Description

In some cases, load merge terminal may display syntax errors, even though the configuration that is being pasted in the terminal is correct.

Symptoms

When using load merge terminal , the user has pasted a prepared configuration to the router. The user then types CNTRL + D at the keyboard to end the input.  At this point, the router complains of syntax error.  If the same configuration is loaded using load merge <filename> , it is accepted and no error is generated.

This does not concern other types of errors that might appear when an attempt to commit the configuration is made.

Solution

This can be due to the speed at which the terminal program is sending characters to the router.  Once the configuration text is pasted, the terminal application starts sending the text in the Transmission Control Protocol (TCP) connection.  If the speed of the sending is too high, TCP retransmissions may not be enough and some packets may be permanently lost.  This is particularly true if the transmission network is causing some traffic to be lost or if the receiving Routing Engine (RE) is too busy.  In this situation, the configuration will be corrupted in the router at arbitrary locations in the text.  When that happens, it will most likely lead to syntax errors being reported on the router.

To resolve the root cause of this issue, an investigation into the quality of the link and the load on the RE needs to be done. However, one effective and easy workaround is to tweak the sending parameters of the terminal application on the user's host. This obviously depends on which application is being used. The following applies to SecureCRT, which was successfully tested in version 6.2.1.

Two parameters can be changed in SecureCRT to alter the speed at which the user input is sent to the router:

  • Line send delay: in milliseconds, fixes the amount of time SecureCRT will wait after sending one whole line.
  • Character send delay: in milliseconds, fixes the amount of time SecureCRT will wait after sending one character.

These parameters can be found under   Options > Session Options > Terminal > Emulation > Advanced.

Some experimentation may be needed to find the correct values. If high values are configured, the user connection may become too slow.