Configuring J-Flow Statistics; Cache Flow Export; Aging Flows; Operation With Nat - Juniper JUNOSE 11.2.X IP SERVICES Configuration Manual

Aging Flows

Operation with NAT

Copyright © 2010, Juniper Networks, Inc.
Type of service (ToS byte) or Differentiated Services code point (DSCP)
Input interface

Cache Flow Export

Using UDP as the transport method, the ERX router can export the content of the flow
cache as the system removes the entries. You can specify one export destination for
each VR.
Each export packet contains a header and flow records. The version 5 header contains
the following fields:
Version-Format version
Count-Number of records in this packet
SysUpTime-System up time value when this packet was built
Unix Timestamp-Number of seconds and nanoseconds since 0000 UTC 1970
(Coordinated Universal Time)
Sequence Number-Number of total records sent on this export stream
Engine type-Type of switching engine (line module or route processor)
NOTE: The J-Flow setting for Engine type is always RP=0.
Engine ID-SRP slot number
If, for any reason, the virtual router is unable to export records to the collector, the unsent
records are discarded. However, the virtual router continues to increase the sequence
number by one as if it sent the records. Discrepancies between the sequence number
and sent records can assist in recognizing discontinuities at the collector end.
After the virtual router creates a flow in the cache, the flow is removed at the expiration
of either the active or the inactive timer.
In sampled environments, methods for detecting the end of a flow can be unreliable. The
active timer places a hard limit on how long a flow may last before the virtual router
closes it and gathers the necessary statistics. If the flow is still active when the active
timer expires, the virtual router creates a new flow entry to replace the closed flow.
The inactive timer removes flows if they do not contain any data traffic for a specified
period of time.
When functioning with Network Address Translation (NAT), J-Flow sampling occurs
before NAT applies any translation.
Chapter 3: Configuring J-Flow Statistics
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