December 2005
Intermediate to advanced
1066 pages
33h 38m
English
Content preview from Understanding Linux Network Internals
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Routing Table Initialization
Routing tables are initialized with fib_hash_init,
defined in net/ipv4/fib_hash.c. It is called by
ip_fib_init, which initializes the IP routing
subsystem, to create the ip_fib_main_table and ip_fib_local_table tables (see the section "Routing Subsystem Initialization" in Chapter 32).
The first time fib_hash_init is called, it creates
the memory pool fn_hash_kmem that will be used to
allocate fib_node data structures.
fib_hash_init first allocates a fib_table data structure and then initializes its virtual
functions to the routines shown in Table
34-1. The function also clears the content of the bottom part of the structure
(fn_hash), which, as shown in Figure 34-1, is used to distribute the
routing entries on different hash tables based on their netmask lengths.
Table 34-1. Initialization of the fib_table's virtual functions
|
Method |
Routine used |
|---|---|
|
tb_lookup |
fn_hash_lookup |
|
tb_insert |
fn_hash_insert |
|
tb_delete |
fn_hash_delete |
|
tb_flush |
fn_hash_flush |
|
tb_select_default |
fn_hash_select_default |
|
tb_dump |
fn_hash_dump |
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