Nortel Networks 24T manual 19 .1Q Tag Assignment

Using the BayStack 410-24T 10BASE-T Switch

In Figure 1-19, 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.

			PVID = 2
Tagged packet
					4
CRC	Data	Tag	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

BS41018A

Figure 1-19. 802.1Q Tag Assignment

As shown in Figure 1-20, 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.

PVID = 2

Port 4

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

Port 5

Tagged member of VLAN 2

CRC Data Tag SA DA

Untagged member	CRC*	(*Recalculated)
of VLAN 2
	Data
	SA	Outgoing
		untagged packet
		changed
	DA
		(tag removed)

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

BS41019A

Figure 1-20. 802.1Q Tagging (After 802.1Q Tag Assignment)

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