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CHAPTER 5 SAR FUNCTION
181
LOCAL LECID
Local LECID.
When the receive LECID filtering function is enabled, the
μ
PD98405 compares the
value in this field with the receive LECID. If they match, all cells in the packet are
discarded. If the LFE bit is set to "0," this field has no meaning.
BACKWARD
POINTER
"VC NUMBER" of the VC linked to the T1 list prior to this VC.
LST
This bit is set to "1" if the VC is linked to the end of the T1 list.
FORWARD
POINTER
"VC NUMBER" of the VC linked to the T1 list subsequent to this VC.
Remarks 1.
Those fields indicated as "Reserved" are reserved for the
μ
PD98405. Do not attempt to
modify these fields except for initialization. Reset all of these fields to 0 at initialization.
2.
Do not modify Word 15, even at initialization, for open VC tables. Word 15 of the receive VC
table holds the pointers and flags required to enable the
μ
PD98405 to manage the VC table.
If Word 15 is modified by an external host, it becomes impossible for the
μ
PD98405 to
manage correctly.
3.
The rate field (EER) is represented as follows:
Rate = 2
e
*(1 + m/512)*nz cells/s
14
0
m
15
Re-
served
9
8
nz
e
13
4.
See also
Section 5.8.4
for details of the ABR parameter.
(3) Status transition of receive channel
The receive channel can assume one of three statuses: non-existent, idle, and active. The host opens a
channel by issuing an Open_Channel command. When the
μ
PD98405 receives this command, it reports
the address of the VC table to the host as a command indication from the free block pool in control
memory. Next, the host writes appropriate parameters (such as the pool number used, AAL-5
processing/raw cell processing, and the maximum allowed segment numbers) to the allocated block by
using the Indirect_Access command. Thus, this block becomes a receive VC table, and the channel enters
idle status.