Configuring sflow, Sflow protocol overview, Interface flow samples – Brocade Network OS Administrator’s Guide v4.1.1 User Manual
Page 525
Configuring sFlow
sFlow protocol overview
The sFlow protocol is an industry-standard technology for monitoring high-speed switched networks.
The sFlow standard consists of an sFlow agent that resides anywhere within the path of the packet and
an sFlow collector that resides on a central server. This release is compliant with sFlow Version 5.
The sFlow agent combines the flow samples and interface counters into sFlow datagrams and forwards
them to the sFlow Collector at regular intervals. The datagrams consist of information on, but not limited
to, packet header, ingress and egress interfaces, sampling parameters, and interface counters. Packet
sampling is typically performed by the ASIC. The sFlow collector analyzes the sFlow datagrams
received from different devices and produces a network-wide view of traffic flows. You can configure up
to five collectors, using both IPv4 and IPv6 addresses.
The sFlow datagram provides information about the sFlow version, its originating agent’s IP address, a
sequence number, one sample, and protocol information.
The sFlow agent uses two forms of operation:
• Time-based sampling of interface counters
• Statistical sampling of switched packets
Be aware of the following limitations:
• If both port-based sampling and flow-based sampling are enabled on an interface, samples are
based on port rate only.
• Port-based and flow-based sFlow are not supported on port channels, FCoE ports, or ISL ports.
Interface flow samples
A flow sample is based on random packets being forwarded to the sFlow collector at defined numeric
intervals, either for the entire Brocade switch or for a single port interface. For example, every 4,096th
packet is forwarded to the sFlow collector for analysis and storage.
The sampling rate is adaptive, and the sFlow agent is free to schedule the sampling to maximize
internal efficiency.
NOTE
This type of random sampling provides estimated flow rates, but not perfect accuracy.
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