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Outbound Link Load Balance

This example shows how to configure outbound link load balancing. Through the configuration of efficient drainage strategy to achieve dynamic link load balancing, improve the export bandwidth utilization.

As shown in the following figure, this lab environment simulates the deployment of equipment at the second-level ISP exit scene.The second-level ISP rent Tele-com, China Netcom and other operators of the bandwidth to the user to achieve Internet access. The figure use to connect to the Internet by Tele-com and to connect to Netcom. The network has two DNS servers: and

Step 1: Configure multiple equal-cost routes

1.Select Network > Routing >Destination, and click New.

  • Destination:
  • Subnet Mask:0
  • Next Hop:interface
  • Interface:ethernet0/1
  • Gateway:

2.Select Network > Routing >Destination, and click Newto configure another equal-cost route.

  • Destination:
  • Subnet Mask:0
  • Next Hop:interface
  • Interface:ethernet0/2
  • Gateway:
Step 2: Configure the outbound interface bandwidth

Network > Interface, select interface ethernet0 / 1, and click Edit to configure the bandwidth as 50M (according to the actual situation to determine the value of the configuration bandwidth).

  • Bandwidth
    • Up Bandwidth:50000000bps
    • Down Bandwidth:50000000bps

Follow the same steps to set the bandwidth of the interface ethernet0 / 2 to 50M.

Step 3: Configure the outbound load balancr profile

Select Network > Outbound >Profile, click New.

  • Profile:1
  • Bandwidth Utillzation : 60%
  • Balance Mode:High Performance
Step 4: Configure the outbound load balancr rule

Select Network > Outbound >Rule, click New.

  • Rule Name:1
  • LLB Profile:Select the Profile "1"
  • Bind Route:Destination Route

  • Vitual Router:trust-vr
  • Destination Address:


Step 5: Verify that outbound load balance is in effect

After completing the above configuration steps, the tester constructs traffic through ethernet0/1 and ethernet0/2 respectively. Then the user logs in to the Web page and captures packets.

1. When the bandwidth of each link does not exceed 30 Mbps (50 M * 60%), the request packet will select the optimal link with low packet loss, small delay, and small jitter.

2. When the optimal link bandwidth exceeds 30Mbps, the request packet will select another link.

3. When both link bandwidths exceed 30 Mbps, the request packets will dynamically increase the bandwidth on each link through two links.

Step 6: Enable the transparent proxy function on the ingress port (optional)

Select Network > Interface, select the one of user-side interface,and clickEdit,

  • IP Configuration:

    • Enable DNS Proxy:Proxy-Trans

In the same way, enable the transparent proxy function for other users.

Step 7: Configure the DNS server to bind to the outgoing interface (optional)

Select Network > DNS > DNS Server, clickNew,

Configure the DNS servers and to interfaces ethernet0/1 and ethernet0/2 respectively.

Step 8: Enable DNS equalization (optional)

Select Network > Outbound > DNS Balance Configuration, click checkbox to enable the DNS Balance function.

Step 9: Verify that DNS Balance Configuration is effective (optional)

After the above configuration steps, when the bandwidth useage of ethernet0/1 is higher than that of ethernet0/2, the DNS request packet will select ethernet0 / 2 as the outgoing interface,so as to select as the DNS server.