GRE Protocol Learning and practice

Generic Routing Encapsulation (English: Generic Routing Encapsulation, abbreviated GRE), a tunneling protocol that encapsulates multiple network layer protocols in a virtual point-to-point link. Developed by Cisco Systems

Here's a simple practice of GRE protocol

The network topology is as follows:

The basic configuration of the router is as follows

1. Configure Basic IP address information

2. Configure the tunnel interface (R1 below)

Interface tunnel    IP address 123.1.1.1 255.255.255.0    tunnel source 202.100.1.1 tunnel    Destination 202.100.2.1exitrouter OSPF 1    log-adjacency-changes    network 123.1.1.0 0.0.0.255 area 0    Network 10.1.1.0 0.0.0.255 Area 0

R3 configuration similar to R1

3.PC1 Ping PC2. See the following information about the capture package

　

Can ping through

4. To view the details of the GRE package, the packet capture analysis is as follows:

From the packet capture information can be seen. The GRE protocol adds a GRE header on top of the original IP and then adds an external IP address for communication.

GRE Protocol Learning and practice