The Enhanced Interior Gateway Routing Protocol (EIGRP) for IPv6 – EIGRPv6. EIGRP is an enhanced version of the IGRP developed by Cisco.
EIGRP for IPv6 works in the same way as EIGRP IPv4 where they can be configured and managed separately.
EIGRPv6 is still a distant-vector routing protocol with same link-state features, The hello process used in the neighbor discovery and the Diffusing Update Algorithm (DUAL) use for loop-free and fast convergence is still much present. Like its fellow IPv6 Protocols ( RIPng and OSPFv3), there are similarities in the processing features of IPv4 routing protocols.
EIGRP for IPv6 still possesses the same overall features and operation as EIGRP for IPv4; only there are a few major differences between them:
• EIGRP for IPv6 uses IPv6 prefixes and lengths rather than IPv4 subnets and masks.
• To establish EIGRP for IPv6 neighbor relationship, it uses IPv6 link-local addresses.
EIGRP for IPv4 does not have the concept of link-local address.
• EIGRP uses built-in authentication features of the IPv6 protocol rather than protocol-specific authentication implemented with IPv4 to guarantee message authentication.
• To transport routing information, EIGRP for IPv6 encapsulates IPv6 prefixes in the IPv6 messages, not in the IPv4 packets.
• IPv6 has no concept of the classful network; so when you use EIGRP for IPv6, there is no automatic summarization at the class boundaries. The only way to summarize IPv6-advertised prefixes is through manual summarization.
• If IPv4 address is not configured on the router, EIGRP for IPv6 requires an EIGRP router ID before it can start running. In IPv4, if you do not configure the EIGRP router ID, the router will automatically assign it using the highest loopback or the highest active interface IPv4 address.
• You configure EIGRP for IPv6 under a specific interface intended to send and receive routing protocol messages. In EIGRP for IPv4, you configure interfaces under the routing protocol configuration mode.
• EIGRP for IPv6 uses assigned dedicated multicast address FF02:: A, whereas EIGRP for IPv4 uses dedicated multicast address 22.214.171.124.
How to configure EIGRPv6.
Unlike its predecessor eigrp IPv4, IPv6 is enabled directly to the interface without the network command. However, you can still use the router configuration mode to enable it and it must be turned on using the shutdown command.
EIGRPv6 Configuration Example:
The 22 is the autonomous system (AS) number. If you look closely, you will notice the prompt changed to(config-rtr) and from here you must use the no shutdown command.
On the interface fa0/0 configuration, same 22 references the AS number that was enabled in the configuration mode.