Dell S4048T-ON, Configuration Manual

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hardware sampling rate is backed-off from 512 to 1024. Note that port 1 maintains its sampling rate of 16384; port 1 is unaffected because it
maintains its configured sampling rate of 16384.:
• If the interface states are up and the sampling rate is not configured on the port, the default sampling rate is calculated based on the
line speed.
• If the interface states are shut down, the sampling rate is set using the global sampling rate.
• If the global sampling rate is non-default, for example 256, and if the sampling rate is not configured on the interface, the sampling rate
of the interface is the global non-default sampling rate, that is, 256.
To avoid the back-off, either increase the global sampling rate or configure all the line card ports with the desired sampling rate even if
some ports have no sFlow configured.
Important Points to Remember
• The Dell Networking OS implementation of the sFlow MIB supports sFlow configuration via snmpset.
• By default, sFlow collection is supported only on data ports. If you want to enable sFlow collection through management ports, use the
management egress-interface-selection
and
application sflow-collector
commands in Configuration and EIS
modes respectively.
• Dell Networking OS exports all sFlow packets to the collector. A small sampling rate can equate to many exported packets. A backoff
mechanism is automatically applied to reduce this amount. Some sampled packets may be dropped when the exported packet rate is
high and the backoff mechanism is about to or is starting to take effect. The dropEvent counter, in the sFlow packet, is always zero.
• Community list and local preference fields are not filled in extended gateway element in the sFlow datagram.
• 802.1P source priority field is not filled in extended switch element in sFlow datagram.
• Only Destination and Destination Peer AS number are packed in the dst-as-path field in extended gateway element.
• If the packet being sampled is redirected using policy-based routing (PBR), the sFlow datagram may contain incorrect extended
gateway/router information.
• The source virtual local area network (VLAN) field in the extended switch element is not packed in case of routed packet.
• The destination VLAN field in the extended switch element is not packed in a Multicast packet.
• Up to 700 packets can be sampled and processed per second.
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 fields 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.
• Confirm 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.
Dell#show sflow
sFlow services are enabled
sFlow 853