RIP route withdraw / triggered updates

[Florian Lohoff]

Hi,
i am trying to be able to withdraw a route advertised via rip with a
triggered update .. Currently disappearing routes only seem to be
deleted by not advertised anymore.

This is my rough solution although it has some problems i do see.

- A triggered update for every withdraw route
- Update contains all routes.

Currently i fail to understand the triggered update infrastructure 
in place already - When reading this code snippet:

    159     FIB_ITERATE_START(&P->rtable, &c->iter, z) {
    160       struct rip_entry *e = (struct rip_entry *) z;
    161
    162       if (!rif->triggered || (!(e->updated < now-5))) {
    163         nullupdate = 0;
    164         i = rip_tx_prepare( p, packet->block + i, e, rif, i );
    165         if (i >= maxi) {
    166           FIB_ITERATE_PUT(&c->iter, z);
    167           goto break_loop;
    168         }
    169       }
    170     } FIB_ITERATE_END(z);
    171     c->done = 1;

Where "rif->triggered = (P->tx_count % 6);" so basically
i am sending every 5th update and ignore the others !?!

I dont get it why a packet is constructed and finally not send.

I'd rather do some dampening and would schedule a triggered update on
the first withdrawn route in lets say 1-2 seconds. 

Flo

diff -Nur bird-1.0.11/proto/rip/rip.c bird-1.0.11.flo/proto/rip/rip.c
--- bird-1.0.11/proto/rip/rip.c	2004-07-15 17:28:13.000000000 +0000
+++ bird-1.0.11.flo/proto/rip/rip.c	2006-08-01 07:46:07.000000000 +0000
@@ -501,6 +501,26 @@
   debug( "\n" );
 }
 
+
+static void
+rip_broadcast(struct proto *p)
+{
+  struct rip_interface *rif;
+  DBG( "RIP: Broadcasting routing tables\n" );
+  WALK_LIST( rif, P->interfaces ) {
+    struct iface *iface = rif->iface;
+
+    if (!iface) continue;
+    if (rif->mode & IM_QUIET) continue;
+    if (!(iface->flags & IF_UP)) continue;
+
+    rif->triggered = (P->tx_count % 6);
+    rip_sendto( p, IPA_NONE, 0, rif );
+  }
+  P->tx_count ++;
+}
+
+
 /**
  * rip_timer
  * @t: timer
@@ -546,21 +566,7 @@
     }
   }
 
-  DBG( "RIP: Broadcasting routing tables\n" );
-  {
-    struct rip_interface *rif;
-    WALK_LIST( rif, P->interfaces ) {
-      struct iface *iface = rif->iface;
-
-      if (!iface) continue;
-      if (rif->mode & IM_QUIET) continue;
-      if (!(iface->flags & IF_UP)) continue;
-
-      rif->triggered = (P->tx_count % 6);
-      rip_sendto( p, IPA_NONE, 0, rif );
-    }
-    P->tx_count ++;
-  }
+  rip_broadcast(p);
 
   DBG( "RIP: tick tock done\n" );
 }
@@ -854,7 +860,16 @@
     struct rip_entry *e = fib_find( &P->rtable, &net->n.prefix, net->n.pxlen );
     if (!e)
       log( L_BUG "%s: Deleting nonexistent entry?!", p->name );
-    fib_delete( &P->rtable, e );
+
+    if (new) {
+      fib_delete( &P->rtable, e );
+    } else {
+      /* Set metric to infinity */
+      e->metric=16;
+      e->updated = e->changed = now;
+
+      rip_broadcast(p);
+    }
   }
 
   if (new) {

Flo
-- 
Florian Lohoff                  flo at rfc822.org             +49-171-2280134
                        Heisenberg may have been here.
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