Tag Archives: GRE

If you want to recall how to configure GRE, just look at GRE on Huawei routers.

You can return to IPSec configuration, reading IPSec on Huawei AR router.

Today, I’m going to put them together and try to configure GRE over IPSec.

Based on the topology below, configure IP adresses and OSPF protocol to ensure connectivity between all routers (omitted here).

Configure tunnel interface on labnario_1 and labnario_3:

[labnario_1]interface Tunnel0/0/0
[labnario_1-Tunnel0/0/0] ip address 10.0.0.1 255.255.255.0 
[labnario_1-Tunnel0/0/0] tunnel-protocol gre
[labnario_1-Tunnel0/0/0] source 150.0.0.1
[labnario_1-Tunnel0/0/0] destination 160.0.0.1

Generic Routing Encapsulation (GRE) is introduced to encapsulate packets. Then these packets can be transmitted over an IPv4 network. GRE provides a mechanism to encapsulate packets of one protocol into packets of another protocol. This allows packets to be transmitted over heterogeneous networks. GRE also provides tunnels to transparently transmit VPN packets. When a device receives a packet that needs to be encapsulated and routed, it adds a GRE header to the packet and encapsulates it into another protocol such as IP. The packet is then forwarded by the IP protocol.

Let’s try to configure GRE tunnel between labnario_1 and labnario_3. All packets sent from PC_1 to PC_2, and vice versa, will be transmitted through the GRE tunnel.

Assure communication between routers in the network. It is omitted here.