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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

  • For IPv6 traffic that is ingressing into an abstract fabric (AF) interface via MPC11E card, and also sampled, the OutputIntf in the flow records may not be captured if nexthop-learning knob is not enabled.PR1680873

  • because of the scale and PPS, race condition between sessions can occur to get a port bitmap which is leading to few out of port errors. Once the bitmap race condition is cleared the same resource will be allocated to subsequent NAT allocation request(resource not wasted). Because of the race condition, we see the resource momentarily unavailable for the allocation as two sessions are trying to allocate the same resource. PR1693824

  • There is increase in memory footprint across different demons after an image upgrade resulting increase in the system memory. PR1694522

  • MX304: When 1G interface is disabled, the interface active defect alarm is not set in show interfaces extensive. PR1712831


  • Traceroute in MPLS OAM may fail with unreachable in ECMP case when topology has multiple ecmp paths in each transit router. This is because destination address is not available. Destination address is computed using base address + bitmap index(available for that leg).Junos currently supports 64 bitvector size.Each transit ecmp legs consumes available bitmap indexes in the echo request packet. When all the bitmap indexes are consumed by the previous transit routers/ecmp legs, then for other ecmp legs bitmap indexes are not available hence multipath information tlv bitmap will be zero leading to unreachable issue as no destination address is available. Even RFC 8029 section 4.1 says full coverage is not possible as below, If several transit LSRs have ECMP, the ingress may attempt to compose these to exercise all possible paths. However, full coverage may not be possible. Hence this is an expected behavior.PR1699685

Passive Mode Tunneling

Passive Mode Tunneling support for MX-SPC3 Services Card (MX240, MX480 and MX960)— Passive mode tunneling has following limitations:

  • MX-SPC3 services card supports header-integrity-check option in service-set configuration to verify the packet header for anomalies in IP, TCP, UDP, and ICMP information. This functionality is opposite to the functionality supported by passive-mode-tunneling option. If you configure both the header-integrity-check statement and the passive-mode-tunneling statement, the configuration will result in error during the commit.

  • MX-SPC3 services card with passive-mode-tunneling support, and header-integrity-check in service-set has following implications with multiple VPNs configuration -

    • If you enable header-integrity-check option, passive-mode-tunneling option should be disabled for all VPNs and service-set can’t have two or more IPsec VPNs with different passive-mode-tunneling value. This means if header-integrity-check option is enabled, a service-set can have only one type of VPN configured with either passive-mode-tunneling enabled or disabled.

    • If you disable header-integrity-check option, then a service-set can have two or more IPsec VPNs with different passive-mode-tunneling value.

  • No flow session output is seen with show security flow session output with packet based processing of IPsec traffic via passive mode tunnels.

Platform and Infrastructure

  • When the deactivate services rpm and deactivate routing-options rpm-tracking CLIs are applied together and then committed, some of the rpm tracked added routes are not deleted from the routing table. Issue cannot be seen using the following steps. 1. deactivate routing-options rpm-tracking 2. commit the configuration then all the rpm tracked routes will be deleted. If the RPM service needs to be deactivated, 3. deactivate services rpm 4. commit. PR1597190

Routing Protocols

  • When routing-options transport-class fallback none is not configured more than 10 transport-classes or advertise more than 10 distinct colors in SRTE. PR1648490

User Interface and Configuration

  • On all Junos OS platforms with persist-group-inheritance might lead to mustd process crash in highly scaled configuration. PR1638847