Specifications

Chapter 3: Configuration
Page 26 724-746-5500 | blackbox.com LGC340A
TX1/2
Ingress Bandwidth
Limit
(CIR)
Monitors the traffic entering the unit (ingress),
discarding traffic that exceeds a fixed Committed
Information Rate (CIR) plus Burst Allocation (BA).
Frames are not held in queue
, they either meet the
bandwidth limits and are accepted into the unit or
they are dropped.
Max Burst Allocation
size (BA)
The BA size is specified in bits; the # of bits above
the bandwidth limit before packets are thrown away.
Ingress Burst
Allocation
Bandwidth Limiting can be set at Ingress of each port
individually by setting the MAX BW Limit in bits/Sec.
and the BA in bits. Traffic in excess of the Bandwidth
limit plus BA for any time interval will be
dropped. This function utilizes an advanced “Leaky
Token-Bucket” algorithm to provide typical resolution
under 5% of the set values at all data rate and
frames sizes.
Egress Traffic
Shaping
Actively controls the transmitter and hard limits the
maximum frame rate that can be sent. Frames can
be delayed in the internal buffers of the unit, waiting
their turn to be sent. If the internal buffers are full,
excess traffic will be dropped. The Unit Rate Control
can be used to alleviate this.
Choose Layer 1, 2 or 3 for the counter, this will
determine how my bytes from the Ethernet frame are
to be included in the calculations.
Layer 1:
Layer 2:
Layer 3:
Preamble + DA to CRC + IFG
Frames DA to CRC
Frames DA to CRC – 18
(- 4 if frame is tagged)
OSI Level Used in
Calculations
(Open Systems
Interconnect, referring
to the seven layers
for TCP/IP)
Explanations:
Preamble
DA
CRC
IFG
= 8 bytes
= EtherNet Destination Address
= EtherNet Checksum
= 12 bytes
Unit Rate Control
Enable/Disable
Allows the end user to globally configure all
Bandwidth settings when enabling Unit Rate Control
(Flow Control). If the END device connected to the
port also has Flow Control enabled, this will ensure
packets will not be dropped.