Connectivity Issue Between Cisco 2811 Routers: Protocol Down De

[Bokamoso212]

Hello Cisco Community,

I'm currently facing a perplexing connectivity issue with two Cisco 2811 routers in my network. Despite configuring different IP addresses on their fe0/1 interfaces and ensuring they're both up with "no shutdown" commands, the protocol remains down. Additionally, when connected to each other, there are no interface lights illuminated.

This situation reminds me of troubleshooting complex network problems, much like the challenges of rectifying errors in systems like SASSA's application processing, where canceling an application might require intricate analysis and adjustments.

I've meticulously checked cable connections, verified the configuration settings, and even attempted auto-negotiation adjustments for speed and duplex, yet the problem persists. Could there be a specific configuration oversight or hardware limitation causing this connectivity issue between the routers?

Any insights, suggestions, or analogous experiences from the community would be immensely helpful in resolving this perplexing issue. Thank you in advance for your assistance.

[atiqbay023]

You should double check if you are using the correct type of Ethernet cable (crossover cable for direct router-to-router connection) and plz check the interface settings on both routers to confirm they match. If the interface lights are not coming on then it might also be worth trying different cables or testing the interfaces with other devices. If all else fails, consider resetting the interfaces and reconfiguring them from scratch. See, if it fix....

[Richard Burts]

Cable issues, especially if connected back to back routers, was the first thing that came to my mind. Would the OP tell us how the routers are connected? 

[MHM Cisco World]

Protocol down' if yoh use serial then use 

Protocol ppp 

Under serial interface

MHM

[Joseph W. Doherty]

I don't recall if the 2811s support auto-MDI.  (If the do support auto-MDI, ports should be in auto mode.) Otherwise, if you're connecting them via Ethernet interfaces you'll either need a cross over cable or place a switch in-line (using straight through cables if switch also doesn't support auto-MDI.)