Lenovo Flex System Fabric CN4093 Application Manual page 119

PVID = 2
Tagged packet
CRC
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As shown in Figure 4, the untagged packet is marked (tagged) as it leaves the
switch through port 5, which is configured as a tagged member of VLAN 2. The
untagged packet remains unchanged as it leaves the switch through port 7, which
is configured as an untagged member of VLAN 2.
Figure 4. 802.1Q tagging (after port‐based VLAN assignment)
Port 1 Port 2
802.1Q Switch
Port 6 Port 7
Untagged memeber
CRC
of VLAN 2
Data
Outgoing
untagged packet
(unchanged)
In Figure 5, tagged incoming packets are assigned directly to VLAN 2 because of
the tag assignment in the packet. Port 5 is configured as a tagged member of VLAN
2, and port 7 is configured as an untagged member of VLAN 2.
Figure 5. 802.1Q tag assignment
PVID = 2
Data Tag SA DA
B efore
As shown in Figure 6, the tagged packet remains unchanged as it leaves the switch
through port 5, which is configured as a tagged member of VLAN 2. However, the
tagged packet is stripped (untagged) as it leaves the switch through port 7, which
is configured as an untagged member of VLAN 2.
Port 3
CRC*
(*Recalculated)
Port 8
SA
DA
Port 1 Port 2
802.1Q Switch
Port 6 Port 7
Tagged member
of VLAN 2
Data Tag SA DA
8100 Priority
16 bits 3 bits 1 bits
After
Key
Priority - User_priority
CFI - Canonical format indicator
VID - VLAN identifier
Port 3
Port 8
Untagged member
of VLAN 2
Chapter 9: VLANs
CFI VID = 2
12 bits
Tagged member
of VLAN 2
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