Ipv4 Over Ipv4 Tunneling; Overview; Configuring An Ipv4 Over Ipv4 Tunnel - HPE FlexNetwork 10500 Series Configuration Manual

IPv4 over IPv4 tunneling

Overview

IPv4 over IPv4 tunneling (RFC 1853) enables isolated IPv4 networks to communicate. For example,
an IPv4 over IPv4 tunnel can connect isolated private IPv4 networks over a public IPv4 network.
Figure 94 IPv4 over IPv4 tunnel
IPv4 header
IPv4 network
IPv4 host
Figure 94 shows the encapsulation and de-encapsulation processes.
•
Encapsulation:
a. Device A receives an IP packet from an IPv4 host and submits it to the IP protocol stack.
b. The IPv4 protocol stack determines how to forward the packet according to the destination
address in the IP header. If the packet is destined for the IPv4 host connected to Device B,
Device A delivers the packet to the tunnel interface.
c. The tunnel interface adds a new IPv4 header to the IPv4 packet and submits it to the IP
protocol stack.
In the new header, the source IP address specifies the tunnel source, and the destination IP
address specifies the tunnel destination.
d. The IP protocol stack uses the destination IP address of the new IP header to look up the
routing table, and then sends the packet out.
•
De-encapsulation:
e. After receiving the packet, Device B delivers it to the IP protocol stack.
f. If the protocol number is 4 (indicating an IPv4 packet is encapsulated within the packet), the
IP protocol stack delivers the packet to the tunnel module for de-encapsulation.
g. The tunnel module de-encapsulates the IP packet and sends it back to the IP protocol stack.
h. The protocol stack forwards the de-encapsulated packet.

Configuring an IPv4 over IPv4 tunnel

Follow these guidelines when you configure an IPv4 over IPv4 tunnel:
•
The tunnel destination address specified on the local device must be identical with the tunnel
source address specified on the tunnel peer device.
•
Do not specify the same source and destination addresses for local tunnel interfaces in the
same tunnel mode.
IPv4 header
IPv4 data
Device A
IPv4 header IPv4 data
IPv4 network
IPv4 tunnel
Device B
255
IPv4 header IPv4 data
IPv4 network
IPv4 host