How is uneven load balancing of an Eth-Trunk solved on CE switches

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Load balancing modes in different service scenarios are different. If load balancing of an Eth-Trunk is uneven, it is generally caused by the inappropriate load balancing mode. Perform the following operations to solve the problem:
1. Check whether the number of Eth-Trunk member interfaces is the nth power of 2.
If not, adjust the number of Eth-Trunk member interfaces to the nth power of 2.
2. Adjust the load balancing mode.
If the IP address in packets changes frequently, use load balancing based on the source or destination IP address so that traffic can be evenly load balanced among physical links. If the MAC address in packets changes frequently and the IP address is fixed, use load balancing based on the source or destination MAC address so that traffic can be evenly load balanced among physical links. If packets are random, you are advised to add the hash factor.
3. Adjust the hash algorithm.
CE7800&CE6800&CE5800 series switches: eth-trunk { hash-mode hash-mode-id | universal-id universal-id } *
CE12800 series switches: eth-trunk { src-interface | seed seed-data | universal-id universal-id | hash-mode hash-mode-id } *
Note:
The load balancing mode is valid only for the outbound interface of traffic. If traffic of the inbound interface is uneven, change the load balancing mode of the outbound interface on the uplink device.
In the scenario where Eth-Trunk and ECMP are deployed and traffic is unevenly load balanced, configure different hash algorithms for the Eth-Trunk and ECMP and change the value of universal-id as needed.

Other related questions:
Load balancing principle of Eth-Trunk member interfaces on CE switches
An Eth-Trunk has 16 timeslots for sending packets at each interval. Eth-Trunk member interfaces use the 16 timeslots to send packets in sequence. When the number of Eth-Trunk member interfaces is the nth power of 2, load balancing can be made more even. For example, if the number of Eth-Trunk member interfaces is 2, 4, or 8 (which is divisible by 16), the timeslot of the packets sent by each interface is an integer, making load balancing even. If it is not the nth power of 2 (for example, 3), a member interface gets 6 times for sending packets from 16 timeslots, while the other two only get 5 times. In this way, load balancing is not even. Therefore, you are advised to set the number of Eth-Trunk member interfaces to the nth power of 2, ensuring even load balancing.

How to configure load balancing for the Eth-Trunk on S series switches
S series switches (except the S1700) use a per-flow load balancing mechanism, which ensures that frames of the same data flow are forwarded on the same physical link, and different data flows are forwarded on different physical links. You can configure common load balancing mode to implement load balancing based on IP addresses or MAC addresses of packets. For L2, IP, and MPLS packets, you can also configure enhanced load balancing mode. Load balancing takes effect only for the outbound traffic. Therefore, load balancing modes can be different on the two ends of a link. 1. Commands for configuring common load balancing mode: [HUAWEI] interface Eth-Trunk 1 [HUAWEI-Eth-Trunk1] load-balance dst-mac 2. Commands for configuring enhanced load balancing mode: [HUAWEI] load-balance-profile a [HUAWEI-load-balance-profile-a] l2 field smac [HUAWEI-load-balance-profile-a] quit [HUAWEI] interface Eth-Trunk 1 [HUAWEI-Eth-Trunk1] load-balance enhanced profile a For configuration cases about common load balancing mode, see "Typical Ethernet Switching Configuration -Link Aggregation Configuration- Example for Configuring Link Aggregation in Manual Mode When Switches Are Directly Connected" in S1720&S2700&S3700&S5700&S6700&S7700&S9700 Typical Configuration Examples. The configuration cases of common load balancing are applicable to all S series switch models. The Sx700 series switch is used here as an example.

Does the switch Eth-Trunk port support the enhanced load balancing mode
In the enhanced mode, the load balancing can be implemented based on the packet type. In V100R006 and earlier versions, the switches do not support this configuration. In V200R001, only the S5700HI and S5710EI support this configuration. In V200R200 and later versions, the S5700HI, S5710HI, and S5710EI support this configuration. The key configuration commands are as follows: 1. Run the load-balance-profile profile-name command to create the enhanced load balancing template and go to the template view. The load balancing mode can be configured for L2 packets, IPV4 packets, IPV6 packets, or MPLS packets. 2. Go to the Eth-Trunk port view, and run load-balance enhanced profile profile-name to use the enhanced load balancing mode for the Eth-Trunk.

How load balancing is implemented on S series switches when link aggregation is configured
For S series switches (except the S1700), there are two load balancing modes: per-packet load balancing and per-flow load balancing. 1. Per-packet load balancing mode When there are multiple physical links between the two devices of the Eth-Trunk, the first data frame of a data flow is transmitted on one physical link, and the second data frame is transmitted on another physical link. In this case, the second data frame may arrive at the peer device earlier than the first data frame. As a result, packet mis-sequencing occurs. 2. Per-flow load balancing mode This mechanism uses the hash algorithm to calculate the address in a data frame and generates a hash key value. Then the system searches for the outbound interface in the Eth-Trunk forwarding table based on the generated hash key value. Each MAC or IP address corresponds to a hash key value, so the system uses different outbound interfaces to forward data. This mechanism ensures that frames of the same data flow are forwarded on the same physical link and implements flow-based load balancing. Per-flow load balancing ensures the correct sequence of data transmission, but cannot ensure the bandwidth usage. Notes: Currently, S series switches support only per-flow load balancing mode, including the following: 1. Load balancing based on the source MAC address of packets; 2. Load balancing based on the destination MAC address of packets; 3. Load balancing based on the source IP address of packets; 4. Load balancing based on the destination IP address of packets; 5. Load balancing based on the source and destination MAC addresses of packets; 6. Load balancing based on the source and destination IP addresses of packets; 7. Enhanced load balancing for L2, IPv4, IPv6, and MPLS packets based on the VLAN ID and source physical interface number. When you configure load balancing modes, follow these guidelines: The load balancing mode only takes effect on the outbound interface of traffic. If load is unevenly distributed on the inbound interfaces, change the load balancing mode on the uplink outbound interfaces. Configure load balancing to ensure data flow is transmitted on all active links instead of only one link, preventing traffic congestion and ensuring normal service operation. For example, if data packets have only one destination MAC address and IP address, you are advised to configure load balancing based on the source MAC address and IP address. If you implement load balancing based on the destination MAC address and IP address, the data flow may be transmitted on only one link, causing traffic congestion.

How can I delete an Eth-Trunk on a CE switch
Before deleting an Eth-Trunk, delete Eth-Trunk member interfaces. For example, Eth-Trunk 2 has two member interfaces: 10GE1/0/1 and 10GE1/0/2. To delete Eth-Trunk 2, perform the following configurations: system-view [~HUAWEI] interface eth-trunk 2 [~HUAWEI-Eth-Trunk2] undo trunkport 10ge 1/0/1 [*HUAWEI-Eth-Trunk2] undo trunkport 10ge 1/0/2 [*HUAWEI-Eth-Trunk2] commit [~HUAWEI-Eth-Trunk2] quit [~HUAWEI] undo interface eth-trunk 2 [*HUAWEI] commit

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