H3C S6850 Series Configuration Guide

3
Protocols and standards
• IEEE 802.1Q, IEEE Standard for Local and Metropolitan Area Networks-Virtual Bridged Local
Area Networks
• IEEE 802.1ad, IEEE Standard for Local and Metropolitan Area Networks-Virtual Bridged Local
Area Networks-Amendment 4: Provider Bridges
Restrictions and guidelines: QinQ configuration
When you configure QinQ, follow these restrictions and guidelines:
• The inner 802.1Q tag of QinQ frames is treated as part of the payload. As a best practice to
ensure correct transmission of QinQ frames, set the MTU to a minimum of 1504 bytes for each
port on their forwarding path. This value is the sum of the default Ethernet interface MTU (1500
bytes) and the length (4 bytes) of a VLAN tag.
• You can use a QoS policy, a VLAN mapping, and QinQ on a port for VLAN tag manipulation. If
their settings conflict, the QoS policy has the highest priority, the VLAN mapping has the
medium priority, and QinQ has the lowest priority.
• QinQ and two-to-two mappings are mutually exclusive. The device does not support adding an
SVLAN tag on a QinQ-enabled port and then modifying the CVLAN and SVLAN IDs.
Enabling QinQ
About enabling QinQ
Enable QinQ on customer-side ports of PEs. A QinQ-enabled port tags an incoming frame with its
PVID.
Restrictions and guidelines
Before you enable or disable QinQ on a port, you must remove any VLAN mappings on the port. For
more information about VLAN mapping, see Layer 2—LAN Switching Configuration Guide.
Procedure
1. Enter system view.
system-view
2. Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view.
interface interface-type interface-number
3. Set the port link type.
port link-type { access | hybrid | trunk }
By default, the link type of a port is
access.
4. Configure the port to allow packets from its PVID to pass through.
{ Assign the access port to the specified VLAN.
port access vlan vlan-id
By default, all access ports belong to VLAN 1.
The PVID of an access port is the VLAN to which the port belongs. The port sends packets
from the VLAN untagged.
{ Configure the hybrid port to send packets from its PVID untagged.
port hybrid vlan vlan-id-list untagged
By default, the hybrid port is an untagged member of the VLAN to which the port belongs
when its link type is access.

H3C S6850 Series Specifications

General

Brand	H3C
Model	S6850 Series
Category	Switch
Language	English