The root cause? The console log from boot clearly showed: "Virtual device serial0 will start disconnected" and "Virtual device serial1 will start disconnected" . The student had never connected the cables from the router to the Frame Relay switch.
Now go build your topology, connect those serial cables, and watch show interface serial0 finally display the glorious words:
A: Because IOU/IOL images are binary-level simulations that run natively on Linux. They do not use the Dynamips virtual device layer. They treat serial interfaces as internal software constructs, not hardware emulations. Conclusion: A Feature, Not a Bug The message "Virtual device serial0 will start disconnected" is the emulator's honest way of telling you, "I have no information about what this port should connect to, so I am leaving it in a safe, disconnected state."
Always read the console boot messages. That "disconnected" line is not a warning; it is a direct status report. Frequently Asked Questions (FAQ) Q: Does this happen on real Cisco hardware? A: No. Real hardware will show "%LINK-3-UPDOWN: Interface Serial0/0, changed state to down" if no cable is plugged in, but it will never announce "virtual device."
Virtual Device Serial0 Will Start Disconnected -
The root cause? The console log from boot clearly showed: "Virtual device serial0 will start disconnected" and "Virtual device serial1 will start disconnected" . The student had never connected the cables from the router to the Frame Relay switch.
A: Because IOU/IOL images are binary-level simulations that run natively on Linux. They do not use the Dynamips virtual device layer. They treat serial interfaces as internal software constructs, not hardware emulations. Conclusion: A Feature, Not a Bug The message "Virtual device serial0 will start disconnected" is the emulator's honest way of telling you, "I have no information about what this port should connect to, so I am leaving it in a safe, disconnected state." The root cause
Always read the console boot messages. That "disconnected" line is not a warning; it is a direct status report. Frequently Asked Questions (FAQ) Q: Does this happen on real Cisco hardware? A: No. Real hardware will show "%LINK-3-UPDOWN: Interface Serial0/0, changed state to down" if no cable is plugged in, but it will never announce "virtual device." Now go build your topology, connect those serial