Ingress Vlan Tagging; Limitations - Lenovo CN4093 Application Manual

Ingress VLAN Tagging

Limitations

126
CN4093 Application Guide for N/OS 8.3
Tagging can be enabled on an ingress port. When a packet is received on an ingress
port, and if ingress tagging is enabled on the port, a VLAN tag with the port PVID
is inserted into the packet as the outer VLAN tag. Depending on the egress port
setting (tagged or untagged), the outer tag of the packet is retained or removed
when it leaves the egress port.
Ingress VLAN tagging is used to tunnel packets through a public domain without
altering the original 802.1Q status.
When ingress tagging is enabled on a port, all packets, whether untagged or
tagged, will be tagged again. As shown in
egress port, the outer tag of the packet is retained when it leaves the egress port. If
tagging is disabled on the egress port, the outer tag of the packet is removed when
it leaves the egress port.
Figure 7. 802.1Q tagging (after ingress tagging assignment)
Untagged packet received on ingress port
PVID = 2
Untagged packet
CRC Data SA DA
Before
Tagged packet received on ingress port
PVID = 2
Tagged packet
CRC* Data Tag 1 SA DA
Before
By default, ingress tagging is disabled. To enable ingress tagging on a port, use the
following commands:
CN 4093(config)# interface port <number>
CN 4093(config-if)# tagpvid-ingress
Ingress tagging cannot be configured with the following features/configurations:
vNIC ports

 VMready ports
 UFP ports
 Management ports
Figure 7, when tagging is enabled on the
802.1Q Switch
Port 1 Port 2 Port 3
CRC* Data Tag SA DA
After
Port 6 Port 7 Port 8
Untagged member
of VLAN 2
CRC Data SA DA
802.1Q Switch
Port 1 Port 2 Port 3
CRC* Data Tag 1 Tag 2 SA DA
After
Port 6 Port 7 Port 8
Untagged member
of VLAN 2
CRC* Data Tag 1 SA DA
Tagged member
of VLAN 2
CRC* Data Tag SA DA
Tagged member
of VLAN 2
CRC* Data Tag 1 Tag 2 SA DA