Overview

This FAQ provides expert-level answers to the most critical B2B technical support queries regarding the configuration and deployment of QinQ (802.1Q-in-Q) stacking on Huawei aggregation switches. Whether you are troubleshooting a complex Layer 2/3 failover scenario or sizing hardware for a new datacenter leaf-spine topology, this guide addresses key pre-sales and post-sales concerns using Huawei-specific CLI commands and hardware insights.

Frequently Asked Questions

Q1: What is the fundamental difference between basic QinQ and selective QinQ (QinQ stacking) on Huawei switches?

Selective QinQ, often referred to as QinQ stacking or VLAN stacking, is an extension of basic QinQ that offers far more granularity. Basic QinQ adds the same outer VLAN tag to all packets arriving at a Layer 2 interface, whereas selective QinQ allows you to add different outer VLAN tags based on specific inner VLAN IDs, 802.1p priorities, or traffic policies . This capability is essential for network architects who need to isolate multiple tenants or departments sharing the same physical infrastructure while providing differentiated services.

Q2: What is the exact CLI sequence to configure QinQ stacking on a Huawei aggregation switch for remote management?

The primary method involves configuring QinQ stacking on a VLANIF interface that corresponds to the management VLAN. For a scenario where the inner VLAN is 10 and the outer stacked VLAN is 20, use the following commands: on the access interface, enable translation, set the link type to hybrid, and define the stack mapping with port vlan-stacking vlan 10 stack-vlan 20 . On the remote device, you must configure the management VLAN, create the VLANIF interface, and apply the qinq stacking vlan 20 command along with an IP address to enable remote management .

Q3: Can I configure QinQ stacking on any interface type, and what are the key limitations?

Selective QinQ can only be enabled on hybrid or trunk interfaces and only takes effect in the inbound direction . A critical limitation is that IP addresses cannot be configured on VLANIF interfaces that correspond to the outer VLAN tags used in VLAN stacking, ensuring Layer 2 forwarding is not disrupted by Layer 3 processing . Additionally, a maximum of eight VLAN ranges can be configured per interface for selective QinQ actions .

Q4: How do I modify or delete specific inner VLAN IDs from an existing selective QinQ configuration?

The method depends on the software version. On switches running a version later than V100R005, one or more inner VLAN IDs can be directly deleted from the configuration. However, on earlier versions (V100R005 or earlier), you cannot directly delete a specific inner VLAN. You must first run the undo port vlan-stacking command to delete the entire selective QinQ configuration, and then reconfigure the desired inner VLAN ranges that need to remain .

Q5: What are the optical transceiver and hardware considerations when deploying QinQ stacking?

QinQ encapsulation adds an additional 4 bytes to the standard 802.1Q frame, increasing the maximum frame length to at least 1504 bytes. Huawei switches are configured by default to allow jumbo frames larger than this, so interface modifications are usually unnecessary . However, specific interface cards, such as the LE0MG24CA and LE0MG24SA, have the limitation of being unable to add double tags to untagged packets, which should be a key consideration during pre-sales hardware selection .

Q6: Is a license required to enable QinQ features on Huawei aggregation switches?

No license is required. QinQ is a fundamental Layer 2 feature of Huawei switches and is not under license control, making it a cost-effective solution for VLAN expansion across the entire portfolio of supported models .

Q7: How does the switch handle power supply failover and hardware-level redundancy when processing QinQ traffic?

While QinQ is a software-level feature, its stability relies on underlying hardware redundancy. Huawei aggregation switches support redundant AC/DC power supplies and fan trays. In the event of a power supply failover, the switch should seamlessly transition to the backup unit. However, it is essential to ensure that the switch's internal resources (TCAM) are not exhausted, as this can affect packet forwarding. For deterministic traffic, ensure that the outer VLAN IDs in the stacking configuration map to existing VLANs; if the outer VLAN ID does not exist, the selective QinQ service will be unavailable .

Q8: What are the recommended best practices for integrating QinQ stacking in a multi-service access network?

Best practices include using selective QinQ rather than basic QinQ to provide service differentiation based on VLAN ranges. For instance, you can allocate specific VLAN ranges for PC Internet access, IPTV, and VIP users, and then map them to distinct outer tags (e.g., 100, 300, 500) on the underlayer provider edge (UPE) . Furthermore, be mindful that VLANs bound to a bridge domain (BD) cannot be specified as the outer stack-vlan .