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Diffstat (limited to 'doc/bird.sgml')
| -rw-r--r-- | doc/bird.sgml | 20 |
1 files changed, 4 insertions, 16 deletions
diff --git a/doc/bird.sgml b/doc/bird.sgml index 44fef1c5..93b701d3 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -2848,14 +2848,6 @@ itself and BGP protocol is usually used for exporting aggregate routes. But the Direct protocol is necessary for distance-vector protocols like RIP or Babel to announce local networks. -<p>There is one notable case when you definitely want to use the direct protocol --- running BIRD on BSD systems. Having high priority device routes for directly -connected networks from the direct protocol protects kernel device routes from -being overwritten or removed by IGP routes during some transient network -conditions, because a lower priority IGP route for the same network is not -exported to the kernel routing table. This is an issue on BSD systems only, as -on Linux systems BIRD cannot change non-BIRD route in the kernel routing table. - <p>There are just few configuration options for the Direct protocol: <p><descrip> @@ -2900,14 +2892,10 @@ interface) or whether an `alien' route has been added by someone else (depending on the <cf/learn/ switch, such routes are either ignored or accepted to our table). -<p>Unfortunately, there is one thing that makes the routing table synchronization -a bit more complicated. In the kernel routing table there are also device routes -for directly connected networks. These routes are usually managed by OS itself -(as a part of IP address configuration) and we don't want to touch that. They -are completely ignored during the scan of the kernel tables and also the export -of device routes from BIRD tables to kernel routing tables is restricted to -prevent accidental interference. This restriction can be disabled using -<cf/device routes/ switch. +<p>Note that routes created by OS kernel itself, namely direct routes +representing IP subnets of associated interfaces, are not imported even with +<cf/learn/ enabled. You can use <ref id="direct" name="Direct protocol"> to +generate these direct routes. <p>If your OS supports only a single routing table, you can configure only one instance of the Kernel protocol. If it supports multiple tables (in order to |