Configuring Ipv4 And Ipv6 Routing; Overview; Routing Table; Static Route - HP 1920 Series User Manual

Configuring IPv4 and IPv6 routing

The term "router" in this chapter refers to both routers and Layer 3 switches.

Overview

A router selects an appropriate route according to the destination address of a received packet and
forwards the packet to the next router. The last router on the path is responsible for sending the packet to
the destination host. Routing provides the path information that guides the forwarding of packets.

Routing table

A router selects optimal routes from the routing table, and sends them to the forwarding information base
(FIB) table to guide packet forwarding. Each router maintains a routing table and a FIB table.
Routes discovered by different routing protocols are available in a routing table and they can be divided
into the following categories by origin:
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Each entry in the FIB table specifies a physical interface that packets destined for a certain address
should go out to reach the next hop—the next router—or the directly connected destination.
A route entry includes the following items:
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Static route

Static routes are manually configured. If a network's topology is simple, you only need to configure static
routes for the network to work correctly.
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Direct routes—Routes discovered by data link protocols, also known as "interface routes."
Static routes—Manually configured routes. Static routes are easy to configure and require fewer
system resources. They work well in small and stable networks, but cannot adjust to network
changes, so you must manually configure the routes again whenever the network topology
changes.
Dynamic routes—Routes that are discovered dynamically by routing protocols.
Destination IP address—Destination IP address or destination network.
Mask (IPv4)/prefix length (IPv6)—Specifies, together with the destination address, the address of
the destination network. A logical AND operation between the destination address and the
network mask/prefix length yields the address of the destination network.
Preference—Routes to the same destination might be discovered by various routing protocols or
manually configured, and routing protocols and static routes have different preferences configured.
The route with the highest preference (the smallest value) is optimal.
Outbound interface—Specifies the interface through which a matching IP packet is to be
forwarded.
Next hop—Specifies the address of the next hop router on the path.
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