Data Center Configuration Basics and Monitoring
This domain tests the practical Junos configuration used on data center leaf and spine switches-VLANs, access and trunk ports, link aggregation, VXLAN/EVPN, and the monitoring commands that prove the design works.
Configuration rules
On ELS-enabled QFX/EX switches, put server ports in family ethernet-switching with interface-mode access and a vlan member. Trunks use interface-mode trunk and a vlan members list. Create the VLAN with set vlans NAME vlan-id N. For LAGs, create ae0, add member interfaces with ether-options 802.3ad ae0, and set LACP active. For VXLAN, map a VLAN to a VNI, configure a VTEP source interface, and enable EVPN with a BGP underlay. MC-LAG uses ICCP plus a multi-chassis protection interface for dual-homing.
Worked example
To connect a server and uplink: set vlans VLAN10 vlan-id 10 set interfaces ge-0/0/5 unit 0 family ethernet-switching interface-mode access vlan members VLAN10 set interfaces ae0 aggregated-ether-options lacp active set interfaces ae0 unit 0 family ethernet-switching interface-mode trunk vlan members [ VLAN10 VLAN20 ] set interfaces ge-0/0/1 ether-options 802.3ad ae0 Then verify with show vlans, show ethernet-switching interface, show lacp interfaces, and show ethernet-switching table. The MAC table confirms the server was learned in VLAN10; LACP shows whether member links are bundled.
Traps
Omitting family ethernet-switching prevents Layer 2 forwarding. A trunk that does not list the VLAN drops that traffic. Both LACP peers set to passive will not form a bundle. For VXLAN, an MTU that ignores the 50-byte encapsulation overhead causes large packets to fail. Monitoring with only interface status misses MAC learning and EVPN database problems.