Datasheet

____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
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Figure 10-36. AAL1 Mapping, General
The structure of the AAL1 header is shown in Table 10-21 be
low.
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-without-CAS
 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) or high-speed interface (up to 51.84 Mbps). The AAL1