Fix WLC conn_timeout issue (#1897)

netmiko/base_connection.py

@@ -935,6 +935,16 @@ def establish_connection(self, width=511, height=1000):
 
                 msg = msg.lstrip()
                 raise NetmikoTimeoutException(msg)
+            except paramiko.ssh_exception.SSHException as no_session_err:
+                self.paramiko_cleanup()
+                if "No existing session" in str(no_session_err):
+                    msg = (
+                        "Paramiko: 'No existing session' error: "
+                        "try increasing 'conn_timeout' to 10 seconds or larger."
+                    )
+                    raise NetmikoTimeoutException(msg)
+                else:
+                    raise
             except paramiko.ssh_exception.AuthenticationException as auth_err:
                 self.paramiko_cleanup()
                 msg = "Authentication failure: unable to connect {device_type} {ip}:{port}".format(

netmiko/cisco/cisco_wlc_ssh.py

@@ -10,6 +10,12 @@
 class CiscoWlcSSH(BaseConnection):
     """Netmiko Cisco WLC support."""
 
+    def __init__(self, *args, **kwargs):
+        # WLC/AireOS has an issue where you can get "No Existing Session" with
+        # the default conn_timeout (so increase conn_timeout to 10-seconds).
+        kwargs.setdefault("conn_timeout", 10)
+        return super().__init__(*args, **kwargs)
+
     def special_login_handler(self, delay_factor=1):
         """WLC presents with the following on login (in certain OS versions)
 

tests/conftest.py

@@ -145,7 +145,7 @@ def commands(request):
 
     # Nokia SR-OS driver is overloaded with both classical-CLI and MD-CLI
     # Swap out the commands to be the MD-CLI commands
-    if device_under_test == 'sros1_md':
+    if device_under_test == "sros1_md":
         test_platform = "nokia_sros_md"
 
     return commands_yml[test_platform]