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What’s Changed in Release 21.4R3

General Routing

  • New ARP and NDP packet classification—We've introduced two CP classes for ARP and NDP packets received over VTEP interface. When your device identifies a packet as ARP or NDP, it performs an ingress port check which verifies whether the VTEP interface receives these packets. If VTEP interface receives the packet, datapath re-writes the CP class to the newly defined values. Based on this new CP class, the system performs the remaining packet processing and forwards the packets toward the host path. The system adds a separate DDoS policer to this ARP traffic, which ensures that the ARP traffic is not triggering underlay ARP DDoS violation.

Interfaces and Chassis

  • Display the donor details of the IPv6 borrower interface—The output for the show interfaces command now displays the donor details of the IPv6 borrower interface.

    [See show interfaces].

  • JNP10K-PWR-DC2 power supplies installed in PTX10008 and PTX10016 routers display as online when the power supplies are switched off— JNP10K-PWR-DC2 power supplies installed in PTX10008 and PTX10016 routers in which Junos OS Release 21.4R1 or Junos OS Evolved Release 21.4R1 is installed display as online in the output of the command show chassis environment psm when the input power feeds are connected, but the power switch on the power supplies are switched off.


  • Starting with Junos OS and Junos Evolved release 21.4R3 a CSPF LSP uses a new instance ID when attempting to re-signal a down LSP.

  • The MPLS EXP bits transmitted in self ping messages are set based on the DSCP/ToS setting of the corresponding IP packet.

Network Management and Monitoring

  • Changes to the NETCONF <edit-config> RPC response (ACX Series, PTX Series, and QFX Series)—When the <edit-config> operation returns an error, the NETCONF server does not emit a <load-error-count> element in the RPC response. In earlier releases, the <edit-config> RPC response includes the <load-error-count> element when the operation fails.


  • OpenConfig container names for Point-to-Multipoint per interface ingress and egress sensors are modified for consistency from "signalling" to "signaling".

Routing Protocols

  • When the krt-nexthop-ack statement is configured, the RPD waits for the next hop to get acknowledged by PFE before using it for a route. Currently, only BGP-labeled routes and RSVP routes support this statement. All other routes ignore this statement.

User Interface and Configuration

  • A new field rollback pending is added to the output of show system commit that identifies whether commit confirmed is issued. It is removed once commit or commit check is issued or commit confirmed is rolled back after rollback timeout.

  • Support for temperature sensor (PTX10001-36MR)—We support the temperature sensor statement at the edit chassis cb hierarchy level. You can use the temperature sensor statement to increase the fan speed and customize the temperature threshold. We recommend certain values for ZR and ZR-M modules to work which helps the temperature to remain within the thresholds.

    [See temperature-sensor.]