# SFlow Input Plugin
The SFlow Input Plugin provides support for acting as an SFlow V5 collector in
accordance with the specification from [sflow.org](https://sflow.org/).
Currently only Flow Samples of Ethernet / IPv4 & IPv4 TCP & UDP headers are
turned into metrics. Counters and other header samples are ignored.
#### Series Cardinality Warning
This plugin may produce a high number of series which, when not controlled
for, will cause high load on your database. Use the following techniques to
avoid cardinality issues:
- Use [metric filtering][] options to exclude unneeded measurements and tags.
- Write to a database with an appropriate [retention policy][].
- Limit series cardinality in your database using the
[max-series-per-database][] and [max-values-per-tag][] settings.
- Consider using the [Time Series Index][tsi].
- Monitor your databases [series cardinality][].
- Consult the [InfluxDB documentation][influx-docs] for the most up-to-date techniques.
### Configuration
```toml
[[inputs.sflow]]
## Address to listen for sFlow packets.
## example: service_address = "udp://:6343"
## service_address = "udp4://:6343"
## service_address = "udp6://:6343"
service_address = "udp://:6343"
## Set the size of the operating system's receive buffer.
## example: read_buffer_size = "64KiB"
# read_buffer_size = ""
```
### Metrics
- sflow
- tags:
- agent_address (IP address of the agent that obtained the sflow sample and sent it to this collector)
- source_id_type(source_id_type field of flow_sample or flow_sample_expanded structures)
- source_id_index(source_id_index field of flow_sample or flow_sample_expanded structures)
- input_ifindex (value (input) field of flow_sample or flow_sample_expanded structures)
- output_ifindex (value (output) field of flow_sample or flow_sample_expanded structures)
- sample_direction (source_id_index, netif_index_in and netif_index_out)
- header_protocol (header_protocol field of sampled_header structures)
- ether_type (eth_type field of an ETHERNET-ISO88023 header)
- src_ip (source_ipaddr field of IPv4 or IPv6 structures)
- src_port (src_port field of TCP or UDP structures)
- src_port_name (src_port)
- src_mac (source_mac_addr field of an ETHERNET-ISO88023 header)
- src_vlan (src_vlan field of extended_switch structure)
- src_priority (src_priority field of extended_switch structure)
- src_mask_len (src_mask_len field of extended_router structure)
- dst_ip (destination_ipaddr field of IPv4 or IPv6 structures)
- dst_port (dst_port field of TCP or UDP structures)
- dst_port_name (dst_port)
- dst_mac (destination_mac_addr field of an ETHERNET-ISO88023 header)
- dst_vlan (dst_vlan field of extended_switch structure)
- dst_priority (dst_priority field of extended_switch structure)
- dst_mask_len (dst_mask_len field of extended_router structure)
- next_hop (next_hop field of extended_router structure)
- ip_version (ip_ver field of IPv4 or IPv6 structures)
- ip_protocol (ip_protocol field of IPv4 or IPv6 structures)
- ip_dscp (ip_dscp field of IPv4 or IPv6 structures)
- ip_ecn (ecn field of IPv4 or IPv6 structures)
- tcp_urgent_pointer (urgent_pointer field of TCP structure)
- fields:
- bytes (integer, the product of frame_length and packets)
- drops (integer, drops field of flow_sample or flow_sample_expanded structures)
- packets (integer, sampling_rate field of flow_sample or flow_sample_expanded structures)
- frame_length (integer, frame_length field of sampled_header structures)
- header_size (integer, header_size field of sampled_header structures)
- ip_fragment_offset (integer, ip_ver field of IPv4 structures)
- ip_header_length (integer, ip_ver field of IPv4 structures)
- ip_total_length (integer, ip_total_len field of IPv4 structures)
- ip_ttl (integer, ip_ttl field of IPv4 structures or ip_hop_limit field IPv6 structures)
- tcp_header_length (integer, size field of TCP structure. This value is specified in 32-bit words. It must be multiplied by 4 to produce a value in bytes.)
- tcp_window_size (integer, window_size field of TCP structure)
- udp_length (integer, length field of UDP structures)
- ip_flags (integer, ip_ver field of IPv4 structures)
- tcp_flags (integer, TCP flags of TCP IP header (IPv4 or IPv6))
### Troubleshooting
The [sflowtool][] utility can be used to print sFlow packets, and compared
against the metrics produced by Telegraf.
```
sflowtool -p 6343
```
If opening an issue, in addition to the output of sflowtool it will also be
helpful to collect a packet capture. Adjust the interface, host and port as
needed:
```
$ sudo tcpdump -s 0 -i eth0 -w telegraf-sflow.pcap host 127.0.0.1 and port 6343
```
[sflowtool]: https://github.com/sflow/sflowtool
### Example Output
```
sflow,agent_address=0.0.0.0,dst_ip=10.0.0.2,dst_mac=ff:ff:ff:ff:ff:ff,dst_port=40042,ether_type=IPv4,header_protocol=ETHERNET-ISO88023,input_ifindex=6,ip_dscp=27,ip_ecn=0,output_ifindex=1073741823,source_id_index=3,source_id_type=0,src_ip=10.0.0.1,src_mac=ff:ff:ff:ff:ff:ff,src_port=443 bytes=1570i,drops=0i,frame_length=157i,header_length=128i,ip_flags=2i,ip_fragment_offset=0i,ip_total_length=139i,ip_ttl=42i,sampling_rate=10i,tcp_header_length=0i,tcp_urgent_pointer=0i,tcp_window_size=14i 1584473704793580447
```
### Reference Documentation
This sflow implementation was built from the reference document
[sflow.org/sflow_version_5.txt](sflow_version_5)
[metric filtering]: https://github.com/influxdata/telegraf/blob/master/docs/CONFIGURATION.md#metric-filtering
[retention policy]: https://docs.influxdata.com/influxdb/latest/guides/downsampling_and_retention/
[max-series-per-database]: https://docs.influxdata.com/influxdb/latest/administration/config/#max-series-per-database-1000000
[max-values-per-tag]: https://docs.influxdata.com/influxdb/latest/administration/config/#max-values-per-tag-100000
[tsi]: https://docs.influxdata.com/influxdb/latest/concepts/time-series-index/
[series cardinality]: https://docs.influxdata.com/influxdb/latest/query_language/spec/#show-cardinality
[influx-docs]: https://docs.influxdata.com/influxdb/latest/
[sflow_version_5]: https://sflow.org/sflow_version_5.txt