PLANET XGS3-24040 - Manual (Page 171)

Chapter 21 Layer 3 Forward Configuration
21-1
Chapter 21 Layer 3 Forward Configuration
Switch supports Layer 3 forwarding which forwards Layer 3 protocol packets (IP packets) across VLANs.
Such forwarding uses IP addresses, when a interface receives an IP packet, it will perform a lookup in its own
routing table and decide the operation according to the lookup result. If the IP packet is destined to another
subnet reachable from this switch, then the packet will be forwarded to the appropriate interface. Switch can
forward IP packets by hardware, the forwarding chip of switch have a host route table and default route table.
Host route table stores host routes to connect to the switch directly; default route table stores network routes
(after aggregation algorithm process).
If the route (either host route or network route) for forwarding unicast traffic exists in the forwarding chip, the
forwarding of traffic will be completely handled by hardware. As a result, forwarding efficiency can be greatly
improved, even to wire speed.
21.1 Layer 3 Interface
21.1.1 Introduction to Layer 3 Interface
Layer 3 interface can be created on switch. The Layer 3 interface is not a physical interface but a virtual
interface. Layer 3 interface is built on VLANs. The Layer 3 interface can contain one or more layer 2 ports
which belong to the same VLAN, or contain no layer 2 ports. At least one of the Layer 2 ports contained in
Layer 3 interface should be in UP state for Layer 3 interface in UP state, otherwise, Layer 3 interface will be in
DOWN state. All layer 3 interfaces in the switch use the same MAC address by default, this address is
selected from the reserved MAC address while creating Layer 3 interface. The Layer 3 interface is the base
for layer 3 protocols. The switch can use the IP addresses set in the layer 3 interfaces to communicate with
the other devices via IP. The switch can forward IP packets between different Layer 3 interfaces. Loopback
interface belongs to Layer 3 interface.
21.1.2 Layer 3 Interface Configuration Task List
Layer 3 Interface Configuration Task List:
1. Create Layer 3 interface
2. Bandwidth for Layer 3 Interface configuration
3. Open or close the VLAN interface
1. Create Layer 3 Interface
Command Explanation
Global Mode