Full description of vro backup configuration

With the development of China's routing industry, the application of backup routers is also more extensive, here we mainly explain the backup router configuration instructions. Network Transmission of some key business data of some enterprises or organizations requires high reliability of network equipment and convenient maintenance. There are multiple backup technologies for Cisco routers. Here we will introduce the router's own backup technology and line backup technology. Generally, a router is a bridge between a LAN and a wan.

The so-called router's own backup technology is designed to solve some fault or local port fault of the router due to its hardware such as memory, CPU) or software IOS, network breakdown caused by the failure of the port or line of the connected local area device. A router's backup router must have at least one vro with the same functions as a working primary router. When the primary router is paralyzed, it replaces the primary router in some way, provides routing services for LAN users. For LAN computers, how to find a backup router when the master router is paralyzed is as follows: proxy ARP, IRDP, dynamic routing, HSRP

1. Proxy ARP

Computers that support Proxy ARP send ARP broadcasts to find the MAC address corresponding to the destination address, whether they communicate with computers in different network segments or in this network segment, the router that knows the destination address will respond to the ARP request and broadcast its MAC address to the source computer. Then, the source computer will send the IP packet to the router, the router finally sends the data packet to the destination. When the master router crashes and the computer communicates again, it will continue to send the Proxy ARP broadcast, back up the router to respond to the request and transmit data.

Disadvantages:

If the main router is paralyzed when data is being transmitted, the computer that is communicating before sending another Proxy ARP request. it is impossible to know that the master router is paralyzed and will continue to send packets to the router, resulting in transmission interruption, the computer that is in communication can find the backup router for transmission only after another Proxy ARP request is sent or restarted.

2. IRDP

Computers that support IRDP in the LAN will listen to the "Hello" multicast packet sent by the primary router. If the computer no longer receives the "Hello" message, it uses the backup router for data transmission.

3. Dynamic Routing

Some computers support dynamic RIP routing to find routers. The disadvantage of this method is that the conversion between the primary router and the backup router is slow. The above three methods are mainly used on the computer side. The Cisco router provides the HSRP technology, which does not require any computer settings, the switching between the primary router and the backup router is transparent, and the switching speed between them is fast.

The backup router using HSRP shares a virtual MAC address and virtual IP address. Each local port that participates in HSRP has a local IP address and a MAC address. Each vro has a weight value, the router with the highest weight works as the primary router, and the other does not work. When the primary router is paralyzed, the router with the highest weight will act as the primary router, and so on. Vrouters regularly exchange weights to determine the working status of the vro. If the primary Router does not send this information packet for a period of time, other backup routers will think that the router is broken, and the backup router with a high weight will take over the virtual MAC address and IP address, responsible for data transmission. Once the primary router returns to normal, it will automatically switch back and take over data transmission again. Then, the backup router stops transmission and is in the backup router status. In addition, HSRP allows the router to monitor the working status of some ports. Once the port fails, it also performs automatic failover. In short, for LAN computers, there is only one gateway, that is, a virtual IP address. All the backup work is automatically completed by the router.