The EIGRP (Enhanced Interior Gateway Routing Protocol) routing protocol was originally designed to work with IPv4, and was later adapted to support IPv6.

Although the routing process and underlying algorithms are very similar between EIGRP for IPv4 and EIGRP for IPv6, there are some key differences in how these protocols are configured and operate.

Here we mention the main differences:

1. Configuration and Operation

• EIGRP for IPv4: It is configured under global configuration mode and uses IPv4 addresses to define neighbors and configure routes.
• EIGRP for IPv6: Configured directly on the specific interfaces where it operates, rather than globally. EIGRP for IPv6 requires that the IPv6 address be configured on the interface before EIGRP can be enabled on that interface.

2. Protocol Integration

• EIGRP for IPv4: Uses IPv4 addressing itself and metrics based on bandwidth and delay to calculate the most optimal routes.
• EIGRP for IPv6: Implements a similar configuration in terms of metrics, but uses IPv6 addresses. Additionally, it needs an EIGRP router identifier (Router ID), which must be configured manually and generally follows the format of an IPv4 address, even though it is being used in an IPv6 environment.

3. Multicast Addresses

• EIGRP for IPv4: Uses the multicast address 224.0.0.10 to send and receive routing updates to other EIGRP routers.
• EIGRP for IPv6: Uses the multicast address FF02::A, which is a specific link-local multicast address for IPv6.

4. Packet Encapsulation

• EIGRP for IPv4: Directly encapsulates your data packets within IPv4 packets.
• EIGRP for IPv6: Uses a slightly different encapsulation approach, adapted for IPv6, although the packet contents and message types are essentially the same as in IPv4.

5. Compatibility and Transition

• EIGRP for IPv4 y EIGRP for IPv6 They operate independently of each other. On a router that needs to support both protocols, each protocol must be configured separately, allowing transition and coexistence in networks that are still migrating from IPv4 to IPv6.

6. Configuration Dependencies

• EIGRP for IPv4 It requires no additional configurations beyond the basic ones to operate.
• EIGRP for IPv6 It depends on IPv6 being enabled and configured correctly on the interfaces before it can be activated, and as mentioned, it needs a manually defined Router ID.

In summary, while the fundamental principles of EIGRP are consistent between IPv4 and IPv6, differences in configuration and operation are adapted to the characteristics of each version of the Internet Protocol, reflecting the natural evolution of the network towards broader support. and robust for IPv6.