Configuring NETGEAR switches

The following commands configure a NETGEAR switch (10.0.0.250), sampling packets at 1-in-512, polling counters every 30 seconds and sending sFlow to an analyzer (10.0.0.50) over UDP using the default sFlow port (6343):

sflow receiver 1 owner collector1 timeout 4294967295 ip 10.0.0.50

For each interface:

sflow sampler 1 rate 512
sflow poller 1 interval 30

A previous posting discussed the selection of sampling rates. Additional information can be found on the NETGEAR web site.

See Trying out sFlow for suggestions on getting started with sFlow monitoring and reporting.

Configuring D-Link switches

The following commands configure a D-Link xStack® DGS-3600 series switch (10.0.0.250), sampling packets at 1-in-512, polling counters every 20 seconds and sending sFlow to an analyzer (10.0.0.50) over UDP using the default sFlow port (6343):

enable sflow
create sflow analyzer_server 1 owner analyzer1 timeout infinite collectoraddress 10.0.0.50
create sflow counter_poller ports all analyzer_server_id 1 interval 20
create sflow flow_sampler ports all analyzer_server_id 1 rate 512

A previous posting discussed the selection of sampling rates. Additional information can be found on the D-Link web site.

See Trying out sFlow for suggestions on getting started with sFlow monitoring and reporting.

Configuring Enterasys switches

The following commands configure an Enterasys switch (10.0.0.250), sampling packets at 1-in-2048, polling counters every 20 seconds and sending sFlow to an analyzer (10.0.0.50) over UDP using the default sFlow port (6343):

set sflow receiver 1 owner analyzer1 timeout 180000
set sflow receiver 1 ip 10.0.0.50

#configure packet sampling instances on ports 1 through 12
#assign to sFlow Collector 1
set sflow port ge.1.1-12 sampler 1
set sflow port ge.1.1-12 sampler maxheadersize 128
set sflow port ge.1.1-12 sampler rate 2048

#configure counter poller instances on ports 1 through 12
#assign to sFlow Collector 1
set sflow port ge.1.1-12 poller 1
set sflow port ge.1.1-12 poller interval 20

A previous posting discussed the selection of sampling rates. Additional information can be found on the Enterasys web site.

See Trying out sFlow for suggestions on getting started with sFlow monitoring and reporting.

Convergence

The diagram shows technologies that are part of the drive toward converge of storage, server and network technologies in the data center.

Virtualization and the need to support virtual machine mobility (e.g. vMotion/XenMotion/Xen Live Migration) is driving the adoption of large, flat, high-speed, layer-2, switched Ethernet fabrics in the data center. A layer-2 fabric allows a virtual machine to keeps its IP address and maintain network connections when it moves (performing a "live" migration).

Networked storage (iSCSI, NFS, FCoE) is also needed to support virtual machine mobility. In addition, moving storage from dedicated SANs to a converged Ethernet fabric reduced cabling and networking costs and improves flexibility. However, migration of storage traffic onto a converged Ethernet fabric dramatically increases bandwidth demands and is one of the factors accelerating the adoption of 10/40/100G Ethernet.

Ethernet standards are evolving to address the needs of convergence. As well as higher speeds, IEEE data center bridging standards add support for lossless Ethernet to improve storage performance and support Fiber Channel over Ethernet (FCoE). The performance and stability of large layer 2 Ethernets is being addressed through new protocols such as shortest path bridging.

Changes are not limited to storage and data networking. Server architectures are changing as convergence blurs the line between the server and the network, extending the Ethernet fabric into servers through blade switches, network adapters and virtual switches.

The current siloed approach to managing storage, servers and networks no longer works in a converged environment where each of these areas is so closely inter-dependent. Fortunately, convergence to an Ethernet fabric brings with it the data center visibility needed to manage the converged data center.

The sFlow standard, implemented by most vendor's Ethernet switches, simplifies management by providing the unified visibility and control needed to fully realize the benefits of virtualization and convergence.

Configuring Dell switches

The following commands configure a Dell PowerConnect 8000 series switch (10.0.0.250), sampling packets at 1-in-512, polling counters every 30 seconds and sending sFlow to an analyzer (10.0.0.50) over UDP using the default sFlow port (6343):

sflow 1 destination 10.0.0.50 owner 1 timeout 4294967295
sflow 1 polling ethernet 1/g1-1/g10 30
sflow 1 sampling ethernet 1/g1-1/g10 512

A previous posting discussed the selection of sampling rates. Additional information can be found on the Dell web site.

See Trying out sFlow for suggestions on getting started with sFlow monitoring and reporting.

AMS-IX

(image from Traffic Statistics >> AMS-IX)

An Internet Exchange (IX) is a specialized location where Internet Service Providers (ISPs) exchange traffic between their networks. Internet exchanges use high performance Ethernet switch fabrics to handle traffic volumes that far exceed anything seen in a typical corporate data center.

The Amsterdam Internet Exchange (AMS-IX) is one of the worlds largest Internet Exchanges (see List of Internet exchange points by size) with peak throughput exceeding 900Gbit/s. Providing network visibility in this environment requires a highly scalable measurement system.

The challenge facing AMX-IX is described in the paper,  sFlow: I can feel your traffic. "The explosion of internet traffic is leading to higher bandwidths and an increased need for high speed networks. To analyze and optimize such networks an efficient monitoring system is required." The paper goes on to describe their selection of sFlow as a measurement technology, "To give the AMS-IX members more insight into their peering traffic and provide information to optimize the network structure, AMS-IX is using sFlow for its traffic analysis."

The scalability of sFlow makes it a popular choice for traffic monitoring in Internet exchanges and in other high performance networking environments (see CERN). While most data center networks don't yet handle the traffic levels of an Internet exchange, virtualization and LAN/SAN convergence are dramatically increasing data center traffic.

Most switch vendors support the sFlow standard. Selecting a high-speed Ethernet switch fabric with sFlow offers a proven, scalable monitoring solution that delivers the data center visibility and control needed to manage costs and fully realize the benefits of virtualization.

Fog

Dense Tule fog in Bakersfield, California

The metaphor of the network as a "cloud" is appealing in its simplicity. The cloud abstraction imagines the network as a uniform communication medium in which location is no longer important. While a well provisioned and managed network can create this illusion, the reality is that networks are far from uniform and effective network visibility and control is required to maintain the illusion.

Using a cloud related metaphor to illustrate the importance of visibility; anyone who has driven in the fog knows how disorientating and dangerous a lack of visibility can be. Ignoring the need for visibility into network traffic in the data center risks turning the network cloud into a dense fog where the dynamic, efficient and flexible services promised by virtualization and cloud computing cannot be realized.

Network convergence to a single high-speed switched Ethernet fabric simplifies connectivity, while the sFlow standard implemented by most vendor's Ethernet switches, simplifies management by providing the network-wide visibility needed to manage network resources and deliver cloud services.