diff options
Diffstat (limited to 'sysdep/unix/krt.c')
| -rw-r--r-- | sysdep/unix/krt.c | 57 |
1 files changed, 33 insertions, 24 deletions
diff --git a/sysdep/unix/krt.c b/sysdep/unix/krt.c index 9bc29808..7aee1f6b 100644 --- a/sysdep/unix/krt.c +++ b/sysdep/unix/krt.c @@ -6,6 +6,39 @@ * Can be freely distributed and used under the terms of the GNU GPL. */ +/** + * DOC: Kernel synchronization + * + * This system dependent module implements the Kernel and Device protocol, + * that is synchronization of interface lists and routing tables with the + * OS kernel. + * + * The whole kernel synchronization is a bit messy and touches some internals + * of the routing table engine, because routing table maintenance is a typical + * example of the proverbial compatibility between different Unices and we want + * to keep the overhead of our krt business as low as possible and avoid maintaining + * a local routing table copy. + * + * The kernel syncer can work in three different modes (according to system config header): + * Either with a single routing table and single KRT protocol [traditional Unix] + * or with many routing tables and separate krt protocols for all of them + * or with many routing tables, but every scan including all tables, so we start + * separate krt protocols which cooperate with each other [Linux 2.2]. + * In this case, we keep only a single scan timer. + * + * We use FIB node flags to keep track of route synchronization status. We also + * attach temporary &rte's to the routing tables, but it cannot harm the rest of + * BIRD since table synchronization is an atomic process. + * + * When starting up, we cheat by looking if there is another + * KRT instance to be initialized later and performing table scan + * only once for all the instances. + */ + +/* + * If you are brave enough, continue now. You cannot say you haven't been warned. + */ + #undef LOCAL_DEBUG #include "nest/bird.h" @@ -18,30 +51,6 @@ #include "unix.h" #include "krt.h" -/* - * The whole kernel synchronization is a bit messy and touches some internals - * of the routing table engine, because routing table maintenance is a typical - * example of the proverbial compatibility between different Unices and we want - * to keep the overhead of our krt business as low as possible and avoid maintaining - * a local routing table copy. - * - * The kernel syncer can work in three different modes (according to system config header): - * o Single routing table, single krt protocol. [traditional Unix] - * o Many routing tables, separate krt protocols for all of them. - * o Many routing tables, but every scan includes all tables, so we start - * separate krt protocols which cooperate with each other. [Linux 2.2] - * In this case, we keep only a single scan timer. - * - * The hacky bits: - * o We use FIB node flags to keep track of route synchronization status. - * o When starting up, we cheat by looking if there is another kernel - * krt instance to be initialized later and performing table scan - * only once for all the instances. - * o We attach temporary rte's to routing tables. - * - * If you are brave enough, continue now. You cannot say you haven't been warned. - */ - static int krt_uptodate(rte *k, rte *e); /* |