portmode hybridswitchportvlan-stack trunkshutdownDell(conf-if-te-1/1)#interface vlan 100Dell(conf-if-vl-100)#untagged tengigabitethernet 1/1Dell(conf-if-vl-100)#interface vlan 101Dell(conf-if-vl-101)#tagged tengigabitethernet 1/1Dell(conf-if-vl-101)#interface vlan 103Dell(conf-if-vl-103)#vlan-stack compatibleDell(conf-if-vl-103-stack)#member tengigabitethernet 1/1Dell(conf-if-vl-103-stack)#do show vlanCodes: * - Default VLAN, G - GVRP VLANsQ: U - Untagged, T - Taggedx - Dot1x untagged, X - Dot1x taggedG - GVRP tagged, M - Vlan-stackNUM Status Description Q Ports* 1 Inactive100 Inactive U Te 1/1101 Inactive T Te 1/1103 Inactive M Te 1/1Debugging VLAN StackingTo debug VLAN stacking, use the following command.• Debug the internal state and membership of a VLAN and its ports.debug memberExample of Debugging a VLAN and its PortsThe port notations are as follows:• MT — stacked trunk• MU — stacked access port• T — 802.1Q trunk port• U — 802.1Q access port• NU — Native VLAN (untagged)Dell# debug member vlan 603vlan id : 603ports : Te 2/4 (MT), Te 3/1(MU), Te 3/25(MT), Te 3/26(MT), Te 3/27(MU)Dell#debug member port tengigabitethernet 2/4vlan id : 603 (MT), 100(T), 101(NU)Dell#VLAN Stacking in Multi-Vendor NetworksThe first field in the VLAN tag is the tag protocol identifier (TPID), which is 2 bytes. In a VLAN-stacking network, after the frame isdouble tagged, the outer tag TPID must match the TPID of the next-hop system.While 802.1Q requires that the inner tag TPID is 0x8100, it does not require a specific value for the outer tag TPID. Systems may useany 2-byte value; Dell Networking OS uses 0x9100 (shown in the following) while non-Dell Networking systems might use a differentvalue.If the next-hop system’s TPID does not match the outer-tag TPID of the incoming frame, the system drops the frame. For example,as shown in the following, the frame originating from Building A is tagged VLAN RED, and then double-tagged VLAN PURPLE onegress at R4. The TPID on the outer tag is 0x9100. R2’s TPID must also be 0x9100, and it is, so R2 forwards the frame.Given the matching-TPID requirement, there are limitations when you employ Dell Networking systems at network edges, at which,frames are either double tagged on ingress (R4) or the outer tag is removed on egress (R3).Service Provider Bridging 775
