Showing results for 
Search instead for 
Did you mean: 

CLI parser limitation

Martin Oles

Recently I have been indirectly witnessed an incident, where guy put from Windows' notepad heaps of commands, where somehow some did not went through correctly. So then it came to my mind a question, if there is some limitation about how many commands or characters  could be sent to router in one "copy paste". I have found some limitation of CLI, but nowhere is mentioned actual number of characters which could be send like this. Do you know if such is somewhere specified?

Thank you.

Martin Oles

2 Replies 2

paolo bevilacqua
Hall of Fame Master Hall of Fame Master
Hall of Fame Master

Pasting into terminal windows and assuming all is good is a bad practice.

Nowerec cisco states limtiations for the simple reason is not possible to do so.

Serial connnections will routinely drop chunks, telnet conenctions will work better not still nothing is guaranteed.

You can use cose "copy ftp://x.x.x.x/fileame running-config" for guaranteed delivery of commands to router.

Otherwise the operator has to visually check that everything went well.


I do not believe that there is any specific limit on how many commands or how many characters can be processed in a single cut and paste. But as Paolo mentions it is quite possible to send data to the CLI more quickly than it can be received - and this is especially a problem when sending commands while connected to the console (whose speed is usually 9600). If you are sending quickly it is possible to over-run the input buffer and the result is dropped commands as you mention.

I typically make sure that my terminal emulator slows down a bit the rate at which it transmits, most especially for connections on the console. And with that I have send quite large config files to a router or switch and not dropped any commands. And Paolo makes a good suggestion that if you are concerned about this then using FTP to send the command file will guarantee that all commands are transferred.




Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Recognize Your Peers