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diff --git a/doc/bird.sgml b/doc/bird.sgml index 366797ba..449a69de 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -1905,6 +1905,70 @@ protocol sections. <chapt>Protocols <label id="protocols"> +<sect>Aggregator +<label id="aggregator"> + +<sect1>Introduction +<label id="aggregator-intro"> +<p>The Aggregator protocol explicitly merges routes by the given rules. There + are four phases of aggregation. First routes are filtered, then sorted into buckets, + then buckets are merged and finally the results are filtered once again. + Aggregating an already aggregated route is forbidden. + +<p>This is an experimental protocol, use with caution. + +<sect1>Configuration +<label id="aggregator-config"> +<p><descrip> + <tag><label id="aggregator-table">table <m/table/</tag> + The table from which routes are exported to get aggregated. + + <tag><label id="aggregator-export">export <m/.../</tag> + A standard channel's <cf/export/ clause, defining which routes are accepted into aggregation. + + <tag><label id="aggregator-rule">aggregate on <m/expr/ | <m/attribute/ [<m/, .../]</tag> + All the given filter expressions and route attributes are evaluated for each route. Then routes + are sorted into buckets where <em/all/ values are the same. Note: due to performance reasons, + all filter expressions must return a compact type, e.g. integer, a BGP + (standard, extended, large) community or an IP address. If you need to compare e.g. modified + AS Paths in the aggregation rule, you can define a custom route attribute and set this attribute + in the export filter. For now, it's mandatory to say <cf/net/ here, we can't merge prefixes yet. + + <tag><label id="aggregation-merge">merge by { <m/filter code/ }</tag> + The given filter code has an extra symbol defined: <cf/routes/. By iterating over <cf/routes/, + you get all the routes in the bucket and you can construct your new route. All attributes + selected in <cf/aggregate on/ are already set to the common values. For now, it's not possible + to use a named filter here. You have to finalize the route by calling <cf/accept/. + + <tag><label id="aggregator-import">import <m/.../</tag> + Filter applied to the route after <cf/merge by/. Here you can use a named filter. + + <tag><label id="aggregator-peer-table">peer table <m/table/</tag> + The table to which aggregated routes are imported. It may be the same table + as <cf/table/. +</descrip> + +<sect1>Example +<label id="aggregator-example"> + +<p><code> +protocol aggregator { + table master6; + export where defined(bgp_path); + /* Merge all routes with the same AS Path length */ + aggregate on net, bgp_path.len; + merge by { + for route r in routes do { + if ! defined(bgp_path) then { bgp_path = r.bgp_path } + bgp_community = bgp_community.add(r.bgp_community); + } + accept; + }; + import all; + peer table agr_result; +} +</code> + <sect>Babel <label id="babel"> |