docs: add fig how policy works

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

3 files changed, 23 insertions, 13 deletions

diff --git a/docs/sources/filter.md b/docs/sources/filter.md
index 4cd604db..041a9be0 100644
--- a/docs/sources/filter.md
+++ b/docs/sources/filter.md
@@ -1,6 +1,6 @@
-# Filter configuration
+# Policy configuration
 
-This page explains GoBGP filter feature. Note that the feature is
+This page explains GoBGP policy feature. Note that the feature is
 still under development. Currently the feature is usable with route
 server use case
 
@@ -10,18 +10,25 @@ Assumed that you finished [Getting Started](https://github.com/osrg/gobgp/blob/m
 
 ## Configuration
 
-A filter consists of a match and an action. A match defines if an
+A policy consists of a match and an action. A match defines if an
 action will be applied to a route. For now, GoBGP uses only the source
 of a peer and a prefix as match conditions. Only dropping and
 accepting are supported as an action.
 
-Currently, GoBGP supports only **import** filter. A peer can defines
-what routes will be imported into its local RIBs.
+GoBGP supports **import** and **export** policies with respect to the
+local routing table. The **import** policy defines what routes will be
+imported into its local RIBs. The **export** policy defines what
+routes will be exported from its local RIBs.
 
-This example the configuration in [Route Server](https://github.com/osrg/gobgp/blob/master/docs/sources/route-server.md) with one more peer (IP:10.0.255.3, AS:65001).
+![Announcement processing model implemented by the Route Server](./policy-rs.png)
 
-Neighbor 10.0.255.1 advertises 10.33.0.0/16 and 10.3.0.0/16 routes. We define a filter
-for neighbor 10.0.255.2 that drops 10.33.0.0/16 route from Neighbor 10.0.255.1.
+This example the configuration in [Route
+Server](https://github.com/osrg/gobgp/blob/master/docs/sources/route-server.md)
+with one more peer (IP:10.0.255.3, AS:65001).
+
+Neighbor 10.0.255.1 advertises 10.33.0.0/16 and 10.3.0.0/16 routes. We
+define an import policy for neighbor 10.0.255.2 that drops
+10.33.0.0/16 route from Neighbor 10.0.255.1.
 
 ```
 [Global]
@@ -41,6 +48,7 @@ for neighbor 10.0.255.2 that drops 10.33.0.0/16 route from Neighbor 10.0.255.1.
     RouteServerClient = true
   [NeighborList.ApplyPolicy]
     ImportPolicies = ["pd2"]
+    ExportPolicies = []
 
 [[NeighborList]]
   NeighborAddress = "10.0.255.3"
@@ -73,13 +81,15 @@ for neighbor 10.0.255.2 that drops 10.33.0.0/16 route from Neighbor 10.0.255.1.
      RejectRoute = true
 ```
 
-Neighbor 10.0.255.2 has *pd2* policy filter. The *pd2* filter consists of *ps2* prefix match and *ns1* neighbor match. The *ps2* specifies 10.33.0.0/16 prefix. The ps2 specifies the exact mask length with **Masklength** keyword. **MasklengthRange** keyword can specify the range of mask length like ```MasklengthRange 24..26```. The *ns1* specifies neighbor 10.0.255.1.
+Neighbor 10.0.255.2 has *pd2* policy. The *pd2* policy consists of *ps2* prefix match and *ns1* neighbor match. The *ps2* specifies 10.33.0.0/16 prefix. The ps2 specifies the exact mask length with **Masklength** keyword. **MasklengthRange** keyword can specify the range of mask length like ```MasklengthRange 24..26```. The *ns1* specifies neighbor 10.0.255.1.
+
+The *pd2* sets *MatchSetOptions* to 1. This means that only when all match conditions meets, the policy will be applied. In this case, this policy will be applied to only 10.33.0.0/16 route from neighbor 10.0.255.1.
 
-The *pd2* sets *MatchSetOptions* to 1. This means that only when all match conditions meets, the filter will be applied. In this case, this filter will be applied to only 10.33.0.0/16 route from neighbor 10.0.255.1.
+If the *pd2* sets *MatchSetOptions* to 0, any of match conditions meets, the policy will be applied. With the above example, the policy will be applied to any routes from neighbor 10.0.255.1 and 10.33.0.16 route from any neighbors.
 
-If the *pd2* sets *MatchSetOptions* to 0, any of match conditions meets, the filter will be applied. With the above example, the filter will be applied to any routes from neighbor 10.0.255.1 and 10.33.0.16 route from any neighbors.
+## Checking
 
-Let's confirm that 10.0.255.1 neighbor advertises two routes.
+Confirm that 10.0.255.1 neighbor advertises two routes.
 
 ```
 $ gobgp show neighbor 10.0.255.1 adj-in
@@ -88,7 +98,7 @@ $ gobgp show neighbor 10.0.255.1 adj-in
    10.33.0.0/16       10.0.255.1      [65001]    00:51:57   [{Origin: 0} {Med: 0}]
 ```
 
-Now let's check out if the filter works as expected.
+Now let's check out if the policy works as expected.
    
 ```
 $ gobgp show neighbor 10.0.255.2 local
diff --git a/docs/sources/policy-rs.png b/docs/sources/policy-rs.png
new file mode 100644
index 00000000..440e76dc
--- /dev/null
+++ b/docs/sources/policy-rs.png
diff --git a/docs/sources/policy-rs.pptx b/docs/sources/policy-rs.pptx
new file mode 100644
index 00000000..25883894
--- /dev/null
+++ b/docs/sources/policy-rs.pptx