Does an AR router that accesses the Internet through multiple upstream interfaces support link aggregation or load balancing

If the multiple upstream interfaces are physical interfaces of the same type (such as GE interface or Eth interface), the bandwidth of these interfaces can be aggregated, which can be deemed equivalent to an Eth-Trunk. The bandwidth of the aggregated interface equals to the sum of the bandwidths of the physical links. For example, If two Eth interfaces are aggregated, the total bandwidth of the aggregated interface is 200 Mbit/s (100 Mbit/s + 100 Mbit/s).
However, if the multiple upstream interfaces are service interfaces, the total bandwidth after aggregation cannot reach the sum of the bandwidths of the interfaces. For example, if two broadband interfaces provided by different vendors, whose bandwidths are 4 Mbit/s and 2 Mbit/s respectively, are aggregated, the rate of the aggregated bandwidth cannot reach 6 Mbit/s. In addition, if the two upstream interfaces use the load balancing ECMP, the rate of the aggregated interface further decreases and may even be lower than the rate of a single upstream interface. The reason is that the interfaces provided by two vendors belong to two different networks, whose packet transmission delays and jitters are different. If the two interfaces are aggregated, the response packets corresponding to TCP link packets (which are used by most services) are disordered, which results in packet reassembly, packet retransmission, or even the disconnection and re-establishment of TCP links. As a result, users cannot access Internet with a high rate or open web pages. In this case, you can take the following measures to try to resolve the problem:
- Use specific routes to distinguish services. Do not use ECMP or use only one upstream interface.
- Use the traffic policy to redirect the next hop to distinguish services, and do not configure load balancing for service.

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