Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?


What’s Changed in Release 21.1R2


  • 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

  • Default FEC Settings (QFX5130-32CD, QFX5220-32CD, and QFX5220-128C)—The default FEC mode for 4x25 optics is changed to FEC91 instead of FEC74. For 4x25G Direct Attach Copper Breakout Cables (DACBO), the default FEC mode remains as FEC74.

    [See show interfaces extensive.].

  • Enhancement to the show interfaces (Aggregated Ethernet) command (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.]

  • Enhancement to the default remnant-holdtime (Junos OS Evolved platforms: QFX5130-32CD, and QFX5220)— Starting this release, the default remnant-holdtime has been increased from 180 seconds to 300 seconds. This provides sufficient time for protocols to start and sync routes from neighbors in a scaled environment, during rpd restart. You can configure remnant-holdtime at the edit routing-options forwarding-table hierarchy level.

    See forwarding-table.]

Layer 2 Features

  • Link selection support for DHCP (QFX Series)—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.]