Commit 9a8f20fc authored by Martin Mareš's avatar Martin Mareš

Better description of the route distribution process.

parent 2eac33f7
......@@ -227,6 +227,24 @@ do_rte_announce(struct announce_hook *a, net *net, rte *new, rte *old, ea_list *
rte_free(old);
}
/**
* rte_announce - announce a routing table change
* @tab: table the route has been added to
* @net: network in question
* @new: the new route to be announced
* @old: previous optimal route for the same network
* @tmpa: a list of temporary attributes belonging to the new route
*
* This function gets a routing table update and announces it
* to all protocols connected to the same table by their announcement hooks.
*
* For each such protocol, we first call its import_control() hook which
* performs basic checks on the route (each protocol has a right to veto
* or force accept of the route before any filter is asked) and adds default
* values of attributes specific to the new protocol (metrics, tags etc.).
* Then it consults the protocol's export filter and if it accepts the
* route, the rt_notify() hook of the protocol gets called.
*/
static void
rte_announce(rtable *tab, net *net, rte *new, rte *old, ea_list *tmpa)
{
......@@ -435,10 +453,19 @@ rte_update_unlock(void)
* rta_clone()), call rte_get_temp() to obtain a temporary &rte, fill in all
* the appropriate data and finally submit the new &rte by calling rte_update().
*
* rte_update() will automatically find the old route defined by the protocol @p
* When rte_update() gets any route, it automatically validates it (checks,
* whether the network and next hop address are valid IP addresses and also
* whether a normal routing protocol doesn't try to smuggle a host or link
* scope route to the table), converts all protocol dependent attributes stored
* in the &rte to temporary extended attributes, consults import filters of the
* protocol to see if the route should be accepted and/or its attributes modified,
* stores the temporary attributes back to the &rte.
*
* Now, having a "public" version of the route, we
* automatically find any old route defined by the protocol @p
* for network @n, replace it by the new one (or removing it if @new is %NULL),
* recalculate the optimal route for this destination and finally broadcast
* the change (if any) to all routing protocols.
* the change (if any) to all routing protocols by calling rte_announce().
*
* All memory used for attribute lists and other temporary allocations is taken
* from a special linear pool @rte_update_pool and freed when rte_update()
......
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