sFlow
sFlow Conceptual Overview
sFlow Technology
Sampled Flow (sFlow) provides a multi-vendor sampling technology that continuously monitors application level traffic flow at wire speed simultaneously on all interfaces. sFlow provides gigabit speed quantitative traffic measurements without impacting network performance.
sFlow has the following network traffic monitoring characteristics:
- sFlow provides a statistical sampling technology designed to be deployed on all ports within a network to provide end-to-end visibility.
- sFlow exports packet samples and topology meta data to a centralized collector application.
- sFlow scales and operates on all switch ports simultaneously.
- eos implements sFlow on all switches, without requiring additional memory or CPU and does not impact data plane forwarding.
- sFlow agents, embedded on network equipment monitoring traffic and generating data.
- sFlow collectors that receive and analyze sFlow data.
Arista switches include an sFlow agent that monitors ingress data through all Ethernet interfaces.
sFlow Agents
The sFlow agent runs a software process as part of the network management software within an Arista switch. It combines interface counters and flow samples into sFlow datagrams sent to an sFlow collector. Packets typically include flow samples and state information of the forwarding/routing table entries associated with each sample. sFlow agents gather additional data from entries originated by BGP.
When packaging data into datagrams, the sFlow Agent performs minimal processing. Immediate data forwarding minimizes agent memory and CPU requirements.
sFlow Collector
An sFlow collector runs software that analyzes and reports network traffic. Collectors receive flow samples and counter samples as sFlow datagrams from sFlow agents.
Arista switches reference the IP address and UDP port of collectors as configurable settings through a CLI command. Arista switches do not include sFlow collector software.
sFlow Data
- Switched flow sampling - Takes a sample by either copying the packet header or extracting feature data.
- Interface statistics sampling - Counter sampling extracts statistics by periodically polling each data source on the device.
sFlow implements flow sampling and counter sampling as part of an integrated system. An sFlow datagram incorporates both sample types.
Arista sFlow Implementation
- Global - Settings that enable packet sampling on the entire switch.
- Interface - Settings that control sampling on individual interfaces when globally enabling sFlow.
- Global - Disable sFlow and BGP sFlow export globally.
- Ethernet and Port Channel Interfaces - Enabling sFlow globally impacts all interfaces. When enabled globally, BGP sFlow export impacts all interfaces.
When globally enabled, the switch performs sFlow polling. The CLI provides commands that globally turn off sampling while counter-polling remains enabled. Sample enabling is not controllable on individual interfaces.
The switch sends sFlow datagrams to the collector at an IP address specified by a global configuration command. If no collector destination exists, the switch samples data without transmitting the resulting datagrams.
Although the CLI enforces the configured sampling rate limit, sFlow may drop samples if it cannot handle the number of samples received over a specified period. Under normal operation, the maximum packet sample rate is one per 16384 packets. The CLI allows for higher sampling rates by using the dangerous keyword.
Configure the switch to allow the routing agent to export BGP information to the sFlow agent. When enabling BGP sFlow export, sFlow adds BGP information to packets with BGP route destinations.
- Sampled Packets
- CPU
- IP Options
- L3 MTU violations
- Flooded packets
- Multicast packets
- IGMP packets
- LACP frames
- PAUSE frames
- STP BPDUs
- BPDU dropped packets
- STP blocked portsNote: Not sampled on 7300X3, 7320X, 7358, 7368, 7388, CCS-710P, CCS-720DF, CCS-720DP, CCS-720DT, CCS-720XP, CCS-722XPM, CCS-750, DCS-7010TX, DCS-7050X3, DCS-7050X4, DCS-7060X, DCS-7060X2, DCS-7060X4, DCS-7060X5, DCS-7260X, DCS-7260X3, DCS-7300X
- PIM hello packets
- VLAN tag violation dropped packetsNote: Not sampled on 7300X3, 7320X, 7358, 7368, 7388, CCS-710P, CCS-720DF, CCS-720DP, CCS-720DT, CCS-720XP, CCS-722XPM, CCS-750, DCS-7010TX, DCS-7050X3, DCS-7050X4, DCS-7060X, DCS-7060X2, DCS-7060X4, DCS-7060X5, DCS-7260X, DCS-7260X3, DCS-7300X
- Packets not sampled:
- L2 MTU violations
- LLDP frames
- CRC error frames
- ACL dropped packetsNote: Use the sflow sample drop include reason acl command to sample these packets on 7289, 7500R3, DCS-7020, DCS-7130, DCS-7132, DCS-7280R, DCS-7280R2, DCS-7280R3, DCS-7500R, DCS-7500R2, DCS-7500R3, DCS-7800, DCS-7800R3, DCS-7280R, DCS-7280R2, DCS-7500R, DCS-7500R2, DCS-7020R, DCS-7280R3, DCS-7500R3, DCS-7800R3
sFlow and Mirroring
sFlow and Mirroring supports using the same interface for a mirroring session and sFlow at the same time. When configured on the same interface, sFlow does not support TAP Aggregation. Enabling TAP Aggregation mode configures the interface as a source for a mirroring session, and sFlow only mirrors packets. No sFlow samples produced.
The following switches support sFlow and Mirroring:
- DCS-7280R
- DCS-7280R2
- DCS-7280E
- DCS-7500R
- DCS-7500R2
- DCS-7500E
- DCS-7050X
- DCS-7060X
- DCS-7250X
- DCS-7260X
- DCS-7300X
However, the following switches have a limitation:
- DCS-7280R
- DCS-7280R2
- DCS-7280E
- DCS-7500R
- DCS-7500R2
- DCS-7500E
- STP BPDUs
- LACP frames
- LLDP frames
- OSPF packets
- PIM HELLO packets
- Packets dropped due to VLAN violations
Hardware Accelerated sFlow
Compatible platforms support hardware-accelerated sFlow. Without hardware acceleration, the software performs all sFlow processing, and performance depends on the capabilities of the host CPU. Aggressive sampling rates also decrease the processing time available for other eos applications.
With hardware acceleration, hardware performs all sFlow processing using specialized chips called accelerators. These accelerators process sampled packets and send out sFlow datagrams in the same manner as the software agent. The CPU has little involvement and dedicates the chips to sFlow with higher performance and the CPU has more availability for other tasks, even with high sampling rates.
The following switches support hardware-accelerated sFlow:
- DCS-7280R3
- DCS-7280SR2A-48YC6
- DCS-7280CR2-60
- DCS-7280CR2A-60
- DCS-7280CR2K-60
- DCS-7280CR2-30
- DCS-7280CR2A-30
- DCS-7280SRAM-48C6
- DCS-7280SR2K-48C6
- DCS-7500R3
- DCS-7500R2A-36CQ-LC
- DCS-7500R2AK-36CQ-LC
- DCS-7500R2AM-36CQ-LC
- DCS-7500R2AK-48YCQ-LC
- DCS-7800R3
The following switches have limitations:
- DCS-7280R
- DCS-7280R2
- DCS-7280E
- DCS-7500R
- DCS-7500R2
- DCS-7500E
- sFlow enabled globally.
- Routing must be enabled in any VRF. This is required for sFlow datagrams to be routed to the collector(s).
switch(config)# [no|default] sflow hardware acceleration
switch(config)# no sflow hardware acceleration module Linecard3
switch(config)# sflow hardware acceleration module Linecard3
Examples
- The following example enables routing on the switch, activates sFlow,
and enables hardware acceleration globally, but forces software
sFlow on Linecard3.
switch(config)# ip routing switch(config)# sflow run switch(config)# sflow hardware acceleration switch(config)# sflow source 10.10.10.1 switch(config)# sflow destination 10.10.10.2 switch(config)# sflow hardware acceleration sample 1024 switch(config)# no sflow hardware acceleration module Linecard3
- The following example displays the IPv6 configuration. Hardware
accelerated sFlow enables either ipv4 or IPv6 collectors. IPv6
configuration takes precedence over ipv4 configuration and disables
ipv4
collectors.
switch(config)# ipv6 unicast-routing switch(config)# ip routing switch(config)# sflow run switch(config)# sflow hardware acceleration switch(config)# sflow source-interface Ethernet1/1 switch(config)# sflow destination 10.10.10.2 switch(config)# sflow hardware acceleration sample 1024 switch(config)# no sflow hardware acceleration module Linecard3
- The command show sflow hardware status
displays the current status of hardware acceleration for sFlow for
fixed
system.
switch(config)#show sflow hardware status Status —— Hardware Acceleration On: No – sFlow must be enabled – sFlow hardware acceleration must be enabled in the CLI – routing must be enabled in any VRF Sample Rate: None
- The command show sflow hardware status
displays the current status of hardware acceleration for sFlow for
modular
system.
switch(config)#show sflow hardware status Status —— Hardware Acceleration On: Yes Sample Rate: 1048576 sFlow Mode Module Active Configured Has sFlow accelerators —————- ————————– ————————– ———————- Linecard3 Software Hardware-accelerated No Linecard4 Software Hardware-accelerated No Linecard5 Hardware-accelerated Hardware-accelerated Yes Linecard6 Hardware-accelerated Hardware-accelerated No
- The command show sflow hardware counters
displays counters specific to sFlow
acceleration.
switch(config)# show sflow hardware counters —————— SflowAccelFpga7:0 —————— Incoming Packet Count : Outgoing Sflow Datagram Count : 0 Outgoing Flow Sample Count : 0 Incoming Processed Packet Count : 0 Receive Packet Drop Count : 0 Packet Truncated Count : 0 Incoming Packet Error Count : 0 Outgoing Processed Datagram Count : 0 Sample Pool : 0 —————— SflowAccelFpga7:1 —————— Incoming Packet Count : 0 Outgoing Sflow Datagram Count : 0 Outgoing Flow Sample Count : 0 Incoming Processed Packet Count : 0 Receive Packet Drop Count : 0 Packet Truncated Count : 0 Incoming Packet Error Count : 0 Outgoing Processed Datagram Count : 0 Sample Pool : 0 —————— Total —————— Incoming Packet Count : 0 Outgoing Sflow Datagram Count : 0 Outgoing Flow Sample Count : 0 Incoming Processed Packet Count : 0 Receive Packet Drop Count : 0 Packet Truncated Count : 0 Incoming Packet Error Count : 0 Outgoing Processed Datagram Count : 0 Sample Pool : 0
- The command show sflow hardware accelerators
displays a list of all hardware accelerators currently present in
the
system.
switch(config)#show sflow hardware accelerators Slice sFlow Accelerator Type PCI Address Direct Connections ——————————————————————————– Linecard7 SflowAccelFpga7:0 halo 0000:85:00.0 Jericho7/0 Linecard9 SflowAccelFpga9:0 halo 0000:a6:00.0 Jericho9/0
- The command show sflow hardware mapping
displays hardware accelerator performs sFlow processing for each
switch chip in the system. Hardware acceleration needs to be enabled
and running, otherwise the output of the command is
empty.
switch(config)#show sflow hardware mapping Chip sFlow Accelerator Direct Connection ———————————————————— Jericho3/0 SflowAccelFpga7:0 False Jericho3/1 SflowAccelFpga7:0 False Jericho4/0 SflowAccelFpga9:0 False Jericho4/1 SflowAccelFpga9:0 False Jericho5/0 SflowAccelFpga7:0 False Jericho5/1 SflowAccelFpga7:0 False Jericho6/0 SflowAccelFpga9:0 False Jericho6/1 SflowAccelFpga9:0 False Jericho7/0 SflowAccelFpga7:0 True Jericho9/0 SflowAccelFpga9:0 True
Configuring sFlow
- Collector location address
- Agent source address
- Polling interval
- Sampling rate
Optionally, sFlow can be configured to include output interface and traffic class information in samples using the sflow sample command, and to include BGP information in samples whose destination is a BGP route using the sflow extension bgp command.
After configuring the sFlow agent, enable sFlow globally to initiate sampling sFlow on the switch.
Platform-specific Considerations
Enabling BGP sFlow export on Arad platform switches, DCS-7280E and DCS-7500E, adds BGP information to some sFlow packets with ECMP destinations.
DCS-7500E switches use actual hardware egress port information in sFlow packets. All other platforms use software simulation to determine the egress port.
Configuring the Collector Location
The sflow destination command specifies the IP address and UDP port of an sFlow collector. The switch supports multiple collectors.
Example
switch(config)# sflow destination 192.0.2.1 6100
switch(config)# sflow destination 2001:0db8::2
switch(config)#
Configuring the Agent Source Address
The sflow source command specifies the source address that the switch places in all sFlow datagrams that it sends to the collector. This address is normally set to an IP address configured on the switch.
Example
switch(config)# sflow source 2001:0db8::21
switch(config)#
The sflow source-interface command can be alternatively used to specify the interface from which an IP address is derived that the switch places in all sFlow datagrams that it sends to the collector. This address is normally set to an IP address configured on the switch.
Example
switch(config)# sflow source-interface vlan 25
switch(config)#
running-config cannot simultaneously contain sflow source and sflow source-interface commands.
Configuring the Polling Interval
The sflow polling-interval command specifies the interval for sending counter data to the sFlow collector. The default interval is two seconds.
Example
switch(config)# sflow polling-interval 10
switch(config)#
Configuring the Sampling Rate and Sample Contents
The sflow sample command sets the packet sampling rate. Packets are sampled at random intervals to avoid inaccurate sampling of periodic events. A rate of 16384 corresponds to an average sample of one per 16384 packets. The default rate is 1048576.
Example
switch(config)# sflow sample 65536
switch(config)#
The sflow sample command can also optionally configure sample packets to include information about the traffic class of the sample. Traffic class is communicated by rewriting the DSCP field in the sample packet.
By default, samples include information about the output interface. To remove this information, use the [no] sflow sample output interface command.
Example
switch(config)# no sflow sample output interface
switch(config)# sflow sample rewrite dscp
switch(config)#
Configuring the sFlow Datagram Size
The default datagram size, 1400, may drop with a Maximum Transmission Unit (MTU) threshold configured. Configure the default maximum datagram payload size of 1400 bytes to a size from 200 to 1500 bytes to avoid fragmentation.
Use the following command to configure the sFlow datagram size as 1500:
switch(config)# sflow datagram size maximum 1500
Enabling BGP sFlow Export
- next hop IP
- AS numbers
- AS system path to the destination
- communities
- local pref
On Arad platform switches (DCS-7280E and DCS-7500E), BGP sFlow export will also add the above BGP information to sample packets with ECMP destination routes unless they exit the switch via a trunk port or subinterface. When egress port is a trunk port or subinterface, the sample packet will only include AS path information from the first path of the ECMP route and a BGP next hop of 0.
On all other switch platforms, ECMP destination routes will include AS path information from the first path, but will identify the BGP next hop as 0.
Example
switch(config)# router bgp 50
switch(config-router-bgp)# exit
switch(config)# sflow extension bgp
switch(config)#
Extended Switch and Router Information
By default, extended switch and router information is added to sFlow sample packets.
- source and destination VLANs and priorities.
- IP version and address of next-hop router.
- source and destination mask lengths.
The no form of sflow extension switch and no form of sflow extension router commands prevent the addition of extended switch and router information to sFlow sample packets.
Example
switch(config)# no sflow extension switch
switch(config)# no sflow extension router
switch(config)#
Support for VPLS on sFlow
For VPLS forwarded traffic, the sFlow datagram includes the name of the VPLS instance and the ID of the pseudowire where the packet egresses.
Use the following command to add the VPLS extension to capture relevant VPLS information:
switch(config)#sflow extension vpls
Enabling sFlow
The sflow run command globally enables sFlow on the switch. The sflow enable command controls sFlow operation on Ethernet and port channel interfaces when sFlow is globally enabled. The sflow enable command has no effect disabling sFlow globally.
Example
switch(config)# sflow run
switch(config)# interface ethernet 10
switch(config-if-Et10)# no sflow enable
switch(config)#
Egress Sampling for sFlow Interfaces
eos supports egress sampling for sFlow on Ethernet interfaces, port channels, and subinterfaces on select platforms. Egress sFlow does not support hardware acceleration. Sample processing occurs in eos.
Configuring Egress Sampling on sFlow Interfaces
eos disables Egress sFlow by default. Use the following command to enable egress sFlow for all interfaces:
switch(config)# sflow interface egress enable default
Override the global egress sFlow configuration by disabling it on a specified interface:
switch(config)# interface Ethernet1
switch(config-if-Et1)# no sflow egress enable
Displaying Egress sFlow Configurations
To display information about the Egress sFlow configuration, use the show sflow interfaces command.
switch# show sflow interfaces
Default ingress sFlow configuration for an interface: Enabled
Default egress sFlow configuration for an interface: Disabled
sFlow Interface (s):
--------------------
Ethernet20/1 - running(Ingress,Egress,Counter)
Ethernet21/1 - running(Ingress,Counter), inactive(Egress)
Port-Channel1 - running(Counter), partial(Egress)
Port-Channel2 - running(Ingress,Egress,Counter)
In the output, the parameter, inactive, indicates that the interface has been configured for Egress sFlow, but not operational. The parameter, partial, displays the Port-Channel inoperational members, but other members are operational.
Adding the parameter, detail, shows active and inactive Port-Channel members.
switch# show sflow interfaces detail
Interface Member Ingress Egress Counter
------------------- ----------------- ------------------ ------------------ -------
Ethernet20/1 running running running
Ethernet21/1 running inactive running
Port-Channel1 unconfigured partial running
Port-Channel1 Ethernet1/1 unconfigured inactive running
Port-Channel1 Ethernet2/1 unconfigured running running
Port-Channel1 Ethernet3/1 unconfigured running running
Port-Channel2 running running running
Verifying an Egress sFlow Configuration
If the configuration does not send Egress samples to the collector, verify that you have active Egress sFlow interfaces:
switch# show sflow interfaces
sFlow Interface (s):
--------------------
Ethernet1 – running(Egress,Counter)
Ethernet2 – running(Ingress,Counter)
Ethernet3 - running(Ingress,Egress,Counter)
Ethernet4 - running(Ingress,Counter), inactive(Egress)
The output, inactive(Egress) indicates that an Egress sFlow has been configured, but not operational.
sFlow Subinterfaces
The sflow sample [input | output] subinterface command configures ifIndex values for subinterfaces on input and output ports to be included in the sFlow sample. These values replace the default parent port ifIndex value. Enabling this feature changes all sFlow samples generated by the switch from compact to the expanded format.
Configuring sFlow Subinterface
The following configures subinterfaces on the switch for sampling.
switch (config)# sflow run
switch (config-if-Et1)# sflow sample input subinterface
switch (config)# sflow sample output subinterface
The following file extract displays the output from a show sflow detail command.
switch# show sflow detail
...
Status
------
...
Sample Switch Extension: Yes
Sample Router Extension: Yes
Sample Tunnel ipv4 Egress Extension: No
Sample Input Subinterface: Yes
Sample Output Subinterface: Yes
Port Channel Output Interface Index: portchannel
Sample Encoding Format: expanded
...
Limitations
- Only some hardware platforms support this feature.
- Only L3 subinterfaces and QinQ L3 subinterfaces support the sFlow output subinterface.
- sFlow does not support tunneled packets such as GRE, MPLSoGRE, and IPinIP.
sFlow commands
Global Configuration commands
Interface Configuration commands
Privileged EXEC Command
sFlow Display commands
clear sflow counters
The clear sflow counters command resets the global sFlow statistics, which includes the number of samples and sample pool. The hardware trigger count is not reset.
The show sflow command displays global sFlow statistics.
Command Mode
Privileged EXEC
Command Syntax
clear sflow counters
Exampleswitch# clear sflow counters
switch#
[no] sflow sample output interface
By default, sFlow samples include information about the output interface of the sampled packet. The no sflow sample output interface command excludes the information.
Command Mode
Global Configuration
Command Syntax
no sflow sample output interface
Exampleswitch(config)# no sflow sample output interface
switch(config)#
sflow destination
The sflow destination command specifies an sFlow collector ipv4 or IPv6 address and, optionally, a UDP port (the default is 6343). The switch supports sFlow collector addresses through multiple sFlow destination commands in running-config.
The no sflow destination and default sflow destination commands remove the specified sFlow collector IP address by deleting the corresponding sflow destination command from running-config.
Command Mode
Global Configuration
Command Syntax
sflow destination dest_addr [UDP_PORT]
no sflow destination dest_addr [UDP_PORT]
default sflow destination dest_addr [UDP_PORT]
- dest_addr sflow collector's IP address.
- UDP_PORT sFlow collectors data reception port.
Options include:
- no parameter port number 6343 (default).
- port_num port number. Value ranges from 0 to 65535.
Example
switch(config)# sflow destination 2001:0db8::2 6100
switch(config)#
sflow enable
The sflow enable command enables sFlow on the configuration mode interface. When globally enabling sFlow using the sflow run command, the command enables sFlow on all interfaces by default. Use the sflow enable command when running-config contains a no sflow enable statement for the specified interface.
The no sflow enable command disables sFlow on the configuration mode interface. When globally disabled, this command persists in running-config but does not affect switch operation.
The default sflow enable command removes the corresponding no sflow enable command from running-config enabling sFlow capability on the interface.
Command Mode
Interface-Ethernet Configuration
Interface-Port-Channel Configuration
Command Syntax
sflow enable
no sflow enable
default sflow enable
Examples- These commands enable sFlow on the switch and disable sFlow on
interface ethernet
12.
switch(config)# sflow run switch(config)# interface ethernet 12 switch(config-if-Et12)# no sflow enable switch(config-if-Et12)#
- This command removes the no sflow
enable command for
interface ethernet 12
from running-config, enabling sFlow on the
interface whenever sFlow is globally
enabled.
switch(config-if-Et12)# sflow enable switch(config-if-Et12)#
sflow extension bgp
The sflow extension bgp command enables BGP export to sFlow. When enabled, the routing agent will export the BGP routing table and autonomous system path information to the sFlow agent. When sFlow receives a sampled packets whose destination is a BGP route, it will look up the following additional BGP routing information and include it in the sample:
- AS numbers
- AS system path to the destination
- Communities
- Local preferences
The no sflow extension bgp and default sflow extension bgp commands disable BGP export to sFlow by deleting the corresponding sflow extension bgp command from running-config.
Command Mode
Global Configuration
Command Syntax
sflow extension bgp
no sflow extension bgp
default sflow extension bgp
Guidelines
- DCS-7500E switches use actual hardware egress port information in sFlow packets. All other platforms use software simulation to determine the egress port.
- On Arad platform switches (DCS-7280E and DCS-7500E), BGP sFlow export works for sample packets with ECMP destination routes unless they exit the switch through a trunk port or subinterface. When a trunk port or subinterface provides the egress port, the sample packet only includes AS path information from the first path of the ECMP route and a BGP next hop of 0.
- On all other switch platforms, ECMP destination routes includes AS path information from the first path, but identifies the BGP next hop as 0.
- DCS-7500E switches use actual hardware egress port information in sFlow packets. All other platforms use software simulation to determine the egress port.
switch(config)# router bgp 50
switch(config-router-bgp)# exit
switch(config)# sflow extension bgp
switch(config)#
sflow extension router
By default, the switch provides extended router information in sFlow packets, including the IP version and address of the next-hop router and source and destination mask lengths.
The no version of the sflow extension router command prevents this information from being included in sFlow packets.
The sflow extension router and default sflow extension router commands restore the default behavior by deleting the corresponding no sflow extension router command from running-config.
Command Mode
Global Configuration
Command Syntax
sflow extension router
no sflow extension router
default sflow extension router
Exampleswitch(config)# no sflow extension router
switch(config)#
sflow extension switch
By default, the switch provides extended switch information in sFlow packets, including source and destination VLANs and priorities.
The no version of the sflow extension switch command prevents this information from being included in sFlow packets.
The sflow extension switch and default sflow extension switch commands restore the default behavior by deleting the corresponding no sflow extension switch command from running-config.
Command Mode
Global Configuration
Command Syntax
sflow extension switch
no sflow extension switch
default sflow extension switch
Exampleswitch(config)# no sflow extension switch
switch(config)#
sflow extension vpls
The sflow extension vpls command enables VPLS exporting to sFlow configuration. When enabled, the routing agent exports VPLS information to the sFlow agent.
The no sflow extension vpls and default sflow extension vpls commands disable VPLS exporting to sFlow by deleting the corresponding sflow extension vpls command from running-config.
Command Mode
Global Configuration
Command Syntax
sflow extension vpls
no sflow extension vpls
default sflow extension vpls
Use the following command to enable VPLS export to sFlow:
switch(config)#sflow extension vpls
sflow interface
The sflow interface command enables the configuration of egress sFlow on an interface.
Command Mode
EXEC
Command Syntax
sflow interface
- This command enables global egress sFlow for all
interfaces.
switch# sflow interface egress enable default
- This command enables egress sFlow on an interface.
switch(config)# interface Ethernet1 switch(config-if-Et1)# sflow egress enable
sflow polling-interval
The sflow polling-interval command specifies the counters polling interval. The switch uses this interval to schedule a ports counter data transmissions to the sFlow collector.
The default interval is two seconds.
The no sflow polling-interval and default sflow polling-interval commands revert the polling interval to the default of two seconds by removing the sflow polling-interval command from running-config.
Command Mode
Global Configuration
Command Syntax
sflow polling-interval interval_period
no sflow polling-interval
default sflow polling-interval
Parameters
interval_period polling interval (seconds). Value ranges from 0 to 3600 (60 minutes). Default is 2.
Example
switch(config)# sflow polling-interval 10
switch(config)#
sflow run
The sflow run command globally enables sFlow on the switch. eos disables the sFlow global setting by default. You cannot enable sFlow on individual interfaces when disabling sFlow globally.
The sflow enable interface configuration command controls sFlow operation on individual Ethernet and Port Channel interfaces when enabling sFlow globally. When enabled globally, it enables sFlow on all interfaces by default.
The no sflow run and default sflow run commands globally disable sFlow on the switch.
Command Mode
Global Configuration
Command Syntax
sflow run
no sflow run
default sflow run
- Use this command to enable sFlow on the
switch.
switch(config)# sflow run switch(config)#
- Use this command to globally disable
sFlow.
switch(config)# no sflow run switch(config)#
sflow sample
The sflow sample
command sets the packet sampling rate. Packets sample at random intervals to avoid inaccurate sampling of periodic events. The packet sampling rate defines the average number of ingress packets that pass through an interface for every sampled packet. A rate of 16384 corresponds to an average sample of one per 16384 packets. The switch may drop samples if it cannot manage the configured sample rate. Under normal operation, the maximum packet sample rate occurs at one per 16384 packets. Specify higher sampling rates with the dangerous option.
By default, samples include information about the output interface. To remove this information, use the [no] sflow sample output interface command.
The sflow sample command can also optionally configure sample packets to include information about the traffic class of the sample. Traffic class is communicated by rewriting the DSCP field in the sample packet.
The no sflow sample and default sflow sample commands reset the packet sampling rate to the default of 1048576 and remove output interface and traffic class information from samples by removing the sflow sample command from the configuration.
Command Mode
Global Configuration
Command Syntax
sflow sample truncate SAMPLE_RATE[rewrite dscp]
no sflow sample
default sflow sample
Parameters
- recommended_rate Integer between
16384 and
16777215.
- dangerous
any_rate permits overriding the
recommended range of sampling rates. The
any_rate value range varies by
platform:
- fm6000 1 to 65535.
- trident 1 to 16777216.
- dangerous
any_rate permits overriding the
recommended range of sampling rates. The
any_rate value range varies by
platform:
- rewrite dscp configures sFlow to rewrite the DSCP field of sample packets to indicate the traffic class of the original packet.
- TRUNCATE sFlow sample truncation size between the range of 128 to 512. By default, the sFlow sample truncate size is set to 128. Note, this option is hidden.
- This command configures the sFlow sampling rate as
65536 (one per
65536
packets).
switch(config)# sflow sample 65536 switch(config)#
- This command configures the sFlow sampling rate as
256 (one per 256
packets).
switch(config)# sflow sample dangerous 256 switch(config)#
- This command configures sFlow to include traffic class information in
samples.
switch(config)# sflow sample rewrite dscp switch(config)#
sflow source
The sflow source command specifies the IP address used in the Agent address filed of the ipv4 or IPv6 sFlow datagram that the switch sends to the collector. This command cannot be used if running-config contains an sflow source-interface command.
The no sflow source and default sflow source commands remove the sflow source command from running-config.
Command Mode
Global Configuration
Command Syntax
sflow source source_addr
no sflow source
default sflow source
Parameter
source_addr source IP address (dotted decimal notation).
Example
switch(config)# sflow source 2001:0db8::2
switch(config)#
sflow source-interface
The sflow source-interface command specifies the source IP address set to the IP address of the specified interfaces that the switch sends to the collector. An sFlow packet specifies both the Agent address in the ipv4 or IPv6 sFlow datagram and the source IP address sent to the collector. This command cannot be used if running-config contains an sflow source command.
The no sflow source-interface and default sflow source-interface commands remove the sflow source-interface command from running-config.
Command Mode
Global Configuration
Command Syntax
sflow source-interface INT_NAME
no sflow source-interface
default sflow source-interface
Parameters
- interface ethernet e_num Ethernet interface specified by e_num.
- interface loopback l_num Loopback interface specified by l_num.
- interface management m_num Management interface specified by m_num.
- interface port-channel p_num Port-Channel Interface specified by p_num.
- interface vlan v_num VLAN interface specified by v_num.
Example
switch(config)# sflow source-interface loopback 0
switch(config)#
show sflow
The show sflow command displays configured sFlow parameters, operational status, and statistics.
The show sflow interfaces command displays the interfaces where sFlow is enabled.
Command Mode
EXEC
Command Syntax
show sflow [detail]
Parameter
detail adds hardware sampling status and number of discarded samples to the information displayed.
- This command displays the base sFlow
information.
switch# show sflow ! Displaying counters that may be stale sFlow Configuration ------------------- Destinations: None (default) Source(s): 0.0.0.0 ( default ) ( VRF: default ) :: ( default ) ( VRF: default ) Sample Rate: 1048576 ( default ) Polling Interval (sec): 2.0 ( default ) Rewrite DSCP value: No Status ------ Running: No Polling On: No Sampling On: No Send Datagrams: No ( Sflow not running ) ( VRF: default ) BGP Export: No ( VRF: default ) Hardware Sample Rate: 1044480 Statistics --More-- ! Displaying counters that may be stale sFlow Configuration ------------------- Destinations: None (default) Source(s): 0.0.0.0 ( default ) ( VRF: default ) :: ( default ) ( VRF: default ) Sample Rate: 1048576 ( default ) Polling Interval (sec): 2.0 ( default ) Rewrite DSCP value: No Status ------ Running: No Polling On: No Sampling On: No Send Datagrams: No ( Sflow not running ) ( VRF: default ) BGP Export: No ( VRF: default ) Hardware Sample Rate: 1044480 Statistics ---------- Total Packets: 0 Number of Samples: 0 Sample Pool: 0 Hardware Trigger: 0 Number of Datagrams: 0
- This command displays the expanded sFlow
information.
switch# show sflow detail ! Displaying counters that may be stale sFlow Configuration ------------------- Destinations: None (default) Source(s): 0.0.0.0 ( default ) ( VRF: default ) :: ( default ) ( VRF: default ) Sample Rate: 1048576 ( default ) Polling Interval (sec): 2.0 ( default ) Rewrite DSCP value: No Status ------ Running: No Polling On: No Sampling On: No Send Datagrams: No ( Sflow not running ) ( VRF: default ) BGP Export: No ( VRF: default ) Hardware Sample Rate: 1044480 Hardware Sampling On: No Sample Output Interface: Yes Sample Switch Extension: Yes Sample Router Extension: Yes Statistics ---------- Total Packets: 0 Number of Samples: 0 Sample Pool: 0 Hardware Trigger: 0 Number of Datagrams: 0 Number of Samples Discarded: 0
show sflow interfaces
The show sflow interfaces command displays the interfaces with sFlow enabled.
The show sflow command displays configured sFlow parameters, operational status, and statistics.
Command Mode
EXEC
Command Syntax
show sflow interfaces
Parameters
detail
- This command displays the show sflow interface message when globally
disabling
sFlow.
switch# show sflow interfaces sFlow Interface (s): -------------------- sFlow is not running
- This command displays the show sflow interface message when enabling
sFlow globally and enabling sFlow on all
interfaces.
switch(config)# sflow run switch(config)# show sflow interfaces Default sFlow configuration for an interface: Disable sFlow Interface (s): -------------------- Ethernet1 running(Counter) Ethernet2 running(Counter) Ethernet3 running(Flow,Counter) Ethernet4 running(Flow,Counter) Ethernet5 running(Flow,Counter)
- To review active and inactive sFlow interfaces, use the sflow
interfaces detail command:
switch# show sflow interfaces detail Interface Member Ingress Egress Counter ------------------- ----------------- ------------------ ------------------ ------- Ethernet20/1 running running running Ethernet21/1 running inactive running Port-Channel1 unconfigured partial running Port-Channel1 Ethernet1/1 unconfigured inactive running Port-Channel1 Ethernet2/1 unconfigured running running Port-Channel1 Ethernet3/1 unconfigured running running Port-Channel2 running running running