Unicast IP Routing
Unicast IP Routing |
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The Windows 2000–based computer running the Routing and Remote Access service, known as a Windows 2000 Router, provides a rich set of features to support IP internetworks:
RIP for IP Support for version 1 and version 2 of RIP for IP, the primary routing protocol used in small to medium IP internetworks.
OSPF Support for the industry standard Open Shortest Path First (OSPF) routing protocol used in large and very large IP internetworks.
DHCP Relay Agent Support for an RFC 1542–compliant Dynamic Host Configuration Protocol (DHCP) Relay Agent, also known as a Boot Protocol (BOOTP) Relay Agent, that transfers messages between DHCP clients and DHCP servers located on separate networks.
Network Address Translator (NAT) Support for network address translation to translate private and public addresses to allow the connection of small office or home office (SOHO) networks to the Internet. The network address translator (NAT) component also includes a Dynamic Host Configuration Protocol (DHCP) allocator and a Domain Name System (DNS) proxy to simplify the configuration of SOHO hosts.
IP Packet Filtering Support for separately configured input and output filters for each IP interface based on key fields in the IP, Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Control Message Protocol (ICMP) headers.
ICMP Router Discovery Support for ICMP Router Advertisements messages to allow the automated discovery of default routers by hosts using ICMP router discovery.
Platform to Support Other IP Routing Protocols Application Programming Interface (API) support that provides a platform to support additional routing protocols such as the Border Gateway Protocol (BGP) for IP. The Windows 2000 Router does not provide BGP, but BGP can be written by third-party independent software vendors. For more information about the API support for third-party routing protocols, see the Windows 2000 Software Development Kit.
When there are multiple sources of routing information, it becomes necessary to define which route sources are better sources than others. For example, when exchanging routes between RIP and OSPF portions of an intranet, the definition of the metric differs between RIP and OSPF. Rather than trying to reconcile the metrics for two routes to the same destination network ID from different route sources, the route learned from the more preferred route source is used and the route from the less preferred route source is ignored, regardless of the metric.
For example, if a router is configured to use both RIP and OSPF, then both RIP and OSPF-learned routes are added to the Route Table Manager (RTM) IP routing table. If the metric of an OSPF learned route is 5 and the metric of the corresponding RIP learned route is 3 and OSPF is the preferred routing protocol, then the OSPF route is added by RTM to the IP forwarding table.
Preference levels for route sources can be configured from the Preference Levels tab on the properties of the IP Routing\General container in the Routing and Remote Access snap-in. The Preference Levels tab allows you to set preference levels for all routes from a specific route source. To set a specific preference level for a static route, use the netsh routing ip add rtmroute command.