2.2.2 Forwarding Principle
The Eth-Trunk forwarding table is composed of the following entries:
l
HASH-KEY value
The key value is calculated through the hash algorithm based on the MAC address or IP
address in a data packet.
l
Interface number
Eth-Trunk forwarding entries are relevant to the number of member interfaces in an Eth-
Trunk. Different HASH-KEY values map different outbound interfaces.
For example, an Eth-Trunk supports a maximum of eight member interfaces. If physical
interfaces 1, 2, 3, and 4 are bundled into an Eth-Trunk, the Eth-Trunk forwarding table
contains four entries, as shown in
. In the Eth-Trunk forwarding table, the
HASH-KEY values are 0, 1, 2, 3, 4, 5, 6, and 7, and the corresponding interface numbers
are 1, 2, 3, 4, 1, 2, 3, and 4.
Figure 2-2
Example of an Eth-Trunk forwarding table
0
3
5
7
1
4
HASH-KEY
PORT
1
2
4
6
2
3
1
2
3
4
The Eth-Trunk module forwards a packet according to the Eth-Trunk forwarding table:
1.
The Eth-Trunk module receives a packet from the MAC sub-layer, and then extracts its
source MAC address/IP address or destination MAC address/IP address.
2.
The Eth-Trunk module calculates the HASH-KEY value using the hash algorithm.
3.
Based on the HASH-KEY value, the Eth-Trunk module searches the Eth-Trunk forwarding
table for the interface number, and then sends the packet from the corresponding interface.
2.2.3 Link Aggregation in Manual Load Balancing Mode
Link aggregation can work in manual load balancing mode or LACP mode depending on whether
LACP is used.
In manual load balancing mode, you must manually create an Eth-Trunk and add member
interfaces to the Eth-Trunk. LACP is not used. In this mode, all active links load balance traffic
evenly. If an active link fails, the other active links share the traffic evenly. The manual load
balancing mode applies to the scenario where a high link bandwidth between two directly
connected devices is required but the remote device does not support the LACP protocol.
2.2.4 Link Aggregation in LACP Mode
Background
An Eth-Trunk in manual load balancing mode can increase the bandwidth. However, the manual
mode can only detect member link disconnections, but cannot detect other faults such as link
layer faults and incorrect link connections.
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
2 Link Aggregation Configuration
Issue 01 (2014-11-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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