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Junos OS Release Notes for ACX Series

 

These release notes accompany Junos OS Release 20.2R1 for the ACX Series. They describe new and changed features, limitations, and known and resolved problems in the hardware and software.

You can also find these release notes on the Juniper Networks Junos OS Documentation webpage, located at https://www.juniper.net/documentation/product/en_US/junos-os.

What's New

Learn about new features introduced in the Junos OS main and maintenance releases for ACX Series routers.

Class of Service (CoS)

  • Support for hierarchical class of service (HCoS) (ACX5448)—Starting with Junos OS Release 20.2R1, ACX5448 devices support up to four levels of hierarchical scheduling (physical interfaces, logical interface sets, logical interfaces, and queues). By default, all interfaces on the ACX5448 use port-based scheduling (eight queues per physical port). To enable hierarchical scheduling, set hierarchical-scheduler at the [edit interfaces interface-name] hierarchy level.

    [See Hierarchical Class of Service in ACX Series Routers.]

EVPN

  • Noncolored SR-TE LSPs with EVPN-MPLS (ACX5448, EX9200, MX Series, and vMX)—Starting in Junos OS Release 20.2R1, ACX5448, EX9200, MX Series, and vMX routers support noncolored static segment routing-traffic engineered (SR-TE) label-switched paths (LSPs) with an EVPN-MPLS core network and the following Layer 2 services running at the edges of the network:

    • E-LAN

    • EVPN-ETREE

    • EVPN-VPWS with E-Line

    Without color, all LSPs resolve using a BGP next hop only.

    The Juniper Networks routers support noncolored SR-TE LSPs in an EVPN-MPLS core network with the following configurations:

    • EVPN running in a virtual switch routing instance

    • Multihoming in active/active and active/standby modes

    The Juniper Networks routers also support noncolored SR-TE LSPs when functioning as a Data Center Interconnect (DCI) device that handles EVPN Type 5 routes.

    [See Static Segment Routing Label Switched Path.]

Interfaces and Chassis

  • Multichassis link aggregation groups, configuration synchronization, and configuration consistency check (ACX5448 routers)—Starting in Junos OS Release 20.2R1, multichassis link aggregation (MC-LAG) includes support of Layer 2 circuit functionality with ether-ccc and vlan-ccc encapsulations.

    MC-LAG enables a client device to form a logical LAG interface using two switches. MC-LAG provides redundancy and load balancing between the two switches, multihoming support, and a loop-free Layer 2 network without running spanning-tree protocols (STPs).

    [See Multichassis Link Aggregation Features, Terms, and Best Practices.]

Juniper Extension Toolkit (JET)

  • Python 3 support for JET (ACX Series, EX Series, MX Series, PTX Series, QFX Series, and SRX Series)—Starting in Junos OS Release 20.2R1, Junos OS can use Python 3 to execute JET scripts. To enable unsigned JET Python applications that support Python 3 to run on devices running Junos OS, use the set system scripts language python3 command.

    [See language (Scripts), Develop Off-Device JET Applications, and Develop On-Device JET Applications.]

Junos Telemetry Interface

MPLS

  • Support for MPLS ping and traceroute for segment routing (ACX Series, MX Series, and PTX Series) Starting in Junos OS Release 20.2R1, we extend the MPLS ping and traceroute support for all types segment routing--traffic engineering (SR-TE) tunnels, including static segment routing tunnels, BGP-SR-TE tunnels, and PCEP tunnels.

    We also support the following features:

    • FEC validation support, as defined in RFC 8287, for paths consisting of IGP segments. Target FEC stack contains single or multiple segment ID sub-TLVs. This involves validating IPv4 IGP-Prefix Segment and IGP-Adjacency Segment ID FEC-stack TLVs.

    • ECMP traceroute support for all types of SR-TE paths.

    We do not support the following:

    • Ping and traceroute for SR-TE tunnel for non-enhanced-ip mode.

    • OAM for IPv6 prefix.

    • BFD

    [See traceroute mpls segment-routing spring-te and ping mpls segment routing spring-te.]

Multicast

  • Support for IPv6 multicast using MLD (ACX5448)—Starting with Junos OS Release 20.2R1, ACX5448 routers support Multicast Listener Discovery (MLD) snooping with MLDv1 and MLDv2 for both any source multicast and SSM. Support for MLD snooping in EVPN was introduced in Junos OS Release 19.4R2.

    MLD snooping for IPv6 is used to optimize Layer 2 multicast forwarding. It works by checking the MLD messages sent between hosts and multicast routers to identify which hosts are interested in receiving IPv6 multicast traffic, and then forwarding the multicast streams to only those VLAN interfaces that are connected to the interested hosts (rather than flooding the traffic to all interfaces). You can enable or disable MLD snooping per VLAN at the [edit protocols mld-snooping vlan vlan-ID] hierarchy level. Note, however, that you cannot use ACX Series routers to connect to a multicast source.

    [See Understanding MLD Snooping, Understanding MLD, and Overview of Multicast Forwarding with IGMP or MLD Snooping in an EVPN-MPLS Environment.]

Network Management and Monitoring

  • Python 3 support for YANG scripts (ACX Series, EX Series, MX Series, PTX Series, QFX Series, and SRX Series)—Starting in Junos OS Release 20.2R1, Junos OS uses Python 3 to execute YANG action and translation scripts that are written in Python. Junos OS does not support using Python 2.7 to execute YANG Python scripts as of this release.

    [See Understanding Python Automation Scripts for Devices Running Junos OS.]

  • Support for port mirroring (ACX5448)—Starting in Junos OS Release 20.2R1, you can use analyzers to mirror copies of packets to a configured destination. Mirroring helps in debugging network problems and also in defending the network against attacks. You can mirror all ingress traffic to a configured port (or port list), using a protocol analyzer application that passes the input to mirror through a list of ports configured through the logical interface. You configure the analyzer at the [edit forwarding-options analyzer] hierarchy level.

    Configuration guidelines and limitations:

    • Maximum of four default analyzer sessions

    • LAGs supported as mirror output; a maximum of eight child members

    • Not supported:

      • Egress mirroring

      • Mirroring on IRB, Virtual Chassis, or management interfaces

      • Nondefault analyzers

    [See show forwarding-options analyzer.]

What's Changed

Learn about what changed in Junos OS main and maintenance releases for ACX Series routers.

General Routing

  • Support for full inheritance paths of configuration groups to be built into the database by default (ACX Series, EX Series, MX Series, PTX Series, QFX Series, and SRX Series)—Starting with Junos OS Release 20.2R1, the persist-groups-inheritance option at the [edit system commit] hierarchy level is enabled by default. To disable this option, use no-persist-groups-inheritance.

    [See commit (System).]

Juniper Extension Toolkit (JET)

  • PASS keyword required for Python 3 JET applications (ACX Series, EX Series, MX Series, PTX Series, QFX Series, and SRX Series)—If you are writing a JET application using Python 3, include the PASS keyword in the Exception block of the script. Otherwise, the application throws an exception when you attempt to run it.

    [See Develop Off-Device JET Applications and Develop On-Device JET Applications.]

  • Updates to IDL for RIB service API bandwidth field (ACX Series, EX Series, MX Series, PTX Series, QFX Series, and SRX Series)—The IDL for the RouteGateway RIB service API has been updated to document additional rules for the bandwidth field. You must set bandwidth only if a next hop has more than one gateway, and if you set it for one gateway on a next hop, you must set it for all gateways. If you set bandwidth when there is only a single usable gateway, it is ignored. If you set bandwidth for one or more gateways but not all gateways on a next hop, you see the error code BANDWIDTH_USAGE_INVALID.

    [See Juniper EngNet.]

Network Management and Monitoring

  • Junos OS only supports using Python 3 to execute YANG Python scripts (ACX Series, EX Series, MX Series, PTX Series, QFX Series, and SRX Series)—Starting in Junos OS Release 20.2R1, Junos OS uses Python 3 to execute YANG action and translation scripts that are written in Python. In earlier releases, Junos OS uses Python 2.7 to execute these scripts.

    [See Understanding Python Automation Scripts for Devices Running Junos OS.]

Known Limitations

Learn about known limitations in this release for ACX 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

  • If Layer 2 VPN sessions have the OAM control-channel option set to router-alert-label, the no-control-word option in the Layer 2 VPN should not be used for BFD sessions to come up. PR1432854

  • The time consumed on 1-Gigabit performance is not equal to that on 10-Gigabit performance. Compensation is done to bring the mean value under class A but the peak-to-peak variations are high and can go beyond 100 ns. It has a latency variation with peak-to-peak variations of around 125–250 ns without any traffic (for example, 5–10 percent of the mean latency introduced by each phy which is of around 2.5us). PR1437175

  • If any queue is configured with high priority, it is expected that accuracy of traffic distribution might vary for normal queues because of chip limitation. PR1485405

  • On ACX5448 routers, aggregated Ethernet LACP toggles with host path traffic with MAC rewrite configuration enabled. PR1495768

Open Issues

Learn about open issues in this release for ACX 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

  • Policer discarded packets are marked as color black. Black color is used to discard the packets in the pipeline. These packets are not really enqueued into the queues (VoQs) in hardware. The hardware queue statistics shows this as discarded. However today, both actual-enqueued and the discarded counts are shown as queue-stats in software. This is a software queue-statistics show issue. PR1414887

  • DHCP clients are not able to scale to 96,000. PR1432849

  • Protocols get forwarded when using non-existing SSM map source address in IGMPv3 instead of pruning. PR1435648

  • Memory leaks are expected in this release. PR1438358

  • When there is a failure of the I2C daemon, core files are generated on ACX5448. PR1455928

  • On ACX5048 routers, the egress queue statistics are not working for the aggregated Ethernet interfaces. PR1472467

  • Issue is seen during unified ISSU to Junos OS Releases 20.2. Unified ISSU is completed, but the Packet Forwarding Engine does not function. Because of this, forwarding is affected. PR1483959

  • Queue statistics are not as expected after you configure physical interface and logical interface shaping with transmit-rate and scheduler-map. PR1488935

  • Port mirroring is not supported on ACX6360-OR. PR1491789

  • When the NETCONF session is established over an outbound SSH connection, the high rate of pushing the configuration to an ephemeral database might result in flapping of the outbound SSH connection or a memory leak issue. PR1497575

  • On the ACX6360 platform, the core file core-ripsaw-node-aftd-expr is generated and you are unable to back trace the file. PR1504717

  • MPLS LSP check is failing while verifying basic lsp_retry_limit. Reset the src_address of the LSP to 0 (if src_address is not configured) whenever it changes its state from up to down. So when the ingress LSP goes to down state, reset it to 0. The script is failing because the script is checking for src_address to be present for the ingress lSP session. PR1505474

  • In a PTP environment, some vendor devices act as slave expecting announce messages at an interval of -3 (8pps) from upstream master device. Currently, announce messages are configured in a range of 0 to 3. To support -3 requirement, a hidden CLI statement set protocol ptp master announce-interval -3 is introduced. In a network or design where you have this requirement, you can configure the hidden CLI or the regular CLI which is in the range of 0 to 3. Both the CLI statements are mutually exclusive, commit error is expected if both are configured. This new change is applicable to all ACX platforms except ACX5000 line of routers. PR1507782

Platform and Infrastructure

  • The CFM REMOTE MEP does not come up after configuration or remains in Start state. PR1460555

Resolved Issues

Learn which issues were resolved in the Junos OS main and maintenance releases for ACX 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

  • Drift messages in ACX2200, which is a PTP hybrid (PTP + Synchronous Ethernet) device. PR1426910

  • ACX5448-D interfaces support: The input bytes value for the show interfaces extensive command is not at par with older ACX Series or MX Series devices. PR1430108

  • On an ACX5448 device, DHCP packets are not transparent over Layer 2 circuit. PR1439518

  • On an ACX5048 device, SNMP polling stops after the link is flapped or the SFP transceiver is replaced, and ACX_COS_HALP(acx_cos_gport_sched_set_strict_priority:987): Failed to detach logs might be seen. PR1455722

  • ACX5448-D and ACX5448-M devices do not display airflow information and temperature sensors as expected. PR1456593

  • Unable to get shared buffer count as expected. PR1468618

  • Loss of manageability on ACX6360-OX platform when its disk gets full. PR1470217

  • ERP might not come up properly when MSTP and ERP are enabled on the same interface. PR1473610

  • The dcpfe core file is generated when disabling or enabling MACsec through Toby scripts. PR1479710

  • Link does not come up when a 100-Gigabit Ethernet port is channelized into four port 25-Gigabit Ethernet interfaces. PR1479733

  • On ACX5448 devices, dnx_nh_mpls_tunnel_install logs are seen. PR1482529

  • FPC crash is seen on ACX5448 platform. PR1485315

  • On an ACX5448 device, Layer 2 VPN with interface ethernet-ccc input-vlan-map/output-vlan-map can cause traffic to be discarded silently. PR1485444

  • On an ACX500-i router, SFW sessions are not getting updated on ms- interfaces. PR1505089

Interfaces and Chassis

  • The status of the MC-AE interface might be shown as unknown when you add the subinterface as part of the VLAN on the peer MC-AE node. PR1479012

Layer 2 Ethernet Services

  • Member links state might be asychronized on a connection between a PE device and a CE device in an EVPN active/active scenario. PR1463791

MPLS

  • BGP session might keep flapping between two directly connected BGP peers because of the incorrect TCP-MSS in use. PR1493431

Routing Protocols

  • The BGP route target family might prevent route reflector from reflecting Layer 2 VPN and Layer 3 VPN routes. PR1492743

VPNs

  • The Layer 2 circuit neighbor might be stuck in RD state at one end of the MG-LAG peer. PR1498040

  • The rpd core files are generated while disabling Layer 2 circuit with connection protection, backup neighbor configuration, and Layer 2 circuit trace logs enabled. PR1502003

Documentation Updates

There are no errata or changes in Junos OS Release 20.2R1 documentation for ACX Series routers.

Migration, Upgrade, and Downgrade Instructions

This section contains the upgrade and downgrade support policy for Junos OS for ACX Series routers. Upgrading or downgrading Junos OS might take several minutes, depending on the size and configuration of the network.

For information about software installation and upgrade, see the Installation and Upgrade Guide.

Upgrade and Downgrade Support Policy for Junos OS Releases

Support for upgrades and downgrades that span more than three Junos OS releases at a time is not provided, except for releases that are designated as Extended End-of-Life (EEOL) releases. EEOL releases provide direct upgrade and downgrade paths—you can upgrade directly from one EEOL release to the next EEOL release even though EEOL releases generally occur in increments beyond three releases.

You can upgrade or downgrade to the EEOL release that occurs directly before or after the currently installed EEOL release, or to two EEOL releases before or after. For example, Junos OS Releases 19.3, 19.4, and 20.1 are EEOL releases. You can upgrade from Junos OS Release 19.3 to Release 19.4 or from Junos OS Release 19.3 to Release 20.1.

You cannot upgrade directly from a non-EEOL release to a release that is more than three releases ahead or behind. To upgrade or downgrade from a non-EEOL release to a release more than three releases before or after, first upgrade to the next EEOL release and then upgrade or downgrade from that EEOL release to your target release.

For more information about EEOL releases and to review a list of EEOL releases, see https://www.juniper.net/support/eol/junos.html.

For information about software installation and upgrade, see the Installation and Upgrade Guide.