2.1 Overview of Transparent Bridging
This section describes the background, advantages, and working principles of transparent
bridges applications in a LAN
Background
Ethernet LANs have become the dominant type of LAN technology due to their robust
expandability and cost effectiveness. On some small-scale networks especially on those scattered
networks, how to achieve communication within a LAN and between LANs remains a problem
that needs to be addressed urgently.
Switches can be used to connect LANs but cannot effectively implement Layer 3
communication. Traditional routers are not ideal for Ethernet LAN interconnections because
they are expensive and entail complex configurations.
Transparent bridging can be used on an Ethernet network to connect LANs with the same
physical medium and transmit data between the LANs. The forwarding behaviors of transparent
bridges are transparent to network users. Transparent bridging achieves Layer 2 data
communication between the LANs on the same network segment and also Layer 3 data
communication between the LANs on different network segments. Transparent bridging extends
distances between network devices and expands networks without requiring end users to perform
additional configurations on devices. Transparent bridging, which is easy to configure, easy to
use, and cost-effective, is a viable solution for small-scale networks, especially scattered
networks.
Local Bridging
A device can be configured with multiple transparent bridges. Interfaces added to a bridge group
can forward and broadcast traffic in the bridge group based on the destination MAC address.
Interfaces usually use dynamic MAC address entries for traffic forwarding. Dynamic MAC
address entries are generated based on the mapping relationship between the MAC address and
the interface. Alternatively, interfaces use static MAC address entries for traffic forwarding.
Static MAC address entries are manually configured and will not age.
, LAN 1 and LAN 2 each have three hosts. Bridge groups are created
and interfaces of hosts in different LANs are added to the same bridge group. In this manner,
hosts in different LANs can communicate with each other at the link layer.
Huawei AR3200 Series Enterprise Routers
Configuration Guide - LAN
2 Transparent Bridging Configuration
Issue 02 (2012-03-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
31