![](http://datasheet.mmic.net.cn/330000/PM7323_datasheet_16444372/PM7323_178.png)
STANDARD PRODUCT
PM7323 RCMP-200
DATASHEET
PMC-960543
ISSUE 2
ROUTING CONTROL, MONITORING, & POLICING
200 MBPS
Proprietary and Confidential to PMC-Sierra, Inc.
and for its Customer’s Internal Use.
167
The value of the "Select" is set to the index of the most significant bit which
differs between the new VC and the "nearest" existing VC, which was found in
step 2. A few insights need highlighting:
1. If there is an overlap between Primary and Secondary Search keys (eg. the
Primary key is the VPI), the intersecting bits are excluded from the binary
search based on the fact they will always be the same in both keys.
2. Due to fact that the Primary Search key includes the PHY identification, NNI
and UNI connections will never reside in the same binary tree. Therefore, the
"Select" determination algorithm need all start its bit comparison at the
correct bit (the first bit of the ATM header for NNI and the fifth bit of the ATM
header for UNI) to ensure a valid search tree.
3. Perform a SRAM write (via the Microprocessor RAM Address and Data
registers) to incorporate the new Secondary Search Table entry in the existing
tree structure. This step must be performed last to ensure a binary search in
progress is not corrupted.
Five distinct types of insertions are possible based on the existing tree structure:
Key to data structure diagrams:
a, b, c -
pointers to Secondary Search Table entries
w, x, y, z
pointers to VC Table entries
k,m,n -
"select" field contents
The shaded boxes indicate those fields which have been created or modified.
1. The binary tree is empty. In this case, the null primary search table pointer is
modified to point to a newly created Secondary Search Table entry. Because
no bits within the Secondary Search Key are required, both the left and right
branches of the Secondary Search Table entry point to the same VC Table
Record. The "select" field should be set to zero.