docs: add route-reflector document

Signed-off-by: ISHIDA Wataru <ishida.wataru@lab.ntt.co.jp>

2 files changed, 70 insertions, 0 deletions

diff --git a/README.md b/README.md
index 62d6b538..c42606bf 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,7 @@ No dependency hell (library, package, etc) thanks to Go.
   * [Typical operation examples](https://github.com/osrg/gobgp/blob/master/docs/sources/cli-operations.md)
   * [Complete syntax](https://github.com/osrg/gobgp/blob/master/docs/sources/cli-command-syntax.md)
  * [Route Server](https://github.com/osrg/gobgp/blob/master/docs/sources/route-server.md)
+ * [Route Reflector](https://github.com/osrg/gobgp/blob/master/docs/sources/route-reflector.md)
  * [Policy](https://github.com/osrg/gobgp/blob/master/docs/sources/policy.md)
  * [EVPN](https://github.com/osrg/gobgp/blob/master/docs/sources/evpn.md)
  * [MRT](https://github.com/osrg/gobgp/blob/master/docs/sources/mrt.md)
diff --git a/docs/sources/route-reflector.md b/docs/sources/route-reflector.md
new file mode 100644
index 00000000..c8fbce50
--- /dev/null
+++ b/docs/sources/route-reflector.md
@@ -0,0 +1,69 @@
+# Route Reflector
+
+This page explains how to set up GoBGP as a route reflector.
+
+## Prerequisites
+
+Assumed you finished [Getting Started](https://github.com/osrg/gobgp/blob/master/docs/sources/getting-started.md).
+
+## Configuration
+
+Configure `RouteReflector.RouteReflectorConfig` section to enable route reflector functionality.
+The configuration below configures two route reflector clients and two normal iBGP peers.
+
+```toml
+[Global]
+  [Global.GlobalConfig]
+    RouterId = "192.168.0.1"
+    As = 65000
+[Neighbors]
+  [[Neighbors.NeighborList]]
+    [Neighbors.NeighborList.NeighborConfig]
+      NeighborAddress = "192.168.10.2"
+      PeerAs = 65000
+    [Neighbors.NeighborList.RouteReflector.RouteReflectorConfig]
+      RouteReflectorClient = true
+      RouteReflectorClusterId = "192.168.0.1"
+  [[Neighbors.NeighborList]]
+    [Neighbors.NeighborList.NeighborConfig]
+      NeighborAddress = "192.168.10.3"
+      PeerAs = 65000
+    [Neighbors.NeighborList.RouteReflector.RouteReflectorConfig]
+      RouteReflectorClient = true
+      RouteReflectorClusterId = "192.168.0.1"
+  [[Neighbors.NeighborList]]
+    [Neighbors.NeighborList.NeighborConfig]
+      NeighborAddress = "192.168.10.4"
+      PeerAs = 65000
+  [[Neighbors.NeighborList]]
+    [Neighbors.NeighborList.NeighborConfig]
+      NeighborAddress = "192.168.10.5"
+      PeerAs = 65000
+```
+
+## Check route reflector behavior
+
+Let's check adj-rib-out of a route reflector client.
+
+```bash
+$ gobgp neighbor 192.168.10.2 adj-out
+Network              Next Hop             AS_PATH              Attrs
+10.0.2.0/24          192.168.10.3                              [{Origin: i} {Med: 0} {LocalPref: 100} {Originator: 192.168.0.3} {ClusterList: [192.168.0.1]}]
+10.0.3.0/24          192.168.10.4                              [{Origin: i} {Med: 0} {LocalPref: 100} {Originator: 192.168.0.4} {ClusterList: [192.168.0.1]}]
+10.0.4.0/24          192.168.10.5                              [{Origin: i} {Med: 0} {LocalPref: 100} {Originator: 192.168.0.5} {ClusterList: [192.168.0.1]}]
+```
+
+You can see the routes from other iBGP peers are reflected.
+Also Originator and ClusterList path attributes are added.
+
+For the normal iBGP peer's adj-rib-out
+
+```bash
+$ gobgp neighbor 192.168.10.4 adj-out
+Network              Next Hop             AS_PATH              Attrs
+10.0.1.0/24          192.168.10.2                              [{Origin: i} {Med: 0} {LocalPref: 100}]
+10.0.2.0/24          192.168.10.3                              [{Origin: i} {Med: 0} {LocalPref: 100}]
+```
+
+Only the routes from route reflector clients are advertised via GoBGP.
+Originator and ClusterList path attributes are not added.