PM7311 pmc-sierra, PM7311 Datasheet - Page 75

• Manufacturer Part Number: PM7311
• Description: Freedm 84a1024l Assp Telecom Standard Datasheet
• Manufacturer: pmc-sierra

Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2021832, Issue 2
10.9.5
Figure 20 Encapsulated Chunk Structure (Full = False)
Byte 0
Byte 6
Byte 12
Byte 18
Byte 24
Byte 30
Figure 21 Linked List Data Structure of a Datagram
Frame Builder (FRMBLD)
Re-assembling frames/packets from fragments requires several steps: 1) the specific session has
to be identified, 2) individual fragments must be re-sequenced, and 3) packets must be re-
constructed from the re-sequenced fragments.
Connection Identification
The header of the datagram is used to index internal record structures needed to support re-
sequencing, and ingress queuing.
A lookup is used for HDLC channels supporting the Frame Relay protocol. The objective is to
reduce the HDLC channel (10 bits) and the Q.922 header (10 bit DLCI) to a 14-bit CI. The
HDLC channel number is concatenated with two bits indicating if the datagram is sequenced,
non-sequenced, corrupt, or control. This value is then concatenated with the DLCI(0-1023) for
sequenced and non sequenced datagrams to produce an index into the SSRAM memory.
Contained at the memory location is the 14 bit CI.
Size
Byte 5
Byte 11
Byte 17
Byte 23
Byte 29
Size = 3
Last = False; Full = True
Last = False; Full = True
Last = True; Full = False
Next address pointer
Next address pointer
Next address pointer
Starting Address
ECC(8)
Byte 4
Byte 10
Byte 16
Byte 22
Byte 28
FREEDM 84A1024L ASSP Telecom Standard Product Data Sheet
Byte 9
Byte 15
Byte 21
Byte 27
L
Byte 3
Address of 1st chunk in Datagram
(stored on a per HDLC channel basis)
F
EC(3)
1st chunk in Datagram
2nd chunk in Datagram
Last chunk in Datagram
NXT_CHUNK_PTR(19)
Byte 2
Byte 8
Byte 14
Byte 20
Byte 26
Byte 1
Byte 7
Byte 13
Byte 19
Byte 25
Released
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