Nortel Networks 450 manual 17 .1Q Tagging 1

BayStack 450 10/100/1000 Series Switches

In Figure 1-17, untagged incoming packets are assigned directly to VLAN 2 (PVID = 2). Port 5 is configured as a tagged member of VLAN 2, and port 7 is configured as an untagged member of VLAN 2.

		PVID = 2
Untagged packet
				4
CRC	Data	SA	DA	Port
	Before

Port 1		Port 2	Port 3
	802.1Q Switch
Port 6		Port 7	Port 8

Port 5

Tagged member of VLAN 2

Untagged member of VLAN 2

BS45011A

Figure 1-17. 802.1Q Tagging (1 of 4)

As shown in Figure 1-18, 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.

PVID = 2

Port 4

Port 1		Port 2	Port 3
	802.1Q Switch
Port 6		Port 7	Port 8

Tagged member of VLAN 2

5
Port	CRC*	Data	Tag	SA	DA
(*Recalculated)

Untagged memeber	CRC
of VLAN 2
	Data
Outgoing	SA
untagged packet	DA
(unchanged)

	8100	Priority	CFI	VID = 2
	16 bits	3 bits	1 bits	12 bits
		After
Key
Priority	- User_priority
CFI	- Canonical format indicator
VID	- VLAN identifier

BS45012A

Figure 1-18. 802.1Q Tagging (2 of 4)

302401-D Rev 00 1-35