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Known Limitations

Learn about known limitations in this release for MX Series routers.

For the most complete and latest information about known Junos OS defects, use the Juniper Networks online Junos Problem Report Search application.

General Routing

  • In a scaled setup with LDP over RSVP configuration and maximum-ecmp as 32 or 64, line card CPU usage can remain high for extended duration on link flap operation. In this duration, LACP might take 5+ minutes to converge and the AE bundle to be active. PR1624219

  • On SRX4600 platform, the CPU may overrun while performing sanity check due to incompatibility issues between ukern scheduler and Linux driver which might lead to traffic loss.PR1641517

  • For GNMI subscriptions, Packet Forwarding Engine does not support filtering in subscription paths. So data is streamed from Packet Forwarding Engine ignoring filtering. PR1668911

  • RE-S-X6-128G-K does not support enabling encryption with GRES. You must enable encryption on each Routing Engine. PR1676928

  • MVRP on PVLAN promiscuous port is not supported. If MVRP is configured on promiscuous port, then hosts connected to secondary VLAN ports will not be able to reach external world through promiscuous port carrying primary VLAN tags. PR1693345


  • When upgrading from releases earlier to Junos OS Release 21.2 and later, validation and upgrade might fail. The upgrading requires using of no-validate configuration statement.PR1568757

  • Below IPC timeouts logs can be seen for statistics query to kernel (queried from CLI or daemons querying internally) when there is configuration churn, or large number of IPCs getting exchanged between kernel and Packet Forwarding Engine in the system. if_pfe_msg_handler: pfe_peer_msg_handler error: error for msg type type, msg subtype subtype, opcode op and peer index index. Default IPC timeout value in kernel for IPC statistics request is 10s. This can be incremented to a larger value by setting below the hidden configuration to avoid IPC timeout errors. set system stats-timeout-lifetime 15 and commit. PR1629930


  • With local reversion ON, there is a possibility of transit router not informing headend of RSVP disabled link when link is flapped more than once. Work around is to remove local-reversion configuration. PR1576979

Network Management and Monitoring

  • Junos OS might translate the custom YANG configuration even after disabling the custom YANG package. PR1599107

Platform and Infrastructure

  • In some scenarios with MPC, major alarm and following messages are generated. This major error is triggered due to parity error, and the impacted queue might drop packets. This might impact the forwarding, to recover MPC card need to be rebooted. PR1303489

  • On MX Series and EX9200 Seriesl platforms, under Ethernet VPN (EVPN) environment, packets routed using IRB interface could not be fragmented due to media maximum transmission unit (MTU) problem. PR1522896

  • After a switchover event, when ppmd calls sendmsg system call to transmit the protocol packets, it gets blocked long enough that a few sendmsg calls cumulatively take up around 7 to 8 seconds. This indirectly impacts the BFD session because the BFD session has a Routing Engine-based detect time of 7.5 seconds to expire. PR1600684

Routing Protocols

  • When routing-options transport-class fallback none is not configured - do not configure more than 10 transport-classes. Or advertise more than 10 distinct colors in SR-TE or FlexAlgo. PR1648490

Services Applications

  • Subscriber sessions on the LNS that send an ICRQ that includes RFC5515 AVPs might fail to establish a session. The client will receive a CDN error "receive-icrq-avp-missing-random-vector" in response. PR1493289

User Interface and Configuration

  • On all Junos OS and Junos OS Evolved platforms configured with persist-group-inheritance, which is enabled by default from Junos OS Release 19.4R3 and later, might lead to mustd process crash in highly scaled configuration. PR1638847