FLOWcontrol™
68
© 2010 Datacom Systems Inc
VERSA
™
stream
Aggregation Example:
Aggregate together the data stream
copies from multiple Network Tap
ports and send them all to a single
Monitor port (or send identical copies
of aggregated data to multiple Monitor
ports for use by different tools).
This may be helpful in a variety of
situations. For example:
a)A monitoring tool is used that
receives data on only a single NIC
card but must see both sides of the
original duplex conversation.
a)Active / Passive redundant link pairs (or dynamically balanced link pairs - e.g.
Etherchannel or Nortel MLT) have been deployed and are tapped for purposes
of providing continuous visibility for a single monitoring tool interface.
b)A dynamic routing scheme such as Asymmetric Routing has been deployed and
traffic from a single conversation may be traversing different physical links.
By default, the A and B ports of any Network Tap are routed to each other and
cannot be changed, or else the Network Tap would cause a break in the network.
The FLOW
control
™ software does not allow the user to make this change.
The flow of network traffic in the diagram
above, can be replicated by the
Aggregation Configuration shown. Data
received on Network Port 1A is sent to
Network Port 1B (to complete the network
tap) and Monitor Port 5. Data received on
Network Port 1B is sent to Network Port
1A (to complete the tap) and is also sent
to Monitor Port 5. The monitoring device
connected to Monitor Port 5 receives data
from both sides of the network
conversation.
When routing Network Tap ports to Monitor Ports, be aware of the
connection speed limitations of the devices connected to the Monitor Port. If
four 1000BaseT Network Tap ports are aggregated and all routed to the
single NIC of a monitoring device, random packet loss may occur -
depending on utilization levels of the tapped links. Random packet loss may
lead to inconsistent network monitoring results.