Routing Tables and Routing Types

Language:

Both routers and hosts maintain a routing table. The routing table lists the IP addresses of networks that the system knows about, including the system's local, default network. The table also lists the IP address of a gateway system for each known network. A gateway is a system that can receive outgoing packets and forward them one hop beyond the local network. See the following example:

Routing Table: IPv4
Destination           Gateway           Flags  Ref    Use   Interface
-------------------- ------------------ ----- -----  ------ ---------
default              198.51.100.10         UG    1    532        net0
224.0.0.0            203.0.113.100          U    1      0        net1
203.0.113.0          203.0.113.100          U    1      0        net1
127.0.0.1            127.0.0.1             UH    1     57         lo0

You can configure static or dynamic types of routing on an Oracle Solaris system. Both types can exist on a single system. A system that implements dynamic routing relies on routing protocols, such as the Routing Information Protocol (RIP) for IPv4 networks and RIP next generation (RIPng) protocol for IPv6 networks, to route network traffic, as well as update routing information in the table. With static routing, information is maintained manually by using the route command. See the route(8) man page.

When you configure routing for the local network or an autonomous system (AS), consider which type of routing to support on particular routers and hosts. The following table shows the different types of routing and networking scenarios for which each routing type is best applied.

Routing Type	Best Uses
Static	Small networks and hosts that get their routes from a default router and default routers that only need to know about one or two routers on the next few hops.
Dynamic	Larger internetworks, including routers on local networks with many hosts and hosts on large autonomous systems. Dynamic routing is the best option for systems on most networks.
Combined static and dynamic	Routers that connect a statically routed network and a dynamically routed network and border routers that connect an interior autonomous system with external networks. Combining both static and dynamic routing on a system is a common practice.

The topology that is described in IPv4 Autonomous System Topology in Planning for Network Deployment in Oracle Solaris 11.4 combines both static and dynamic routing.

Note - Two routes that are going to the same destination does not automatically cause a system to perform load balancing or failover. If you need these capabilities, use IPMP. For more information, see Chapter 2, About IPMP Administration in Administering TCP/IP Networks, IPMP, and IP Tunnels in Oracle Solaris 11.4.