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Configuring the PoS Module
Table 3-13: Format of NetFlow Version 1 Export Datagram Header
Field Name
Octets
version
2
count
2
SysUptime
4
unix_secs
4
unix_nsecs
4
The IP addresses (or hostnames) and UDP port numbers of the available flow collectors
can be configured on a per-switch basis. The flow collection architecture example in
Figure 3-10 illustrates how multiple BlackDiamond switches might export flow records
to flow-collector devices that, in turn, feed records into a central collector-server. Other
flow-collector architectures are also possible. For example, each SONET port might
export statistics to a dedicated flow-collector device.
The ExtremeWare NetFlow implementation for the PoS module also enables a single
SONET port to distribute statistics across multiple groups of flow-collector devices. This
NetFlow distribution feature enables a scalable collection architecture that is able to
accommodate high volumes of exported data. The NetFlow distribution feature is
enabled by configuring export distribution groups that contain the addresses of multiple
flow-collector devices. The feature uses a distribution algorithm that ensures all of the
records for a given flow are exported to the same collector. The algorithm also ensures
that the flow records for both the ingress and egress directions of a TCP or UDP
connection are exported to the same collector when both flows traverse the SONET link
and both filters are configured to export to the same group. For example, a potentially
different group can be associated with a filter. The flow records that match the filter are
then sent to one of the flow collector devices in that group. You could also establish
redundancy by allowing multiple flow collector devices per group so that data is still
collected as long as there is one working flow collector device in that group.
To implement flow-collector devices, you can choose from commercial software
products and public-domain software packages.
3-62
Field Description
Header version=1.
Number of flow records in datagram.
Current time in milliseconds since the switch booted.
Current count of seconds since 0000 UTC 1970.
Current count of residual nanoseconds since 0000 UTV
1970.
Packet Over SONET Module Installation and User Guide
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