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Chapter 14 Layer 3 Forward
Configuration
ES4626/ES4650 supports Layer3 forwarding. Layer3 forwarding is to forward Layer3
protocol packets (IP packets) across VLANs. Such forwarding addresses using IP address,
when a port receives an IP packet, it will index in its own route table and decide the
operation according to the index result. If the IP packet is destined to another subnet
reachable from this switch, then the packet will be forwarded from the appropriate port.
ES4626/ES4650 can forward IP packets by hardware, the forwarding chip of
ES4626/ES4650 has a host route table and default route table. Host route table stores
host route connect to the switch directly, default route table stores segment routes (after
aggregation algorithm process).
If the route (either host route or segment route) for forwarding unicast traffic exists in the
forwarding chip, rather than processing by the CPU in router, the forwarding of traffic will
be completely handled by hardware. As a result, forwarding speed can be greatly
improved, even to line speed.
14.1 Layer 3 Interface
14.1.1 Introduction to Layer3 Interface
Layer3 interface can be created on ES4626/ES4650. Layer3 interface is not physical
interface but a virtual interface. Layer3 interface is built on VLANs. Layer3 interface can
contain one or more layer2 interface of the same VLAN, or no layer2 interfaces. At least
one of Layer2 interfaces contained in Layer3 interface should be in UP state for Layer3
interface in the UP state, otherwise, Layer3 interface will be in the DOWN state. All layer3
interfaces in the switch use the same MAC address, this address is selected from the
reserved MAC address on creating Layer3 interface. Layer3 interface is the base for
layer3 protocols. The switch can use the IP address set in layer3 interface to
communicate with the other devices via IP. The switch can forward IP packets between
different Layer3 interfaces.