Figure 2 thro, In figure 2 – Juniper Networks EX2500 User Manual
Page 41
VLAN Tagging
27
Chapter 2: VLANs
Figure 2: Port-Based VLAN Assignment
As shown in Figure 3, 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 3: 802.1Q Tagging (after Port-Based VLAN Assignment)
In Figure 4, 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 4: 802.1Q Tag Assignment
Port 6
DA
SA
Data
CRC
BS45011A
Port 7
Port 8
Port 1
Port 4
Port 5
Port 2
Port 3
802.1Q Switch
PVID = 2
Untagged packet
Untagged member
of VLAN 2
Tagged member
of VLAN 2
B
efore
BS45012A
Port 6
Port 7
Port 8
Port 1
Port 4
Port 5
Port 2
Port 3
802.1Q Switch
Key
Priority
CFI
VID
- User_priority
- Canonical format indicator
- VLAN identifier
PVID = 2
Tagged member
of VLAN 2
Untagged memeber
of VLAN 2
After
DA
SA
Data
CRC
(*Recalculated)
Outgoing
untagged packet
(unchanged)
DA
SA
Data
CRC*
Tag
VID = 2
Priority
16 bits
3 bits
1 bits
12 bits
8100
CFI
Port 6
DA
SA
Tag
Data
CRC
Tagged packet
BS45013A
Port 7
Port 8
Port 1
Port 4
Port 5
Port 2
Port 3
802.1Q Switch
PVID = 2
Untagged member
of VLAN 2
Tagged member
of VLAN 2
B
efore