1. Overview of dual-machine hot standby technology
The traditional networking method is as shown in the figure. All interactive messages between internal users and external users pass through Firewall A.
If Firewall A fails, communications between all hosts in the internal network that use Firewall A as the default gateway and the external network will be interrupted, and communication reliability cannot be guaranteed.
Dual-machine hot standby is a solution applied to servers. Its structural idea is that the host and slave machines are connected through the TCP/IP network. Under normal circumstances, the master machine is in working status and the slave machine is in monitoring status. Once the slave machine detects that the master machine is abnormal, The slave machine will replace the master machine in a short period of time and fully realize the functions of the master machine.
2. Router VRRP dual-machine hot standby configuration
Device redundancy is achieved through the VRRP protocol in router networking:
VRRP characters can be preempted:
- When a single-side link failure occurs in a vrrp dual-machine hot standby network, the master role on both sides is inconsistent, resulting in the network being unable to connect. Solution: Ensure that the main roles on both sides are consistent
- When in a vrrp dual-machine hot standby network, the master roles on both sides are inconsistent, the link does not fail, and data communication is not affected, but the round-trip paths are inconsistent. For routers, check the routing table when forwarding data.
Network topology: