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Intermediate System to Intermediate System
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Network Layer — Routing
Protocol Overview
Full Name
Intermediate System to Intermediate System
Abbreviation
IS-IS
OSI Layer
Network Layer
Category
Routing
RFC
RFC 5308
About IS-IS
Link-state routing protocol operating directly over Layer 2, not IP. Preferred by large ISPs and service providers for its scalability, fast convergence, and traffic engineering capabilities.
Network Layer
Routing
Standards Reference
IS-IS is defined in RFC 5308, published by the Internet Engineering Task Force (IETF). RFCs are the official standards documents for internet protocols and are freely available for public review.