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Aggregated Ethernet Interfaces Overview

Learn about aggregated Ethernet interfaces, how to configure an aggregated Ethernet interface, LACP, and other supported features.

You can group or bundle multiple Ethernet interfaces together to form a single link layer interface known as the aggregated Ethernet interface (aex) or a link aggregation group (LAG). The IEEE 802.3ad standard defines link aggregation of Ethernet interfaces and provides a method by which you can group or bundle multiple Ethernet interfaces. Bundling multiple interfaces together enables you to increase the supported bandwidth. The device treats the aggregated Ethernet interface or LAG as a single link instead of a combination of multiple links.

Benefits

  • Increased bandwidth and cost effectiveness—The aggregated link provides higher bandwidth than the bandwidth provided by each individual link without requiring new equipment.

  • Increased resiliency and availability—If any of the physical links goes down, the traffic is reassigned to another member link.

  • Load balancing—The aggregated Ethernet bundle balances the load between its member links if a link fails.

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

Review the Platform-Specific Maximum Interfaces Per LAG Behavior section for notes related to your platform.

Guidelines to Configure Aggregated Ethernet Interfaces

Consider the following guidelines as you configure an aggregated Ethernet interface.

  • For Junos OS Evolved, if you add a new member interface to the aggregated Ethernet bundle, a link flap event is generated. The physical interface is deleted as a regular interface and then added back as a member. During this time, the details of the physical interface are lost.

  • Use the gigether-options statement to configure aggregated Ethernet interfaces on the member link interfaces.

Configure Aggregated Ethernet Interfaces

Follow these steps to configure aggregated Ethernet interfaces on your routing device.

  1. Specify the number of aggregated Ethernet bundles you want on your device. If you specify the device-count value as 2, you can configure two aggregated bundles.

  2. Specify the members you want to include within the aggregated Ethernet bundle and add the member individually. Aggregated interfaces are numbered from ae0 through ae4092.

  3. Specify the link speed for the aggregated Ethernet links. When you specify the speed, all the interfaces that make up the aggregated Ethernet bundle have the same speed. You can also configure the member links of an aggregated Ethernet bundle with a combination of rates—that is, mixed rates—for efficient bandwidth utilization.
  4. Specify the minimum number of links for the aggregated Ethernet interface (aex) —that is, the defined bundle— to be labeled up. By default, only one link must be up for the bundle to be labeled up.

    You cannot configure the minimum number of links and the minimum bandwidth at the same time. They are mutually exclusive.

  5. (Optional) Specify the minimum bandwidth for the aggregated Ethernet links. You cannot configure link protection with minimum bandwidth.

  6. Specify an interface family and the IP address for the aggregated Ethernet bundle. Aggregated Ethernet interfaces can be VLAN-tagged or untagged.

    Untagged Interface

  7. (Optional) Configure your device to collect multicast statistics for the aggregated Ethernet interface.

  8. Verify and commit the configuration.

  9. (Optional) Delete an aggregated Ethernet Interface.

Enhanced Link Aggregation Group

When you associate a physical interface with an aggregated Ethernet interface, the physical child links are also associated with the parent aggregated Ethernet interface to form a link aggregation group (LAG). So, one child next hop is created for each member link of an aggregated Ethernet interface for each VLAN interface. For example, an aggregate next hop for an aggregated Ethernet interface with 16 member links leads to the creation of 17 next hops per VLAN.

When you configure enhanced LAG, child next hops are not created for member links and, as a result, a higher number of next hops can be supported. To configure enhanced LAG, you must configure the device’s network services mode as enhanced-ip. This feature is not supported if the device’s network services mode is set to operate in the enhanced-ethernet mode. This feature is enabled by default if the network services mode on the device is configured as enhanced-mode.

Benefits

  • Reduction in memory and CPU usage to support aggregated Ethernet interfaces.

  • Improvement in system performance and scaling numbers.

Mixed-Rate Aggregated Ethernet Interfaces

On Juniper Networks devices, you can configure the member links of an aggregated Ethernet bundle to operate at different link speeds (also known as rates). The configured aggregated Ethernet bundle is known as a mixed-rate aggregated Ethernet bundle. When you configure the member links of an aggregated Ethernet bundle in LAN mode as well as WAN mode for 10-Gigabit Ethernet interfaces, the configuration is known as mixed-mode configuration.

Benefits

  • Efficient bandwidth utilization—When you configure the member links with different link speeds, the bandwidth is efficiently and completed used.

  • Load balancing—Balances the load between member links within an aggregated Ethernet bundle if a link fails.

Guidelines to Configure Mixed-Rate Aggregated Ethernet Links

Consider the following guidelines as you configure a mixed-rate aggregated Ethernet bundle:

  • You can configure a maximum of 64 member links to form a mixed aggregated Ethernet bundle.

  • When you mix a 10-Gigabit Ethernet interface in LAN mode and a 10-Gigabit Ethernet interface in WAN mode in the same aggregated bundle on the routers, it is not considered a mixed-rate aggregate. To mix the interfaces having the same speed but different framing options, you need not use the mixed statement at the [edit interfaces interface-name aggregated-ether-options link-speed] hierarchy level.

  • Mixed-rate aggregated Ethernet links can interoperate with non-Juniper Networks aggregated Ethernet member links provided that mixed-rate aggregated Ethernet load balancing is configured at egress.

  • After you configure a mixed-rate aggregated Ethernet link on a 100-Gigabit Ethernet PIC with CFP, changing aggregated Ethernet link protection or LACP link protection configurations results in aggregated Ethernet link flapping. Also, changing the configuration of a mixed aggregated Ethernet link can result in aggregated Ethernet link flapping.

  • Packets are dropped when the total throughput of the hash flow exiting a member link (or the throughput of multiple hash flows exiting a single member link) exceeds the link speed of the member link. This can happen when the egress member link changes because of a link failure and the hash flow switches to a member link of speed that is less than the total throughput of the hash flow.

  • Mixed-rate aggregated Ethernet links do not support rate-based CoS components such as scheduler, shaper, and policer. However, the default CoS settings are supported on the mixed-rate aggregated Ethernet links.

  • Load balancing of the egress traffic across the member links of a mixed-rate aggregated Ethernet link is proportional to the rates of the member links. Egress multicast load balancing is not supported on mixed aggregated Ethernet interfaces.

  • Mixed-rate aggregated Ethernet interface do not support aggregated Ethernet link protection, link protection on a 1:1 model, and LACP link protection.

Configure Mixed-Rate Aggregated Ethernet Interfaces

Follow these steps to configure mixed-rate aggregated Ethernet interfaces on your routing device.

  1. Specify the number of aggregated Ethernet bundles you want on your device. If you specify the device-count value as 2, you can configure two aggregated bundles.

  2. Specify the members you want to include within the aggregated Ethernet bundle and add the member individually. Aggregated interfaces are numbered from ae0 through ae4092.

  3. Specify the link speed for the aggregated Ethernet links. When you specify the speed as mixed, you can configure the member links of an aggregated Ethernet bundle with a combination of rates—that is, mixed rates—for efficient bandwidth utilization.
  4. Specify the minimum bandwidth for the aggregated Ethernet links.

  5. Verify and commit the configuration.

Configure LACP

Follow these steps to configure LACP on an aggregated Ethernet interfaces on your routing device.

  1. Specify the LACP transmission mode - active or passive

  2. Specify the interval at which the interfaces send LACP packets. When you configure different intervals for the active and passive interfaces, the actor transmits the packets at the rate that is configured on the partner’s interface.

  3. Configure the LACP system ID. The user-defined system identifier in LACP enables two ports from two different devices to act as though they were part of the same aggregate group. The system identifier is a 48-bit (6-byte) globally unique field. It is used in combination with a 16-bit system-priority value, which results in a unique LACP system identifier.

  4. Configure the LACP system priority at the Aggregated Ethernet interface level. This system priority takes precedence over the priority value that is configured at the global [edit chassis] level. The device with numerically lower value (higher priority value) becomes the controlling device. If both devices have the same LACP system priority value, the device MAC address determines which device is in control.

  5. (Optional) Configure the LACP administrative key.

  6. Specify the time period, in seconds, for which LACP maintains the state of a member link as expired. To prevent excessive flapping of a LAG member link, you can configure LACP to prevent the transition of an interface from down to up for a specified interval.

  7. Configure the device to process packets received on a member link irrespective of the LACP state if the aggregated interface status is up.

  8. Verify and commit the configuration.

Configure Targeted Distribution Across Aggregated Ethernet Member Links

This example shows how to configure primary and backup targeted distribution lists for aggregated Ethernet member links. Member links are assigned membership to the distribution lists. Logical interfaces of the aggregated Ethernet bundle are then assigned membership to the primary list and the backup list.

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the [edit] hierarchy level, and then enter commit from configuration mode.

Step-by-Step Procedure

To configure targeted distribution:

  1. Create a global apply group and specify the primary list and the backup list.

  2. Attach the defined apply group to the aggregated Ethernet interface.

  3. Create the logical interfaces and configure its parameters.

Results

From configuration mode, confirm your configuration by using the show command. If the output does not display the intended configuration, repeat the configuration instructions in this example to correct it.

Requirements

This example uses the following software and hardware components:

  • Junos OS Release 16.1 and later releases

  • One MX Series 5G Universal Routing Platform

Overview

Targeted distribution provides a mechanism to direct traffic through specified links of an aggregated Ethernet bundle, and also assigns roles to member links to handle link failure scenarios. You can configure targeted distribution to load-balance the traffic between the aggregated Ethernet bundle member links. You can map a logical interface to a single link only for the outgoing traffic.

This example uses the apply-groups configuration for specifying the distribution lists for the logical interfaces of the aggregated Ethernet member links. You can use the apply-groups statement to inherit the Junos OS configuration statements from a configuration group. The apply-groups configuration statement in the example shows the odd-numbered member links of the aggregated Ethernet bundle being assigned the primary list dl2 and even-numbered member links being assigned primary list dl1.

The aggregated Ethernet interface used in this example is ae10 with units 101, 102, 103, and 104. The physical interface ge-0/0/3 is specified as distribution list dl1 and ge-0/0/4 as dl2. The distribution list dl1 is assigned as the primary list for those logical interface unit numbers of the aggregated Ethernet bundle ending in an odd number. Alternatively, the distribution list dl2 is the primary list for those ending in an even number.

To configure targeted distribution, you must:

  1. Create a global apply group.

  2. Assign each member of the aggregated Ethernet interface to a different distribution list.

  3. Attach the apply group to the aggregated Ethernet interface.

  4. Create the logical interfaces. The apply group automatically assigns the distribution lists to each member of the aggregated Ethernet bundle as required.

Verification

Verify Targeted Distribution of Logical Interfaces

Purpose

Verify that the logical interfaces are assigned to the distribution lists.

Action

To verify that the logical interfaces are assigned to the distribution lists, enter the show interfaces detail or extensive command.

The show interfaces detail or extensive command output shows the logical interfaces ending in an odd number being assigned to the distribution list dl1 (ge-0/0/3) and those ending in an even number being assigned to the distribution list dl2 (ge-0/0/4) by default. If there is a failure of either of those interfaces, the logical interfaces switch to the interfaces in the backup list or continue to use the active member interface. For example, on the aggregated Ethernet bundle ae10.101, the primary interface shown is ge-0/0/4 and on the aggregated Ethernet bundle ae10.102, the primary interface is ge-0/0/3, and similarly for the other logical interfaces.

MAC Address on Aggregated Ethernet Interfaces

You can configure source MAC address and destination MAC address-based accounting for MAC addresses that are dynamically learned on aggregated Ethernet interfaces.

By default, dynamic learning of source and destination MAC addresses on aggregated Ethernet interfaces is disabled. When you enable this feature, you can configure source and destination MAC address-based accounting on the routed interfaces on MX Series routers with DPCs and MPCs. Also, when you enable dynamic learning of MAC addresses, the MAC-filter settings for each member link of the aggregated Ethernet bundle is updated. The limit on the maximum number of MAC addresses that can be learned from an interface does not apply to this dynamic learning of MAC addresses functionality.

Destination MAC-based accounting is supported only for MAC addresses dynamically learned at the ingress interface, including each individual child or member link of the aggregated Ethernet bundle. MPCs do not support destination MAC address learning. Dynamic learning of MAC addresses can be supported on only the aggregated Ethernet interface or on selective individual member links. MAC learning support on the bundle depends on the capability of individual member links. If a link in the bundle does not contain the capability to support MAC learning or accounting, it is disabled on the aggregated Ethernet bundle.

The MAC data for the aggregated bundle is displayed after collecting data from individual child links. On DPCs, these packets are accounted in the egress direction (Output Packet/Byte count), whereas on MPCs, these packets are not accounted because DMAC learning is not supported. This difference in behavior also occurs between child links on DPCs and MPCs. Because this feature to enable dynamic learning is related to collecting MAC database statistics from child links that are based on the command that is issued from the CLI, there is an impact on the time it takes to display the data on the console based on the size of the MAC database and the number of child links spread across different FPCs.

Benefits

Compute Statistics—Enables you to compute MAC Address statistics for dynamically learned MAC addresses.

Platform-Specific Maximum Interfaces Per LAG Behavior

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

Use the following table to review platform-specific behavior for your platform:

Platform

Difference

ACX Series

ACX Series routers that support LAG, support a maximum of 255 interfaces per LAG.

MX Series

MX Series routers that support LAG, support a maximum of 64 interfaces per LAG.

PTX Series

PTX Series routers that support LAG, support a maximum of 64 interfaces per LAG.