E-Trunk Application in Dual-homing Networking

Service Overview

Eth-Trunk implements link reliability between single devices. However, if a device fails, Eth-Trunk does not take effect.

To improve network reliability, carriers introduced the device redundancy method that requires master and backup devices. If the master device or primary link fails, the backup device can take over user services. However, in this situation, the master and backup devices must be dual-homed by a downstream device, and inter-device link reliability must be ensured.

In dual-homing networking, Virtual Router Redundancy Protocol (VRRP) can be used to ensure device-level reliability, and Eth-Trunk can be used to ensure link reliability. In some cases, however, traffic cannot be switched to the backup device and secondary link simultaneously if the master device or primary link fails. As a result, traffic is interrupted. To address this issue, use Enhanced Trunk (E-Trunk) to implement both device- and link-level reliability.

Networking Description

In Figure 1, the customer edge (CE) is dual-homed to the virtual private LAN service (VPLS) network, and Eth-Trunk is deployed on the CE and provider edges (PEs) to implement link reliability.

In normal situations, the CE communicates with remote devices on the VPLS network through PE1. If PE1 or the link between the CE and PE1 fails, the CE cannot communicate with PE1. To ensure that services are not interrupted, deploy an E-Trunk on PE1 and PE2. If PE1 or the link between the CE and PE1 fails, traffic is switched to PE2. The CE then continues to communicate with remote devices on the VPLS network through PE2. If PE1 or the link between the CE and PE1 recovers, traffic is switched back to PE1. An E-Trunk provides backup between Eth-Trunk links of the PEs, improving device-level reliability.

Figure 1 E-Trunk dual-homing networking

Feature Deployment