Allied Telesis AT-9000 Series User Manual
Page 801
AT-9000 Switch Command Line User’s Guide
773
Obviously, mapping source MAC addresses to egress ports can become
cumbersome if you are dealing with a MAC address-based VLAN that
encompasses many ports and nodes. Fortunately, the egress ports of a
VLAN are considered as a community and, as such, need only be
designated as an egress port of one address in the VLAN to be considered
an egress port of all the addresses.
For instance, referring to the previous example, if workstation 1 sends a
packet containing an unknown destination MAC address, the switch does
not flood the packet to just ports 5 and 6, even though those are the
designated egress ports for packets from workstation 1. Rather, it floods it
out all egress ports assigned to all the MAC addresses of the VLAN,
except, of course, the port where the packet was received. In the example,
the switch would flood the packet out ports 2 through 6.
The community characteristic of egress ports in MAC address-based
VLANs relieves you from having to map each address to its corresponding
egress port. Instead, you only need to be sure that all the egress ports in a
MAC address-based VLAN are assigned to at least one address.
It is also important to note that a MAC address must be assigned at least
one egress port to be considered a member of a MAC address-based
VLAN. VLAN membership of packets from a source MAC address not
assigned any egress ports is determined by the PVID of the port where the
packets are received.
Because egress ports are considered as a community within a VLAN, you
can simplify the mappings by assigning all the egress ports to just one
MAC address and assigning the rest of the addresses to just one port. This
makes adding or deleting MAC addresses or egress ports easier. Here is
how the example might look.
Table 74. Mappings of MAC Addresses to Egress Ports Example
MAC address
End Node
Switch Egress
Port
00:30:84:54:1A:45
Workstation 1 (Port 1)
5, 6
00:30:84:C3:5A:11
Workstation 2 (Port 2)
5, 6
00:30:84:22:67:17
Workstation 3 (Port 3)
5, 6
00:30:84:78:75:1C
Workstation 4 (Port 4)
5, 6
00:30:79:7A:11:10
Server (Port 5)
1-4
00:30:42:53:10:3A
Printer (Port 6)
1-4