Tunneling Overview
Tunneling, in a accepted sense, is encapsulating traffic. Added specifically, the appellation usually refers to
the action of encapsulating cartage at a accustomed band of the OSI seven-layer archetypal aural another
protocol active at the aforementioned layer. Therefore, encapsulating IPv6 packets aural IPv4 packets and
encapsulating IPv4 packets aural IPv6 packets are both advised tunneling.
For the purposes of this book, which is to accommodated the CCIE Routing and Switching blueprint
requirements, in this area we are mostly absorbed in methods of accustomed IPv6 over IPv4
networks, not the added way around. This affiliate additionally does not analyze methods of tunneling IPv6
inside IPv6. However, you should be acquainted that both of these types of tunneling exist, in addition
792 Affiliate 20: IP Version 6
to the ones covered here. With that in mind, accede some of the added accepted tunneling
methods, starting with a arbitrary in Table 20-6.
In case you are not accustomed with implementing tunnels based on IPv4, booty a moment to awning the
basic accomplish involved:
Step 1 Ensure end-to-end IPv4 reachability amid the adit endpoints.
Step 2 Create the adit interface application the interface adit n command.
Step 3 Select a adit antecedent interface and configure it application the adit source
interface {interface-type-number | ip-address} command.
Step 4 For nonautomatic adit types, configure the adit destination application the
tunnel destination {ip-address | ipv6-address | hostname} command. To
use the hostname argument, DNS or bounded hostname-to-IP-address
mapping is required.
Step 5 Configure the adit IPv6 abode (or prefix, depending on adit type).
Step 6 Configure the adit approach application the adit approach approach command.
Table 20-7 shows the Cisco IOS adit modes and the destinations for the adit types covered in
this section.
Table 20-6 Arbitrary of Tunneling Methods
Tunnel Approach Topology and Abode Space Applications
Automatic 6to4 Point-to-multipoint; 2002::/16
addresses
Connecting abandoned IPv6 island
networks.
Manually configured Point-to-point; any abode space;
requires dual-stack abutment at both
ends
Carries alone IPv6 packets across
IPv4 networks.
IPv6 over IPv4 GRE Point-to-point; unicast addresses;
requires dual-stack abutment at both
ends
Carries IPv6, CLNS, and other
traffic.
ISATAP Point-to-multipoint; any multicast
addresses
Intended for abutting IPv6
hosts aural a distinct site.
Automatic IPv4-
compatible
Point-to-multipoint; ::/96 address
space; requires dual-stack abutment at
both ends
Deprecated. Cisco recommends
using ISATAP tunnels instead.
Coverage in this book is limited.
Cisco IOS Adit Modes and Destinations
Tunnel Blazon Adit Approach Destination
Manual ipv6ip An IPv4 address
GRE over IPv4 gre ip An IPv4 address
Automatic 6to4 ipv6ip 6to4 Automatically determined
ISATAP ipv6ip isatap Automatically determined
Automatic IPv4-compatible ipv6ip auto-tunnel Automatically determined
Let’s booty a afterpiece attending at the methods of accustomed IPv6 cartage over an IPv4 network.