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Diffstat (limited to 'proto/ospf/ospf.c')
| -rw-r--r-- | proto/ospf/ospf.c | 56 |
1 files changed, 55 insertions, 1 deletions
diff --git a/proto/ospf/ospf.c b/proto/ospf/ospf.c index ef06c709..93483986 100644 --- a/proto/ospf/ospf.c +++ b/proto/ospf/ospf.c @@ -1,11 +1,65 @@ /* * BIRD -- OSPF * - * (c) 1999 Ondrej Filip <feela@network.cz> + * (c) 1999-2000 Ondrej Filip <feela@network.cz> * * Can be freely distributed and used under the terms of the GNU GPL. */ +/** + * DOC: Open Shortest Path First (OSPF) + * + * As OSPF protocol is quite complicated and complex implemenation is + * split into many files. In |ospf.c| you can find mostly interfaces + * for communication with nest. (E.g. reconfiguration hooks, shutdown + * and inicialisation and so on.) In |packet.c| you can find various + * functions for sending and receiving generic OSPF packet. There are + * also routins for autentications, checksumming. |Iface.c| contains + * interface state machine, allocation and deallocation of OSPF's + * interface data structures. |Neighbor.c| includes neighbor state + * machine and function for election of Designed Router and Backup + * Designed router. In |hello.c| there are routines for sending + * and receiving hello packets as well as functions for maintaining + * wait times and inactivity timer. |Lsreq.c|, |lsack.c|, |dbdes.c| + * contains functions for sending and receiving link-state request, + * link-state acknoledge and database description respectively. + * In |lsupd.c| there are function for sending and receiving + * link-state updates and also flooding algoritmus. |Topology.c| is + * a place where routins for searching LSAs in link-state database, + * adding and deleting them, there are also functions for originating + * various types of LSA. (router lsa, net lsa, external lsa) |Rt.c| + * contains routins for calculating of routing table. + * + * Just one instance of protocol is able to hold LSA databases for + * multiple OSPF areas and exhange routing information between + * multiple neighbors and calculate routing tables. The core + * structure is &proto_ospf, to which multiple &ospf_area and + * &ospf_iface are connected. To &ospf_area is connected + * &top_hash_graph, which is a dynamic hashing structure that + * describes link-state database. It allows fast search, adding + * and deleting. Every area has it's own area_disp() that is + * responsible for late originating of router LSA, calcutating + * of routing table and it also ages and flushes LSA database. This + * function is called in regular intervals. + * To every &ospf_iface is connected one or more + * &ospf_neighbors. This structure contains many timers and queues + * for building adjacency and exchange routing messages. + * + * BIRD's OSPF implementation respects RFC2328 in every detail but + * some of inner function differs. RFC recommends to make a snapshot + * of link-state database when new adjacency is building and send + * database description packets based on information of this + * snapshot. The database can be quite large in some networks so + * I rather walk through &slist structure which allows me to + * continue even if actual LSA I worked on is deleted. New + * LSA are added to the tail of this slist. + * + * I also don't build another, new routing table besides the old + * one because nest helps me. I simply flush all calculated and + * deleted routes into nest's routing table. It's simplyfies + * this process and spares memory. + */ + #include "ospf.h" static int |