NEC Network Controller uPD98502 User Manual
Page 266
CHAPTER 4 ATM CELL PROCESSOR
266
Preliminary User’s Manual S15543EJ1V0UM
(2) Packet descriptor
Figure 4-27. Transmit Queue Packet Descriptor
1
0 ENC CLPM
PTI
GFC
IM C10 AAL MB
CPCS-UU
CPI
31 30 29 28 27 26
24 23
20 19 18 17 16 15
8
7
0
Buffer Directory Address
31
0
Encapsulation mode is indicated.
1
LLC encapsulation
ENC
0
No encapsulation
CLP bit in the packet header is indicated.
00
Sets CLP bit in all cells as 0.
11
Sets CLP bit in all cells as 1.
01
Sets CLP bit in all cells except last cell as 1, and only CLP bit in last cell as 0.
CLPM
10
Not used.
PTI field in the packet header. Since this field indicates cell payload type, takes different
transmission procedure according to this field .
000
User data cell without congestion.
001
User data cell without congestion. Last cell in the packet.
Prohibited to be set by user. If this value is set, treats as 000.
010
User data cell with congestion.
011
User data cell with congestion. Last cell in the packet.
Prohibited to be set by user. If this value is set, treats as 010.
100
OAM F5 cell used to carry information between segments
101
OAM F5 cell used to carry information between end to end.
110
Prohibited to be set by user.
PTI
111
Prohibited to be set by user.
GFC
GFC field in the packet header is indicated.
IM
Indicates if ATM Cell Processor issues the transmitting indication to V
R
4120A.
1: Doesn’t send any transmitting indication to V
R
4120A.
0: Sends transmitting indications to V
R
4120A.
Indicates if CRC-10 should be inserted or not.
1
Insert CRC-10 in every cell.
C10
0
Not insert CRC-10.
Indicates if the transmitting packet is AAL-5 packet or not.
1
AAL-5 mode.
AAL
0
Raw cell mode. ATM Cell Processor treats cells in this packet as Raw cell.
Mailbox number for storing transmitting indication for this packet is indicated.
1
Mailbox number 3.
MB
0
Mailbox number 2.
CPCS-UU
User information. In AAL-5 mode, ATM Cell Processor inserts the pattern in this field to the CPI
field in the trailer. In Raw cell mode, this field is ignored.
CPI
User information. In AAL-5 mode, ATM Cell Processor inserts the pattern in this field to the CPI
field in the trailer. In Raw cell mode, this field is ignored.