IP datagram routing (IP group forwarding)

IP datagram routing (IP packet forwarding process) Answer: The grouping forwarding algorithm is as follows: (1) extract the IP address D of the target host from the datagram header and obtain that the destination network address is N. (2) If N is a network address directly connected to this vro, it will be delivered directly. Instead of going through other vrouters, it will directly deliver the datagram to the destination address; otherwise, even if it is indirectly delivered. (3) If the route table contains a specific host route whose destination address is D, the datagram is transmitted to the next hop router specified in the route table. Otherwise, execute (4) (4). If there is a route entry that reaches network N in the route table, send the datagram to the next hop router specified in the route table. Otherwise, execute (5) (5) if there is a default route in the route table, the datagram is sent to the default router specified in the route table. Otherwise, run (6 ). (6) Report an error in the forwarding group. As an intermediate device, what are the differences between hubs, switches, and routers? A: The differences are mainly from the working level, connection network type, and working principle, whether there is a conflict domain or broadcast domain. Hub: working on the physical layer and shared bandwidth. Working principle: for example, a hub with eight ports is connected to eight computers. The Hub is in the "center" of the network and forwards signals through the hub. Eight computers can communicate with each other. Vswitch: It works on the data link layer and exclusively occupies the bandwidth. its working principle is also called a switch-type hub. It re-generates the information and forwards it to the specified port after internal processing, with Automatic addressing and switching, the switch independently sends each information packet from the source port to the destination port based on the destination address of the information packet transmitted, avoid collision with other ports. A vswitch in the broad sense is a device that implements information exchange in a communication system. Traditional vswitches can only be divided into conflicting domains and cannot be divided into broadcast domains. Router: works at the network layer. The basic function of a vro is to transmit data (IP packets) to the correct network. The segments include: 1. IP datagram forwarding, including datagram path finding and transmission; 2. subnet isolation to prevent broadcast storms. 3. Maintain route tables and exchange route information with other routers. This is the basis for IP packet forwarding; 4. IP datagram error handling and simple congestion control; 5. Filtering and accounting of IP datagram. Vro can separate broadcast domains