You can configure Juniper EX2300, EX3400, and EX4300 Switches using the following steps:
set sflow collector {NETFLOW_SERVER_IP} udp-port
{NETFLOW_SERVER_LISTENER_PORT}
Enter global configuration mode on the router or MSFC, and issue the following commands for each interface on which you want to enable flow:
set sflow interfaces {INTERFACE_NAME}
set sflow polling-interval 20
set sflow sample-rate 1000