Unicast routing overview

  • Article

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Unicast routing overview

Unicast routing is the forwarding of traffic destined to a single location on an internetwork from a source host to a destination host by using routers. An internetwork is at least two networks that are connected by routers. A router is a network layer intermediate system that is used to connect networks together based on a common network layer protocol such as TCP/IP. A network is a portion of the networking infrastructure (encompassing repeaters, hubs, and bridges/Layer 2 switches) that is bounded by routers and is associated with the same network layer address known as a network address or network ID.

A typical router is connected to two or more networks over LAN or WAN media. Computers on a network can send packets to computers on other networks by forwarding the packets to the router. The router examines the packet and uses the destination network address in the packet header to decide which interface to use to forward the packet. Through routing protocols (OSPF, RIP, and others), a router learns network information (such as network addresses) from neighboring routers, and then propagates this information to routers on other networks to enable connectivity between all computers on all networks.

The server running Routing and Remote Access can route IP and AppleTalk traffic.

IP routing

The IP network protocol is part of a suite of Internet protocols known as Transmission Control Protocol/Internet Protocol (TCP/IP). IP is used to communicate across any set of interconnected IP networks. IP routers are either static routers (routes are established by an administrator and do not change until the administrator changes them) or dynamic routers (routes are updated dynamically by using routing protocols).

IP routing is the forwarding of IP traffic from a source host to a destination host through IP routers. At each router, the next hop is determined by matching the destination IP address within the packet with the best route in the routing table.

Routing and Remote Access includes support for two IP unicast routing protocols:

  • Routing Information Protocol (RIP) for IP

  • Open Shortest Path First (OSPF) This feature is not available on the Itanium-based versions of the Windows operating systems. This content is not available in this preliminary release.

Routing and Remote Access is not limited to supporting just RIP for IP and OSPF. The server running Routing and Remote Access is an extensible platform; other vendors can create additional IP routing protocols, such as Interior Gateway Routing Protocol (IGRP) and Border Gateway Protocol (BGP).

For more information about the IP unicast routing protocols supported by Routing and Remote Access, see RIP for IP and OSPF.

AppleTalk routing

AppleTalk is used primarily in Apple Macintosh environments.

Routing and Remote Access includes support for the Routing Table Maintenance Protocol (RTMP) routing protocol.