This is rather broad and vague question.
Lockstep requires at least one command sent per tick to indicate there is no actions happened. Also you need to send a packet to verify to other clients that the client has received their packets.
Each step every player needs to send his commands (wrapped into one packet for simplicity) and confirmations of receiving other players commands to each client. Without optimizations, general approach formula can start at:
((Commands_per_step * Player_count) + (Confirmations_per_step * Player_count)) * Steps_per_second
2 * N * Player_count * Steps_per_second
For 8p game at 10 ticks a second that is around 160 packets per client per second. Not including utility packets like ping or text, they can be bundled with commands.
Is 160 too much ? For the number in you exact circumstances, you best off at writing a test app that spews packets and measure how much is too much. Ask your friends around the world to test it and collect the stats.
However there is a place for optimizations. In best case, you can optimize by bundling everything client needs to send into 1 packet (per step or even more rare), sent to the game server and making it replicate and spew packets to all clients as needed. That will increase lag slightly, but save you packet count.