Integrated Intermediate System-to-Intermediate System
IS-IS is an OSI link-state hierarchical routing protocol that is based on work originally done at Digital Equipment Corporation for DECnet/OSI (DECnet Phase V). This protocol floods the network with link-state information to build a complete, consistent picture of network topology.
The International Organization for Standardization (ISO) has developed the following routing protocols for use in the Open System Interconnection (OSI) protocol suite:
- Intermediate System-to-Intermediate System (IS-IS) protocol
- End System-to-Intermediate System (ES-IS) protocol
- Interdomain routing protocol (IDRP)
The American National Standards Institute (ANSI) X3S3.3 (network and transport layers) committee was the motivating force behind ISO standardization of IS-IS, which was originally developed to route in ISO connectionless network protocol (CLNP) networks. A version has since been created that supports both CLNP and IP networks. It is usually referred to as integrated IS-IS; this is the version discussed here.
OSI routing protocols are summarized in several ISO documents; those dealing with IS-IS are as follows:
- ISO 10589: Standards definition for IS-IS
- RFC 1195: Intermediate IS-IS
In this tutorial:
- OSPF Basics
- What Is a Routing Protocol?
- Basic Routing Protocol Operation
- Link-State Versus Distance Vector Routing Protocols
- Link-State Routing Protocols
- OSPF Characteristics
- Integrated Intermediate System-to-Intermediate System
- Distance Vector Routing Protocols
- Selecting a Routing Protocol
- Operational Considerations
- Protocols Supported
- Routing Hierarchies
- IP Address Management
- IP Encapsulation Support
- Technical Considerations
- Routing Updates
- Scalability
- Business Considerations
- SPF Overview
- OSPF Routing Hierarchy
- Hierarchical Network Design Techniques
- Routing Types Within an OSPF Network
- External Routes
- OSPF Areas
- Characteristics of a Standard OSPF Area
- Stub Areas
- Not-So-Stubby Areas
- OSPF Operational Environment
- Types of OSPF Routers
- OSPF Network Types
- Router Identification
- Neighbors
- Adjacencies