bgpd: advertise VNI subnet

In EVPN symmetric routing, not all subnets are presents everywhere.
We have multiple scenarios where a host might not get learned locally.
1. GARP miss
2. SVI down/up
3. Silent host

We need a mechanism to resolve such hosts. In order to achieve this,
we will be advertising a subnet route from a box and that box will help
in resolving the ARP to such hosts.

Signed-off-by: Mitesh Kanjariya <mitesh@cumulusnetworks.com>

1 files changed, 82 insertions, 0 deletions

diff --git a/bgpd/bgp_evpn_vty.c b/bgpd/bgp_evpn_vty.c
index b463896c4..932046f7e 100644
--- a/bgpd/bgp_evpn_vty.c
+++ b/bgpd/bgp_evpn_vty.c
@@ -2272,6 +2272,32 @@ static void evpn_unset_advertise_default_gw(struct bgp *bgp,
 }
 
 /*
+ * evpn - enable advertisement of default g/w
+ */
+static void evpn_set_advertise_subnet(struct bgp *bgp,
+				      struct bgpevpn *vpn)
+{
+	if (vpn->advertise_subnet)
+		return;
+
+	vpn->advertise_subnet = 1;
+	bgp_zebra_advertise_subnet(bgp, vpn->advertise_subnet, vpn->vni);
+}
+
+/*
+ * evpn - disable advertisement of default g/w
+ */
+static void evpn_unset_advertise_subnet(struct bgp *bgp,
+					struct bgpevpn *vpn)
+{
+	if (!vpn->advertise_subnet)
+		return;
+
+	vpn->advertise_subnet = 0;
+	bgp_zebra_advertise_subnet(bgp, vpn->advertise_subnet, vpn->vni);
+}
+
+/*
  * EVPN (VNI advertisement) enabled. Register with zebra.
  */
 static void evpn_set_advertise_all_vni(struct bgp *bgp)
@@ -2330,6 +2356,9 @@ static void write_vni_config(struct vty *vty, struct bgpevpn *vpn)
 		if (vpn->advertise_gw_macip)
 			vty_out(vty, "   advertise-default-gw\n");
 
+		if (vpn->advertise_subnet)
+			vty_out(vty, "   advertise-subnet\n");
+
 		vty_out(vty, "  exit-vni\n");
 	}
 }
@@ -2440,6 +2469,56 @@ DEFUN (no_bgp_evpn_advertise_all_vni,
 	return CMD_SUCCESS;
 }
 
+DEFUN (bgp_evpn_advertise_vni_subnet,
+       bgp_evpn_advertise_vni_subnet_cmd,
+       "advertise-subnet",
+       "Advertise the subnet corresponding to VNI\n")
+{
+	struct bgp *bgp_vrf = NULL;
+	struct bgp *bgp = VTY_GET_CONTEXT(bgp);
+	VTY_DECLVAR_CONTEXT_SUB(bgpevpn, vpn);
+
+	if (!bgp)
+		return CMD_WARNING;
+
+	if (!vpn)
+		return CMD_WARNING;
+
+	bgp_vrf = bgp_lookup_by_vrf_id(vpn->tenant_vrf_id);
+	if (!bgp_vrf)
+		return CMD_WARNING;
+
+	if (!(advertise_type5_routes(bgp_vrf, AFI_IP) ||
+	      advertise_type5_routes(bgp_vrf, AFI_IP6))) {
+		vty_out(vty,
+			"%%Please enable ip prefix advertisement under l2vpn evpn in %s",
+			vrf_id_to_name(bgp_vrf->vrf_id));
+		return CMD_WARNING;
+	}
+
+	evpn_set_advertise_subnet(bgp, vpn);
+	return CMD_SUCCESS;
+}
+
+DEFUN (no_bgp_evpn_advertise_vni_subnet,
+       no_bgp_evpn_advertise_vni_subnet_cmd,
+       "no advertise-subnet",
+       NO_STR
+       "Advertise All local VNIs\n")
+{
+	struct bgp *bgp = VTY_GET_CONTEXT(bgp);
+	VTY_DECLVAR_CONTEXT_SUB(bgpevpn, vpn);
+
+	if (!bgp)
+		return CMD_WARNING;
+
+	if (!vpn)
+		return CMD_WARNING;
+
+	evpn_unset_advertise_subnet(bgp, vpn);
+	return CMD_SUCCESS;
+}
+
 DEFUN (bgp_evpn_advertise_type5,
        bgp_evpn_advertise_type5_cmd,
        "advertise " BGP_AFI_CMD_STR "" BGP_SAFI_CMD_STR,
@@ -4118,5 +4197,8 @@ void bgp_ethernetvpn_init(void)
 			&bgp_evpn_advertise_default_gw_vni_cmd);
 	install_element(BGP_EVPN_VNI_NODE,
 			&no_bgp_evpn_advertise_default_gw_vni_cmd);
+	install_element(BGP_EVPN_VNI_NODE, &bgp_evpn_advertise_vni_subnet_cmd);
+	install_element(BGP_EVPN_VNI_NODE,
+			&no_bgp_evpn_advertise_vni_subnet_cmd);
 #endif
 }