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Showing posts from November, 2012

ISIS - Intermediate System to Intermediate System Intro

There is much information about ISIS history and present state, when I want to study something new I am looking for the small bullets that make subject easier to understand, once I got the basics I am taking each point and digging into it, here I would like to give the key elements for understanding ISIS and I would have to say  from the start that every point can be elaborated into at least an article if not a book (exaggerating) by itself:ISIS link state protocol (most important key to start with and easiest to remember)ISO protocol working based on CLNP (Connection Less Network Protocol)Support IP Routing Router (Node or IS) Addressing use 8 – 20 byte hex format address ( AREA + SYS-ID + NSEL )ISIS have 2 hierarchy called Level 1 and Level 2IS can be either Level 1 or Level 2 or Level 1 + 2Level 1 may only have neighbor relations within the same area and only with L1 or L1 + L2 ISLevel 2 may establish neighbors relation with other areas, Level 2 also refer to as backbone (some time…