bgpd: add config knobs to disable rx and tx of ead-per-evi routes

Some vendors only advertise EAD-per-ES routes i.e. they do not
advertise EAD-per-EVI routes. To interop with these vendors we need
to relax the dependancy on EAD-per-EVI routes to activate a remote ES-PE.

Sample config -
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
router bgp 5553
 address-family l2vpn evpn
  disable-ead-evi-rx
>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Ticket: CM-31177

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>

bgpd/bgp_evpn_mh.c

@@ -990,6 +990,10 @@ static void bgp_evpn_local_type1_evi_route_add(struct bgp *bgp,
 	struct prefix_evpn p;
 	struct bgp_evpn_es_evi *es_evi;
 
+	/* EAD-per-EVI routes have been suppressed */
+	if (!bgp_mh_info->ead_evi_tx)
+		return;
+
 	if (CHECK_FLAG(es->flags, BGP_EVPNES_ADV_EVI))
 		/* EAD-EVI route add for this ES is already done */
 		return;
@@ -2717,14 +2721,20 @@ static void bgp_evpn_es_evi_vtep_re_eval_active(struct bgp *bgp,
 {
 	bool old_active;
 	bool new_active;
+	uint32_t ead_activity_flags;
 
 	old_active = !!CHECK_FLAG(evi_vtep->flags, BGP_EVPN_EVI_VTEP_ACTIVE);
 
+	if (bgp_mh_info->ead_evi_rx)
 		/* Both EAD-per-ES and EAD-per-EVI routes must be rxed from a PE
 		 * before it can be activated.
 		 */
-	if ((evi_vtep->flags & BGP_EVPN_EVI_VTEP_EAD) ==
+		ead_activity_flags = BGP_EVPN_EVI_VTEP_EAD;
-			BGP_EVPN_EVI_VTEP_EAD)
+	else
+		/* EAD-per-ES is sufficent to activate the PE */
+		ead_activity_flags = BGP_EVPN_EVI_VTEP_EAD_PER_ES;
+
+	if ((evi_vtep->flags & ead_activity_flags) == ead_activity_flags)
 		SET_FLAG(evi_vtep->flags, BGP_EVPN_EVI_VTEP_ACTIVE);
 	else
 		UNSET_FLAG(evi_vtep->flags, BGP_EVPN_EVI_VTEP_ACTIVE);
@@ -3075,9 +3085,9 @@ int bgp_evpn_local_es_evi_add(struct bgp *bgp, esi_t *esi, vni_t vni)
 	bgp_evpn_es_evi_local_info_set(es_evi);
 
 	/* generate an EAD-EVI for this new VNI */
-	build_evpn_type1_prefix(&p, BGP_EVPN_AD_EVI_ETH_TAG,
-			&es->esi, es->originator_ip);
 	if (CHECK_FLAG(es->flags, BGP_EVPNES_ADV_EVI)) {
+		build_evpn_type1_prefix(&p, BGP_EVPN_AD_EVI_ETH_TAG, &es->esi,
+					es->originator_ip);
 		if (bgp_evpn_type1_route_update(bgp, es, vpn, &p))
 			flog_err(EC_BGP_EVPN_ROUTE_CREATE,
 					"%u: EAD-EVI route creation failure for ESI %s VNI %u",
@@ -3700,6 +3710,9 @@ void bgp_evpn_mh_init(void)
 	bgp_mh_info->pend_es_list = list_new();
 	listset_app_node_mem(bgp_mh_info->pend_es_list);
 
+	bgp_mh_info->ead_evi_rx = BGP_EVPN_MH_EAD_EVI_RX_DEF;
+	bgp_mh_info->ead_evi_tx = BGP_EVPN_MH_EAD_EVI_TX_DEF;
+
 	/* config knobs - XXX add cli to control it */
 	bgp_mh_info->ead_evi_adv_for_down_links = true;
 	bgp_mh_info->consistency_checking = true;

bgpd/bgp_evpn_mh.h

@@ -261,6 +261,15 @@ struct bgp_evpn_mh_info {
 	/* Use L3 NHGs for host routes in symmetric IRB */
 	bool install_l3nhg;
 	bool host_routes_use_l3nhg;
+	/* Some vendors are not generating the EAD-per-EVI route. This knob
+	 * can be turned off to activate a remote ES-PE when the EAD-per-ES
+	 * route is rxed i.e. not wait on the EAD-per-EVI route
+	 */
+	bool ead_evi_rx;
+#define BGP_EVPN_MH_EAD_EVI_RX_DEF true
+	/* Skip EAD-EVI advertisements by turning off this knob */
+	bool ead_evi_tx;
+#define BGP_EVPN_MH_EAD_EVI_TX_DEF true
 };
 
 /****************************************************************************/

bgpd/bgp_evpn_vty.c

@@ -3757,6 +3757,26 @@ DEFPY (bgp_evpn_use_es_l3nhg,
 	return CMD_SUCCESS;
 }
 
+DEFPY (bgp_evpn_ead_evi_rx_disable,
+       bgp_evpn_ead_evi_rx_disable_cmd,
+       "[no$no] disable-ead-evi-rx",
+       NO_STR
+       "Activate PE on EAD-ES even if EAD-EVI is not received\n")
+{
+	bgp_mh_info->ead_evi_rx = no? true :false;
+	return CMD_SUCCESS;
+}
+
+DEFPY (bgp_evpn_ead_evi_tx_disable,
+       bgp_evpn_ead_evi_tx_disable_cmd,
+       "[no$no] disable-ead-evi-tx",
+       NO_STR
+       "Don't advertise EAD-EVI for local ESs\n")
+{
+	bgp_mh_info->ead_evi_tx = no? true :false;
+	return CMD_SUCCESS;
+}
+
 DEFPY (bgp_evpn_advertise_pip_ip_mac,
        bgp_evpn_advertise_pip_ip_mac_cmd,
        "[no$no] advertise-pip [ip <A.B.C.D> [mac <X:X:X:X:X:X|X:X:X:X:X:X/M>]]",
@@ -5751,6 +5771,20 @@ void bgp_config_write_evpn_info(struct vty *vty, struct bgp *bgp, afi_t afi,
 			vty_out(vty, "  no use-es-l3nhg\n");
 	}
 
+	if (bgp_mh_info->ead_evi_rx != BGP_EVPN_MH_EAD_EVI_RX_DEF) {
+		if (bgp_mh_info->ead_evi_rx)
+			vty_out(vty, "  no disable-ead-evi-rx\n");
+		else
+			vty_out(vty, "  disable-ead-evi-rx\n");
+	}
+
+	if (bgp_mh_info->ead_evi_tx != BGP_EVPN_MH_EAD_EVI_TX_DEF) {
+		if (bgp_mh_info->ead_evi_tx)
+			vty_out(vty, "  no disable-ead-evi-tx\n");
+		else
+			vty_out(vty, "  disable-ead-evi-tx\n");
+	}
+
 	if (!bgp->evpn_info->dup_addr_detect)
 		vty_out(vty, "  no dup-addr-detection\n");
 
@@ -5896,6 +5930,8 @@ void bgp_ethernetvpn_init(void)
 	install_element(BGP_EVPN_NODE, &bgp_evpn_flood_control_cmd);
 	install_element(BGP_EVPN_NODE, &bgp_evpn_advertise_pip_ip_mac_cmd);
 	install_element(BGP_EVPN_NODE, &bgp_evpn_use_es_l3nhg_cmd);
+	install_element(BGP_EVPN_NODE, &bgp_evpn_ead_evi_rx_disable_cmd);
+	install_element(BGP_EVPN_NODE, &bgp_evpn_ead_evi_tx_disable_cmd);
 
 	/* test commands */
 	install_element(BGP_EVPN_NODE, &test_es_add_cmd);

doc/user/bgp.rst

@@ -2682,6 +2682,20 @@ the traffic.
 Similarly traffic received from ES peers via the overlay cannot be forwarded
 to the server. This is split-horizon-filtering with local bias.
 
+Knobs for interop
+"""""""""""""""""
+Some vendors do not send EAD-per-EVI routes. To interop with them we
+need to relax the dependency on EAD-per-EVI routes and activate a remote
+ES-PE based on just the EAD-per-ES route.
+
+Note that by default we advertise and expect EAD-per-EVI routes.
+
+.. index:: disable-ead-evi-rx
+.. clicmd:: [no] disable-ead-evi-rx
+
+.. index:: disable-ead-evi-tx
+.. clicmd:: [no] disable-ead-evi-tx
+
 Fast failover
 """""""""""""
 As the primary purpose of EVPN-MH is redundancy keeping the failover efficient