Net Optics PA-CU-AR - Manual (Page 11)

10/100 Port Aggregator Tap

The Tap applies a first-in, first-out
process to all packets. Once the burst
has ended and the NIC's utilization is
again below 100 percent, the Tap first
processes the packets that were stored
in memory. As long as the NICʼs
utilization remains below 100 percent,
this process continues uninterrupted
until the memory clears.
Once the memory has cleared, each
monitoring device begins receiving new
data directly from the link. Each using
a single NIC, both monitoring devices
receive all traffic from Side A and Side B,
including physical layer errors.
State 3: Side A + Side B is once again less than 100%
of the NIC's receive capacity.
Example: On a 100 Mbps link, Side A is again at 30 Mbps and Side B
remains at 50 Mbps. The NIC's utilization is again at 80%.
1
Memory
Firewall Router
Monitoring
Device 1
2
Monitoring
Device 2
Side B
Side A
Side A +
Side B
Active Response Dual
Port Aggregator Tap
®
www.netoptics.com
B 1 2 A
Figure 6: Return to 80% Utilization
The extra 40 Mbps of traffic is
stored in the 1 megabyte buffer
for Port A. Memory continues to
fill until the 1 megabyte capacity
is reached, or the burst ends.
(A separate 1 megabyte buffer is
also available to handle a burst
on Port B.)
State 2: Side A + Side B becomes greater than 100%
of the NIC's receive capacity.
Example: There is a burst of traffic, so Side A is now at 90 Mbps while
Side B remains at 50 Mbps. The NIC's utilization is at 140%, requiring the
use of memory to help prevent data loss.
Each using a single NIC, the monitoring
devices both receive all combined traffic
from Side A and Side B, including physical
layer errors.
2
Memory
Firewall Router
Monitoring
Device 1
1
Monitoring
Device 2
Side B
Side A
Side A +
Side B
Active Response Dual
Port Aggregator Tap
®
www.netoptics.com
B 1 2 A
Figure 5: 140% Utilization