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Aggregated Ethernet Link Protection

Learn how to provide link protection for aggregated Ethernet Interfaces and configure the link protection for aggregated Ethernet interfaces. Learn also how to configure primary and backup links for aggregated Ethernet interfaces.

Link Protection Overview

Learn about link protection on aex and its benefits.

Aggregated Ethernet Link Protection is a mechanism to provide link-level redundancy and fast failover for aggregated Ethernet links, ensuring continuous traffic flow even if one or more physical links in the aggregation fail.

You can achieve link protection primarily through features such as:

  • Link Protection for MPLS LSPs: On Juniper EX Series switches and routers running Junos OS, link protection can be configured on interfaces used by Label Switched Paths (LSPs). This creates a bypass LSP that reroutes traffic over an alternate path if the primary interface fails, enabling fast reroute and minimizing traffic disruption.

  • Spanning Tree Protocols (STP, RSTP, MSTP): Juniper devices use spanning tree protocols to prevent Layer 2 loops while allowing redundant paths. Loop protection features prevent interfaces from transitioning to forwarding states that would cause loops, enhancing network stability

  • Ethernet Ring Protection Switching (ERPS): For ring topologies, Juniper supports ERPS, which blocks one link in the ring (the Ring Protection Link) to prevent loops and quickly switches traffic to backup links upon failure, ensuring high availability.

In the context of aggregated Ethernet links (such as LAGs or aggregated Ethernet interfaces), Juniper’s link protection mechanisms work together with these protocols to provide fast failover and loop prevention, maintaining network resilience and minimizing downtime.

On aggregated Ethernet interfaces, you designate a primary and backup link to support link protection. Egress traffic passes only through the designated primary link. This includes transit traffic and locally generated traffic on the router or switch. When the primary link fails, traffic is routed through the backup link. Because some traffic loss is unavoidable, egress traffic is not automatically routed back to the primary link when the primary link is reestablished. Instead, you manually control when traffic should be diverted back to the primary link from the designated backup link.

Use Feature Explorer to confirm platform and release support for specific features.

Use Platform-Specific Link Protection to review platform-specific behaviors for your platform:

Benefits

The main benefits include:

  • Increased Bandwidth and Cost Efficiency: Aggregating multiple links increases total bandwidth beyond what a single link can provide, without needing new hardware.

  • Improved Resiliency and Availability: If one physical link in the bundle fails, traffic is automatically redistributed to the remaining active links, maintaining connectivity and minimizing downtime

  • Load Balancing: Traffic is balanced across the member links based on Layer 3/4 information or session IDs, optimizing utilization and performance

  • Link Monitoring and Protection: Using LACP, Junos OS monitors the state of each link in the bundle, ensuring that only correctly connected links are active and providing protection against link failures.

Platform-Specific Link Protection

Platform

Difference

ACX Series

  • ACX7000 Series routers that support link protection can operate in revertive mode. Enable auto-revertive operation using the following command:

    set interfaces ae1 aggregated-ether-options link-protection revertive