Adding upstream version 9.1.upstream/9.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1416 insertions, 0 deletions

diff --git a/ospf6d/ospf6_gr_helper.c b/ospf6d/ospf6_gr_helper.c
new file mode 100644
index 0000000..be1042f
--- /dev/null
+++ b/ospf6d/ospf6_gr_helper.c
@@ -0,0 +1,1416 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * OSPF6 Graceful Restart helper functions.
+ *
+ * Copyright (C) 2021-22 Vmware, Inc.
+ * Rajesh Kumar Girada
+ */
+
+#include <zebra.h>
+
+#include "log.h"
+#include "vty.h"
+#include "command.h"
+#include "prefix.h"
+#include "stream.h"
+#include "zclient.h"
+#include "memory.h"
+#include "table.h"
+#include "lib/bfd.h"
+#include "lib_errors.h"
+#include "jhash.h"
+
+#include "ospf6_proto.h"
+#include "ospf6_lsa.h"
+#include "ospf6_lsdb.h"
+#include "ospf6_route.h"
+#include "ospf6_message.h"
+
+#include "ospf6_top.h"
+#include "ospf6_area.h"
+#include "ospf6_interface.h"
+#include "ospf6_neighbor.h"
+#include "ospf6_intra.h"
+#include "ospf6d.h"
+#include "ospf6_gr.h"
+#include "lib/json.h"
+#include "ospf6d/ospf6_gr_helper_clippy.c"
+
+DEFINE_MTYPE_STATIC(OSPF6D, OSPF6_GR_HELPER, "OSPF6 Graceful restart helper");
+
+unsigned char conf_debug_ospf6_gr;
+
+static int ospf6_grace_lsa_show_info(struct vty *vty, struct ospf6_lsa *lsa,
+				     json_object *json, bool use_json);
+
+struct ospf6_lsa_handler grace_lsa_handler = {.lh_type = OSPF6_LSTYPE_GRACE_LSA,
+					      .lh_name = "Grace",
+					      .lh_short_name = "GR",
+					      .lh_show =
+						      ospf6_grace_lsa_show_info,
+					      .lh_get_prefix_str = NULL,
+					      .lh_debug = 0};
+
+const char *ospf6_exit_reason_desc[] = {
+	"Unknown reason",
+	"Helper in progress",
+	"Topology Change",
+	"Grace timer expiry",
+	"Successful graceful restart",
+};
+
+const char *ospf6_restart_reason_desc[] = {
+	"Unknown restart",
+	"Software restart",
+	"Software reload/upgrade",
+	"Switch to redundant control processor",
+};
+
+const char *ospf6_rejected_reason_desc[] = {
+	"Unknown reason",
+	"Helper support disabled",
+	"Neighbour is not in FULL state",
+	"Supports only planned restart but received for unplanned",
+	"Topo change due to change in lsa rxmt list",
+	"LSA age is more than Grace interval",
+};
+
+static unsigned int ospf6_enable_rtr_hash_key(const void *data)
+{
+	const struct advRtr *rtr = data;
+
+	return jhash_1word(rtr->advRtrAddr, 0);
+}
+
+static bool ospf6_enable_rtr_hash_cmp(const void *d1, const void *d2)
+{
+	const struct advRtr *rtr1 = d1;
+	const struct advRtr *rtr2 = d2;
+
+	return (rtr1->advRtrAddr == rtr2->advRtrAddr);
+}
+
+static void *ospf6_enable_rtr_hash_alloc(void *p)
+{
+	struct advRtr *rid;
+
+	rid = XCALLOC(MTYPE_OSPF6_GR_HELPER, sizeof(struct advRtr));
+	rid->advRtrAddr = ((struct advRtr *)p)->advRtrAddr;
+
+	return rid;
+}
+
+static void ospf6_disable_rtr_hash_free(void *rtr)
+{
+	XFREE(MTYPE_OSPF6_GR_HELPER, rtr);
+}
+
+static void ospf6_enable_rtr_hash_destroy(struct ospf6 *ospf6)
+{
+	if (ospf6->ospf6_helper_cfg.enable_rtr_list == NULL)
+		return;
+
+	hash_clean_and_free(&ospf6->ospf6_helper_cfg.enable_rtr_list,
+			    ospf6_disable_rtr_hash_free);
+}
+
+/*
+ * Extracting tlv info from GRACE LSA.
+ *
+ * lsa
+ *   ospf6 grace lsa
+ *
+ * Returns:
+ * interval : grace interval.
+ * reason   : Restarting reason.
+ */
+static int ospf6_extract_grace_lsa_fields(struct ospf6_lsa *lsa,
+					  uint32_t *interval, uint8_t *reason)
+{
+	struct ospf6_lsa_header *lsah = NULL;
+	struct tlv_header *tlvh = NULL;
+	struct grace_tlv_graceperiod *gracePeriod;
+	struct grace_tlv_restart_reason *grReason;
+	uint16_t length = 0;
+	int sum = 0;
+
+	lsah = lsa->header;
+	if (ntohs(lsah->length) <= OSPF6_LSA_HEADER_SIZE) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug("%s: undersized (%u B) lsa", __func__,
+				   ntohs(lsah->length));
+		return OSPF6_FAILURE;
+	}
+
+	length = ntohs(lsah->length) - OSPF6_LSA_HEADER_SIZE;
+
+	for (tlvh = TLV_HDR_TOP(lsah); sum < length && tlvh;
+	     tlvh = TLV_HDR_NEXT(tlvh)) {
+
+		/* Check TLV len against overall LSA */
+		if (sum + TLV_SIZE(tlvh) > length) {
+			if (IS_DEBUG_OSPF6_GR)
+				zlog_debug(
+					"%s: Malformed packet: Invalid TLV len:%d",
+					__func__, TLV_SIZE(tlvh));
+			return OSPF6_FAILURE;
+		}
+
+		switch (ntohs(tlvh->type)) {
+		case GRACE_PERIOD_TYPE:
+			gracePeriod = (struct grace_tlv_graceperiod *)tlvh;
+			*interval = ntohl(gracePeriod->interval);
+			sum += TLV_SIZE(tlvh);
+
+			/* Check if grace interval is valid */
+			if (*interval > OSPF6_MAX_GRACE_INTERVAL
+			    || *interval < OSPF6_MIN_GRACE_INTERVAL)
+				return OSPF6_FAILURE;
+			break;
+		case RESTART_REASON_TYPE:
+			grReason = (struct grace_tlv_restart_reason *)tlvh;
+			*reason = grReason->reason;
+			sum += TLV_SIZE(tlvh);
+
+			if (*reason >= OSPF6_GR_INVALID_REASON_CODE)
+				return OSPF6_FAILURE;
+			break;
+		default:
+			if (IS_DEBUG_OSPF6_GR)
+				zlog_debug("%s, Ignoring unknown TLV type:%d",
+					   __func__, ntohs(tlvh->type));
+		}
+	}
+
+	return OSPF6_SUCCESS;
+}
+
+/*
+ * Grace timer expiry handler.
+ * HELPER aborts its role at grace timer expiry.
+ *
+ * thread
+ *    thread pointer
+ *
+ * Returns:
+ *    Nothing
+ */
+static void ospf6_handle_grace_timer_expiry(struct event *thread)
+{
+	struct ospf6_neighbor *nbr = EVENT_ARG(thread);
+
+	ospf6_gr_helper_exit(nbr, OSPF6_GR_HELPER_GRACE_TIMEOUT);
+}
+
+/*
+ * API to check any change in the neighbor's
+ * retransmission list.
+ *
+ * nbr
+ *    ospf6 neighbor
+ *
+ * Returns:
+ *    TRUE  - if any change in the lsa.
+ *    FALSE - no change in the lsas.
+ */
+static bool ospf6_check_chg_in_rxmt_list(struct ospf6_neighbor *nbr)
+{
+	struct ospf6_lsa *lsa, *lsanext;
+
+	for (ALL_LSDB(nbr->retrans_list, lsa, lsanext)) {
+		struct ospf6_lsa *lsa_in_db = NULL;
+
+		/* Fetching the same copy of LSA form LSDB to validate the
+		 * topochange.
+		 */
+		lsa_in_db =
+			ospf6_lsdb_lookup(lsa->header->type, lsa->header->id,
+					  lsa->header->adv_router, lsa->lsdb);
+
+		if (lsa_in_db && lsa_in_db->tobe_acknowledged) {
+			ospf6_lsa_unlock(&lsa);
+			if (lsanext)
+				ospf6_lsa_unlock(&lsanext);
+
+			return OSPF6_TRUE;
+		}
+	}
+
+	return OSPF6_FALSE;
+}
+
+/*
+ * Process Grace LSA.If it is eligible move to HELPER role.
+ * Ref rfc3623 section 3.1 and rfc5187
+ *
+ * ospf
+ *    Ospf6 pointer.
+ *
+ * lsa
+ *    Grace LSA received from RESTARTER.
+ *
+ * restarter
+ *    ospf6 neighbour which requests the router to act as
+ *    HELPER.
+ *
+ * Returns:
+ *    status.
+ *    If supported as HELPER : OSPF_GR_HELPER_INPROGRESS
+ *    If Not supported as HELPER : OSPF_GR_HELPER_NONE
+ */
+int ospf6_process_grace_lsa(struct ospf6 *ospf6, struct ospf6_lsa *lsa,
+			    struct ospf6_neighbor *restarter)
+{
+	uint8_t restart_reason = 0;
+	uint32_t grace_interval = 0;
+	uint32_t actual_grace_interval = 0;
+	struct advRtr lookup;
+	int ret;
+
+	/* Extract the grace lsa packet fields */
+	ret = ospf6_extract_grace_lsa_fields(lsa, &grace_interval,
+					     &restart_reason);
+	if (ret != OSPF6_SUCCESS) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug("%s, Wrong Grace LSA packet.", __func__);
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	if (IS_DEBUG_OSPF6_GR)
+		zlog_debug(
+			"%s, Grace LSA received from %s(%pI4), grace interval:%u, restart reason:%s",
+			__func__, restarter->name, &restarter->router_id,
+			grace_interval,
+			ospf6_restart_reason_desc[restart_reason]);
+
+	/* Verify Helper enabled globally */
+	if (!ospf6->ospf6_helper_cfg.is_helper_supported) {
+		/* Verify Helper support is enabled for the
+		 * current neighbour router-id.
+		 */
+		lookup.advRtrAddr = restarter->router_id;
+
+		if (!hash_lookup(ospf6->ospf6_helper_cfg.enable_rtr_list,
+				 &lookup)) {
+			if (IS_DEBUG_OSPF6_GR)
+				zlog_debug(
+					"%s, HELPER support is disabled, So not a HELPER",
+					__func__);
+			restarter->gr_helper_info.rejected_reason =
+				OSPF6_HELPER_SUPPORT_DISABLED;
+			return OSPF6_GR_NOT_HELPER;
+		}
+	}
+
+	/* Check neighbour is in FULL state and
+	 * became a adjacency.
+	 */
+	if (!IS_NBR_STATE_FULL(restarter)) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug(
+				"%s, This Neighbour %pI6 is not in FULL state.",
+				__func__, &restarter->linklocal_addr);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF6_HELPER_NOT_A_VALID_NEIGHBOUR;
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	/* Based on the restart reason from grace lsa
+	 * check the current router is supporting or not
+	 */
+	if (ospf6->ospf6_helper_cfg.only_planned_restart
+	    && !OSPF6_GR_IS_PLANNED_RESTART(restart_reason)) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug(
+				"%s, Router supports only planned restarts but received the GRACE LSA due to an unplanned restart",
+				__func__);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF6_HELPER_PLANNED_ONLY_RESTART;
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	/* Check the retransmission list of this
+	 * neighbour, check any change in lsas.
+	 */
+	if (ospf6->ospf6_helper_cfg.strict_lsa_check
+	    && restarter->retrans_list->count
+	    && ospf6_check_chg_in_rxmt_list(restarter)) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug(
+				"%s, Changed LSA in Rxmt list.So not Helper.",
+				__func__);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF6_HELPER_TOPO_CHANGE_RTXMT_LIST;
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	/* LSA age must be less than the grace period */
+	if (ntohs(lsa->header->age) >= grace_interval) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug(
+				"%s, Grace LSA age(%d) is more than the grace interval(%d)",
+				__func__, lsa->header->age, grace_interval);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF6_HELPER_LSA_AGE_MORE;
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	if (ospf6->gr_info.restart_in_progress) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug(
+				"%s: router is in the process of graceful restart",
+				__func__);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF6_HELPER_RESTARTING;
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	/* check supported grace period configured
+	 * if configured, use this to start the grace
+	 * timer otherwise use the interval received
+	 * in grace LSA packet.
+	 */
+	actual_grace_interval = grace_interval;
+	if (grace_interval > ospf6->ospf6_helper_cfg.supported_grace_time) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug(
+				"%s, Received grace period %d is larger than supported grace %d",
+				__func__, grace_interval,
+				ospf6->ospf6_helper_cfg.supported_grace_time);
+		actual_grace_interval =
+			ospf6->ospf6_helper_cfg.supported_grace_time;
+	}
+
+	if (OSPF6_GR_IS_ACTIVE_HELPER(restarter)) {
+		EVENT_OFF(restarter->gr_helper_info.t_grace_timer);
+
+		if (ospf6->ospf6_helper_cfg.active_restarter_cnt > 0)
+			ospf6->ospf6_helper_cfg.active_restarter_cnt--;
+
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug(
+				"%s, Router is already acting as a HELPER for this nbr,so restart the grace timer",
+				__func__);
+	} else {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug(
+				"%s, This Router becomes a HELPER for the neighbour %pI6",
+				__func__, &restarter->linklocal_addr);
+	}
+
+	/* Became a Helper to the RESTART neighbour.
+	 * change the helper status.
+	 */
+	restarter->gr_helper_info.gr_helper_status = OSPF6_GR_ACTIVE_HELPER;
+	restarter->gr_helper_info.recvd_grace_period = grace_interval;
+	restarter->gr_helper_info.actual_grace_period = actual_grace_interval;
+	restarter->gr_helper_info.gr_restart_reason = restart_reason;
+	restarter->gr_helper_info.rejected_reason = OSPF6_HELPER_REJECTED_NONE;
+
+	/* Increment the active restart nbr count */
+	ospf6->ospf6_helper_cfg.active_restarter_cnt++;
+
+	if (IS_DEBUG_OSPF6_GR)
+		zlog_debug("%s, Grace timer started.interval:%u", __func__,
+			   actual_grace_interval);
+
+	/* Start the grace timer */
+	event_add_timer(master, ospf6_handle_grace_timer_expiry, restarter,
+			actual_grace_interval,
+			&restarter->gr_helper_info.t_grace_timer);
+
+	return OSPF6_GR_ACTIVE_HELPER;
+}
+
+/*
+ * Api to exit from HELPER role to take all actions
+ * required at exit.
+ * Ref rfc3623 section 3. and rfc51872
+ *
+ * ospf6
+ *    Ospf6 pointer.
+ *
+ * nbr
+ *    Ospf6 neighbour for which it is acting as HELPER.
+ *
+ * reason
+ *    The reason for exiting from HELPER.
+ *
+ * Returns:
+ *    Nothing.
+ */
+void ospf6_gr_helper_exit(struct ospf6_neighbor *nbr,
+			  enum ospf6_helper_exit_reason reason)
+{
+	struct ospf6_interface *oi = nbr->ospf6_if;
+	struct ospf6 *ospf6;
+
+	if (!oi)
+		return;
+
+	ospf6 = oi->area->ospf6;
+
+	if (!OSPF6_GR_IS_ACTIVE_HELPER(nbr))
+		return;
+
+	if (IS_DEBUG_OSPF6_GR)
+		zlog_debug("%s, Exiting from HELPER support to %pI6, due to %s",
+			   __func__, &nbr->linklocal_addr,
+			   ospf6_exit_reason_desc[reason]);
+
+	/* Reset helper status*/
+	nbr->gr_helper_info.gr_helper_status = OSPF6_GR_NOT_HELPER;
+	nbr->gr_helper_info.helper_exit_reason = reason;
+	nbr->gr_helper_info.actual_grace_period = 0;
+	nbr->gr_helper_info.recvd_grace_period = 0;
+	nbr->gr_helper_info.gr_restart_reason = 0;
+	ospf6->ospf6_helper_cfg.last_exit_reason = reason;
+
+	/* If the exit not triggered due to grace timer
+	 * expiry, stop the grace timer.
+	 */
+	if (reason != OSPF6_GR_HELPER_GRACE_TIMEOUT)
+		EVENT_OFF(nbr->gr_helper_info.t_grace_timer);
+
+	if (ospf6->ospf6_helper_cfg.active_restarter_cnt <= 0) {
+		zlog_err(
+			"OSPF6 GR-Helper: Number of active Restarters should be greater than zero.");
+		return;
+	}
+	/* Decrement active restarter count */
+	ospf6->ospf6_helper_cfg.active_restarter_cnt--;
+
+	/* check exit triggered due to successful completion
+	 * of graceful restart.
+	 */
+	if (reason != OSPF6_GR_HELPER_COMPLETED) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug("%s, Unsuccessful GR exit. RESTARTER : %pI6",
+				   __func__, &nbr->linklocal_addr);
+	}
+
+	/*Recalculate the DR for the network segment */
+	dr_election(oi);
+
+	/* Originate a router LSA */
+	OSPF6_ROUTER_LSA_SCHEDULE(nbr->ospf6_if->area);
+
+	/* Originate network lsa if it is an DR in the LAN */
+	if (nbr->ospf6_if->state == OSPF6_INTERFACE_DR)
+		OSPF6_NETWORK_LSA_SCHEDULE(nbr->ospf6_if);
+}
+
+/*
+ * Process max age Grace LSA.
+ * It is a indication for successful completion of GR.
+ * If router acting as HELPER, It exits from helper role.
+ *
+ * ospf6
+ *    Ospf6 pointer.
+ *
+ * lsa
+ *    Grace LSA received from RESTARTER.
+ *
+ * nbr
+ *    ospf6 neighbour which request the router to act as
+ *    HELPER.
+ *
+ * Returns:
+ *    Nothing.
+ */
+void ospf6_process_maxage_grace_lsa(struct ospf6 *ospf6, struct ospf6_lsa *lsa,
+				    struct ospf6_neighbor *restarter)
+{
+	uint8_t restart_reason = 0;
+	uint32_t grace_interval = 0;
+	int ret;
+
+	/* Extract the grace lsa packet fields */
+	ret = ospf6_extract_grace_lsa_fields(lsa, &grace_interval,
+					     &restart_reason);
+	if (ret != OSPF6_SUCCESS) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug("%s, Wrong Grace LSA packet.", __func__);
+		return;
+	}
+
+	if (IS_DEBUG_OSPF6_GR)
+		zlog_debug("%s, GraceLSA received for neighbour %pI4.",
+			   __func__, &restarter->router_id);
+
+	ospf6_gr_helper_exit(restarter, OSPF6_GR_HELPER_COMPLETED);
+}
+
+/*
+ * Actions to be taken  when topo change detected
+ * HELPER will be exited upon a topo change.
+ *
+ * ospf6
+ *    ospf6 pointer
+ * lsa
+ *    topo change occurred due to this lsa(type (1-5  and 7)
+ *
+ * Returns:
+ *    Nothing
+ */
+void ospf6_helper_handle_topo_chg(struct ospf6 *ospf6, struct ospf6_lsa *lsa)
+{
+	struct listnode *i, *j, *k;
+	struct ospf6_neighbor *nbr = NULL;
+	struct ospf6_area *oa = NULL;
+	struct ospf6_interface *oi = NULL;
+
+	if (!ospf6->ospf6_helper_cfg.active_restarter_cnt)
+		return;
+
+	/* Topo change not required to be handled if strict
+	 * LSA check is disabled for this router.
+	 */
+	if (!ospf6->ospf6_helper_cfg.strict_lsa_check)
+		return;
+
+	if (IS_DEBUG_OSPF6_GR)
+		zlog_debug("%s, Topo change detected due to lsa details : %s",
+			   __func__, lsa->name);
+
+	lsa->tobe_acknowledged = OSPF6_TRUE;
+
+	for (ALL_LIST_ELEMENTS_RO(ospf6->area_list, i, oa))
+		for (ALL_LIST_ELEMENTS_RO(oa->if_list, j, oi)) {
+
+			/* Ref rfc3623 section 3.2.3.b and rfc5187
+			 * If change due to external LSA and if the area is
+			 * stub, then it is not a topo change. Since Type-5
+			 * lsas will not be flooded in stub area.
+			 */
+			if (IS_AREA_STUB(oi->area)
+			    && ((lsa->header->type == OSPF6_LSTYPE_AS_EXTERNAL)
+				|| (lsa->header->type == OSPF6_LSTYPE_TYPE_7)
+				|| (lsa->header->type
+				    == OSPF6_LSTYPE_INTER_ROUTER))) {
+				continue;
+			}
+
+			for (ALL_LIST_ELEMENTS_RO(oi->neighbor_list, k, nbr)) {
+
+				ospf6_gr_helper_exit(nbr,
+						     OSPF6_GR_HELPER_TOPO_CHG);
+			}
+		}
+}
+
+/* Configuration handlers */
+/*
+ * Disable/Enable HELPER support on router level.
+ *
+ * ospf6
+ *    Ospf6 pointer.
+ *
+ * status
+ *    TRUE/FALSE
+ *
+ * Returns:
+ *    Nothing.
+ */
+static void ospf6_gr_helper_support_set(struct ospf6 *ospf6, bool support)
+{
+	struct ospf6_interface *oi;
+	struct advRtr lookup;
+	struct listnode *i, *j, *k;
+	struct ospf6_neighbor *nbr = NULL;
+	struct ospf6_area *oa = NULL;
+
+	if (ospf6->ospf6_helper_cfg.is_helper_supported == support)
+		return;
+
+	ospf6->ospf6_helper_cfg.is_helper_supported = support;
+
+	/* If helper support disabled, cease HELPER role for all
+	 * supporting neighbors.
+	 */
+	if (support == OSPF6_FALSE) {
+		for (ALL_LIST_ELEMENTS_RO(ospf6->area_list, i, oa))
+			for (ALL_LIST_ELEMENTS_RO(oa->if_list, j, oi)) {
+
+				for (ALL_LIST_ELEMENTS_RO(oi->neighbor_list, k,
+							  nbr)) {
+
+					lookup.advRtrAddr = nbr->router_id;
+					/* check if helper support enabled for
+					 * the corresponding  routerid.
+					 * If enabled,
+					 * dont exit from helper role.
+					 */
+					if (hash_lookup(
+						    ospf6->ospf6_helper_cfg
+							    .enable_rtr_list,
+						    &lookup))
+						continue;
+
+					ospf6_gr_helper_exit(
+						nbr, OSPF6_GR_HELPER_TOPO_CHG);
+				}
+			}
+	}
+}
+
+/*
+ * Api to enable/disable strict lsa check on the HELPER.
+ *
+ * ospf6
+ *    Ospf6 pointer.
+ *
+ * enabled
+ *    True - disable the lsa check.
+ *    False - enable the strict lsa check.
+ *
+ * Returns:
+ *    Nothing.
+ */
+static void ospf6_gr_helper_lsacheck_set(struct ospf6 *ospf6, bool enabled)
+{
+	if (ospf6->ospf6_helper_cfg.strict_lsa_check == enabled)
+		return;
+
+	ospf6->ospf6_helper_cfg.strict_lsa_check = enabled;
+}
+
+/*
+ * Api to set the supported restart reason.
+ *
+ * ospf6
+ *    Ospf6 pointer.
+ *
+ * only_planned
+ *    True: support only planned restart.
+ *    False: support for planned/unplanned restarts.
+ *
+ * Returns:
+ *    Nothing.
+ */
+
+static void
+ospf6_gr_helper_set_supported_onlyPlanned_restart(struct ospf6 *ospf6,
+						  bool only_planned)
+{
+	ospf6->ospf6_helper_cfg.only_planned_restart = only_planned;
+}
+
+/*
+ * Api to set the supported grace interval in this router.
+ *
+ * ospf6
+ *    Ospf6 pointer.
+ *
+ * interval
+ *    The supported grace interval..
+ *
+ * Returns:
+ *    Nothing.
+ */
+static void ospf6_gr_helper_supported_gracetime_set(struct ospf6 *ospf6,
+						    uint32_t interval)
+{
+	ospf6->ospf6_helper_cfg.supported_grace_time = interval;
+}
+
+/* API to walk and print  all the Helper supported router ids */
+static int ospf6_print_vty_helper_dis_rtr_walkcb(struct hash_bucket *bucket,
+						 void *arg)
+{
+	struct advRtr *rtr = bucket->data;
+	struct vty *vty = (struct vty *)arg;
+	static unsigned int count;
+
+	vty_out(vty, "%-6pI4,", &rtr->advRtrAddr);
+	count++;
+
+	if (count % 5 == 0)
+		vty_out(vty, "\n");
+
+	return HASHWALK_CONTINUE;
+}
+
+/* API to walk and print  all the Helper supported router ids.*/
+static int ospf6_print_json_helper_dis_rtr_walkcb(struct hash_bucket *bucket,
+						  void *arg)
+{
+	struct advRtr *rtr = bucket->data;
+	struct json_object *json_rid_array = (struct json_object *)arg;
+	struct json_object *json_rid;
+	char router_id[16];
+
+	inet_ntop(AF_INET, &rtr->advRtrAddr, router_id, sizeof(router_id));
+
+	json_rid = json_object_new_object();
+
+	json_object_string_add(json_rid, "routerId", router_id);
+	json_object_array_add(json_rid_array, json_rid);
+
+	return HASHWALK_CONTINUE;
+}
+
+/*
+ * Enable/Disable HELPER support on a specified advertisement
+ * router.
+ *
+ * ospf6
+ *    Ospf6 pointer.
+ *
+ * advRtr
+ *    HELPER support for given Advertisement Router.
+ *
+ * support
+ *    True - Enable Helper Support.
+ *    False - Disable Helper Support.
+ *
+ * Returns:
+ *    Nothing.
+ */
+static void ospf6_gr_helper_support_set_per_routerid(struct ospf6 *ospf6,
+						     struct in_addr router_id,
+						     bool support)
+{
+	struct advRtr temp;
+	struct advRtr *rtr;
+	struct listnode *i, *j, *k;
+	struct ospf6_interface *oi;
+	struct ospf6_neighbor *nbr;
+	struct ospf6_area *oa;
+
+	temp.advRtrAddr = router_id.s_addr;
+
+	if (support == OSPF6_FALSE) {
+		/*Delete the routerid from the enable router hash table */
+		rtr = hash_lookup(ospf6->ospf6_helper_cfg.enable_rtr_list,
+				  &temp);
+
+		if (rtr) {
+			hash_release(ospf6->ospf6_helper_cfg.enable_rtr_list,
+				     rtr);
+			ospf6_disable_rtr_hash_free(rtr);
+		}
+
+		/* If helper support is enabled globally
+		 * no action is required.
+		 */
+		if (ospf6->ospf6_helper_cfg.is_helper_supported)
+			return;
+
+		/* Cease the HELPER role fore neighbours from the
+		 * specified advertisement router.
+		 */
+		for (ALL_LIST_ELEMENTS_RO(ospf6->area_list, i, oa))
+			for (ALL_LIST_ELEMENTS_RO(oa->if_list, j, oi)) {
+
+				for (ALL_LIST_ELEMENTS_RO(oi->neighbor_list, k,
+							  nbr)) {
+
+					if (nbr->router_id != router_id.s_addr)
+						continue;
+
+					if (OSPF6_GR_IS_ACTIVE_HELPER(nbr))
+						ospf6_gr_helper_exit(
+						nbr,
+						OSPF6_GR_HELPER_TOPO_CHG);
+				}
+			}
+
+	} else {
+		/* Add the routerid to the enable router hash table */
+		(void)hash_get(ospf6->ospf6_helper_cfg.enable_rtr_list, &temp,
+			       ospf6_enable_rtr_hash_alloc);
+	}
+}
+
+static void show_ospfv6_gr_helper_per_nbr(struct vty *vty, json_object *json,
+					  bool uj, struct ospf6_neighbor *nbr)
+{
+	if (!uj) {
+		vty_out(vty, "   Routerid : %pI4\n", &nbr->router_id);
+		vty_out(vty, "   Received Grace period : %d(in seconds).\n",
+			nbr->gr_helper_info.recvd_grace_period);
+		vty_out(vty, "   Actual Grace period : %d(in seconds)\n",
+			nbr->gr_helper_info.actual_grace_period);
+		vty_out(vty, "   Remaining GraceTime:%ld(in seconds).\n",
+			event_timer_remain_second(
+				nbr->gr_helper_info.t_grace_timer));
+		vty_out(vty, "   Graceful Restart reason: %s.\n\n",
+			ospf6_restart_reason_desc[nbr->gr_helper_info
+							  .gr_restart_reason]);
+	} else {
+		char nbrid[16];
+		json_object *json_neigh = NULL;
+
+		inet_ntop(AF_INET, &nbr->router_id, nbrid, sizeof(nbrid));
+		json_neigh = json_object_new_object();
+		json_object_string_add(json_neigh, "routerid", nbrid);
+		json_object_int_add(json_neigh, "recvdGraceInterval",
+				    nbr->gr_helper_info.recvd_grace_period);
+		json_object_int_add(json_neigh, "actualGraceInterval",
+			nbr->gr_helper_info.actual_grace_period);
+		json_object_int_add(json_neigh, "remainGracetime",
+				    event_timer_remain_second(
+					    nbr->gr_helper_info.t_grace_timer));
+		json_object_string_add(json_neigh, "restartReason",
+			ospf6_restart_reason_desc[
+				nbr->gr_helper_info.gr_restart_reason]);
+		json_object_object_add(json, nbr->name, json_neigh);
+	}
+}
+
+static void show_ospf6_gr_helper_details(struct vty *vty, struct ospf6 *ospf6,
+					json_object *json, bool uj, bool detail)
+{
+	struct ospf6_interface *oi;
+
+	/* Show Router ID. */
+	if (uj) {
+		char router_id[16];
+
+		inet_ntop(AF_INET, &ospf6->router_id, router_id,
+			  sizeof(router_id));
+		json_object_string_add(json, "routerId", router_id);
+	} else
+		vty_out(vty,
+			" OSPFv3 Routing Process (0) with Router-ID %pI4\n",
+			&ospf6->router_id);
+
+	if (!uj) {
+
+		if (ospf6->ospf6_helper_cfg.is_helper_supported)
+			vty_out(vty,
+				" Graceful restart helper support enabled.\n");
+		else
+			vty_out(vty,
+				" Graceful restart helper support disabled.\n");
+
+		if (ospf6->ospf6_helper_cfg.strict_lsa_check)
+			vty_out(vty, " Strict LSA check is enabled.\n");
+		else
+			vty_out(vty, " Strict LSA check is disabled.\n");
+
+		if (ospf6->ospf6_helper_cfg.only_planned_restart)
+			vty_out(vty,
+				" Helper supported for planned restarts only.\n");
+		else
+			vty_out(vty,
+				" Helper supported for Planned and Unplanned Restarts.\n");
+
+		vty_out(vty,
+			" Supported Graceful restart interval: %d(in seconds).\n",
+			ospf6->ospf6_helper_cfg.supported_grace_time);
+
+		if (OSPF6_HELPER_ENABLE_RTR_COUNT(ospf)) {
+			vty_out(vty, " Enable Router list:\n");
+			vty_out(vty, "   ");
+			hash_walk(ospf6->ospf6_helper_cfg.enable_rtr_list,
+				  ospf6_print_vty_helper_dis_rtr_walkcb, vty);
+			vty_out(vty, "\n\n");
+		}
+
+		if (ospf6->ospf6_helper_cfg.last_exit_reason
+		    != OSPF6_GR_HELPER_EXIT_NONE) {
+			vty_out(vty, " Last Helper exit Reason :%s\n",
+				ospf6_exit_reason_desc
+					[ospf6->ospf6_helper_cfg
+						 .last_exit_reason]);
+
+			if (ospf6->ospf6_helper_cfg.active_restarter_cnt)
+				vty_out(vty,
+					" Number of Active neighbours in graceful restart: %d\n",
+					ospf6->ospf6_helper_cfg
+						.active_restarter_cnt);
+			else
+				vty_out(vty, "\n");
+		}
+
+
+	} else {
+		json_object_string_add(
+			json, "helperSupport",
+			(ospf6->ospf6_helper_cfg.is_helper_supported)
+				? "Enabled"
+				: "Disabled");
+		json_object_string_add(
+			json, "strictLsaCheck",
+			(ospf6->ospf6_helper_cfg.strict_lsa_check)
+				? "Enabled"
+				: "Disabled");
+
+#if CONFDATE > 20240401
+		CPP_NOTICE("Remove deprecated json key: restartSupoort")
+#endif
+		json_object_string_add(
+			json, "restartSupoort",
+			(ospf6->ospf6_helper_cfg.only_planned_restart)
+				? "Planned Restart only"
+				: "Planned and Unplanned Restarts");
+
+		json_object_string_add(
+			json, "restartSupport",
+			(ospf6->ospf6_helper_cfg.only_planned_restart)
+				? "Planned Restart only"
+				: "Planned and Unplanned Restarts");
+
+		json_object_int_add(
+			json, "supportedGracePeriod",
+			ospf6->ospf6_helper_cfg.supported_grace_time);
+
+		if (ospf6->ospf6_helper_cfg.last_exit_reason !=
+		    OSPF6_GR_HELPER_EXIT_NONE)
+			json_object_string_add(
+				json, "lastExitReason",
+				ospf6_exit_reason_desc
+					[ospf6->ospf6_helper_cfg
+						 .last_exit_reason]);
+
+		if (ospf6->ospf6_helper_cfg.active_restarter_cnt)
+			json_object_int_add(
+				json, "activeRestarterCnt",
+				ospf6->ospf6_helper_cfg.active_restarter_cnt);
+
+		if (OSPF6_HELPER_ENABLE_RTR_COUNT(ospf6)) {
+			struct json_object *json_rid_array =
+				json_object_new_array();
+
+			json_object_object_add(json, "enabledRouterIds",
+					       json_rid_array);
+
+			hash_walk(ospf6->ospf6_helper_cfg.enable_rtr_list,
+				  ospf6_print_json_helper_dis_rtr_walkcb,
+				  json_rid_array);
+		}
+	}
+
+	if (detail) {
+		int cnt = 1;
+		struct listnode *i, *j, *k;
+		struct ospf6_area *oa;
+		json_object *json_neighbors = NULL;
+
+		for (ALL_LIST_ELEMENTS_RO(ospf6->area_list, i, oa))
+			for (ALL_LIST_ELEMENTS_RO(oa->if_list, j, oi)) {
+				struct ospf6_neighbor *nbr;
+
+				if (uj) {
+					json_object_object_get_ex(
+						json, "neighbors",
+						&json_neighbors);
+					if (!json_neighbors) {
+						json_neighbors =
+						json_object_new_object();
+						json_object_object_add(
+							json, "neighbors",
+							json_neighbors);
+					}
+				}
+
+				for (ALL_LIST_ELEMENTS_RO(oi->neighbor_list, k,
+							  nbr)) {
+
+					if (!OSPF6_GR_IS_ACTIVE_HELPER(nbr))
+						continue;
+
+					if (!uj)
+						vty_out(vty,
+							" Neighbour %d :\n",
+							cnt++);
+
+					show_ospfv6_gr_helper_per_nbr(
+						vty, json_neighbors, uj, nbr);
+
+				}
+			}
+	}
+}
+
+/* Graceful Restart HELPER  config Commands */
+DEFPY(ospf6_gr_helper_enable,
+      ospf6_gr_helper_enable_cmd,
+      "graceful-restart helper enable [A.B.C.D$rtr_id]",
+      "ospf6 graceful restart\n"
+      "ospf6 GR Helper\n"
+      "Enable Helper support\n"
+      "Advertisement Router-ID\n")
+{
+	VTY_DECLVAR_CONTEXT(ospf6, ospf6);
+
+	if (rtr_id_str != NULL) {
+
+		ospf6_gr_helper_support_set_per_routerid(ospf6, rtr_id,
+							 OSPF6_TRUE);
+
+		return CMD_SUCCESS;
+	}
+
+	ospf6_gr_helper_support_set(ospf6, OSPF6_TRUE);
+
+	return CMD_SUCCESS;
+}
+
+DEFPY(ospf6_gr_helper_disable,
+      ospf6_gr_helper_disable_cmd,
+      "no graceful-restart helper enable [A.B.C.D$rtr_id]",
+      NO_STR
+      "ospf6 graceful restart\n"
+      "ospf6 GR Helper\n"
+      "Enable Helper support\n"
+      "Advertisement Router-ID\n")
+{
+	VTY_DECLVAR_CONTEXT(ospf6, ospf6);
+
+	if (rtr_id_str != NULL) {
+
+		ospf6_gr_helper_support_set_per_routerid(ospf6, rtr_id,
+							 OSPF6_FALSE);
+
+		return CMD_SUCCESS;
+	}
+
+	ospf6_gr_helper_support_set(ospf6, OSPF6_FALSE);
+
+	return CMD_SUCCESS;
+}
+
+DEFPY(ospf6_gr_helper_disable_lsacheck,
+      ospf6_gr_helper_disable_lsacheck_cmd,
+      "graceful-restart helper lsa-check-disable",
+      "ospf6 graceful restart\n"
+      "ospf6 GR Helper\n"
+      "disable strict LSA check\n")
+{
+	VTY_DECLVAR_CONTEXT(ospf6, ospf6);
+
+	ospf6_gr_helper_lsacheck_set(ospf6, OSPF6_FALSE);
+	return CMD_SUCCESS;
+}
+
+DEFPY(no_ospf6_gr_helper_disable_lsacheck,
+      no_ospf6_gr_helper_disable_lsacheck_cmd,
+      "no graceful-restart helper lsa-check-disable",
+      NO_STR
+      "ospf6 graceful restart\n"
+      "ospf6 GR Helper\n"
+      "diasble strict LSA check\n")
+{
+	VTY_DECLVAR_CONTEXT(ospf6, ospf6);
+
+	ospf6_gr_helper_lsacheck_set(ospf6, OSPF6_TRUE);
+	return CMD_SUCCESS;
+}
+
+DEFPY(ospf6_gr_helper_planned_only,
+      ospf6_gr_helper_planned_only_cmd,
+      "graceful-restart helper planned-only",
+      "ospf6 graceful restart\n"
+      "ospf6 GR Helper\n"
+      "supported only planned restart\n")
+{
+	VTY_DECLVAR_CONTEXT(ospf6, ospf6);
+
+	ospf6_gr_helper_set_supported_onlyPlanned_restart(ospf6, OSPF6_TRUE);
+
+	return CMD_SUCCESS;
+}
+
+DEFPY(no_ospf6_gr_helper_planned_only, no_ospf6_gr_helper_planned_only_cmd,
+      "no graceful-restart helper planned-only",
+      NO_STR
+      "ospf6 graceful restart\n"
+      "ospf6 GR Helper\n"
+      "supported only for planned restart\n")
+{
+	VTY_DECLVAR_CONTEXT(ospf6, ospf6);
+
+	ospf6_gr_helper_set_supported_onlyPlanned_restart(ospf6, OSPF6_FALSE);
+
+	return CMD_SUCCESS;
+}
+
+DEFPY(ospf6_gr_helper_supported_grace_time,
+      ospf6_gr_helper_supported_grace_time_cmd,
+      "graceful-restart helper supported-grace-time (10-1800)$interval",
+      "ospf6 graceful restart\n"
+      "ospf6 GR Helper\n"
+      "supported grace timer\n"
+      "grace interval(in seconds)\n")
+{
+	VTY_DECLVAR_CONTEXT(ospf6, ospf6);
+
+	ospf6_gr_helper_supported_gracetime_set(ospf6, interval);
+	return CMD_SUCCESS;
+}
+
+DEFPY(no_ospf6_gr_helper_supported_grace_time,
+      no_ospf6_gr_helper_supported_grace_time_cmd,
+      "no graceful-restart helper supported-grace-time (10-1800)$interval",
+      NO_STR
+      "ospf6 graceful restart\n"
+      "ospf6 GR Helper\n"
+      "supported grace timer\n"
+      "grace interval(in seconds)\n")
+{
+	VTY_DECLVAR_CONTEXT(ospf6, ospf6);
+
+	ospf6_gr_helper_supported_gracetime_set(ospf6,
+						OSPF6_MAX_GRACE_INTERVAL);
+	return CMD_SUCCESS;
+}
+
+/* Show commands */
+DEFPY(show_ipv6_ospf6_gr_helper,
+      show_ipv6_ospf6_gr_helper_cmd,
+      "show ipv6 ospf6 graceful-restart helper [detail] [json]",
+      SHOW_STR
+      "Ipv6 Information\n"
+      "OSPF6 information\n"
+      "ospf6 graceful restart\n"
+      "helper details in the router\n"
+      "detailed information\n" JSON_STR)
+{
+	int idx = 0;
+	bool uj = use_json(argc, argv);
+	struct ospf6 *ospf6 = NULL;
+	json_object *json = NULL;
+	bool detail = false;
+
+	ospf6 = ospf6_lookup_by_vrf_name(VRF_DEFAULT_NAME);
+	if (ospf6 == NULL) {
+		vty_out(vty, "OSPFv3 is not configured\n");
+		return CMD_SUCCESS;
+	}
+
+	if (argv_find(argv, argc, "detail", &idx))
+		detail = true;
+
+	if (uj)
+		json = json_object_new_object();
+
+	show_ospf6_gr_helper_details(vty, ospf6, json, uj, detail);
+
+	if (uj)
+		vty_json(vty, json);
+
+	return CMD_SUCCESS;
+}
+
+/* Debug commands */
+DEFPY(debug_ospf6_gr, debug_ospf6_gr_cmd,
+      "[no$no] debug ospf6 graceful-restart",
+      NO_STR DEBUG_STR OSPF6_STR "Graceful restart\n")
+{
+	if (!no)
+		OSPF6_DEBUG_GR_ON();
+	else
+		OSPF6_DEBUG_GR_OFF();
+
+	return CMD_SUCCESS;
+}
+
+/*
+ * Api to display the grace LSA information.
+ *
+ * vty
+ *    vty pointer.
+ * lsa
+ *    Grace LSA.
+ * json
+ *    json object
+ *
+ * Returns:
+ *    Nothing.
+ */
+static int ospf6_grace_lsa_show_info(struct vty *vty, struct ospf6_lsa *lsa,
+				     json_object *json, bool use_json)
+{
+	struct ospf6_lsa_header *lsah = NULL;
+	struct tlv_header *tlvh = NULL;
+	struct grace_tlv_graceperiod *gracePeriod;
+	struct grace_tlv_restart_reason *grReason;
+	uint16_t length = 0;
+	int sum = 0;
+
+	lsah = lsa->header;
+	if (ntohs(lsah->length) <= OSPF6_LSA_HEADER_SIZE) {
+		if (IS_DEBUG_OSPF6_GR)
+			zlog_debug("%s: undersized (%u B) lsa", __func__,
+				   ntohs(lsah->length));
+		return OSPF6_FAILURE;
+	}
+
+	length = ntohs(lsah->length) - OSPF6_LSA_HEADER_SIZE;
+
+	if (vty) {
+		if (!use_json)
+			vty_out(vty, "TLV info:\n");
+	} else {
+		zlog_debug("  TLV info:");
+	}
+
+	for (tlvh = TLV_HDR_TOP(lsah); sum < length && tlvh;
+	     tlvh = TLV_HDR_NEXT(tlvh)) {
+
+		/* Check TLV len */
+		if (sum + TLV_SIZE(tlvh) > length) {
+			if (vty)
+				vty_out(vty, "%% Invalid TLV length: %d\n",
+					TLV_SIZE(tlvh));
+			else if (IS_DEBUG_OSPF6_GR)
+				zlog_debug("%% Invalid TLV length: %d",
+					   TLV_SIZE(tlvh));
+			return OSPF6_FAILURE;
+		}
+
+		switch (ntohs(tlvh->type)) {
+		case GRACE_PERIOD_TYPE:
+			gracePeriod = (struct grace_tlv_graceperiod *)tlvh;
+			sum += TLV_SIZE(tlvh);
+
+			if (vty) {
+				if (use_json)
+					json_object_int_add(
+						json, "gracePeriod",
+						ntohl(gracePeriod->interval));
+				else
+					vty_out(vty, "   Grace period:%d\n",
+						ntohl(gracePeriod->interval));
+			} else {
+				zlog_debug("    Grace period:%d",
+					   ntohl(gracePeriod->interval));
+			}
+			break;
+		case RESTART_REASON_TYPE:
+			grReason = (struct grace_tlv_restart_reason *)tlvh;
+			sum += TLV_SIZE(tlvh);
+			if (vty) {
+				if (use_json)
+					json_object_string_add(
+						json, "restartReason",
+						ospf6_restart_reason_desc
+							[grReason->reason]);
+				else
+					vty_out(vty, "   Restart reason:%s\n",
+						ospf6_restart_reason_desc
+							[grReason->reason]);
+			} else {
+				zlog_debug("    Restart reason:%s",
+					   ospf6_restart_reason_desc
+						   [grReason->reason]);
+			}
+			break;
+		default:
+			break;
+		}
+	}
+
+	return 0;
+}
+
+void ospf6_gr_helper_config_init(void)
+{
+
+	ospf6_install_lsa_handler(&grace_lsa_handler);
+
+	install_element(OSPF6_NODE, &ospf6_gr_helper_enable_cmd);
+	install_element(OSPF6_NODE, &ospf6_gr_helper_disable_cmd);
+	install_element(OSPF6_NODE, &ospf6_gr_helper_disable_lsacheck_cmd);
+	install_element(OSPF6_NODE, &no_ospf6_gr_helper_disable_lsacheck_cmd);
+	install_element(OSPF6_NODE, &ospf6_gr_helper_planned_only_cmd);
+	install_element(OSPF6_NODE, &no_ospf6_gr_helper_planned_only_cmd);
+	install_element(OSPF6_NODE, &ospf6_gr_helper_supported_grace_time_cmd);
+	install_element(OSPF6_NODE,
+			&no_ospf6_gr_helper_supported_grace_time_cmd);
+
+	install_element(VIEW_NODE, &show_ipv6_ospf6_gr_helper_cmd);
+
+	install_element(CONFIG_NODE, &debug_ospf6_gr_cmd);
+	install_element(ENABLE_NODE, &debug_ospf6_gr_cmd);
+}
+
+
+/*
+ * Initialize GR helper config data structure.
+ *
+ * ospf6
+ *    ospf6 pointer
+ *
+ * Returns:
+ *    Nothing
+ */
+void ospf6_gr_helper_init(struct ospf6 *ospf6)
+{
+	if (IS_DEBUG_OSPF6_GR)
+		zlog_debug("%s, GR Helper init.", __func__);
+
+	ospf6->ospf6_helper_cfg.is_helper_supported = OSPF6_FALSE;
+	ospf6->ospf6_helper_cfg.strict_lsa_check = OSPF6_TRUE;
+	ospf6->ospf6_helper_cfg.only_planned_restart = OSPF6_FALSE;
+	ospf6->ospf6_helper_cfg.supported_grace_time = OSPF6_MAX_GRACE_INTERVAL;
+	ospf6->ospf6_helper_cfg.last_exit_reason = OSPF6_GR_HELPER_EXIT_NONE;
+	ospf6->ospf6_helper_cfg.active_restarter_cnt = 0;
+
+	ospf6->ospf6_helper_cfg.enable_rtr_list = hash_create(
+		ospf6_enable_rtr_hash_key, ospf6_enable_rtr_hash_cmp,
+		"Ospf6 enable router hash");
+}
+
+/*
+ * De-initialize GR helper config data structure.
+ *
+ * ospf6
+ *    ospf6 pointer
+ *
+ * Returns:
+ *    Nothing
+ */
+void ospf6_gr_helper_deinit(struct ospf6 *ospf6)
+{
+
+	if (IS_DEBUG_OSPF6_GR)
+		zlog_debug("%s, GR helper deinit.", __func__);
+
+	ospf6_enable_rtr_hash_destroy(ospf6);
+}
+
+static int ospf6_cfg_write_helper_enable_rtr_walkcb(struct hash_bucket *backet,
+						    void *arg)
+{
+	struct advRtr *rtr = backet->data;
+	struct vty *vty = (struct vty *)arg;
+
+	vty_out(vty, " graceful-restart helper enable %pI4\n", &rtr->advRtrAddr);
+	return HASHWALK_CONTINUE;
+}
+
+int config_write_ospf6_gr_helper(struct vty *vty, struct ospf6 *ospf6)
+{
+	if (ospf6->ospf6_helper_cfg.is_helper_supported)
+		vty_out(vty, " graceful-restart helper enable\n");
+
+	if (!ospf6->ospf6_helper_cfg.strict_lsa_check)
+		vty_out(vty, " graceful-restart helper lsa-check-disable\n");
+
+	if (ospf6->ospf6_helper_cfg.only_planned_restart)
+		vty_out(vty, " graceful-restart helper planned-only\n");
+
+	if (ospf6->ospf6_helper_cfg.supported_grace_time
+	    != OSPF6_MAX_GRACE_INTERVAL)
+		vty_out(vty,
+			" graceful-restart helper supported-grace-time %d\n",
+			ospf6->ospf6_helper_cfg.supported_grace_time);
+
+	if (OSPF6_HELPER_ENABLE_RTR_COUNT(ospf6)) {
+		hash_walk(ospf6->ospf6_helper_cfg.enable_rtr_list,
+			  ospf6_cfg_write_helper_enable_rtr_walkcb, vty);
+	}
+
+	return 0;
+}
+
+int config_write_ospf6_debug_gr_helper(struct vty *vty)
+{
+	if (IS_DEBUG_OSPF6_GR)
+		vty_out(vty, "debug ospf6 graceful-restart\n");
+	return 0;
+}