Traffic Is Not Load Balanced Between Eth-Trunk Member Interfaces Due to an
Incorrect Load Balancing Mode
Fault Symptom
As shown in Figure 3-3, RouterA and RouterB communicate by using an Eth-Trunk. After the
display interface command is run on RouterA, the command output shows that the outgoing
traffic rate on Eth2/0/1 is 80 Mbit/s and the outgoing traffic rate on Eth2/0/2 is 20 Mbit/s. That
is, outgoing traffic is not load balanced between Eth2/0/1 and Eth2/0/2.
Figure 3-3 Network diagram of Eth-Trunk load balancing
RouterB
Eth2/0/1
Eth2/0/2Eth2/0/2
Eth2/0/1
Eth-Trunk1
RouterA
Fault Analysis
1. Run the display current-configuration command on the Routers to check the
configuration of Eth-Trunk 1. The command outputs show that the load balancing mode
of Eth-Trunk 1 is src-dst-ip. That is, load balancing is performed based on the Exclusive-
Or result of source and destination IP addresses. RouterA and RouterB communicate at
Layer 2; therefore, the load balancing mode does not apply to this scenario.
This fault is caused by the incorrect load balancing mode.
Procedure
Step 1 Run the system-view command on RouterA to enter the system view.
Step 2 Run the interface interface-type interface-number command to enter the Eth-Trunk interface
view.
Step 3 Run the load-balance dst-mac command to set the load balancing mode to dst-mac (load
balancing based on destination MAC addresses).
Run the display interface [ number [ interface-type ] ] command on RouterA to check the traffic
rates on Eth2/0/1 and Eth2/0/2. You can see that traffic is load balanced on the two interfaces.
----End
Summary
In the Layer 3 communication scenario, select the IP address-based load balancing modes. In
the Layer 2 communication scenario, select the MAC address-based load balancing modes.
Huawei AR2200-S Series Enterprise Routers
Troubleshooting 3 Physical Connection and Interfaces
Issue 01 (2012-01-06) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
52
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