L-ET4148-50C-DB LSI, L-ET4148-50C-DB Datasheet - Page 24

• Manufacturer Part Number: L-ET4148-50C-DB
• Manufacturer: LSI

Specifications of L-ET4148-50C-DB

• Lead Free Status / RoHS Status: Supplier Unconfirmed

ET4148-50
Preliminary Data Sheet
Single-Chip 48 x 1 Gbit/s + 2 x 10 Gbits/s Layer 2+ Ethernet Switch
April 2006
Functional Description
(continued)
Access Control
(continued)
Receive packets are associated with access control lists (ACLs) based on either their receive port or the VLAN to
which they’ve been assigned. If the ACL associated with a receive packet is empty, then the packet is automatically
permitted to be received and processed normally. No further action is taken by the ACL process in this case.
For a nonempty ACL, each of the packet’s fields that make up the ACL 5-tuple are submitted to a look-up, which
ultimately results in the gathering of five access control entry (ACE) map values. These ACE maps indicate which
of the ACEs that make up the ACL have criteria that are satisfied by the corresponding field in the receive packet.
For example, a TCP destination port value of 3,027 may satisfy one rule that stipulates a range of 3,000 to 4,000
and another that specifies all values less than 7,000. In this example, 2 bits in the corresponding ACE map are
asserted with each bit indicating which ACE has matching criteria.
Once all five ACE maps have been retrieved, they are ANDed together in a bitwise fashion to indicate those ACEs
where all five criteria are satisfied by the fields in the receive packet. The leftmost bit in the resulting ACE map indi-
cates the first ACE in the ACL that matches all of the criteria. In the case where multiple ACEs match the against
the receive packet, it is the one that appears first in the ACL that is applied to the receive packet.
The actions that may be carried out as a result of a matching ACE are as follows:
1. Packet denial or permission
2. Packet logging
3. Priority reassignment
The ET4148-50 may also be configured to automatically log all denied packets.
24
Agere Systems Inc.
Agere Systems - Proprietary