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How to recover telnet/console hang in XR




There are a couple different variants of telnet/console hanging. This is mainly when using telnet to connect to a serial port over network. In some cases the XR telnet is hung, and other cases it is the internal Serial to XR Console session.  


There can be nested telnets:

Server                 Serial                XR Console                    XR telnet destination
                           <— internal telnet-->
    <—------------------ telnet to XR Console—————>
                                                <—— XR telnet to XR connected destination —>

Escape Sequence List

The following are the escape sequences for the various telnets:

1) XR telnet escape: ^^q = CTRL-SHIFT-6 followed by q
2) Serial to XR console escape: ^q  = CTRL-SHIFT-Q  (CTRL-q seems to work also)
3) Server telnet to Serial escape ^]   = CTRL-]


1) Kill the XR Telnet first if it exists.
- if you login to XR main console, if pressing keys cause garbage characters to appear, then you are probably still connected via the XR Telnet process


-if you can get to an XR aux port, you can see a telnet process running for the connection you made:

bash-4.3# ps -ef | grep telnet 

root 21303 20957 0 19:36 pts/2 00:00:02 telnet 0x1 -m 0x0 -p

^^q -> you may or may not get telnet prompt, this may exit immediately
ctrl+] -> exit Server to XR session
telnet back to Serial and go to (2)

2) Kill the Serial to XR Console 
- After killing the XR telnet process in (1), or if pressing [Enter] repeatedly shows nothing on the the screen

ctrl+Q -> upper case Q, though lower case seems to work sometimes

3) Kill Server to Serial Telnet

Telnet back for prompt.  Hit [Enter] multiple times

NOTE:  in some cases, even after you get XR Console back, double characters or garbage character appear.  Ctrl+], quit, [Enter] to exit Server to Serial Telnet, and then
telnet back

NOTE: sometimes the telnet prompt does not appear when hitting escape sequence.  Type quit, [Enter] anyway.

NOTE: The above can be used on Admin Console also

NOTE: Sometimes you need to exit the Server to XR Console session (^], quit) then telnet back in to clear the next level.
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