Users Guide

VLANs 819
Configuring Double VLAN Tagging
Dell EMC Networking N-Series switches use switchport dot1q-tunnel mode
to configure an interface as a customer edge (CE) interface. The dot1q-
tunnel mode is an overlay on switchport access mode. In particular,
configuring the access mode PVID sets the outer dot1q-tunnel VLAN ID.
Changing the switchport mode on a CE port to access, general, or trunk,
effectively disables tunneling on the interface.
CE interfaces can be physical ports or port-channels. Untagged frames
received on the CE interface are processed as if they belong to the PVID and
are transmitted out the service provider (SP) interface with a single VLAN tag
(presuming that the destination MAC address has been learned on the SP
interface). Tagged frames received on the CE interface are transmitted out
the service provider (SP) interface with an outer tag containing the access
mode native VLAN ID and the inner tag as received on the CE interface.
CE interfaces MUST be configured in dot1q-tunnel mode with the PVID
configured with the outer tag (native) VLAN ID for the associated service
provider (SP) interface. Configure the outer VLAN ID using the switchport
access vlan command. All MAC address learning and forwarding occurs on
the outer VLAN tag MAC addresses. The VLAN ID must be common to both
the SP port and the CE ports.
The service provider interface MUST be configured for egress tagging (trunk
or general mode) with a native VLAN identical to the PVID of the associated
CE ports. SP interfaces SHOULD be configured with a single outer VLAN
ID. Be aware that a trunk mode port accepts untagged packets on the native
VLAN and be a member of any existing or newly created VLANs by default.
It is not possible to configure an inner VLAN TPID value. The inner VLAN
TPID value is always 802.1Q (0x8100). Up to four unique outer TPIDs may
be configured in the system. An outer TPID/EtherType (other than 802.1Q)
must be configured in Global Configuration mode prior to configuration on
an interface. The outer TPID/EtherType must be configured on the interface
prior to putting the interface into tunnel mode.
Multiple groups of associated CE and SP ports can be defined by configuring
the groups with unique VLAN IDs. An outer TPID/EtherType (other than
802.1Q) must be configured in Global Configuration mode prior to
configuration on an interface. The outer TPID/EtherType must be configured
on the interface prior to putting the interface into tunnel mode.