Description

This article explains why native IRBb interface shows down if trunk VLAN of the physical interface does not include native VLAN ID in L2NG.

Solution

Configurations for L2NG of native vlan : 

set interfaces xe-0/1/6 native-vlan-id 100   <-- vlan 100 is native vlan
set interfaces xe-0/1/6 unit 0 family ethernet-switching interface-mode trunk
set interfaces xe-0/1/6 unit 0 family ethernet-switching vlan members 1417
set interfaces xe-0/1/6 unit 0 family ethernet-switching vlan members 1421
set interfaces xe-0/1/6 unit 0 family ethernet-switching vlan members 1433
set interfaces xe-0/1/6 unit 0 family ethernet-switching vlan members 1461-1462
set interfaces irb unit 100 family inet address 1.1.1.2/24
set interfaces irb unit 1417 family inet address 10.0.192.146/30
set interfaces irb unit 1421 family inet address 10.0.192.130/30
set interfaces irb unit 1433 family inet address 10.0.192.138/30
set interfaces irb unit 1461 family inet address 10.0.192.154/30
set interfaces irb unit 1462 family inet address 10.0.192.162/30

set vlans A14_A17 vlan-id 1417
set vlans A14_A17 l3-interface irb.1417
set vlans A14_A21 vlan-id 1421
set vlans A14_A21 l3-interface irb.1421
set vlans A14_A33 vlan-id 1433
set vlans A14_A33 l3-interface irb.1433
set vlans A14_P61 vlan-id 1461
set vlans A14_P61 l3-interface irb.1461
set vlans A14_P62 vlan-id 1462
set vlans A14_P62 l3-interface irb.1462
set vlans CRYPTO_MGMT vlan-id 100
set vlans CRYPTO_MGMT l3-interface irb.100

root@d08-26# run show interfaces irb terse
Interface               Admin Link Proto    Local                 Remote
irb                     up    up
irb.100                 up    down inet     1.1.1.2/24  <-- native vlan l3 interface is up down
irb.1417                up    up   inet     10.0.192.146/30
irb.1421                up    up   inet     10.0.192.130/30
irb.1433                up    up   inet     10.0.192.138/30
irb.1461                up    up   inet     10.0.192.154/30
irb.1462                up    up   inet     10.0.192.162/30

 

After adding vlan 100 in trunk vlan, it is up up: 

root@d08-26# set interfaces xe-0/1/6.0 family ethernet-switching vlan members 100

{master:0}[edit]
root@d08-26# commit
configuration check succeeds
commit complete

{master:0}[edit]
root@d08-26# run show interfaces irb.100 terse
Interface               Admin Link Proto    Local                 Remote
irb.100                 up    up   inet     1.1.1.2/24


While Legacy L2 has a different behavior: 

set interfaces xe-0/1/1 unit 0 family ethernet-switching port-mode trunk
set interfaces xe-0/1/1 unit 0 family ethernet-switching vlan members 1417
set interfaces xe-0/1/1 unit 0 family ethernet-switching vlan members 1421
set interfaces xe-0/1/1 unit 0 family ethernet-switching vlan members 1433
set interfaces xe-0/1/1 unit 0 family ethernet-switching vlan members 1461-1462
set interfaces xe-0/1/1 unit 0 family ethernet-switching native-vlan-id 100  <-- Native vlan is not configured under interface directly.
set interfaces vlan unit 100 family inet address 2.2.2.2/24
set interfaces vlan unit 1417 family inet address 17.0.0.1/24

set vlans v100 vlan-id 100
set vlans v100 l3-interface vlan.100
set vlans v1417 vlan-id 1417
set vlans v1417 l3-interface vlan.1417
set vlans v1421 vlan-id 1421
set vlans v1433 vlan-id 1433
set vlans v1461 vlan-id 1461
set vlans v1462 vlan-id 1462

root@d01-37# run show interfaces vlan terse
Interface               Admin Link Proto    Local                 Remote
vlan                    up    up
vlan.100                up    up   inet     2.2.2.2/24   <-- Native vlan's l3 interface is up up.
vlan.1417               up    up   inet     17.0.0.1/24

When you need to connect l3 native VLAN interface, configure add native VLAN in trunk VLAN members for L2NG code.