Service Manual

sFlow

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 Points to Remember

• Dell Networking OS recommends that the sFlow Collector be connected to the Dell Networking chassis through a line card port rather

than the route processor module (RPM) Management Ethernet port.

• The system exports all sFlow packets to the sFlow 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.

• 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.

• The source virtual local area network (VLAN) field in the extended switch element is not packed if there is a routed packet.

• The destination VLAN field in the extended switch element is not packed if there is 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 sflow extended-switch enable).

• 1600 packets when you enable extended-router and/or extended-gateway information packing

Topics:

• sflow collector

• sflow enable (Global)

• sflow ingress-enable

• sflow extended-switch enable

• sflow max-header-size extended

• sflow polling-interval (Global)

• sflow polling-interval (Interface)

• sflow sample-rate (Global)

• sflow sample-rate (Interface)

• show sflow

• show sflow stack-unit

1126 sFlow