Revision 71ca7716 doc/bird.sgml

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doc/bird.sgml
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to prevent accidental interference. This restriction can be disabled using
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<cf/device routes/ switch.
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<p>If your OS supports only a single routing table, you can configure only one
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instance of the Kernel protocol. If it supports multiple tables (in order to
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allow policy routing; such an OS is for example Linux 2.2), you can run as many instances as you want, but each of
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them must be connected to a different BIRD routing table and to a different
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<p>If your OS supports only a single routing table, you can configure
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only one instance of the Kernel protocol. If it supports multiple
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tables (in order to allow policy routing; such an OS is for example
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Linux), you can run as many instances as you want, but each of them
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must be connected to a different BIRD routing table and to a different
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kernel table.
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<p>Because the kernel protocol is partially integrated with the
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connected routing table, there are two limitations - it is not
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possible to connect more kernel protocols to the same routing table
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and changing route attributes (even the kernel ones) in an export
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filter of a kernel protocol does not work. Both limitations can be
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overcome using another routing table and the pipe protocol.
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<sect1>Configuration
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<p><descrip>
......
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	only on systems supporting multiple routing tables.
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</descrip>
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<p>The Kernel protocol doesn't define any route attributes.
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<sect1>Attributes
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<p>The Kernel protocol defines several attributes. These attributes
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are translated to appropriate system (and OS-specific) route attributes.
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We support these attributes:
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<descrip>
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	<tag>ip <cf/krt_prefsrc/</tag> (Linux) The preferred source address.
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 	Used in source address selection for outgoing packets. Have to
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 	be one of IP addresses of the router.
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	<tag>int <cf/krt_realm/</tag> (Linux) The realm of the route. Can be
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	used for traffic classification.
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</descrip>
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<sect1>Example
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<p>A simple configuration can look this way:
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<p><code>
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protocol kernel {
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	import all;
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	export all;
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}
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</code>

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