Sflow - Dell Force10 S4810P Reference Manual

sFlow

sFlow commands are supported by the Dell Force10 operating software (FTOS) on all Dell Force10 C-Series, E-Series, S-
Series, Z-Series, or S4810 platforms.
FTOS sFlow monitoring system includes an sFlow Agent and an sFlow Collector.
• The sFlow Agent combines the flow samples and interface counters into sFlow datagrams and forwards them to
the sFlow Collector.
• The sFlow Collector analyses the sFlow Datagrams received from the different devices and produces a network-
wide view of traffic flows.
Important Point to Remember
• Dell Force10 recommends that the sFlow Collector be connected to the Dell Force10 chassis through a line card
port rather than the route processor module (RPM) Management Ethernet port.
• FTOS exports all sFlow packets to the sFlow Collector. A small sampling rate can equate to a large number of
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.
• sFlow sampling is done on a per-port basis.
• Community list and local preference fields are not filled up in the extended gateway element in the sFlow
datagram.
• The 802.1P source priority field is not filled up in the extended switch element in the sFlow datagram.
• Only Destination and Destination Peer AS numbers are packed in the dst-as-path field in the 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.
• sFlow does not support packing extended information for IPv6 packets. Only the first 128 bytes of the IPv6 packet
is shipped in the datagram.
• The source virtual local area network (VLAN) field in the extended switch element is not packed in case of a
routed packet.
• The destination VLAN field in the extended switch element is not packed in case of a multicast packet.
• The maximum number of packets that can be sampled and processed per second is:
– 7500 packets when no extended information packing is enabled.
– 7500 packets when only extended-switch information packing is enabled (refer to
switch enable).
– 1600 packets when extended-router and/or extended-gateway information packing is enabled (refer to
sflow extended-gateway enable)
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sflow extended-
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