Setup Guide

Back-O Mechanism
If the sampling rate for an interface is set to a very low value, the CPU can get overloaded with ow samples under high-trac conditions.
In such a scenario, a binary back-o mechanism gets triggered, which doubles the sampling-rate (halves the number of samples per
second) for all interfaces. The backo mechanism continues to double the sampling-rate until the CPU condition is cleared. This is as per
sFlow version 5 draft. After the back-o changes the sample-rate, you must manually change the sampling rate to the desired value.
As a result of back-o, the actual sampling-rate of an interface may dier from its congured sampling rate. You can view the actual
sampling-rate of the interface and the congured 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 conguration from the LAG port.
Enabling Extended sFlow
Extended sFlow packs additional information in the sFlow datagram depend on the type of sampled packet. The platform supports
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.
NOTE
: The entire AS path is not included. BGP community-list and local preference information are not included. These elds
are assigned default values and are not interpreted by the collector.
• Enable extended sFlow.
sflow [extended-switch] [extended-router] [extended-gateway] enable
By default packing of any of the extended information in the datagram is disabled.
• Conrm that extended information packing is enabled.
show sflow
Examples of Verifying Extended sFlow
The bold line shows that extended sFlow settings are enabled on all three types.
DellEMC#show sflow
sFlow services are enabled
Egress Management Interface sFlow services are disabled
Global default sampling rate: 32768
Global default counter polling interval: 20
Global default extended maximum header size: 128 bytes
Global extended information enabled: none
1 collectors configured
Collector IP addr: 100.1.1.1, Agent IP addr: 1.1.1.2, UDP port: 6343 VRF: Default
0 UDP packets exported
0 UDP packets dropped
0 sFlow samples collected
stack-unit 1 Port set 0
Te 1/1: configured rate 16384, actual rate 16384
DellEMC#
If you did not enable any extended information, the show output displays the following (shown in bold).
DellEMC#show sflow
sFlow services are disabled
948
sFlow