Added "what is router" to introduction.
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@ -32,7 +32,17 @@ This document contains documentation for BIRD Internet Routing Daemon
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<sect1>What is BIRD
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<sect1>What is BIRD
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<p><label id="intro"> You may wonder what 'BIRD' means. It is acronym of 'BIRD Internet Routing
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<p><label id="intro"> You may wonder what 'BIRD' means. It is acronym of 'BIRD Internet Routing
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Daemon', and we think that's cool name. Its task is similar to what firmware of Cisco routers does,
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Daemon', and we think that's cool name.
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<p>Routers are devices for connecting networks. Router has several
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network interfaces, listens for packets on them, and forwards packets
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closer to their destination. For simple situations, such as tree,
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static routing is enough and your kernel can do routing for you. For
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more complicated topologies, you need routers to talk to eachother (in
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order to discover alternate ways to deliver packets after network
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failure). Routing deamon is the beast that accomplishes this
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communication. It does not forward packets itself, but it tells kernel
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where to forward them. Its task is similar to what firmware of Cisco routers does,
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or what gated <HTMLURL URL="http://www.gated.org/"> or GNU zebra <HTMLURL
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or what gated <HTMLURL URL="http://www.gated.org/"> or GNU zebra <HTMLURL
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URL="http://www.zebra.org/"> does. However, you can not run Cisco's firmware on "normal" computer
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URL="http://www.zebra.org/"> does. However, you can not run Cisco's firmware on "normal" computer
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and gated is really hard to configure and comes under wrong license. BIRD is being developed on
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and gated is really hard to configure and comes under wrong license. BIRD is being developed on
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@ -96,8 +106,8 @@ protocol rip {
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<sect1>Global options
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<sect1>Global options
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<p><descrip>
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<p><descrip>
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<tag>log "<m/filename/"|syslog|stderr all|{ <m/list of
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<tag>log "<m/filename/"|syslog|stderr all|{ <m/list of classes/ }</tag>
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classes/ }</tag> set logging of classes (either all or <cf/{
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set logging of classes (either all or <cf/{
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error, trace }/ etc.) into selected destination. Classes are:
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error, trace }/ etc.) into selected destination. Classes are:
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<cf/debug/ for debugging message, <cf/trace/, <cf/info/,
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<cf/debug/ for debugging message, <cf/trace/, <cf/info/,
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<cf/remote/ for messages about misbehavior of remote side, <cf/warning/,
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<cf/remote/ for messages about misbehavior of remote side, <cf/warning/,
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@ -241,7 +251,9 @@ syntax. Returning value exits from current function (this is similar to C).
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<p>Filters are declared in similar way to functions, except they can not have explicit
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<p>Filters are declared in similar way to functions, except they can not have explicit
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parameters. They get route table entry as implicit parameter. Route table entry is passed implicitly
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parameters. They get route table entry as implicit parameter. Route table entry is passed implicitly
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to any functions being called. Filter must terminate with either accept or reject statement.
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to any functions being called. Filter must terminate with either
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accept or reject statement. If there's runtime error in filter, route
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is rejected.
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<sect1>Data types
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<sect1>Data types
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@ -313,7 +325,8 @@ booleans (that is to prevent you from shooting in the foot).
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<p>Filter language supports common integer operations <cf>(+,-,*,/)</cf>, parentheses <cf/(a*(b+c))/, comparison
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<p>Filter language supports common integer operations <cf>(+,-,*,/)</cf>, parentheses <cf/(a*(b+c))/, comparison
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<cf/(a=b, a!=b, a<b, a>=b)/. Special operators include <cf/˜/ for "in" operation. In operation can be
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<cf/(a=b, a!=b, a<b, a>=b)/. Special operators include <cf/˜/ for "in" operation. In operation can be
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used on element and set of that elements, or on ip and prefix, or on prefix and prefix or on bgppath and bgpmask. Its result
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used on element and set of that elements, or on ip and prefix, or on
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prefix and prefix or on bgppath and bgpmask or on pair and clist. Its result
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is true if element is in given set or if ip address is inside given prefix. Operator <cf/=/ is used to assign value
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is true if element is in given set or if ip address is inside given prefix. Operator <cf/=/ is used to assign value
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to variable.
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to variable.
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