Virtual Device Serial0 Will Start Disconnected Link

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.

The no shutdown command fixes administratively down (interface disabled by software). It does fix hardware down (no cable, no carrier signal). The "virtual device will start disconnected" message is a hardware-level notification. You cannot fix it with IOS commands; you must fix it in the emulator GUI. The Clock Rate Caveat (DCE vs DTE) Even after you connect the virtual cable, you might still face a down/down or up/down status. After fixing the "start disconnected" message, ensure you have a clock rate set on the DCE side. virtual device serial0 will start disconnected

Now go build your topology, connect those serial cables, and watch show interface serial0 finally display the glorious words: The root cause

If you have ever fired up a Cisco router in Dynamips , GNS3 , EVE-NG , or Cisco Packet Tracer , you have likely seen the console output slowly crawl by until it halts at a seemingly concerning line: "Virtual device serial0 will start disconnected" For many students, this message triggers an instinct to panic. Is the router broken? Is the image corrupted? Will Serial0/0 ever come up? You cannot fix it with IOS commands; you

[[router R1]] image = c7200.bin serial0 = "R2 serial0" This tells Dynamips to create a direct serial cable between the two virtual devices on boot. A common mistake is logging into the router and typing:

[[router R1]] image = c7200.bin serial0 = "disconnected" To this:

A: In Dynamips/GNS3, no. The hardware state is decided at boot. You must shut down, connect the cable, and restart the router. In EVE-NG with newer QEMU images, you may hot-plug, but it is not recommended.