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Software Upgrade may cause a switch to load partial configuration upon booting up due to strict configuration checks in 15.1 and 14.1X53

  [TSB17116] Show Article Properties


Alert Type:
PSN - Product Support Notification
Alert Description:
Before the introduction of stricter configuration checking introduced by PR957178; configuration statements which used to be allowed in JUNOS software version 12.3 are now deem invalid in JUNOS version 15.1 and 14.1X53. The consequence of this is when upgrade EX switches from 12.3 to 15.1 or 14.1X53 ,  switch may loose its configuration and run in a Linecard mode or may go to "Amnesiac" Mode. 
Solution:
PR 957178  changed the behavior of the ‘interface-range’ configuration statement in 15.1R1.  Prior to fix of PR 957178 , more specific configuration on the interface would supersede what was configured in the interface-range.  In 15.1, if there was specific interface configuration, the configuration in ‘interface-range’ will append to it.  If, for example, there is a mismatch of VLAN assignment between the interface-range and the direct interface configuration, 15.1 will append the configured VLAN and cause an invalid configuration. As in  15.1 configuration checks have been made stricter to avoid invalid configuration and EX switches do not support configuration validation during upgrade it is highly recommended to test the configuration as described in "Implementation Section" even if you do not have interface-range specific configuration.


12.3 behavior
 
interfaces {
    interface-range TEST {
        member-range ge-0/0/0 to ge-0/0/10;
        unit 0 {
            family ethernet-switching {
                port-mode access;
                vlan {
                    members 100;
                }
            }
        }
    }
    ge-0/0/0 {
        unit 0 {
            family ethernet-switching {
                port-mode access;
                vlan {
                    members 200;
                }
            }
        }
    }
}
 
·
 
root@# show interfaces ge-0/0/0 | display inheritance 
unit 0 {
    family ethernet-switching {
        port-mode access;
        vlan {
            members 200;
        }
    }
}
 
15.1 behavior
 
  • Interface range TEST is setting ge-0/0/0 to ge-0/0/10 for VLAN member 100
  • Physical interface ge-0/0/0 is explicitly configured for VLAN 200
 
interfaces {
    interface-range TEST {
        member-range ge-0/0/0 to ge-0/0/10;
        unit 0 {
            family ethernet-switching {
                port-mode access;
                vlan {
                    members 100;
                }
            }
        }
    }
    ge-0/0/0 {
        unit 0 {
            family ethernet-switching {
                port-mode access;
                vlan {
                    members 200;
                }
            }
        }
    }
}
 
  • There is a strict configuration check in 15.1 with interface-range inheritance to report the commit error incase of invalid configuration.
 
root@# show interfaces ge-0/0/0 | display inheritance    
unit 0 {
    family ethernet-switching {
        port-mode access;
        vlan {
            ##
            ## '100' was expanded from interface-range 'TEST'
            ##
            members [ 200 100 ];
        }
    }
}
 
 
root@# commit check 
[edit interfaces ge-0/0/0 unit 0 family ethernet-switching]
  'vlan'
    Access interface can be part of only one vlan 
error: configuration check-out failed
 

If user upgrades to 15.1 or later with  such configuration , the switch will boot up with following error and Virutal-chassis members may come up as Linecard mode or some functionality may not work.

Ethernet Switching Process: Access interface <ge-0/0/0.0> has more than one vlan member: <ns-services> and <ns-management>
mgd: error: configuration check-out failed
Warning: Commit failed, activating partial configuration.



 
Implementation:

Below steps are recommended when you plan to upgrade to 15.1 based software version to ensure you configuration 12.3. based configuration is valid in 15.1 based software versions. 

It is recommended to verify the configuration in 15.1R1 or later in non-production unit before upgrading to 15.1 Release  in production.  Following steps are recommended.
  • Prepare a dedicated non-production EX device already running 15.1 based software version. 
  • Load the upgrade candidate’s configuration into the device
  •  Run ‘test configuration  <configuration path>’   to validate the 12.3 configuration for commit errors and syntax errors on the 15.1 device
    • If the "test" fails, correct the invalid configuration and re-run test until all validation passes
    • If the test  succeeds, the candidate configuration could be upgraded
    •  
In case of any help, please contact JTAC or open the case in Case Manager.

 
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