Intel BLADE SERVER IXM5414E - Manuale (Pagina 55)

32 Intel® Blade Server Ethernet Switch Module IXM5414E: Installation and User’s Guide:A Guide for Technically
will be dropped. If the ingress port is a member of the 802.1Q VLAN, the packet is passed to the
forwarding function.
If the packet is not tagged with VLAN information, the ingress port will tag the packet with its own
PVID as a VID (if the port is configured to accept untagged packets) and pass it to the forwarding
function.
The forwarding function determines the destination port. If the destination, or egress, port is a
member of the same VLAN as the packet the destination port transmits the packet on its attached
network segment. If the egress port is not a member of the VLAN, the packet is dropped.
IEEE 802.1Q VLAN configuration
The switch module initially configures one VLAN (VID = 1) named DEFAULT. The factory default
setting assigns all ports on the switch module to VLAN I. As new VLANs are configured, their
respective member ports are removed from VLAN 1. In addition, the VLAN ID value of 4095 is
reserved for internal use. Following is additional configuration information:
• Packets cannot cross VLANs. If a member of one VLAN is to connect to a member of another
VLAN, the link must be through an external router.
• If no VLANs are configured on the switch module, all packets will be forwarded to any
destination port. Packets with unknown source addresses will be flooded to all ports. Broadcast
and multicast packets will also be flooded to all ports.
Protocol-based VLANs (PBVLANs)
The main purpose of Protocol-based VLANs (PBVLANs) is to selectively process packets based on
their upper-layer protocol by setting up protocol-based filters. Packets are bridged through user-
specified ports based on their protocol.
In PBVLANs, the VLAN classification of a packet is based on its protocol (IP, IPX, etc.).
PBVLANs help optimize network traffic because protocol-specific broadcast messages are sent only
to end stations using that protocol. End stations do not receive unnecessary traffic and bandwidth is
used more efficiently. It is a flexible method that provides a logical grouping of users. An IP subnet
or an IPX network, for example, can each be assigned its own VLAN.
In port-based VLAN classification, the Port VLAN Identifier (PVID) is associated with the physical
ports. The VLAN ID (VID) for an untagged packet is equal to the PVID of the port. In port- and
protocol-based VLAN classifications, multiple VIDs are associated with each of the physical ports.
Each VID is also associated with a protocol. The ingress rules used to classify incoming packets
include the use of the packet's protocol in addition to the PVID to determine the VLAN to which the
packet belongs. This approach requires one VID on each port for each protocol for which the filter is
desired.
To configure PBVLAN support perform the following steps:
• Create and name a group.
• Assign one or more of the protocols – IP, IPX or ARP – to the group.
• Assign a VID to it.
• Specify the port(s) to which it applies.
If a tagged packet is received on a port in a PBVLAN group it will be processed using normal IEEE
802.1Q rules. If an untagged or priority-tagged packet is received, and the port is a member of a