Examples Of Flooding And Forwarding Decisions; Example 1: Flooding Decisions For Protocol-Based Vlans - 3Com 4007 Implementation Manual

Examples of Flooding
and Forwarding
Decisions
For each port on which the frame is to be transmitted, if that port is
tagged for the VLAN associated with the frame, transmit the frame as a
tagged frame; otherwise, transmit the frame as an untagged frame.
If the transmit port is not a member of the assigned VLAN, the frame is
transmitted untagged. For VLANs in allOpen mode on Multilayer
Switching Modules, this result may occur in either of these situations:
If the frame is assigned to the null VLAN. (The frame can still be
forwarded if the address was statically entered in the address table or
dynamically learned on another VLAN.)
If the frame is assigned to a specific VLAN but the transmit port is not
part of this VLAN.
This section provides several examples of flooding and forwarding
decisions.

Example 1: Flooding Decisions for Protocol-based VLANs

Table 58 lists how flooding decisions are made according to three VLANs
that are set up by protocol (assuming a 12-port configuration).
Table 58 Protocol-based VLANs and Flooding Decisions
Index VLAN
1 Default
2 IP
3 IPX
Is
Data flooded
received on on this
this port VLAN
IP - port 1 VLAN 2
IPX - port 11 VLAN 3
XNS - port 1 VLAN 1
Ports
1–12
1–8
9–11
Because
IP data received matches IP VLAN on the source (receive)
port.
IPX data received matches IPX VLAN on the source port.
XNS data received matches no protocol VLAN, so the
Default VLAN is used.
Rules of VLAN Operation 299