Sflow Agent Address Assignment; Configuring Sflow Monitoring Technology - Juniper EX9200 Features Manual

sFlow Agent Address Assignment

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Copyright © 2016, Juniper Networks, Inc.
interfaces is reduced by half and allotted to interfaces that have a lower sampling rate.
Therefore, when the processor's sampling limit is reached, the sampling rate is adapted
such that it does not load the processor any further. If the switch is rebooted, the adaptive
sampling rate is reset to the user-configured sampling rate. Also, if you modify the
sampling rate, the adaptive sampling rate changes.
The advantage of adaptive sampling is that the switch continues to operate at its optimum
level even when there is a change in the traffic patterns in the interfaces. You do not need
to make any changes. Because the sampling rate adapts dynamically to changing network
conditions, the resources are utilized optimally resulting in a high-performance network.
Infrequent sampling flows might not be reported in the sFlow information, but over time,
the majority of flows are reported. On the basis of the configured sampling rate N, 1 out
of N packets is captured and sent to the collector. This type of sampling does not provide
a result that is 100 percent accurate in the analysis, but it does provide a result of
quantifiable accuracy. A user-configured polling interval defines how often the sFlow
data for a specific interface are sent to the collector, but an sFlow agent can also schedule
polling.
NOTE: sFlow technology on EX Series switches does not support graceful
restart. When a graceful restart occurs, the adaptive sampling rate is set to
the user-configured sampling rate.
The sFlow collector uses the sFlow agent's IP address to determine the source of the
sFlow data. You can configure the IP address of the sFlow agent to ensure that the agent
ID of the sFlow agent remains constant. If you do not configure the IP address of the
sFlow agent, an IP address is automatically assigned to the agent. This is the IP address
of one of the following interfaces configured on the switch taken in the given order of
priority:
1. Virtual management Ethernet (VME) interface
2. Management Ethernet interface
If neither of the preceding interfaces has been configured, the IP address of any Layer 3
interface or the routed VLAN interface (RVI) is assigned to the agent. At least one interface
must be configured on the switch for an IP address to be automatically assigned to the
agent. When the agent's IP address is assigned automatically, the IP address is dynamic
and changes when the switch reboots.
sFlow data can be used to provide network traffic visibility information. You can explicitly
configure the IP address to be assigned to source data (sFlow datagrams). If you do not
explicitly configure that address, the IP address of the configured Gigabit Ethernet
interface, 10-Gigabit Ethernet interface, or the RVI is used as the source IP address.
Example: Configuring sFlow Technology to Monitor Network Traffic on EX Series
Switches on page 27
Chapter 2: Configuring sFlow Monitoring Technology
25