Implement configurable GTP path ICMP error behaviour

[vkatsuba]

erGW version

2.8.5

Description

• Motivation
  In the network an ICMP error packet can be received on a GTP path for intermittent errors, resulting in the undesirable behaviour of immediately removing all the contexts bound to the path. The path management improvement in the linked Improve ICMP error handling behaviour in ERGW GTP Path maintenance #303 ticket is a larger change, that can take while to implement.
• Proposal
  As a short term solution and prerequisite for ticket Improve ICMP error handling behaviour in ERGW GTP Path maintenance #303, this ticket proposes to implement a configuration option where the behaviour of the GTP path upon receiving an ICMP error can be configured.

Current behavior

ICMP error packets immediately remove all the contexts bound to the path without the possibility to influence the behaviour.

Expected behavior

erGW has a configuration option in the path_management configuration section that allows the choice of action in case of ICMP errors from the following possibilities:

• immediate : (default) which it the current behaviour of the system
• ignore : ignore the ICMP error and rely only on path failure detection based on echo messages

The name of the new configuration could be icmp_error_handling.

Example of new option:

{path_management, [
    {icmp_error_handling, ignore}
]}