![](http://datasheet.mmic.net.cn/Maxim-Integrated-Products/DS34T102GN-_datasheet_97090/DS34T102GN-_85.png)
____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
85 of 366
10.6.11.2 Buffer Descriptor First Dword
Used for all paths. Located at offset 0x0 from the start of the buffer.
Table 10-24. Buffer Descriptor First Dword Fields (Used for all Paths)
Bits
Data Element
Description
[31]
MPLS/MEF/L2TIPV3
or UDP/IP-specific
OAM
For ETH TDM and for CPU TDM indicates that the buffer holds a packet with
MPLS / MEF / L2TPv3 Ethertype. For ETH CPU indicates that the buffer holds a
UDP/IP-specific OAM packet.
[30]
RST
RX Reset command (the bundle is in reset process).
For ETHTDM and for CPUTDM: used by the Packet Classifier or by the CPU to
inform the next blocks in flow that the bundle was reset. The buffer contains no real data.
[29:27]
Buffer contents
000: Backwards-compatible (experimental) format packet going to the AAL1 payload-
type machine
001: Standard format packet going to the AAL1 payload-type machine
010: Reserved
011: Non-TDMoP/MPLS packet (this buffer isn’t assigned to any bundle)
100: Standard format packet going to the HDLC payload-type machine
101: Reserved
110: Standard format packet going to the RAW payload-type machine
111: Backwards-compatible (experimental) format packet going to the HDLC payload-
type machine
[26:16]
Length/Rst_Ts
Packet Length or Payload Length
For TDMCPU, TDMTDM, CPUTDM and ETHTDM: payload length in bytes
(received bytes + control word if present + RTP header bytes in case of MPLS/MEF
packet using RTP and control word)
For TDMETH, ETHCPU and CPUETH: packet length in bytes, without CRC
For Buffer Contents =101: total length of packets concatenated in the buffer, in bytes
For RST packets: the reset timeslot number
Note: Length must be less than 1951 bytes.
Note: Offset and Length sum must be less than 2000 bytes.
[15]
Reserved
Must be set to zero.
[14:8]
Offset
For ETHCPU, TDMETH and CPUETH: offset in bytes from start of buffer to start
of packet
For ETHTDM, TDMCPU, CPUTDM: offset in bytes from start of buffer to start of
payload or to the control word if present
For TDMTDM: bits 13-8 hold the internal bundle number from which the buffer has
been transmitted
For CPUETH, when Buffer Content (above) is different than 011, must be calculated
as follows: tx_payload_offset – header_length
Note: Offset and Length sum must be less than 2000 bytes.
Note: header_length is the number of bytes from start of packet to the control word (or to
start of the payload if control word is not used).
[7]
HW/SW Type
The pool the buffer has been extracted from and should be returned to.
0: HW buffers pool
1: SW buffers pool
For packets coming from Ethernet:
0: destination = payload-type machines
1: destination = CPU
[6]
RTP
For ETHTDM, ETHCPU, TDMTDM and CPU TDM indicates whether the packet
includes an RTP header.
[5:0]
Bundle number
For TDM TDM: destination internal bundle number.
For any other bundle: packet internal bundle number