Ip-In-Ip De-Capsulation - Cisco NCS 5500 Series Configuration Manual

IP-in-IP De-capsulation

source IP address on Router2. In this example, OSPF is used as the routing protocol between the two routers.
You can also configure BGP or IS-IS as the routing protocol.
RP/0/RP0/CPU0:Router1# configure
RP/0/RP0/CPU0:Router1(config)#
RP/0/RP0/CPU0:Router1(config-if)# tunnel mode gre ipv4
RP/0/RP0/CPU0:Router(config-if)# ipv4 address 10.1.1.1 255.255.255.0
RP/0/RP0/CPU0:Router1(config-if)# tunnel source 192.168.1.1
RP/0/RP0/CPU0:Router1(config-if)# tunnel destination 192.168.2.1
RP/0/RP0/CPU0:Router1(config-if)# exit
RP/0/RP0/CPU0:Router1(config)# interface Loopback 0
RP/0/RP0/CPU0:Router1(config-if)# ipv4 address 1.1.1.1
RP/0/RP0/CPU0:Router1(config-if)# exit
RP/0/RP0/CPU0:Router1(config)# router ospf 1
RP/0/RP0/CPU0:Router1(config-ospf)# router-id 192.168.4.1
RP/0/RP0/CPU0:Router1(config-ospf)# area 0
RP/0/RP0/CPU0:Router1(config-ospf-ar)# interface tunnel-ip 30
RP/0/RP0/CPU0:Router1(config-ospf-ar)#
RP/0/RP0/CPU0:Router1(config-ospf-ar)# commit
RP/0/RP0/CPU0:Router2# configure
RP/0/RP0/CPU0:Router2(config)#
RP/0/RP0/CPU0:Router2(config-if)# tunnel mode gre ipv4
RP/0/RP0/CPU0:Router2(config-if)# ipv4 address 10.1.1.2 255.255.255.0
RP/0/RP0/CPU0:Router2(config-if)# tunnel source 192.168.2.1
RP/0/RP0/CPU0:Router2(config-if)# tunnel destination 192.168.1.1
RP/0/RP0/CPU0:Router2(config-if)# exit
RP/0/RP0/CPU0:Router2(config)# interface Loopback 0
RP/0/RP0/CPU0:Router2(config-if)# ipv4 address 2.2.2.2
RP/0/RP0/CPU0:Router2(config)# router ospf 1
RP/0/RP0/CPU0:Router2(config-ospf)# router-id 192.168.3.1
RP/0/RP0/CPU0:Router2(config-ospf)# area 0
RP/0/RP0/CPU0:Router2(config-ospf-ar)# interface tunnel-ip 30
RP/0/RP0/CPU0:Router2(config-ospf-ar)# interface Loopback 0
RP/0/RP0/CPU0:Router2(config-if)# commit
IP-in-IP De-capsulation
Encapsulation of datagrams in a network is done for multiple reasons, such as when a source server wants to
influence the route that a packet takes to reach the destination host. The source server is also known as the
encapsulation server.
IP-in-IP encapsulation involves the insertion of an outer IP header over the existing IP header. The source
and destination address in the outer IP header point to the end points of the IP-in-IP tunnel. The stack of IP
headers are used to direct the packet over a predetermined path to the destination, provided the network
adminstrator knows the loopback addresses of the routers transporting the packet. This tunneling mechanism
can be used for determining availability and latency for most network architectures. It is to be noted that the
entire path from source to the destination does not have to be included in the headers, but a segment of the
network can be chosen for directing the packets.
Interface and Hardware Component Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release
6.1.x
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interface tunnel-ip 30
interface Loopback 0
interface tunnel-ip 30
Configuring GRE Tunnels