parity LSB for the sequence number octet (P
format AAL1 SAR PDUs only)
E
1
(P format AAL1 SAR PDUs only) Even byte parity MSB for pointer octet
Pointer
7
(P format AAL1 SAR PDUs only) Indicates the next structure boundary. It is always located at the first
possible position in the sequence number cycle in which a structure boundary occurs. The pointer
indicates one of 93 octets (46 octets of the current AAL1 SAR PDU + 47 octets of the next AAL1 SAR
PDU). P=0 indicates that the first octet of the current AAL1 SAR PDU’s payload is the first octet of the
structure. P=93 indicates that the last octet of the next AAL1 SAR PDU is the final octet of the
structure.
The AAL1 block supports the following bundle types:
• Unstructured
• Structured
• Structured-with-CAS.
Unstructured bundles, for E1/T1 interfaces, support rates of N × 64 kbps, where N is the number of timeslots
configured to be assigned to a bundle. Unstructured bundles may also carry traffic of the whole low-speed interface
(up to 4.6 Mbps), E1/T1 interface (2.048Mbps/1.544 Mbps) and high-speed interface (up to 51.84 Mbps). The AAL1