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Known Behavior


This section contains the known behavior, system maximums, and limitations in hardware and software in Junos OS Release 17.1R2 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.

Class of Service (CoS)

  • Filtering for Routing Engine sourced packets (MX Series)—Starting in Junos OS Release 17.1R1, support is added for filtering on Differentiated Services Code Point (DSCP) and forwarding class for Routing Engine sourced packets. This includes IS-IS packets encapsulated in generic routing encapsulation (GRE). With this change comes a new order of precedence. When upgrading from a previous version of Junos OS where you have both a class of service (CoS) and firewall filter, and both include DSCP or forwarding class filter actions, the criteria in the firewall filter automatically takes precedence over the CoS settings. The same is true when creating new configurations; that is, where the same settings exist, the firewall filter takes precedence over the CoS, regardless of which was created first.

General Routing

  • The rpd process might crash if ECMP routes have more than 38 IS-IS IPv6 next hops—If the maximum-ecmp 64 statement is enabled and ECMP routes have more than 38 IS-IS IPv6 next hops, then the rpd process might crash because the next hop gateway addresses get overwritten and stored in a circular buffer.


    If all the next-hop IP addresses are IPv6 addresses, you can configure only 38 ECMP next-hop addresses for IS-IS.

High Availability (HA) and Resiliency

  • Unified ISSU incompatibility with VPLS dynamic profiles (MX Series)—Using unified ISSU to upgrade from an earlier Junos OS release to Junos OS Release 17.1R1 does not work if VPLS dynamic profiles are configured and enhanced subscriber management is not configured.

    [See ISSU System Requirements]

Interfaces and Chassis

  • Reordering of MAC addresses after a Routing Engine switchover—In Junos OS Release 14.2 and later, if you configure multiple aggregated Ethernet interfaces, the MAC address of the aggregated Ethernet interfaces displayed in the show interfaces ae number command output might get reordered after a Routing Engine switchover or restart.

    As a workaround, you can configure static MAC addresses for aggregated Ethernet interfaces. Any external dependency, such as filtering of the MAC addresses that are assigned before the reboot, becomes invalid if the MAC address changes.

Software Installation and Upgrade

  • On a broadband network gateway (BNG) that is running enhanced subscriber management, you must take the service cards offline before you can perform an in-service software upgrade (ISSU) to Junos OS Release 17.1 from a Junos OS release that includes the application-aware policy control feature (16.1R4 and later).

Subscriber Management and Services

  • If a graceful Routing Engine switchover (GRES) is triggered by an operational mode command, the state of aggregated services interfaces (ASIs) are not preserved. For example:

    However, if GRES is triggered by a CLI commit or FPC restart or crash, the backup Routing Engine updates the ASI state. For example: