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diff --git a/docs/gettingstarted/developers/fib20/prefixes.rst b/docs/gettingstarted/developers/fib20/prefixes.rst new file mode 100644 index 00000000000..5e0437ae3b3 --- /dev/null +++ b/docs/gettingstarted/developers/fib20/prefixes.rst @@ -0,0 +1,17 @@ +.. _prefixes: + +Prefixes +^^^^^^^^ + +Some nomenclature used to describe prefixes: + +* 1.1.1.1 This is an address since it has no associated mask +* 1.1.1.0/24 This is a prefix. +* 1.1.1.1/32 This is a host prefix (the mask length is the size of the address). + +Prefix A is more specific than B if its mask length is longer, and less specific if +the mask is shorter. For example, 1.1.1.0/28 is more specific than 1.1.1.0/24. A +less specific prefix that overlaps with a more specific is the **covering** prefix. +For example, 1.1.1.0/24 is the covering prefix for 1.1.1.0/28 and 1.1.1.0/28 is termed +the **covered** prefix. A covering prefix is therefore always less specific than its +covered prefixes. |