User guide

1-12 Packet Over SONET Module Installation and User Guide
Overview
The PoS module also supports port tunneling. Port tunneling can be used to
encapsulate and transport the raw High-Level Data Link Control (HDLC) encapsulated
byte stream from one PoS port to another PoS port across an MPLS network. This
allows service providers to tunnel different types of SONET HDLC streams across a
non-SONET backbone like Ethernet.
NetFlow Statistics
Each PoS port can maintain and export statistics for the flows that traverse the
associated SONET link.
Per-flow statistics are useful for many management purposes, including:
• Accounting and billing
• Network capacity planning and trend analysis
• Network monitoring
• Workload characterization
• User profiling
• Data warehousing and mining
Each PoS module can maintain two million flow records. Per-flow statistics are reported
in the NetFlow, Version 1 format, which groups flow records together into UDP
datagrams for export to a flow-collector device.
The PoS module also provides a NetFlow distribution feature to provide a growth path
to more scalable and robust collection architectures. This feature allows a single PoS
port to distribute statistics across multiple groups of flow-collector devices in a
load-balanced manner. The function also includes a health-check feature that
significantly improves the reliability of the collection architecture. The health-checker
ensures that only responsive flow-collector devices are included in the effective export
distribution lists.
To further enhance scalability, the PoS module also offers filters and filter-based
aggregation options that allow you to configure a PoS port to maintain statistics
selectively for only those flows matching specified filters. The aggregation options can
further reduce the volume of exported data by enabling a single set of statistics to be
maintained for all the flows that match an aggregation filter.