set interfaces ethernet eth1 address '192.0.2.1/30'
set interfaces ethernet eth1 description 'LAN'
set system option kernel memory default-hugepage-size '2M'
set system option kernel memory hugepage-size 2M hugepage-count '2048'
set system sflow interface 'eth1'
set system sflow server 127.0.0.1
set system sflow vpp
set vpp settings interface eth1 driver 'dpdk'
set vpp settings interface eth2 driver 'dpdk'
set vpp settings unix poll-sleep-usec '222'
set vpp sflow interface 'eth1'

vyos@r14# sudo vppctl show sflow
sflow sampling-rate 10000
sflow sampling-direction ingress
sflow polling-interval 20
sflow header-bytes 128
sflow enable eth1
Status
  interfaces enabled: 1
  packet samples sent: 0
  packet samples dropped: 0
  counter samples sent: 16
  counter samples dropped: 0
[edit]
vyos@r14# 
[edit]
vyos@r14# delete vpp sflow 
[edit]
vyos@r14# commit
[edit]
vyos@r14# 
[edit]
vyos@r14# sudo vppctl show sflow
sflow sampling-rate 10000
sflow sampling-direction ingress
sflow polling-interval 20
sflow header-bytes 128
sflow enable eth1
Status
  interfaces enabled: 1
  packet samples sent: 0
  packet samples dropped: 0
  counter samples sent: 16
  counter samples dropped: 0
[edit]
vyos@r14#