Capture traffic using Wireshark and then import the pcap files into Ostinato; and then generate frames back into the network. In this example we will get Ostinato to be the root of the spanning tree.My Full CCNA course is here http://ccnax.com.
Free software worth $200: https://goo.gl/613TUF
Ostinato – Network Traffic Generator Part 7. Easily create packets for testing in your GNS3 network.
Ostinato is a packet crafter, network traffic generator and analyzer with a friendly GUI. Also a powerful Python API for network test automation. Craft and send packets of several streams with different protocols at different rates. Think of it as “Wireshark in Reverse”.