Cisco PacketTracer

Cisco PacketTracer screenshots

Cisco Packet Tracer is a powerful network simulation program

Alternative downloads

SmartRF Packet Sniffer
Packet Sniffer is a PC software application used to display and store RF packets.
2.18.1
FREE
Colasoft Packet Player
Open captured packet trace files and play them back in the network.
2.3
Cisco CDP Monitor
It is a network monitor and troubleshooting tool for network administrator.
3.3