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What’s Changed in Release 21.3R1

Authentication and Access Control

  • Command to automate SSH key-based authentication (ACX Series, PTX Series, and QFX Series)—You can set up SSH-key based authentication between the network device and a remote host by issuing the request security ssh password-less-authentication operational mode command. When you execute the command with the appropriate options, the device generates SSH keys for the current user, provided the user does not already have existing keys, and transfers the user's public key to the authorized_keys file of the specified user on the remote host.

    [See request security ssh password-less-authentication.]

Class of Service

  • Junos OS Evolved now correctly displays the index for show class-of-service commands.


  • Minimum auto-recovery time reduced for duplicate MAC address detection (ACX Series, PTX Series and QFX Series)—Junos OS has changed the minimum value allowed for auto-recovery time for duplicate MAC address detection from 5 minutes to 1 minute. The auto-recovery time is the length of time that the device suppresses a duplicate MAC address. Reducing the auto-recovery time allows customers to quickly recover from a MAC address duplication state. You configure the auto-recovery-time option under the duplicate-mac-detection statement at the edit routing-instances routing-instance-name protocols evpn or edit protocols evpn hierarchy.

    [See Changing Duplicate MAC Address Detection Settings .]

General Routing

  • Enhancement to the show chassis pic command—You can now view additional information about the optics when you run the show chassis pic command. The output now displays the following additional field:

    MSA Version: Multi-source Agreements (MSA) version that the specified optics is compliant to. Values supported are: SFP+/SFP28 -- SFF-8472 (versions 9.3 - 12.3), QSFP+/QSFP28 -- SFF 8363 (versions 1.3 - 2.10), and QSFP-DD -- CMIS 3.0, 4.0, 5.0.

    Previously, the show chassis pic command did not display this additional field.

    [See show chassis pic.]

  • Enhancement to the show interfaces (Aggregated Ethernet) command (ACX Series, PTX Series, and QFX Series)—When you run the show interfaces extensive command for Aggregated Ethernet interfaces. You can now view following additional fields for MAC statistics : Receive, Transmit, Broadcast and Multicast packets.

    [See show chassis pic.]

Interfaces and Chassis

  • When configuring multiple flexible tunnel interface (FTI) tunnels, the source and destination address pair needs to be unique only among the FTI tunnels of the same tunnel encapsulation type. Prior to this PR, the source and destination address pair had to be unique among all the FTI tunnels regardless of the tunnel encapsulation type.

Junos XML API and Scripting

  • Changes to how command-line arguments are passed to Python op scripts (ACX Series, PTX Series, and QFX Series)—When the device passes command-line arguments to a Python op script, it prefixes a hyphen (-) to single-character argument names, and it prefixes two hyphens (—) to multi-character argument names. The prefix enables you to use standard command-line parsing libraries to handle the arguments. In earlier releases, the device prefixes a single hyphen (-) to all argument names.

    [See Declaring and Using Command-Line Arguments in Op Scripts.]

Layer 2 Features

  • Link selection support for DHCP—We have introduced the link-selection statement at the [edit forwarding-options dhcp-relay relay-option-82] hierarchy level, which allows DHCP relay to add suboption 5 to option 82. Suboption 5 allows DHCP proxy clients and relay agents to request an IP address for a specific subnet from a specific IP address range and scope. Prior to this release, the DHCP relay dropped packets during the renewal DHCP process and the DHCP server used the leaf's address as a destination to acknowledge the DHCP renewal message.

    [See relay-option-82.]

Network Management and Monitoring

  • Changes in contextEngineID for SNMPv3 INFORMS (ACX Series, PTX Series, and QFX Series)—Now the contextEngineID of SNMPv3 INFORMS is set to the local engine-id of Junos devices. In earlier releases, the contextEngineID of SNMPv3 INFORMS was set to remote engine-id.

    [See SNMP MIBs and Traps Supported by Junos OS.]