Foundry Networks Switch and Router Installation And Configuration Manual page 922

Foundry Switch and Router Installation and Configuration Guide
• If the packet is a Layer 3 packet but cannot be forwarded as described above, but the port is a member of a
Layer 3 protocol VLAN for the packet's protocol, the device forwards the packet on all the Layer 3 protocol
VLAN's ports.
• If the packet cannot be forwarded based on either of the VLAN membership types listed above, but the packet
can be forwarded at Layer 2, the device forwards the packet on all the ports within the receiving port's port-
based VLAN.
Protocol VLANs differ from IP sub-net, IPX network, and AppleTalk VLANs in an important way. Protocol VLANs
accept any broadcast of the specified protocol type. An IP sub-net, IPx network, or AppleTalk VLAN accepts only
broadcasts for the specified IP sub-net, IPX network, or AppleTalk cable range.
NOTE: Protocol VLANs are different from IP sub-net, IPX network, and AppleTalk cable VLANs. A port-based
VLAN cannot contain both an IP sub-net, IPX network, or AppleTalk cable VLAN and a protocol VLAN for the
same protocol. For example, a port-based VLAN cannot contain both an IP protocol VLAN and an IP sub-net
VLAN.
Layer 2 Port-Based VLANs
On all Foundry devices, you can configure port-based VLANs. A port-based VLAN is a subset of ports on a
Foundry device that constitutes a Layer 2 broadcast domain.
By default, all the ports on a Foundry device are members of the default VLAN. Thus, all the ports on the device
constitute a single Layer 2 broadcast domain. You can configure multiple port-based VLANs. When you
configure a port-based VLAN, the device automatically removes the ports you add to the VLAN from the default
VLAN.
25 - 2 December 2000