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Packet Over SONET (PoS) Modules
Up to 32 export distribution groups can be configured on a Black Diamond 6800 series switch. Each of
these groups can contain the addresses of up to eight flow-collector devices. A particular export group
can then be specified for each filter, which provides a high-degree of flexibility.
A filter-based aggregation capability is also offered to further enhance scalability. Each filter can be
configured to be either a per-flow filter or an aggregation filter. When a flow matches a filter that is
configured as an aggregation, normal per-flow statistics are not maintained for the flow. Instead, a
single set of statistics is maintained for all the flows that match the aggregation filter, which can
substantially reduce the volume of exported data.
Aggregated flow statistics are also exported in the NetFlow Version 1 format. The nexthop field of the
flow record (see Table 63) is set to xFFFF to indicate that the record is associated with a filter-based
aggregation. The srcaddr, dstaddr, srcport, dstport, and prot fields of an aggregated flow record are set to
the corresponding value components of the associated filter specification.
Export Criteria
TCP flow records are exported when the associated connection is terminated. Flow records are also
exported on an age basis. All flow records, including aggregation records, are examined at least once
every 30 minutes. If the age of the flow is greater than a configurable time, the record is exported. If the
flow is still active, a new flow record will be created when the next packet arrives.
The PoS module transmits a NetFlow Export Datagram when 25 flow records are ready for export, or
when at least one flow has been awaiting export for one second.
Enabling and Disabling Flow Statistics
To enable the flow statistics function on the specified SONET port, use the following command:
enable flowstats ports <portlist>
The flow statistics function is disabled by default.
NOTE
Flow statistics are collected only on SONET ports that are configured to use the IP Control Protocol
(IPCP). No flow statistics are collected on ports that are configured to use the Bridging Control Protocol
(BCP). You will not be prevented from enabling the flow statistics function on ports not configured for
IPCP, but statistics will not be collected on those ports.
To disable the flow statistics function on the specified SONET port, use the following command:
disable flowstats ports <portlist>
The flow statistics function is disabled by default.
Configuring the Export Destination
A single SONET port can distribute statistics across multiple groups of flow-collector devices. This
NetFlow distribution capability makes it possible to create a collection architecture that scales to
accommodate high volumes of exported data. It also offers a health-checking function that improves the
reliability of the collection architecture by ensuring that only responsive flow-collector devices are
included in active export distribution lists.
The distribution algorithm ensures that all the records for a given flow are exported to the same
collector. The algorithm also ensures that flow records for both the ingress and egress directions of a
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ExtremeWare 7.0.0 Software User Guide