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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/bird.sgml | 35 |
1 files changed, 29 insertions, 6 deletions
diff --git a/doc/bird.sgml b/doc/bird.sgml index 5859c77..86f4c50 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -1420,12 +1420,20 @@ 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>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 -allow policy routing; such an OS is for example Linux 2.2), you can run as many instances as you want, but each of -them must be connected to a different BIRD routing table and to a different +<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 allow policy routing; such an OS is for example +Linux), you can run as many instances as you want, but each of them +must be connected to a different BIRD routing table and to a different kernel table. +<p>Because the kernel protocol is partially integrated with the +connected routing table, there are two limitations - it is not +possible to connect more kernel protocols to the same routing table +and changing route attributes (even the kernel ones) in an export +filter of a kernel protocol does not work. Both limitations can be +overcome using another routing table and the pipe protocol. + <sect1>Configuration <p><descrip> @@ -1450,12 +1458,27 @@ kernel table. only on systems supporting multiple routing tables. </descrip> -<p>The Kernel protocol doesn't define any route attributes. +<sect1>Attributes + +<p>The Kernel protocol defines several attributes. These attributes +are translated to appropriate system (and OS-specific) route attributes. +We support these attributes: + +<descrip> + <tag>ip <cf/krt_prefsrc/</tag> (Linux) The preferred source address. + Used in source address selection for outgoing packets. Have to + be one of IP addresses of the router. + + <tag>int <cf/krt_realm/</tag> (Linux) The realm of the route. Can be + used for traffic classification. +</descrip> + +<sect1>Example + <p>A simple configuration can look this way: <p><code> protocol kernel { - import all; export all; } </code> |