L-ET4148-50C-DB LSI, L-ET4148-50C-DB Datasheet - Page 31

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

Specifications of L-ET4148-50C-DB

• Lead Free Status / RoHS Status: Supplier Unconfirmed

Preliminary Data Sheet
April 2006
Agere Systems Inc.
Functional Description
Policing
The accumulation process is triggered with each receive packet. The length (byte count) of each receive packet
within the associated flow is added to the policer’s accumulator. If the aggregate byte rate is greater than the band-
width permitted by the leak delta, then the value in the accumulator will tend to increase. The traffic flow is not con-
sidered out of profile until the value in the accumulator exceeds the user-defined accumulator limit. The setting of
this limit establishes the policer’s strictness. In other words, a higher limit means that the policer will tolerate a
longer out-of-profile burst before declaring the flow out-of-profile.
Once the flow is declared out-of-profile, several options are available for dealing with individual packets within the
flow. The ET4148-50 may be configured to discard all out-of-profile traffic. In this case, every packet in the flow is
discarded for as long as the accumulator is greater than the limit.
Alternately, the ET4148-50 may be configured to only discard out-of-profile traffic if the packet buffer is indicating
that it is congested. This congestion may be either global in nature (the total number of allocated buffers is greater
than the global congestion threshold) or local (the number of buffers allocated to the associated receive port is
greater that its congestion threshold).
Finally, the ET4148-50 has the ability to change the priority level of the receive packets for those flows that are out
of profile. The priority demotion takes place during egress processing immediately prior to transmission.
(continued)
Single-Chip 48 x 1 Gbit/s + 2 x 10 Gbits/s Layer 2+ Ethernet Switch
(continued)
Agere Systems - Proprietary
ET4148-50
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