Reference Guide

sflow collector ip-address agent-addr ip-address [number [max-datagram-size
number] ] | [max-datagram-size number ]
The default UDP port is 6343.
The default max-datagram-size is 1400.
Changing the Polling Intervals
The sflow polling-interval command configures the polling interval for an interface in the maximum number
of seconds between successive samples of counters sent to the collector.
This command changes the global default counter polling (20 seconds) interval. You can configure an interface to use a
different polling interval.
To configure the polling intervals globally (in CONFIGURATION mode) or by interface (in INTERFACE mode), use the
following command.
• Change the global default counter polling interval.
CONFIGURATION mode or INTERFACE mode
sflow polling-interval interval value
– interval value: in seconds.
The range is from 15 to 86400 seconds.
The default is 20 seconds.
Back-Off Mechanism
If the sampling rate for an interface is set to a very low value, the CPU can get overloaded with flow samples under high-
traffic conditions.
In such a scenario, a binary back-off mechanism gets triggered, which doubles the sampling-rate (halves the number of
samples per second) for all interfaces. The backoff mechanism continues to double the sampling-rate until the CPU
condition is cleared. This is as per sFlow version 5 draft. After the back-off changes the sample-rate, you must manually
change the sampling rate to the desired value.
As a result of back-off, the actual sampling-rate of an interface may differ from its configured sampling rate. You can
view the actual sampling-rate of the interface and the configured sample-rate by using the show sflow command.
sFlow on LAG ports
When a physical port becomes a member of a LAG, it inherits the sFlow configuration from the LAG port.
Enabling Extended sFlow
The S-Series platforms support extended-switch information processing only.
Extended sFlow packs additional information in the sFlow datagram depending on the type of sampled packet. You can
enable the following options:
• extended-switch — 802.1Q VLAN ID and 802.1p priority information.
• extended-router — Next-hop and source and destination mask length.
• extended-gateway — Source and destination AS number and the BGP next-hop.
641