What is the difference between IS-IS and EIGRPv6?

1 IS-IS Overview

IS-IS stands for Intermediate System to Intermediate System, and it is a link-state routing protocol that originated from the ISO/OSI model. It was initially designed for connectionless network service (CLNS) networks that use network layer addresses, but it was later adapted to support IPv4 and IPv6 networks as well. IS-IS uses a hierarchical structure of areas and levels, where level 1 routers exchange routing information within an area, level 2 routers exchange routing information between areas, and level 1-2 routers act as boundary routers. IS-IS uses a shortest path first (SPF) algorithm to calculate the best routes based on link metrics.

2 EIGRPv6 Overview

EIGRPv6 stands for Enhanced Interior Gateway Routing Protocol version 6, and it is a distance-vector routing protocol that evolved from the Cisco proprietary EIGRP for IPv4 networks. It was standardized by the IETF in 2013, and it supports multiple address families, including IPv6. EIGRPv6 uses a hybrid approach of maintaining neighbor relationships, sending partial updates, and using a diffusing update algorithm (DUAL) to avoid loops and converge quickly. EIGRPv6 uses a composite metric that considers bandwidth, delay, reliability, load, and MTU.

3 IS-IS Features

IS-IS offers several features that can be beneficial for efficient network design and performance. It supports variable length subnet masking (VLSM) and classless interdomain routing (CIDR) for efficient address space usage, as well as authentication of routing updates for enhanced security. Additionally, it can support multiple instances on the same interface for flexible network design and transition. Furthermore, traffic engineering extensions can be used to optimize network resources and performance. Lastly, it supports IPv6 address families using multi-topology IS-IS (MT-IS-IS), allowing the coexistence of IPv4 and IPv6 networks and the use of different topologies for each address family.

4 EIGRPv6 Features

EIGRPv6 offers several features that can improve routing efficiency and performance. These include route summarization and filtering to reduce the size of the routing table and bandwidth consumption of updates, unequal cost load balancing to distribute traffic over multiple paths with different metrics, stub routing to limit propagation of updates from remote or low-end routers, graceful restart to resume operation after a temporary failure without losing neighbor relationships or routing information, and IPv6 address families using named EIGRP for multiple EIGRP processes with different parameters and policies for each address family.

5 IS-IS Configuration

To configure IS-IS for IPv6, you need to enable IPv6 routing on the router with the ipv6 unicast-routing command and enable IS-IS on the router with the router isis command. Additionally, you must assign a network entity title (NET) to the router with the net command and enable IS-IS on the interfaces that will participate in routing with the ipv6 router isis command. Furthermore, you should configure the level of the router with the is-type command and configure the metric of the interfaces with the metric command. This will help you to identify and prioritize your router in the IS-IS domain.