Scaling Your Data Center with the Juniper QFX5120-48Y Switch

The QFX5120-48Y is a one-rack-unit Juniper data center switch with 48 downlink ports that run at 25GbE, 10GbE or 1GbE and 8 uplink ports that run at 100GbE or 40GbE. The version with front-to-back airflow is the QFX5120-48Y-AFO. This page sets out what Juniper's QFX5120 system overview says about that model, and where it sits in Juniper's lifecycle notices.

The QFX5120-48Y-AFI is the back-to-front airflow version of the QFX5120-48Y, with 48 downlink ports that run 25GbE, 10GbE or 1GbE.

At a glance

Ports and breakout

The 48 downlinks are SFP28 cages, which take 25G optics and cables and also accept SFP+ and SFP modules for 10GbE and 1GbE. The 8 uplinks are QSFP28 cages numbered 48 through 55. Juniper supports channelization on all eight: a 40GbE port splits into four 10GbE interfaces and a 100GbE port splits into four 25GbE interfaces, both with breakout cables. One switch can therefore serve a rack of servers on 25GbE and still take 100GbE links up to the spine.

Airflow: AFO or AFI

Juniper sells the QFX5120 in two airflow directions. A switch with front-to-back airflow is the AFO version, with air entering at the port side. A switch with back-to-front airflow is the AFI version, with air in through the rear vents and out at the front. Juniper's cooling topic says fan modules and power supplies must all match: mixing airflow directions in one chassis is not allowed. Pick the version that matches the aisle the ports face, and when you buy a spare fan module or power supply, match its airflow label to the switch.

Software

The QFX5120 runs Junos OS. Juniper lists the following among the benefits and software features of the QFX5120 line:

• IP fabrics with EVPN-VXLAN overlays, for Layer 2 and Layer 3 network virtualization.
• EVPN, BGP, MPLS, Layer 3 VPN, IPv6 Provider Edge (6PE), segment routing and MC-LAG.
• Telemetry, and automation with Python, Ansible, YANG, Chef and zero-touch provisioning.
• PTP support, which Juniper says lets the QFX5120 meet the needs of the financial services and broadcast media industries.

Lifecycle

Juniper lists the QFX5120-48Y-AFI, QFX5120-48Y-AFO and QFX5120-48Y-DC-AFI under a SKU transformation notice, TSB17951, announced on January 20, 2021, with an end of sale date of October 4, 2021. The notice gives no end of support date for these part numbers, and Juniper's QFX Series dates page is where to read it. If you run a QFX5120-48Y, hold a tested spare of the same airflow and power version.

Where to look

Townsend lists the QFX5120 family on the Juniper QFX5120 page, and the wider series is on the Juniper QFX page. Every switch is tested before it ships. For another airflow or a DC version, send the requirement through a quote request.