FAQ-Can the AR Implement Link Aggregation or Load Balancing When Multiple AR Uplinks Are Used to Access the Internet

Publication Date:  2015-04-30 Views:  123 Downloads:  0
Issue Description
Can the AR Implement Link Aggregation or Load Balancing When Multiple AR Uplinks Are Used to Access the Internet?
Solution
If physical interfaces of multiple uplinks are of the same type (GE or Ethernet interfaces), these interfaces can constitute an Eth-Trunk. The bandwidth of the Eth-Trunk is the sum of bandwidths of multiple physical links. For example, the bandwidths of two Ethernet interface are 200 Mbit/s (100 Mbit/s + 100 Mbit/s).

If two service interfaces are used, for example, bandwidths of two carriers are leased, among which one is 4 Mbit/s and the other is 2 Mbit/s, 6 Mbit/s bandwidth for Internet access cannot be implemented. If ECMP is configured on the two service interfaces, Internet access through one uplink may be faster than Internet access through the two service interfaces. This is because two carriers use different networks on which the delay and jitter are different. Mis-sequencing of TCP packets (most services use TCP) may occur. As a result, TCP packets are reassembled and retransmitted, or even TCP connections are torn down and reestablished. The Internet access speed is slow and web pages cannot be opened. Use the following methods to solve the problem:
  • Use specific routes to different services, do not use ECMP, or use only one uplink interface.
  • Use a traffic policy containing redirection to next hop addresses so that services are not load balanced.

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