sFlow
Fixed Switch Configuration Guide 18-13
Configuring Poller and Sampler Instances
A poller instance performs counter sampling on the data source to which it is configured. You
must first associate a receiver/Collector in the sFlow Receivers Table with the poller instance,
before configuring the polling interval with the set sflow port poller command.
A sampler instance performs packet flow sampling on the data source to which it is configured.
You must first associate a receiver/Collector in the sFlow Receivers Table with the sampler
instance, before configuring the sampling rate or maximum number of bytes copied from sampled
packets. A maximum of 32 sampler instances can be configured per switch or stack of switches.
When a receiver times out or is cleared from the sFlow Receivers Table, all poller and sampler
instances associated with that receiver are also cleared from the switch’s configuration.
Configuring a Management Interface
The set sflow interface command allows you to configure the management interface used by the
sFlow Agent when sending sampling datagrams to the sFlow Collector. Any of the interfaces,
including VLAN routing interfaces, can be configured as the management interface.
An interface must have an IP address assigned to it before it can be set as the management
interface. If no interface is specified, then the Host VLAN will be used as the management
interface.
If a non-loopback interface is configured as the management interface, application packet egress is
restricted to that interface if the server can be reached from that interface. Otherwise, the packets
are transmitted over the first available route. Packets from the application server are received on
the configured interface.
If a loopback interface is configured, and there are multiple paths to the application server, the
outgoing interface (gateway) is determined based on the best route lookup. Packets from the
application server are then received on the sending interface. If route redundancy is required,
therefore, a loopback interface should be configured.
Parameter Defaults
Table 18-6 Default sFlow Parameters
Parameter Description Default Value
maxdatagram The maximum number of data bytes
that can be sent in a single sample
datagram.
1400 bytes
UDP port The UDP port on the receiver/Collector
to which the sample datagrams should
be sent.
6343
Polling interval Poller instance polling interval 0 (Counter sampling is disabled)
maxheadersize The maximum number of bytes that
should be copied from the sampler
packet.
128 bytes
Sampler rate The statistical sampling rate for
sampling from this data source. The
value of rate specifies the number of
incoming packets from which one
packet will be sampled.
0 (Sampling is disabled)
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