Configuring APS Load Sharing Between Circuit Pairs

When two routing platforms are connected to a single ADM, you can have them back up each other on two different pairs of circuits. This arrangement provides load balancing between the routing platforms if one of the working circuits fails.

Figure 56 illustrates load sharing between circuits on two routing platforms. Router A has a working circuit “Start” and a protect circuit “Up,” and Router B has a working circuit “Up” and a protect circuit “Start.” Under normal circumstances, Router A carries the “Start” circuit traffic and Router B carries the “Up” circuit traffic. If the working circuit “Start” were to fail, Router B would end up carrying all the traffic for both the “Start” and “Up” circuits.

To balance the load between the circuits, you pair the two circuits. In this case, you pair the “Start” and “Up” circuits. Then, if the working circuit “Start” fails, the two routing platforms automatically switch the “Up” traffic from the working to the protect circuit so that each routing platform is still carrying only one circuit’s worth of traffic. That is, the working circuit on Router A would be “Up” and the working circuit on Router B would be “Start.”

Figure 56: APS Load Sharing Between Circuit Pairs

To configure load sharing between two working–protect circuit pairs, include the paired-group statement when configuring one of the circuits on one of the routing platforms. In this statement, the group-name is the name of the group you assigned to one of the circuits with the working-circuit and protect-circuit statements. The JUNOS software automatically configures the remainder of the load-sharing setup based on the group name.

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