Configuring Junos OS for Supporting Aggregated Devices

To define virtual links, you need to specify the associations between physical and logical devices within the [edit interfaces] hierarchy, and assign the correct number of logical devices by including the device-count statement at the [edit chassis aggregated-devices ethernet] and [edit chassis aggregated-devices sonet] hierarchy levels:

[edit chassis]
aggregated-devices {
    ethernet {
        device-count number;
    }
    sonet {
        device-count number;
    }
}

The aggregated interfaces are numbered from ae0 through ae4091. The maximum number of aggregated interfaces supported by different routers is listed below:

• For PTX Series routers, you can configure a maximum of 128 aggregated interfaces.

• For M Series and T Series routers, you can configure a maximum of 128 aggregated interfaces (LAG bundles).

• In Junos release 14.2R2 and earlier, you can configure a maximum of 480 aggregated interfaces on MX Series routers.

• In Junos release 14.2R3 and later, you can configure a maximum of 1000 aggregated interfaces on MX240, MX480, and MX960 routers.

• In Junos release 14.2R3 and later, you can configure a maximum of 800 aggregated interfaces on MX2010 and MX2020 routers.

• In Junos OS 15.1F5 and 15.1F6 releases, you can configure a maximum of 480 aggregated interfaces on MX240, MX480, and MX960 routers.

• In Junos OS 15.1F5 and 15.1F6 releases, you can configure a maximum of 800 aggregated interfaces on MX2010 and MX2020 routers.

For SONET/SDH, starting with Junos OS Release 13.2, the maximum number of logical interfaces is 64, numbered from as0 through as63. In releases before Junos OS Release 13.2, the maximum was 16.

Table 1 lists the MX Series routers and the maximum number of interfaces per LAG and the maximum number of LAG groups they support. MX Series routers can support up to 64 LAGs.

Link Aggregation Control Protocol (LACP) is one method of bundling several physical interfaces to form one logical interface. You can configure both VLAN-tagged and untagged aggregated Ethernet with or without LACP enabled. LACP exchanges are made between actors and partners. An actor is the local interface in an LACP exchange. A partner is the remote interface in an LACP exchange.

LACP link protection enables you to force active and standby links within an aggregated Ethernet. You configure LACP link protection by using the link-protection and system-priority statements at either the chassis or interface level and by configuring port priority at the interface level using the system-priority statement. Configuring LACP parameters at the chassis level results in all aggregated Ethernet interfaces using the defined values unless overridden by the LACP configuration on a specific interface.

[edit chassis]
aggregated-devices {
    ethernet {
        lacp {
            link-protection {
                non-revertive;
            }
            system-priority priority;
        }
    }
}

To enable LACP link protection for aggregated Ethernet interfaces on the chassis, use the link-protection statement at the [edit chassis aggregated-devices ethernet lacp] hierarchy level:

[edit chassis aggregated-devices ethernet lacp]
link-protection {
    non-revertive;
}

By default, LACP link protection reverts to a higher-priority (lower-numbered) link when that higher-priority link becomes operational or a link is added to the aggregator that is determined to be higher in priority. However, you can suppress link calculation by adding the non-revertive statement to the LACP link protection configuration. In nonrevertive mode, after a link is active and collecting and distributing packets, the subsequent addition of a higher-priority (better) link does not result in a switch, and the current link remains active.

To configure LACP system priority for aggregated Ethernet interfaces on the chassis, use the system-priority statement at the [edit chassis aggregated-devices ethernet lacp] hierarchy level:

[edit chassis aggregated-devices ethernet lacp]
system-priority priority;

The system priority is a 2-octet binary value that is part of the LACP system ID. The LACP system ID consists of the system priority as the two most-significant octets and the interface MAC address as the six least-significant octets. The system with the numerically lower value for system priority has the higher priority. By default, system priority is 127, with a range of 0 through 65,535.

To configure the maximum links limit, use the maximum-links statement at the [edit chassis aggregated-devices] hierarchy level:

[edit chassis aggregated-devices]
maximum-links maximum-links-limit;

If you use Junos Fusion with Junos OS Release 14.2R3, you need to ensure that link aggregation (and STP) work properly by configuring timers for the periodic packet management (PPM) daemons on the aggregation and satellite devices. We recommend using the following timer values:

[edit routing-options ppm]
    redistribution-timer 120;
    tcp-keepalive-interval 3000;
    tcp-keepalive-idle 3000;

Starting in Junos OS Release 14.2R4, the timer values that ensure proper link aggregation and STP functions are configured by default if you use Junos Fusion with Junos OS.