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@@ -0,0 +1 @@ +D prog-intro.sgml diff --git a/doc/prog-proto.sgml b/doc/prog-proto.sgml deleted file mode 100644 index 45ef88d..0000000 --- a/doc/prog-proto.sgml +++ /dev/null @@ -1,91 +0,0 @@ -<!-- - BIRD Programmer's Guide: Protocols - - (c) 2000 Martin Mares <mj@ucw.cz> ---> - -<sect>Routing protocols - -<sect1>Introduction - -<p>The routing protocols are the BIRD's heart and a fine amount of code -is dedicated to their management and for providing support functions to them. -(-: Actually, this is the reason why the directory with sources of the core -code is called <tt/nest/ :-). - -<p>When talking about protocols, one need to distinguish between <em/protocols/ -and protocol <em/instances/. A protocol exists exactly once, not depending on whether -it's configured on not and it can have an arbitrary number of instances corresponding -to its "incarnations" requested by the configuration file. Each instance is completely -autonomous, has its own configuration, its own status, its own set of routes and its -own set of interfaces it works on. - -<p>A protocol is represented by a <struct/protocol/ structure containing all the basic -information (protocol name, default settings and pointers to most of the protocol -hooks). All these structures are linked in the <param/protocol_list/ list. - -<p>Each instance has its own <struct/proto/ structure describing all its properties: protocol -type, configuration, a resource pool where all resources belonging to the instance -live, various protocol attributes (take a look at the declaration of <struct/proto/ in -<tt/protocol.h/), protocol states (see below for what do they mean), connections -to routing tables, filters attached to the protocol -and finally a set of pointers to the rest of protocol hooks (they -are the same for all instances of the protocol, but in order to avoid extra -indirections when calling the hooks from the fast path, they are stored directly -in <struct/proto/). The instance is always linked in both the global instance list -(<param/proto_list/) and a per-status list (either <param/active_proto_list/ for -running protocols, <param/initial_proto_list/ for protocols being initialized or -<param/flush_proto_list/ when the protocol is being shut down). - -<p>The protocol hooks are described in the next chapter, for more information about -configuration of protocols, please refer to the configuration chapter and also -to the description of the <func/proto_commit/ function. - -<sect1>Protocol states - -<p>As startup and shutdown of each protocol are complex processes which can be affected -by lots of external events (user's actions, reconfigurations, behaviour of neighboring routers etc.), -we have decided to supervise them by a pair of simple state machines -- the protocol -state machine and a core state machine. - -<p>The <em/protocol state machine/ corresponds to internal state of the protocol -and the protocol can alter its state whenever it wants to. There exist -the following states: - -<descrip> - <tag/PS_DOWN/ The protocol is down and waits for being woken up by calling its - start() hook. - <tag/PS_START/ The protocol is waiting for connection with the rest of the - network. It's active, it has resources allocated, but it still doesn't want - any routes since it doesn't know what to do with them. - <tag/PS_UP/ The protocol is up and running. It communicates with the core, - delivers routes to tables and wants to hear announcement about route changes. - <tag/PS_STOP/ The protocol has been shut down (either by being asked by the - core code to do so or due to having encountered a protocol error). -</descrip> - -<p>Unless the protocol is in the <tt/PS_DOWN/ state, it can decide to change -its state by calling the <func/proto_notify_state/ function. - -<p>At any time, the core code can ask the protocol to shut down by calling its stop() hook. - -<p>The <em/core state machine/ takes care of the core view of protocol state. -The states are traversed according to changes of the protocol state machine, but -sometimes the transitions are delayed if the core needs to finish some actions -(for example sending of new routes to the protocol) before proceeding to the -new state. There exist the following core states: - -<descrip> - <tag/FS_HUNGRY/ The protocol is down, it doesn't have any routes and - doesn't want them. - <tag/FS_FEEDING/ The protocol has reached the <tt/PS_UP/ state, but - we are still busy sending the initial set of routes to it. - <tag/FS_HAPPY/ The protocol is up and has complete routing information. - <tag/FS_FLUSHING/ The protocol is shutting down (it's in either <tt/PS_STOP/ - or <tt/PS_DOWN/ state) and we're flushing all of its routes from the - routing tables. -</descrip> - -<sect1>Functions of the protocol module - -<p>The protocol module provides the following functions: |