Routing and Remote Access Service
Routing and Remote Access Service |
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The unicast IP components of the Routing and Remote Access service are shown in Figure 2.2.
Figure 2.2 Unicast IP and the Routing and Remote Access Service
The following sections describe typical unicast IP routing processes in terms of the Routing and Remote Access service unicast IP routing components.
An incoming packet is handed first to the IP forwarder, which finds a route and then hands it to the IP filtering driver to check for input filters and output filters. If approved for acceptance by the input filters and for forwarding by the output filters, the packet is handed back to the IP forwarder driver, which forwards the packet over the appropriate interface using Network Driver Interface Specification (NDIS). If the input or output filters do not permit the packet to be forwarded, the packet is silently discarded. If a route is not found, an ICMP Destination Unreachable-Host Unreachable message is sent back to the source of the packet.
An incoming packet is handed first to the IP forwarder, which notes that the packet is not to be routed (destination IP address is the router or a broadcast address). The IP forwarder then hands it to the IP filtering driver to check for input filters. If accepted by the input filters, the packet is handed up to the TCP/IP driver, which processes the packet. If the packet is not accepted by the input filters, the packet is silently discarded.
An outgoing TCP/IP packet is handed by the TCP/IP driver to the IP filtering driver, which checks for output filters. If approved for sending by the output filters, the packet is handed to the IP forwarder, which sends the packet using the best route over the appropriate interface using NDIS. If the packet is not approved by the output filters, the packet is silently discarded. If a route is not found, an IP routing error is indicated to the source application of the packet.
The RIP for IP and OSPF routing protocols operate like any other Windows Sockets application sending and receiving IP packets.
RIP for IP and OSPF update routes in the Route Table Manager. Based on the best route and route source ranking, the table of best routes is updated in the IP forwarder.
