SFlow vs SNMP vs NetFlow: What Are the Differences?

Posted on January 16, 2020
August 8, 2020

Effective network monitor and traffic management are vital for ensuring peak network performance. While SFlow, NetFlow and SNMP offer different means to monitor network traffic. A question arises from time to time: SFlow vs NetFlow vs SNMP, which is the best? This article will provide some insights into the issue by addressing differences between SFlow vs NetFlow, SFlow vs SNMP and NetFlow vs SNMP.

SFlow vs NetFlow

Initial Purpose

SFlow was designed to be compatible on many different platforms of network switches and routers and uses a dedicated chip built into the hardware, which removes the burden of the CPU and memory of the router or switch. While NetFlow was a proprietary technology that is used in Cisco's Internet Operating System (IOS). It is a software-based technology.

Packet Dealing

SFlow is a pure packet sampling technology. It is almost impossible to get 100% accurate values for each host's traffic without sophisticated algorithms guessing the exact amount of session bytes. While NetFlow can be nearly 100% accurate at representing who is communicating through the device while having a very small impact on the CPU. It can track all incoming sessions on each NetFlow-enabled interface.

Figure 1 What is sFlow.png

Figure 1: What is sFlow

Figure 2 What is NetFlow.png

Figure 2: What is NetFlow

The most notable difference of SFlow vs NetFlow is that SFlow is network layer independent and has the ability to sample everything and to access traffic from OSI layer 2-7, while NetFlow is restricted to IP traffic only.

Feature NetFlow sFlow
Packet capture Does not capture any packets. Copies all packets and samples 1 in N to send to the collector
Protocol support Layer 2, IP, and IPv6 Network-layer-independent
Configurable packet fields Flexible NetFlow – user-configurable field option (templates) Fixed protocol information fields
Flow records Supports IPv4 and IPv6 flow records for all traffic No flow records created; copies the first N bytes of the packet
Hardware acceleration Yes, flow records are created in hardware with no impact on the data plane No hardware acceleration; packets are captured in software
Byte count (total number of bytes in the flow) Yes Yes (partially)

SNMP vs SFlow

SNMP (Simple Network Management Protocol) is the basic means of gathering bandwidth and network usage data. The most common use of SNMP is monitoring the bandwidth usage of routers and switches port by port as well as monitoring device readings such as memory, CPU load, etc. SNMP is commonly recommended for most standard situations since it does not support the differentiation of traffic by service/ protocol. SNMP is proved to be a very popular network management protocol, mainly being used for network monitoring. Regarding performance management on routers/switches, especially in a multiprotocol case, a layer independent SFlow should be the choice to collect, monitor and analyze data traffic.

SNMP vs NetFlow

NetFlow emerges as a more compact protocol than SNMP that scales better for performance collection and network traffic management. A couple of big differences between SNMP vs NetFlow are:

  • SNMP can be used for real-time (i.e. every second) and although NetFlow provides beginning and end times for each flow, it isn't nearly as real-time as SNMP.

  • NetFlow tells you who and with what is consuming the bandwidth, it is also much more verbose than SNMP and therefore NetFlow exports consume much more disk space for historical information.

  • SNMP can be used to collect CPU and memory utilization and that just isn’t available yet using NetFlow.

  • SFlow vs SNMP vs NetFlow: Which Do You Prefer?

    SFlow vs NetFlow vs SNMP, the differences are hence clear: SNMP for standard network monitoring whereas SFlow/NetFlow for high traffic network traffic collection, monitoring and analysis. As for SFlow vs NetFlow, the former is better in the multiprotocol network while the latter is better for IP based traffic that demands improved accuracy and scalability. Vendors on the market are shipping out switches that support sFlow, NetFlow and SNMP, which is a wise choice to save investment.

    Related article:

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