Description

This article explains the difference of behavior in executing 'commit check' after the same interface configuration changes between L2NG switches and Legacy switches.

Symptoms

On L2NG switches (EX4300, EX4600, EX9200 and QFX series), 'commit check' will allow an interface to be a member of a non-existing vLAN using vlan-id. This is a valid configuration:

{master:0}[edit]
root# show | compare
[edit interfaces]
+ xe-0/0/0 {
+        unit 0 {
+              family ethernet-switching {
+                     vlan {
+                           members 10;
+                   }
+             }
+        }
+ }

{master:0}[edit]
root# commit check
configuration check succeeds

However, while configuring an interface with a vLAN membership with a non-existing vLAN name, 'commit check' will generate the following error:

{master:0}[edit]
root# show | compare
[edit interfaces]
+ xe-0/0/11 {
+         unit 0 {
+              family ethernet-switching {
+                    vlan {
+                         members TEST;
+                }
+            }
+       }
+ }

{master:0}[edit]
root# commit check
error: In routing-instance default-switch vlan TEST configured under interface xe-0/0/11.0 does not exist
error: configuration check-out failed

Solution

On L2NG switches, the behavior above is expected. The vlan-id is allowed on an interface as a pre-provision to introduce flexibility. The actual vLAN gets programmed after the vLAN is configured.

This behavior is different on Legacy EX switches (EX2200, EX3300, EX4200, EX4500, EX4550, EX6200, EX8200) where commit check will generate an error when configuring an interface to be a member of a non existing vLAN.