GRE (Generic Routing
encapsulation)
Ø
It
is the simplest protocol
Ø
It
encapsulate inside or outside ip address
Ø
GRE
is nothing to do with encryption that IPsec provide
Ø
We
use GRE for Multicast traffic
Ø
It
allow us to start treating the VPN connection like we using private link
R1 interface
Configuration
Ø
R1(config)#interface
serial 1/0
Ø
R1(config-if)#description
CONNECTED WITH INTERNET
Ø
R1(config-if)#ip
address 100.100.100.2 255.255.255.252
Ø
R1(config-if)#no
shut
Ø
R1(config-if)#exit
Ø
R1(config)#interface
fastEthernet 0/0
Ø
R1(config-if)#description
CONNECTED WITH SW1
Ø
R1(config-if)#ip
address 192.168.2.1 255.255.255.0
Ø
R1(config-if)#no
shut
Ø
R1(config-if)#exit
Internet Router interface
Configuration
Ø
internet(config)#interface
serial 1/0
Ø
internet(config-if)#description
CONNECTED WITH R1
Ø
internet(config-if)#ip
address 100.100.100.1 255.255.255.252
Ø
internet(config-if)#clock
rate 64000
Ø
internet(config-if)#no
shut
Ø
internet(config-if)#exit
Ø
internet(config)#interface
serial 1/1
Ø
internet(config-if)#description
CONNECTED WITH R2
Ø
internet(config-if)#ip
address 200.200.200.1 255.255.255.252
Ø
internet(config-if)#clock
rate 64000
Ø
internet(config-if)#no
shut
Ø
internet(config-if)#exit
Router 2 interface
Configuration
Ø
R2(config)#interface
serial 1/1
Ø
R2(config-if)#description
CONNECTED WITH INTERNET
Ø
R2(config-if)#ip
address 200.200.200.2 255.255.255.252
Ø
R2(config-if)#no
shut
Ø
R2(config-if)#exit
Ø
R2(config)#interface
fastEthernet 0/0
Ø
R2(config-if)#description
CONNECTED WITH SW2
Ø
R2(config-if)#ip
address 10.250.250.1 255.255.255.0
Ø
R2(config-if)#no
shut
Ø
R2(config-if)#exit
GRE Tunnel interface
Configuration in R1 and R2
Ø
R1(config)#interface
tunnel 1 1:- Tunnel Number
Ø
R1(config-if)#description
TUNNEL DIRECTLY CONNECTING TO R2
Ø
R1(config-if)#tunnel
source 100.100.100.2 source Public ip address of R1
Ø
R1(config-if)#tunnel
destination 200.200.200.2 Destination Public
ip address of R2
Ø
R1(config-if)#ip
address 172.16.16.1 255.255.255.252 Private ip address for
Tunnel
Ø
R1(config-if)#exit
Ø
R2(config)#interface
tunnel 2 2:- Tunnel Number
Ø
R2(config-if)#description
TUNNEL DIRECTLY CONNECTING TO R1
Ø
R2(config-if)#tunnel
source 200.200.200.2 source Public ip address of R2
Ø
R2(config-if)#tunnel
destination 100.100.100.2 Destination Public
ip address of R1
Ø
R2(config-if)#ip
address 172.16.16.2 255.255.255.252 Private ip address
for Tunnel
Ø
R2(config-if)#exit
Protocol Configuration in
R1 and R2 to exchange their route
Ø
R1(config)#router
rip
Ø
R1(config-router)#version
2
Ø
R1(config-router)#network
192.168.2.0 {R1 internal network}
Ø
R1(config-router)#network
172.16.16.0 {R1 Tunnel
Network}
Ø
R1(config-router)#no
auto-summary
Ø
R1(config-router)#exit
Ø
R1(config)#ip
route 0.0.0.0 0.0.0.0 s1/0 {default route to internet}
Ø
R2(config)#router
rip
Ø
R2(config-router)#version
2
Ø
R2(config-router)#network
10.250.250.0 {R2 internal
network}
Ø
R2(config-router)#network
172.16.16.0 {R2 Tunnel
Network}
Ø
R2(config-router)#no
auto-summary
Ø
R2(config-router)#exit
Ø
R2(config)#ip
route 0.0.0.0 0.0.0.0 s1/1 {default route to internet}
Troubleshooting &
Verification Commands
Ø
Show
ip interface brief
Ø
Show
ip route
Ø
Show
interfaces tunnel 2 (Tunnel Number)
Ø
Verify
using
Ø
Traceroute
from PC1 to PC2
Ø
All the
traffic will go through Tunnel
Ø
GRE tunnel acts as all the devices are connected in same Ethernet
segment
Ø
And also It hides the public address
Click here to Download The PDF File
Hello and thank you for this example!
ReplyDeleteHowever, please explain to me how the INTERNET router forwards the packets in this case since it's not configured with any routing protocol. and in Packet tracer, if I don't use INTERNET router, it doesn't work!
Hello and thank you for this example!
ReplyDeleteHowever, please explain to me how the INTERNET router forwards the packets in this case since it's not configured with any routing protocol. and in Packet tracer, if I don't use INTERNET router, it doesn't work!
Great Article
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