Restoring a Lost Connection to a Rout... Log Out | Topics | Search
Moderators | Edit Profile

CN Discussion » Technical Guides and Frequently Asked Questions » Restoring a Lost Connection to a Router/Switch « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Arseny Taranenko
Username: Admin

Registered: 12-2003
Posted on Sunday, September 23, 2007 - 01:08 pm:   

If during your reservation you are unable to telnet to one of the devices in your pod and see blank output instead of the device prompt, follow the procedure below.

The most likely cause of not being able to reach a device console is the presence of another console connection to the device. Console ports can only accept one connection at a time. If you are already connected and try establishing a second connection, you will see a blank output instead of a device prompt. The solution is to terminate the first console connection. If you still have access to the first connection, simply terminate the telnet session with the “Ctrl-]” keys and the “quit” command. If you don’t have access to the first telnet session which is usually the case, you will need to kill the telnet process blocking your access as following:

1. To clear all console sessions, use "killall TELNET".

2. To clear individual telnet sessions, find the process IDs of the telnet sessions under your username. Under the Linux server prompt issue the command “ps – u username”. For example: “ps – u ataranen”

3. Terminate all the telnet sessions one by one; issue the command “kill procID”, where procID is the process ID of the telnet session displayed in the previous step. For example “kill 29478”. Repeat this command for the rest of the telnet sessions.

The most likely cause of this problem is a brief loss of the Internet connection. Every router/switch console connection consists of two parts: connection to the Linux server, and connection from the server to the console port of the device. A brief loss of the Internet will terminate the connection to the server, but will not effect the connection from the server to the console. When the server connection is restored, it may be necessary to terminate the previous telnet session from the server to the device prior to issuing the new telnet command. If after terminating all the telnet processes you are still unable to reach the console, there could be a physical problem with the device.

Add Your Message Here
Username: Posting Information:
This is a private posting area. Only registered users and moderators may post messages here.
Options: Enable HTML code in message
Automatically activate URLs in message

Topics | Last Day | Last Week | Tree View | Search | Help/Instructions | Program Credits Administration