An LPM prefix is represented by a pair of parameters (128-bit key, depth), with depth in the range of 1 to 128.
An LPM rule is represented by an LPM prefix and some user data associated with the prefix.
The prefix serves as the unique identifier for the LPM rule.
-In this implementation, the user data is 1-byte long and is called "next hop",
+In this implementation, the user data is 21-bits long and is called "next hop",
which corresponds to its main use of storing the ID of the next hop in a routing table entry.
The main methods exported for the LPM component are:
Implementation Details
~~~~~~~~~~~~~~~~~~~~~~
-This is a modification of the algorithm used for IPv4 (see Section 19.2 "Implementation Details").
+This is a modification of the algorithm used for IPv4 (see :ref:`lpm4_details`).
In this case, instead of using two levels, one with a tbl24 and a second with a tbl8, 14 levels are used.
The implementation can be seen as a multi-bit trie where the *stride*
By splitting the process in different tables/levels and limiting the number of tbl8s,
we can greatly reduce memory consumption while maintaining a very good lookup speed (one memory access per level).
-.. image40_png has been renamed
-|tbl24_tbl8_tbl8|
+.. figure:: img/tbl24_tbl8_tbl8.*
+
+ Table split into different levels
+
An entry in a table contains the following fields:
-------------------------
The LPM algorithm is used to implement the Classless Inter-Domain Routing (CIDR) strategy used by routers implementing IP forwarding.
-
-.. |tbl24_tbl8_tbl8| image:: img/tbl24_tbl8_tbl8.*