Protocol-Sensitive VLANS
When the CoreBuilder system receives data that has a broadcast, multicast, or unknown destination address, it forwards the data to all ports. This process is referred to as bridge flooding.
Protocol-sensitive VLANs group one or more switch ports together for a specified network layer 3 protocol, such as IP or AppleTalk. These VLANs make flooding decisions based on the network layer protocol of the frame. In addition, for IP VLANs, you can also make flooding decisions based on layer 3 subnet address information. Protocol-sensitive VLANs allow the restriction of flood traffic for both routable and nonroutable protocols. They have a relatively simple configuration comprising one or more protocols and groups of switch ports. These protocol-sensitive VLANs operate independent of each other. Additionally, the same switch port can belong to multiple VLANs. For example, you can assign port 1 on a CoreBuilder to several IP subnetwork VLANs, plus one IPX VLAN, one AppleTalk VLAN, and one NetBIOS VLAN. In a multiprotocol environment, protocol-sensitive VLANs can be very effective for controlling broadcast and multicast flooding.
Two or more types of VLANs can coexist in the CoreBuilder system. When associating received data with a particular VLAN configuration in a multiple VLAN configuration, port group VLANs, MAC address group VLANs, and application-oriented VLANs always take precedence over protocol-sensitive VLANs.
The CoreBuilder protocol-sensitive VLAN configuration includes three elements: protocol suite, switch ports, and layer 3 addressing information for IP VLANs.
Protocol Suite
The protocol suite describes which protocol entities can comprise a protocol-sensitive VLAN. For example, CoreBuilder VLANs support the IP protocol suite, which is made up of the IP, ARP, and RARP protocols. Table C-1lists the protocol suites that the CoreBuilder supports, as well as the protocol types included in each protocol suite.
