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diff --git a/docs/sources/filter-detail.md b/docs/sources/filter-detail.md new file mode 100644 index 00000000..9eb2bee6 --- /dev/null +++ b/docs/sources/filter-detail.md @@ -0,0 +1,319 @@ +# Detail of Policy configuration + +This page shows how to write your own policies. + +As [Policy configuration](https://github.com/osrg/gobgp/blob/master/docs/sources/policy.md) shows, you can put import or export policies to control the route advertisement. Basically a policy has condition part and an action part, and a condition part has prefix match and neighbor match. An action part has the rule to accept or reject(if it's import, otherwise discard) routes. + +The policy configuration on GoBGP consists of DefinedSets and PolicyDefinitionList in its configuration file. + + - DefinedSets + + A single DefinedSets entry has prefix match thas is named PrefixSetList and neighbor match part that is named NeighborSetList and combines 2 parts with the name. + It is possible to refer the combination using its name from policy. + + - PolicyDefinitionList + + PolicyDefinitionList is a list of policy. + A single element of PolicyDefinitionList has statements that combine a condition with an action and we can say it's policy. + + +## Definition Steps + +These are steps to define policy; + +1. define DefinedSets + - define PrefixSetList + - define NeighborSetList +2. define PolicyDefinitionList +3. attach policies to a neighbor + +### 1. Defining DefinedSets +DefineSets has prefix information and neighbor information in PrefixSetList and NeighborSetList section, and GoBGP uses these information to evaluate routes. +Defining DefinedSets is needed at first. +PrefixSetList and NeighborSetList section are prefix match part and neighbor match part. + +- DefinedSets example + + ``` + [[DefinedSets.PrefixSetList]] + PrefixSetName = "ps1" + # prefix match part + [[DefinedSets.PrefixSetList.PrefixList]] + Address = "10.33.0.0" + Masklength = 16 + MasklengthRange = 21...24 + # neighbor match part + [[DefinedSets.NeighborSetList]] + NeighborSetName = "ns1" + [[DefinedSets.NeighborSetList.NeighborInfoList]] + Address = "10.0.255.1" + ``` + +--- + +#### PrefixSetList +PrefixSetList has PrefixList as its element. PrefixList has prefix information to match destination's address and we can specify route's NLRI inside. + +PrefixList has 3 elements. + +| Parent | Element |Description | Example | Optional | +| ------------------------------------- |-----------------|-------------------|------------|------------| +| DefinedSets.PrefixSetList | PrefixSetName | name of PrefixSet | "10.33.0.0"| | +| DefinedSets.PrefixSetList.PrefixList | Address | prefix address | "10.33.0.0"| | +| | Masklength | prefix length | 16 | | +| | MasklengthRange | range of length | "25..28" | Yes | + + +##### Examples +- example 1 + - Match routes whose high order 2 octets of NLRI is 10.33 and its prefix length is between from 21 to 24 + + ``` + # example 1 + [[DefinedSets.PrefixSetList]] + PrefixSetName = "ps1" + [[DefinedSets.PrefixSetList.PrefixList]] + Address = "10.33.0.0" + Masklength = 16 + MasklengthRange = "21...24" + ``` + + - If you define a PrefixList that doesn't have MasklengthRange, it matches routes that have just 10.33.0.0/16 as NLRI. + + +- example 2 + - If you want to evaluate multiple routes with a single PrefixSetList, you can do this by adding an another PrefixList like this; + + ``` + # example 2 + [[DefinedSets.PrefixSetList]] + PrefixSetName = "ps1" + [[DefinedSets.PrefixSetList.PrefixList]] + Address = "10.33.0.0" + Masklength = 16 + MasklengthRange = "21...24" + [[DefinedSets.PrefixSetList.PrefixList]] + Address = "10.50.0.0" + Masklength = 16 + MasklengthRange = "21...24" + ``` + - This prefix match checks if a route has 10.33.0.0/21 to 24 **or** 10.50.0.0/21 to 24. + + +- example 3 + - PrefixSetName under PrefixSetList is reference to a single PrefixSet. + - If you want to add different PrefixSet more, you can add other blocks that form the same structure with example 1. + + ``` + # example 3 + # PrefixSetList + [[DefinedSets.PrefixSetList]] + PrefixSetName = "ps1" + [[DefinedSets.PrefixSetList.PrefixList]] + Address = "10.33.0.0" + Masklength = 16 + MasklengthRange = "21...24" + # another PrefixSetList + [[DefinedSets.PrefixSetList]] + PrefixSetName = "ps2" + [[DefinedSets.PrefixSetList.PrefixList]] + Address = "10.50.0.0" + Masklength = 16 + MasklengthRange = "21...24" + ``` + +--- + +#### NeighborSetList + +NeighborSetList has NeighborInfoList as its element and NeighborInfoList has neighbor information to match the sender of the routes. +It is necessary to specify a neighbor address in NeighborInfoList. +NeighborInfoList has 1 elements. + +| Parent | Element |Description | Example | Optional | +| --------------------------------------------- |----------|--------------------|-------------|------------| +| DefinedSets.NeighborSetList | Name | name of NeighborSet| "ns1 "| | +| DefinedSets.NeighborSetList.NeighborInfoList | Address | neighbor's address | "10.0.255.1"| | + +##### Examples + +- example 1 + - Match routes which come from the neighbor 10.0.255.1 + + ``` + # example 1 + [[DefinedSets.NeighborSetList]] + NeighborSetName = "ns1" + [[DefinedSets.NeighborSetList.NeighborInfoList]] + Address = "10.0.255.1" + ``` + +- example 2 + - Match routes which come from the neighbor 10.0.255.1 +Neighbor Match needs be defined within DefinedSets as follows. + ``` + # example 2 + [[DefinedSets.NeighborSetList]] + NeighborSetName = "ns2" + [[DefinedSets.NeighborSetList.NeighborInfoList]] + Address = "10.0.255.1" + ``` + +- example 3 + - As with PrefixSet, NeighborSet can have multiple NeighborInfoList like this; + + ``` + # example 3 + [[DefinedSets.NeighborSetList]] + NeighborSetName = "ns3" + [[DefinedSets.NeighborSetList.NeighborInfoList]] + Address = "10.0.255.1" + [[DefinedSets.NeighborSetList.NeighborInfoList]] + Address = "10.0.255.2" + ``` + + - - This example checks if a route comes from neighbor 10.0.255.1 **or** 10.0.255.2. + +--- + +### 2. Defining PolicyDefinitionList +PolicyDefinitionList consists of condition and action of the policy. The condition part evaluates routes from neighbors and applies action if the routes match a condition. For the definition of PolicyDefinitionList, you can use DefinedSets above to specify conditions. + +PolicyDefinitionList has PolicyDefinition as its element and the PolicyDefinition is just a policy. +You can write condition and action under StatementList. + + - an example of PolicyDefinitionList + + ``` + [[PolicyDefinitionList]] + Name = "example-policy" + [[PolicyDefinitionList.StatementList]] + Name = "statement1" + [PolicyDefinitionList.StatementList.Conditions] + MatchPrefixSet = "ps2" + MatchNeighborSet = "ns1" + MatchSetOptions = 1 + [PolicyDefinitionList.StatementList.Actions] + RejectRoute = true + ``` + +The elements of PolicyDefinitionList are as follows; + +| Parent | Element |Description |Example| +| ---------------------------------------------- |------------------|-----------------------------------------------------------------------------------------------|------| +| PolicyDefinitionList | name | policy's name | "pd1"| +| PolicyDefinitionList.StatementList | name | statements's name | "pd1"| +| PolicyDefinitionList.StatementList.Conditions | MatchPrefixSet | prefix match name used in its policy definition | "ps2"| +| | MatchNeighborSet | neighbor match name used in its policy definition |"ns1" | +| | MatchSetOptions | option for the check;<br> 0 means **ANY**,<br> 1 means **ALL**,<br> 2 means **INVERT** | 1 | +|PolicyDefinitionList.StatementList.Actions | RejectRoute | action for the route which matches PrefixSet and NeighborSet. if true, this route is rejected | true | + +##### Examples + - example 1 + - This PolicyDefinition has PrefixSet *ps1* and NeighborSet *ns1* as its condition and routes matche the condition is rejected. + + ``` + # example 1 + [[PolicyDefinitionList]] + Name = "policy1" + [[PolicyDefinitionList.StatementList]] + Name = "statement1" + [PolicyDefinitionList.StatementList.Conditions] + MatchPrefixSet = "ps2" + MatchNeighborSet = "ns1" + MatchSetOptions = 1 + [PolicyDefinitionList.StatementList.Actions] + RejectRoute = true + ``` + +- example 2 + - PolicyDefinition has two statements + + ``` + # example 2 + [[PolicyDefinitionList]] + Name = "pd1" + # first statement - (1) + [[PolicyDefinitionList.StatementList]] + Name = "statement1" + [PolicyDefinitionList.StatementList.Conditions] + MatchPrefixSet = "ps1" + MatchNeighborSet = "ns1" + MatchSetOptions = 1 + [PolicyDefinitionList.StatementList.Actions] + RejectRoute = true + # second statement - (2) + [[PolicyDefinitionList.StatementList]] + Name = "statement2" + [PolicyDefinitionList.StatementList.Conditions] + MatchPrefixSet = "ps2" + MatchNeighborSet = "ns2" + MatchSetOptions = 1 + [PolicyDefinitionList.StatementList.Actions] + RejectRoute = true + ``` + - if a route matches the condition inside the first statement(1), GoBGP applies its action and quits the policy evaluation. + + +- example 3 + - If you want to add other policies, just add PolicyDefinitionList block following the first one like this; + ``` + # example 3 + # first policy + [[PolicyDefinitionList]] + Name = "policy1" + + [[PolicyDefinitionList.StatementList]] + Name = "statement1" + [PolicyDefinitionList.StatementList.Conditions] + MatchPrefixSet = "ps1" + MatchNeighborSet = "ns1" + MatchSetOptions = 1 + [PolicyDefinitionList.StatementList.Actions] + RejectRoute = true + +# second policy + [[PolicyDefinitionList]] + Name = "policy2" + + [[PolicyDefinitionList.StatementList]] + Name = "statement2" + [PolicyDefinitionList.StatementList.Conditions] + MatchPrefixSet = "ps2" + MatchNeighborSet = "ns2" + MatchSetOptions = 1 + [PolicyDefinitionList.StatementList.Actions] + RejectRoute = true + ``` + +--- + +### 3. Attaching policy +You can attach policies to a neighbor after defining policy. +To attach policies to a neighbor, you need to add policy's name to NeighborList.ApplyPolicy in the neighbor's setting. + +You can attach policies to the import policy or the export policy inside the neighbor configuration. +This example attatches *policy1* to import policy and *policy2* to export policy. + +``` +[[NeighborList]] +NeighborAddress = "10.0.255.2" +PeerAs = 65002 +[NeighborList.RouteServer] +RouteServerClient = true +[NeighborList.ApplyPolicy] +ImportPolicies = ["policy1"] +ExportPolicies = ["policy2"] +DefaultImportPolicy = 0 +DefaultExportPolicy = 0 +``` + +NeighborList has a section to specify policies and the section's name is ApplyPolicy. +The ApplyPolicy has 4 elements. + +| Parent | Element | Description | Example | +|---------------------------|---------------------|-------------------------------------------------------------------------------|------------| +| NeighborList.ApplyPolicy | ImportPolicies | PolicyDefinitionList.name for import policy | "policy1" | +| | ExportPolicies | PolicyDefinitionList.name for export policy | "policy1" | +| | DefaultImportPolicy | action if the route isn't applied any policy;<br> 0 means import,<br> 1 means reject | 0 | +| | DefaultExportPolicy | action if the route isn't applied any policy;<br> 0 means export,<br> 1 means discard | 0 | |