GRE over IPSEC VPN advanced configuration practice (with topo experimental environment)

The network topology is as follows:

User needs:

• PC1 and PC2 on the intranet can access each other;

1、GRE over IPSEC

1. Advantages and disadvantages of IPSEC

 IPSEC Advantages:

• Can securely encrypt data/authentication;

 IPSEC Disadvantages:

• Multicast encrypted traffic is not supported;
• Dynamic routing protocols are not supported, and routes cannot be exchanged between sites;
• Large-scale routing scenarios require handwriting of a large number of ACLs for interesting flows;
• In large-scale routing scenarios, it is necessary to write detailed routes and default routes for the headquarters and branches;

There will be problems when using IPSEC when the network is modified and expanded, or when the network size is too large.

2. Advantages and Disadvantages of GRE

GRE Disadvantages:

• Communication data cannot be encrypted;

GRE advantages:

• Support multicast traffic;
• Support dynamic routing protocols and exchange routes between sites;
• No need to hand-write a large number of routes and interesting flows;

2. Basic configuration

IP address configuration:

[FW1]int g1/0/1
[FW1-GigabitEthernet1/0/1]ip address 172.16.1.2 30
[FW1-Giga