53sFlowThe Dell Networking operating software (OS) supports sFlow commands on the S4810 platform.Dell Networking operating software sFlow monitoring system includes an sFlow Agent and an sFlowCollector.• The sFlow Agent combines the flow samples and interface counters into sFlow datagrams andforwards them to the sFlow Collector.• The sFlow Collector analyses the sFlow Datagrams received from the different devices and producesa network-wide view of traffic flows.Important Points to Remember• Dell Networking recommends that the sFlow Collector be connected to the Dell Networking chassisthrough a line card port rather than the route processor module (RPM) Management Ethernet port.• Dell Networking operating software exports all sFlow packets to the sFlow Collector. A small samplingrate can equate to many exported packets. A backoff mechanism is automatically applied to reducethis amount. Some sampled packets may be dropped when the exported packet rate is high and thebackoff mechanism is about to or is starting to take effect. The dropEvent counter, in the sFlowpacket, 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 thesFlow 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 extendedgateway element.• If the packet being sampled is redirected using policy-based routing (PBR), the sFlow datagram maycontain incorrect extended gateway/router information.• sFlow does not support packing extended information for IPv6 packets. Only the first 128 bytes of theIPv6 packet is shipped in the datagram.• The source virtual local area network (VLAN) field in the extended switch element is not packed ifthere is a routed packet.• The destination VLAN field in the extended switch element is not packed if there is a multicast packet.• The sFlow sampling functionality is supported only for egress traffic and not for ingress traffic.• 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 sflowextended-switch enable).1542 sFlow
