3Com 10002211 manual VLAN Exception Flooding

C-6 APPENDIX C: VLANS ON THE COREBUILDER SYSTEM

This example shows how flooding decisions are made according to VLANs set up by protocol (assuming an 18-port switch):

Index	VLAN	Ports
1	Default	1 - 18
2	IP	1 - 12
3	IPX	11 - 16

Data received on	Is flooded on	Because
IP - port 1	VLAN 2	IP data received matches IP VLAN on the
		source port.
IPX - port 11	VLAN 3	IPX data received matches IPX VLAN on the
		source port.
XNS - port 1	VLAN 1	XNS data received matches no protocol
		VLAN, so the Default VLAN is used.

VLAN Exception Flooding

If data arrives on a switch port for a certain protocol and VLANs for that protocol are defined in the system but not on that switch port, the default VLAN defines the flooding domain for that data. This case is called VLAN exception flooding.

This example shows how the VLAN exception flooding decision is made (assuming an 18-port switch):

Index	VLAN	Ports
1	Default	1 - 18
2	IP	1 - 10

Data received on	Is flooded on	Because
XNS - port 1	VLAN 1	XNS data does not match any defined VLAN
		in the system.
IP - port 2	VLAN 2	IP data received matches IP VLAN 2 for
		source ports 1 - 10.
IP - port 12	VLAN 1	IP data received on source port 12 does not
		match any defined source port for IP VLAN,
		so the Default VLAN is used.