Examples of configuring GRE tunnels using hardware from various manufacturers
April 17, 2024
ID 205377
Cisco equipment
R1(config)# interface Tunnel1
R1(config-if)# ip address 10.10.20.1 255.255.255.252
R1(config-if)# tunnel source 1.1.1.1
R1(config-if)# tunnel destination 2.2.2.2
R1(config)# interface Tunnel2
R1(config-if)# ip address 10.10.20.5 255.255.255.252
R1(config-if)# tunnel source 1.1.1.1
R1(config-if)# tunnel destination 3.3.3.3
Juniper equipment
Implementation of GRE tunneling on EX switches somewhat differs from GRE tunnel implementation on MX routers.
To use GRE, first you must allocate a physical interface card (PIC) whose resources will be used to process GRE.
A special feature of EX switches is that you need to specify an Ethernet port that will be disabled so that its resource can be used.
This example uses ge-0/0/10:
set chassis fpc 0 pic 0 tunnel-port 10 tunnel-services
Configuration:
chassis {
fpc 0 {
pic 0 {
tunnel-port 10 {
tunnel-services;
}
}
}
}
On MX routers, you do not need to specify an interface and disable it:
set chassis fpc 0 pic 0 tunnel-services bandwidth 1g
Configuration:
chassis {
fpc 0 {
pic 0 {
tunnel-services {
bandwidth 10g;
}
}
}
}
Tunnel interfaces are named according to the format gr-*, and are numbered according to the number of the Ethernet interface that was disabled at the first step.
Multiple tunnels on various subinterfaces (units) can be created on one interface:
set interfaces gr-0/0/10 unit 0 tunnel source 1.1.1.1
set interfaces gr-0/0/10 unit 0 tunnel destination 2.2.2.2
set interfaces gr-0/0/10 unit 0 family inet address 10.10.20.1/30
set interfaces gr-0/0/10 unit 1 tunnel source 1.1.1.1
set interfaces gr-0/0/10 unit 1 tunnel destination 3.3.3.3
set interfaces gr-0/0/10 unit 1 family inet address 10.10.20.5/30
Configuration:
interfaces {
gr-0/0/10 {
unit 0 {
tunnel {
source 1.1.1.1;
destination 2.2.2.2;
}
family inet {
address 10.10.20.1/30;
}
}
unit 1 {
tunnel {
source 1.1.1.1;
destination 3.3.3.3;
}
family inet {
address 10.10.20.5/30;
}
}
}
}
