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frr/isisd/isis_lfa.c

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/*
* Copyright (C) 2020 NetDEF, Inc.
* Renato Westphal
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; see the file COPYING; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <zebra.h>
#include "linklist.h"
#include "log.h"
#include "memory.h"
#include "vrf.h"
#include "table.h"
#include "srcdest_table.h"
#include "plist.h"
#include "zclient.h"
#include "isis_common.h"
#include "isisd.h"
#include "isis_misc.h"
#include "isis_adjacency.h"
#include "isis_circuit.h"
#include "isis_lsp.h"
#include "isis_spf.h"
#include "isis_route.h"
#include "isis_mt.h"
#include "isis_tlvs.h"
#include "isis_spf_private.h"
#include "isis_zebra.h"
#include "isis_errors.h"
DEFINE_MTYPE_STATIC(ISISD, ISIS_SPF_NODE, "ISIS SPF Node");
DEFINE_MTYPE_STATIC(ISISD, ISIS_LFA_TIEBREAKER, "ISIS LFA Tiebreaker");
DEFINE_MTYPE_STATIC(ISISD, ISIS_LFA_EXCL_IFACE, "ISIS LFA Excluded Interface");
DEFINE_MTYPE_STATIC(ISISD, ISIS_RLFA, "ISIS Remote LFA");
static inline int isis_spf_node_compare(const struct isis_spf_node *a,
const struct isis_spf_node *b)
{
return memcmp(a->sysid, b->sysid, sizeof(a->sysid));
}
RB_GENERATE(isis_spf_nodes, isis_spf_node, entry, isis_spf_node_compare)
/**
* Initialize list of SPF nodes.
*
* @param nodes List of SPF nodes
*/
void isis_spf_node_list_init(struct isis_spf_nodes *nodes)
{
RB_INIT(isis_spf_nodes, nodes);
}
/**
* Clear list of SPF nodes, releasing all allocated memory.
*
* @param nodes List of SPF nodes
*/
void isis_spf_node_list_clear(struct isis_spf_nodes *nodes)
{
while (!RB_EMPTY(isis_spf_nodes, nodes)) {
struct isis_spf_node *node = RB_ROOT(isis_spf_nodes, nodes);
if (node->adjacencies)
list_delete(&node->adjacencies);
if (node->lfa.spftree)
isis_spftree_del(node->lfa.spftree);
if (node->lfa.spftree_reverse)
isis_spftree_del(node->lfa.spftree_reverse);
isis_spf_node_list_clear(&node->lfa.p_space);
RB_REMOVE(isis_spf_nodes, nodes, node);
XFREE(MTYPE_ISIS_SPF_NODE, node);
}
}
/**
* Add new node to list of SPF nodes.
*
* @param nodes List of SPF nodes
* @param sysid Node System ID
*
* @return Pointer to new IS-IS SPF node structure.
*/
struct isis_spf_node *isis_spf_node_new(struct isis_spf_nodes *nodes,
const uint8_t *sysid)
{
struct isis_spf_node *node;
node = XCALLOC(MTYPE_ISIS_SPF_NODE, sizeof(*node));
memcpy(node->sysid, sysid, sizeof(node->sysid));
node->adjacencies = list_new();
isis_spf_node_list_init(&node->lfa.p_space);
RB_INSERT(isis_spf_nodes, nodes, node);
return node;
}
/**
* Lookup SPF node by its System ID on the given list.
*
* @param nodes List of SPF nodes
* @param sysid Node System ID
*
* @return Pointer to SPF node if found, NULL otherwise
*/
struct isis_spf_node *isis_spf_node_find(const struct isis_spf_nodes *nodes,
const uint8_t *sysid)
{
struct isis_spf_node node = {};
memcpy(node.sysid, sysid, sizeof(node.sysid));
return RB_FIND(isis_spf_nodes, nodes, &node);
}
/**
* LFA tiebreaker RB-tree comparison function.
*
* @param a First LFA tiebreaker
* @param b Second LFA tiebreaker
*
* @return -1 (a < b), 0 (a == b) or +1 (a > b)
*/
int lfa_tiebreaker_cmp(const struct lfa_tiebreaker *a,
const struct lfa_tiebreaker *b)
{
if (a->index < b->index)
return -1;
if (a->index > b->index)
return 1;
return a->type - b->type;
}
/**
* Initialize list of LFA tie-breakers.
*
* @param area IS-IS area
* @param level IS-IS level
*/
void isis_lfa_tiebreakers_init(struct isis_area *area, int level)
{
lfa_tiebreaker_tree_init(&area->lfa_tiebreakers[level - 1]);
}
/**
* Clear list of LFA tie-breakers, releasing all allocated memory.
*
* @param area IS-IS area
* @param level IS-IS level
*/
void isis_lfa_tiebreakers_clear(struct isis_area *area, int level)
{
while (lfa_tiebreaker_tree_count(&area->lfa_tiebreakers[level - 1])
> 0) {
struct lfa_tiebreaker *tie_b;
tie_b = lfa_tiebreaker_tree_first(
&area->lfa_tiebreakers[level - 1]);
isis_lfa_tiebreaker_delete(area, level, tie_b);
}
}
/**
* Add new LFA tie-breaker to list of LFA tie-breakers.
*
* @param area IS-IS area
* @param level IS-IS level
* @param index LFA tie-breaker index
* @param type LFA tie-breaker type
*
* @return Pointer to new LFA tie-breaker structure.
*/
struct lfa_tiebreaker *isis_lfa_tiebreaker_add(struct isis_area *area,
int level, uint8_t index,
enum lfa_tiebreaker_type type)
{
struct lfa_tiebreaker *tie_b;
tie_b = XCALLOC(MTYPE_ISIS_LFA_TIEBREAKER, sizeof(*tie_b));
tie_b->index = index;
tie_b->type = type;
tie_b->area = area;
lfa_tiebreaker_tree_add(&area->lfa_tiebreakers[level - 1], tie_b);
return tie_b;
}
/**
* Remove LFA tie-breaker from list of LFA tie-breakers.
*
* @param area IS-IS area
* @param level IS-IS level
* @param tie_b Pointer to LFA tie-breaker structure
*/
void isis_lfa_tiebreaker_delete(struct isis_area *area, int level,
struct lfa_tiebreaker *tie_b)
{
lfa_tiebreaker_tree_del(&area->lfa_tiebreakers[level - 1], tie_b);
XFREE(MTYPE_ISIS_LFA_TIEBREAKER, tie_b);
}
static bool lfa_excl_interface_hash_cmp(const void *value1, const void *value2)
{
return strmatch(value1, value2);
}
static unsigned int lfa_excl_interface_hash_make(const void *value)
{
return string_hash_make(value);
}
static void *lfa_excl_interface_hash_alloc(void *p)
{
return XSTRDUP(MTYPE_ISIS_LFA_EXCL_IFACE, p);
}
static void lfa_excl_interface_hash_free(void *arg)
{
XFREE(MTYPE_ISIS_LFA_EXCL_IFACE, arg);
}
/**
* Initialize hash table of LFA excluded interfaces.
*
* @param circuit IS-IS interface
* @param level IS-IS level
*/
void isis_lfa_excluded_ifaces_init(struct isis_circuit *circuit, int level)
{
circuit->lfa_excluded_ifaces[level - 1] = hash_create(
lfa_excl_interface_hash_make, lfa_excl_interface_hash_cmp,
"LFA Excluded Interfaces");
}
/**
* Clear hash table of LFA excluded interfaces, releasing all allocated memory.
*
* @param nodes List of SPF nodes
*/
void isis_lfa_excluded_ifaces_clear(struct isis_circuit *circuit, int level)
{
hash_clean(circuit->lfa_excluded_ifaces[level - 1],
lfa_excl_interface_hash_free);
}
/**
* Add new interface to hash table of excluded interfaces.
*
* @param circuit IS-IS interface
* @param level IS-IS level
* @param ifname Excluded interface name
*/
void isis_lfa_excluded_iface_add(struct isis_circuit *circuit, int level,
const char *ifname)
{
hash_get(circuit->lfa_excluded_ifaces[level - 1], (char *)ifname,
lfa_excl_interface_hash_alloc);
}
/**
* Remove interface from hash table of excluded interfaces.
*
* @param circuit IS-IS interface
* @param level IS-IS level
* @param ifname Excluded interface name
*/
void isis_lfa_excluded_iface_delete(struct isis_circuit *circuit, int level,
const char *ifname)
{
char *found;
found = hash_lookup(circuit->lfa_excluded_ifaces[level - 1],
(char *)ifname);
if (found) {
hash_release(circuit->lfa_excluded_ifaces[level - 1], found);
lfa_excl_interface_hash_free(found);
}
}
/**
* Lookup excluded interface.
*
* @param circuit IS-IS interface
* @param level IS-IS level
* @param ifname Excluded interface name
*/
bool isis_lfa_excluded_iface_check(struct isis_circuit *circuit, int level,
const char *ifname)
{
return hash_lookup(circuit->lfa_excluded_ifaces[level - 1],
(char *)ifname);
}
/**
* Check if a given IS-IS adjacency needs to be excised when computing the SPF
* post-convergence tree.
*
* @param spftree IS-IS SPF tree
* @param id Adjacency System ID (or LAN ID of the designated router
* for broadcast interfaces)
*
* @return true if the adjacency needs to be excised, false
* otherwise
*/
bool isis_lfa_excise_adj_check(const struct isis_spftree *spftree,
const uint8_t *id)
{
const struct lfa_protected_resource *resource;
if (spftree->type != SPF_TYPE_RLFA && spftree->type != SPF_TYPE_TI_LFA)
return false;
/*
* Adjacencies formed over the failed interface should be excised both
* when using link and node protection.
*/
resource = &spftree->lfa.protected_resource;
if (!memcmp(resource->adjacency, id, ISIS_SYS_ID_LEN + 1))
return true;
return false;
}
/**
* Check if a given IS-IS node needs to be excised when computing the SPF
* post-convergence tree.
*
* @param spftree IS-IS SPF tree
* @param id Node System ID
*
* @return true if the node needs to be excised, false otherwise
*/
bool isis_lfa_excise_node_check(const struct isis_spftree *spftree,
const uint8_t *id)
{
const struct lfa_protected_resource *resource;
if (spftree->type != SPF_TYPE_TI_LFA)
return false;
/*
* When using node protection, nodes reachable over the failed interface
* must be excised.
*/
resource = &spftree->lfa.protected_resource;
if (resource->type == LFA_LINK_PROTECTION)
return false;
if (isis_spf_node_find(&resource->nodes, id))
return true;
return false;
}
struct tilfa_find_pnode_prefix_sid_args {
uint32_t sid_index;
};
static int tilfa_find_pnode_prefix_sid_cb(const struct prefix *prefix,
uint32_t metric, bool external,
struct isis_subtlvs *subtlvs,
void *arg)
{
struct tilfa_find_pnode_prefix_sid_args *args = arg;
struct isis_prefix_sid *psid;
if (!subtlvs || subtlvs->prefix_sids.count == 0)
return LSP_ITER_CONTINUE;
psid = (struct isis_prefix_sid *)subtlvs->prefix_sids.head;
/* Require the node flag to be set. */
if (!CHECK_FLAG(psid->flags, ISIS_PREFIX_SID_NODE))
return LSP_ITER_CONTINUE;
args->sid_index = psid->value;
return LSP_ITER_STOP;
}
/* Find Prefix-SID associated to a System ID. */
static uint32_t tilfa_find_pnode_prefix_sid(struct isis_spftree *spftree,
const uint8_t *sysid)
{
struct isis_lsp *lsp;
struct tilfa_find_pnode_prefix_sid_args args;
lsp = isis_root_system_lsp(spftree->lspdb, sysid);
if (!lsp)
return UINT32_MAX;
args.sid_index = UINT32_MAX;
isis_lsp_iterate_ip_reach(lsp, spftree->family, spftree->mtid,
tilfa_find_pnode_prefix_sid_cb, &args);
return args.sid_index;
}
struct tilfa_find_qnode_adj_sid_args {
const uint8_t *qnode_sysid;
mpls_label_t label;
};
static int tilfa_find_qnode_adj_sid_cb(const uint8_t *id, uint32_t metric,
bool oldmetric,
struct isis_ext_subtlvs *subtlvs,
void *arg)
{
struct tilfa_find_qnode_adj_sid_args *args = arg;
struct isis_adj_sid *adj_sid;
if (memcmp(id, args->qnode_sysid, ISIS_SYS_ID_LEN))
return LSP_ITER_CONTINUE;
if (!subtlvs || subtlvs->adj_sid.count == 0)
return LSP_ITER_CONTINUE;
adj_sid = (struct isis_adj_sid *)subtlvs->adj_sid.head;
args->label = adj_sid->sid;
return LSP_ITER_STOP;
}
/* Find Adj-SID associated to a pair of System IDs. */
static mpls_label_t tilfa_find_qnode_adj_sid(struct isis_spftree *spftree,
const uint8_t *source_sysid,
const uint8_t *qnode_sysid)
{
struct isis_lsp *lsp;
struct tilfa_find_qnode_adj_sid_args args;
lsp = isis_root_system_lsp(spftree->lspdb, source_sysid);
if (!lsp)
return MPLS_INVALID_LABEL;
args.qnode_sysid = qnode_sysid;
args.label = MPLS_INVALID_LABEL;
isis_lsp_iterate_is_reach(lsp, spftree->mtid,
tilfa_find_qnode_adj_sid_cb, &args);
return args.label;
}
/*
* Compute the MPLS label stack associated to a TI-LFA repair list. This
* needs to be computed separately for each adjacency since different
* neighbors can have different SRGBs.
*/
static struct mpls_label_stack *
tilfa_compute_label_stack(struct lspdb_head *lspdb,
const struct isis_spf_adj *sadj,
const struct list *repair_list)
{
struct mpls_label_stack *label_stack;
struct isis_tilfa_sid *sid;
struct listnode *node;
size_t i = 0;
/* Allocate label stack. */
label_stack = XCALLOC(MTYPE_ISIS_NEXTHOP_LABELS,
sizeof(struct mpls_label_stack)
+ listcount(repair_list)
* sizeof(mpls_label_t));
label_stack->num_labels = listcount(repair_list);
for (ALL_LIST_ELEMENTS_RO(repair_list, node, sid)) {
const uint8_t *target_node;
struct isis_sr_block *srgb;
mpls_label_t label;
switch (sid->type) {
case TILFA_SID_PREFIX:
if (sid->value.index.remote)
target_node = sid->value.index.remote_sysid;
else
target_node = sadj->id;
srgb = isis_sr_find_srgb(lspdb, target_node);
if (!srgb) {
zlog_warn("%s: SRGB not found for node %s",
__func__,
print_sys_hostname(target_node));
goto error;
}
/* Check if the SID index falls inside the SRGB. */
if (sid->value.index.value >= srgb->range_size) {
flog_warn(
EC_ISIS_SID_OVERFLOW,
"%s: SID index %u falls outside remote SRGB range",
__func__, sid->value.index.value);
goto error;
}
/*
* Prefix-SID: map SID index to label value within the
* SRGB.
*/
label = srgb->lower_bound + sid->value.index.value;
break;
case TILFA_SID_ADJ:
/* Adj-SID: absolute label value can be used directly */
label = sid->value.label;
break;
default:
flog_err(EC_LIB_DEVELOPMENT,
"%s: unknown TI-LFA SID type [%u]", __func__,
sid->type);
exit(1);
}
label_stack->label[i++] = label;
}
return label_stack;
error:
XFREE(MTYPE_ISIS_NEXTHOP_LABELS, label_stack);
return NULL;
}
static int tilfa_repair_list_apply(struct isis_spftree *spftree,
struct isis_vertex *vertex_dest,
const struct isis_vertex *vertex_pnode,
const struct list *repair_list)
{
struct isis_vertex_adj *vadj;
struct listnode *node;
for (ALL_LIST_ELEMENTS_RO(vertex_dest->Adj_N, node, vadj)) {
struct isis_spf_adj *sadj = vadj->sadj;
struct mpls_label_stack *label_stack;
/*
* Don't try to apply the repair list if one was already applied
* before (can't have ECMP past the P-node).
*/
if (vadj->label_stack)
continue;
if (!isis_vertex_adj_exists(spftree, vertex_pnode, sadj))
continue;
label_stack = tilfa_compute_label_stack(spftree->lspdb, sadj,
repair_list);
if (!label_stack) {
char buf[VID2STR_BUFFER];
vid2string(vertex_dest, buf, sizeof(buf));
zlog_warn(
"%s: %s %s adjacency %s: failed to compute label stack",
__func__, vtype2string(vertex_dest->type), buf,
print_sys_hostname(sadj->id));
return -1;
}
vadj->label_stack = label_stack;
}
return 0;
}
/*
* Check if a node belongs to the extended P-space corresponding to a given
* destination.
*/
static bool lfa_ext_p_space_check(const struct isis_spftree *spftree_pc,
const struct isis_vertex *vertex_dest,
const struct isis_vertex *vertex)
{
struct isis_spftree *spftree_old = spftree_pc->lfa.old.spftree;
struct isis_vertex_adj *vadj;
struct listnode *node;
/* Check the local P-space first. */
if (isis_spf_node_find(&spftree_pc->lfa.p_space, vertex->N.id))
return true;
/*
* Check the P-space of the adjacent routers used to reach the
* destination.
*/
for (ALL_LIST_ELEMENTS_RO(vertex_dest->Adj_N, node, vadj)) {
struct isis_spf_adj *sadj = vadj->sadj;
struct isis_spf_node *adj_node;
adj_node =
isis_spf_node_find(&spftree_old->adj_nodes, sadj->id);
if (!adj_node)
continue;
if (isis_spf_node_find(&adj_node->lfa.p_space, vertex->N.id))
return true;
}
return false;
}
/* Check if a node belongs to the Q-space. */
static bool lfa_q_space_check(const struct isis_spftree *spftree_pc,
const struct isis_vertex *vertex)
{
return isis_spf_node_find(&spftree_pc->lfa.q_space, vertex->N.id);
}
/* This is a recursive function. */
static int tilfa_build_repair_list(struct isis_spftree *spftree_pc,
struct isis_vertex *vertex_dest,
const struct isis_vertex *vertex,
const struct isis_vertex *vertex_child,
struct isis_spf_nodes *used_pnodes,
struct list *repair_list)
{
struct isis_vertex *pvertex;
struct listnode *node;
bool is_pnode, is_qnode;
char buf[VID2STR_BUFFER];
struct isis_tilfa_sid sid_dest = {}, sid_qnode = {}, sid_pnode = {};
uint32_t sid_index;
mpls_label_t label_qnode;
if (IS_DEBUG_LFA) {
vid2string(vertex, buf, sizeof(buf));
zlog_debug("ISIS-LFA: vertex %s %s", vtype2string(vertex->type),
buf);
}
/* Push original Prefix-SID label when necessary. */
if (VTYPE_IP(vertex->type) && vertex->N.ip.sr.present) {
pvertex = listnode_head(vertex->parents);
assert(pvertex);
sid_index = vertex->N.ip.sr.sid.value;
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: pushing Prefix-SID to %pFX (index %u)",
&vertex->N.ip.p.dest, sid_index);
sid_dest.type = TILFA_SID_PREFIX;
sid_dest.value.index.value = sid_index;
sid_dest.value.index.remote = true;
memcpy(sid_dest.value.index.remote_sysid, pvertex->N.id,
sizeof(sid_dest.value.index.remote_sysid));
listnode_add_head(repair_list, &sid_dest);
}
if (!vertex_child)
goto parents;
if (vertex->type != VTYPE_NONPSEUDO_IS
&& vertex->type != VTYPE_NONPSEUDO_TE_IS)
goto parents;
if (!VTYPE_IS(vertex_child->type))
vertex_child = NULL;
/* Check if node is part of the extended P-space and/or Q-space. */
is_pnode = lfa_ext_p_space_check(spftree_pc, vertex_dest, vertex);
is_qnode = lfa_q_space_check(spftree_pc, vertex);
/* Push Adj-SID label when necessary. */
if ((!is_qnode
|| spftree_pc->lfa.protected_resource.type == LFA_NODE_PROTECTION)
&& vertex_child) {
/*
* If vertex is the penultimate hop router, then pushing an
* Adj-SID towards the final hop means that the No-PHP flag of
* the original Prefix-SID must be honored. We do that by
* removing the previously added Prefix-SID from the repair list
* when those conditions are met.
*/
if (vertex->depth == (vertex_dest->depth - 2)
&& VTYPE_IP(vertex_dest->type)
&& vertex_dest->N.ip.sr.present
&& !CHECK_FLAG(vertex_dest->N.ip.sr.sid.flags,
ISIS_PREFIX_SID_NO_PHP)) {
list_delete_all_node(repair_list);
}
label_qnode = tilfa_find_qnode_adj_sid(spftree_pc, vertex->N.id,
vertex_child->N.id);
if (label_qnode == MPLS_INVALID_LABEL) {
zlog_warn("ISIS-LFA: failed to find %s->%s Adj-SID",
print_sys_hostname(vertex->N.id),
print_sys_hostname(vertex_child->N.id));
return -1;
}
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: pushing %s->%s Adj-SID (label %u)",
print_sys_hostname(vertex->N.id),
print_sys_hostname(vertex_child->N.id),
label_qnode);
sid_qnode.type = TILFA_SID_ADJ;
sid_qnode.value.label = label_qnode;
listnode_add_head(repair_list, &sid_qnode);
}
/* Push Prefix-SID label when necessary. */
if (is_pnode) {
/* The same P-node can't be used more than once. */
if (isis_spf_node_find(used_pnodes, vertex->N.id)) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: skipping already used P-node");
return 0;
}
isis_spf_node_new(used_pnodes, vertex->N.id);
if (!vertex_child) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: destination is within Ext-P-Space");
return 0;
}
sid_index =
tilfa_find_pnode_prefix_sid(spftree_pc, vertex->N.id);
if (sid_index == UINT32_MAX) {
zlog_warn(
"ISIS-LFA: failed to find Prefix-SID corresponding to PQ-node %s",
print_sys_hostname(vertex->N.id));
return -1;
}
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: pushing Node-SID to %s (index %u)",
print_sys_hostname(vertex->N.id), sid_index);
sid_pnode.type = TILFA_SID_PREFIX;
sid_pnode.value.index.value = sid_index;
listnode_add_head(repair_list, &sid_pnode);
/* Apply repair list. */
if (spftree_pc->area->srdb.config.msd
&& listcount(repair_list)
> spftree_pc->area->srdb.config.msd) {
zlog_warn(
"ISIS-LFA: list of repair segments exceeds locally configured MSD (%u > %u)",
listcount(repair_list),
spftree_pc->area->srdb.config.msd);
return -1;
}
if (tilfa_repair_list_apply(spftree_pc, vertex_dest, vertex,
repair_list)
!= 0)
return -1;
return 0;
}
parents:
for (ALL_LIST_ELEMENTS_RO(vertex->parents, node, pvertex)) {
struct list *repair_list_parent;
bool ecmp;
int ret;
ecmp = (listcount(vertex->parents) > 1) ? true : false;
repair_list_parent = ecmp ? list_dup(repair_list) : repair_list;
ret = tilfa_build_repair_list(spftree_pc, vertex_dest, pvertex,
vertex, used_pnodes,
repair_list_parent);
if (ecmp)
list_delete(&repair_list_parent);
if (ret != 0)
return ret;
}
return 0;
}
static const char *lfa_protection_type2str(enum lfa_protection_type type)
{
switch (type) {
case LFA_LINK_PROTECTION:
return "link protection";
case LFA_NODE_PROTECTION:
return "node protection";
default:
return "unknown protection type";
}
}
static const char *
lfa_protected_resource2str(const struct lfa_protected_resource *resource)
{
const uint8_t *fail_id;
static char buffer[128];
fail_id = resource->adjacency;
snprintf(buffer, sizeof(buffer), "%s.%u's failure (%s)",
print_sys_hostname(fail_id), LSP_PSEUDO_ID(fail_id),
lfa_protection_type2str(resource->type));
return buffer;
}
static bool
spf_adj_check_is_affected(const struct isis_spf_adj *sadj,
const struct lfa_protected_resource *resource,
const uint8_t *root_sysid, bool reverse)
{
if (!!CHECK_FLAG(sadj->flags, F_ISIS_SPF_ADJ_BROADCAST)
!= !!LSP_PSEUDO_ID(resource->adjacency))
return false;
if (CHECK_FLAG(sadj->flags, F_ISIS_SPF_ADJ_BROADCAST)) {
if (!memcmp(sadj->lan.desig_is_id, resource->adjacency,
ISIS_SYS_ID_LEN + 1))
return true;
} else {
if (!reverse
&& !memcmp(sadj->id, resource->adjacency, ISIS_SYS_ID_LEN))
return true;
if (reverse && !memcmp(sadj->id, root_sysid, ISIS_SYS_ID_LEN))
return true;
}
return false;
}
/* Check if the given vertex is affected by a given local failure. */
static bool
spf_vertex_check_is_affected(const struct isis_vertex *vertex,
const uint8_t *root_sysid,
const struct lfa_protected_resource *resource)
{
struct isis_vertex_adj *vadj;
struct listnode *node;
size_t affected_nhs = 0;
/* Local routes don't need protection. */
if (VTYPE_IP(vertex->type) && vertex->depth == 1)
return false;
for (ALL_LIST_ELEMENTS_RO(vertex->Adj_N, node, vadj)) {
struct isis_spf_adj *sadj = vadj->sadj;
if (spf_adj_check_is_affected(sadj, resource, root_sysid,
false))
affected_nhs++;
}
/*
* No need to compute backup paths for ECMP routes, except if all
* primary nexthops share the same broadcast interface.
*/
if (listcount(vertex->Adj_N) == affected_nhs)
return true;
return false;
}
/* Check if a given RLFA/TI-LFA post-convergence SPF vertex needs protection. */
static bool lfa_check_needs_protection(const struct isis_spftree *spftree_pc,
const struct isis_vertex *vertex)
{
struct isis_vertex *vertex_old;
/* Only local adjacencies need TI-LFA Adj-SID protection. */
if (spftree_pc->type == SPF_TYPE_TI_LFA && VTYPE_IS(vertex->type)
&& !isis_adj_find(spftree_pc->area, spftree_pc->level,
vertex->N.id))
return false;
vertex_old = isis_find_vertex(&spftree_pc->lfa.old.spftree->paths,
&vertex->N, vertex->type);
if (!vertex_old)
return false;
/* Skip vertex if it's already protected by local LFA. */
if (CHECK_FLAG(vertex_old->flags, F_ISIS_VERTEX_LFA_PROTECTED))
return false;
return spf_vertex_check_is_affected(
vertex_old, spftree_pc->sysid,
&spftree_pc->lfa.protected_resource);
}
/**
* Check if the given SPF vertex needs protection and, if so, compute and
* install the corresponding repair paths.
*
* @param spftree_pc The post-convergence SPF tree
* @param vertex IS-IS SPF vertex to check
*
* @return 0 if the vertex needs to be protected, -1 otherwise
*/
int isis_tilfa_check(struct isis_spftree *spftree_pc,
struct isis_vertex *vertex)
{
struct isis_spf_nodes used_pnodes;
char buf[VID2STR_BUFFER];
struct list *repair_list;
int ret;
if (!spftree_pc->area->srdb.enabled)
return -1;
if (!lfa_check_needs_protection(spftree_pc, vertex)) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: %s %s unaffected by %s",
vtype2string(vertex->type),
vid2string(vertex, buf, sizeof(buf)),
lfa_protected_resource2str(
&spftree_pc->lfa.protected_resource));
return -1;
}
/*
* Check if the route/adjacency was already covered by node protection.
*/
if (VTYPE_IS(vertex->type)) {
struct isis_adjacency *adj;
adj = isis_adj_find(spftree_pc->area, spftree_pc->level,
vertex->N.id);
if (adj
&& isis_sr_adj_sid_find(adj, spftree_pc->family,
ISIS_SR_LAN_BACKUP)) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: %s %s already covered by node protection",
vtype2string(vertex->type),
vid2string(vertex, buf, sizeof(buf)));
return -1;
}
}
if (VTYPE_IP(vertex->type)) {
struct route_table *route_table;
route_table = spftree_pc->lfa.old.spftree->route_table_backup;
if (route_node_lookup(route_table, &vertex->N.ip.p.dest)) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: %s %s already covered by node protection",
vtype2string(vertex->type),
vid2string(vertex, buf, sizeof(buf)));
return -1;
}
}
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: computing repair path(s) of %s %s w.r.t %s",
vtype2string(vertex->type),
vid2string(vertex, buf, sizeof(buf)),
lfa_protected_resource2str(
&spftree_pc->lfa.protected_resource));
/* Create base repair list. */
repair_list = list_new();
isis_spf_node_list_init(&used_pnodes);
ret = tilfa_build_repair_list(spftree_pc, vertex, vertex, NULL,
&used_pnodes, repair_list);
isis_spf_node_list_clear(&used_pnodes);
list_delete(&repair_list);
if (ret != 0)
zlog_warn(
"ISIS-LFA: failed to compute repair path(s) of %s %s w.r.t %s",
vtype2string(vertex->type),
vid2string(vertex, buf, sizeof(buf)),
lfa_protected_resource2str(
&spftree_pc->lfa.protected_resource));
return ret;
}
static bool
spf_adj_node_is_affected(struct isis_spf_node *adj_node,
const struct lfa_protected_resource *resource,
const uint8_t *root_sysid)
{
struct isis_spf_adj *sadj;
struct listnode *node;
for (ALL_LIST_ELEMENTS_RO(adj_node->adjacencies, node, sadj)) {
if (sadj->metric != adj_node->best_metric)
continue;
if (spf_adj_check_is_affected(sadj, resource, root_sysid,
false))
return true;
}
return false;
}
static bool vertex_is_affected(struct isis_spftree *spftree_root,
const struct isis_spf_nodes *adj_nodes,
bool p_space, const struct isis_vertex *vertex,
const struct lfa_protected_resource *resource)
{
struct isis_vertex *pvertex;
struct listnode *node, *vnode;
for (ALL_LIST_ELEMENTS_RO(vertex->parents, node, pvertex)) {
struct isis_spftree *spftree_parent;
struct isis_vertex *vertex_child;
struct isis_vertex_adj *vadj;
bool reverse = false;
if (p_space && resource->type == LFA_NODE_PROTECTION) {
if (isis_spf_node_find(&resource->nodes, vertex->N.id))
return true;
goto parents;
}
/* Check if either the vertex or its parent is the root node. */
if (memcmp(vertex->N.id, spftree_root->sysid, ISIS_SYS_ID_LEN)
&& memcmp(pvertex->N.id, spftree_root->sysid,
ISIS_SYS_ID_LEN))
goto parents;
/* Get SPT of the parent vertex. */
if (!memcmp(pvertex->N.id, spftree_root->sysid,
ISIS_SYS_ID_LEN))
spftree_parent = spftree_root;
else {
struct isis_spf_node *adj_node;
adj_node = isis_spf_node_find(adj_nodes, pvertex->N.id);
assert(adj_node);
spftree_parent = adj_node->lfa.spftree;
assert(spftree_parent);
reverse = true;
}
/* Get paths pvertex uses to reach vertex. */
vertex_child = isis_find_vertex(&spftree_parent->paths,
&vertex->N, vertex->type);
if (!vertex_child)
goto parents;
/* Check if any of these paths use the protected resource. */
for (ALL_LIST_ELEMENTS_RO(vertex_child->Adj_N, vnode, vadj))
if (spf_adj_check_is_affected(vadj->sadj, resource,
spftree_root->sysid,
reverse))
return true;
parents:
if (vertex_is_affected(spftree_root, adj_nodes, p_space,
pvertex, resource))
return true;
}
return false;
}
/* Calculate set of nodes reachable without using the protected interface. */
static void lfa_calc_reach_nodes(struct isis_spftree *spftree,
struct isis_spftree *spftree_root,
const struct isis_spf_nodes *adj_nodes,
bool p_space,
const struct lfa_protected_resource *resource,
struct isis_spf_nodes *nodes)
{
struct isis_vertex *vertex;
struct listnode *node;
for (ALL_QUEUE_ELEMENTS_RO(&spftree->paths, node, vertex)) {
char buf[VID2STR_BUFFER];
if (!VTYPE_IS(vertex->type))
continue;
/* Skip root node. */
if (!memcmp(vertex->N.id, spftree_root->sysid, ISIS_SYS_ID_LEN))
continue;
/* Don't add the same node twice. */
if (isis_spf_node_find(nodes, vertex->N.id))
continue;
if (!vertex_is_affected(spftree_root, adj_nodes, p_space,
vertex, resource)) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: adding %s",
vid2string(vertex, buf, sizeof(buf)));
isis_spf_node_new(nodes, vertex->N.id);
}
}
}
/**
* Helper function used to create an SPF tree structure and run reverse SPF on
* it.
*
* @param spftree IS-IS SPF tree
*
* @return Pointer to new SPF tree structure.
*/
struct isis_spftree *isis_spf_reverse_run(const struct isis_spftree *spftree)
{
struct isis_spftree *spftree_reverse;
spftree_reverse = isis_spftree_new(
spftree->area, spftree->lspdb, spftree->sysid, spftree->level,
spftree->tree_id, SPF_TYPE_REVERSE,
F_SPFTREE_NO_ADJACENCIES | F_SPFTREE_NO_ROUTES);
isis_run_spf(spftree_reverse);
return spftree_reverse;
}
/*
* Calculate the Extended P-space and Q-space associated to a given link
* failure.
*/
static void lfa_calc_pq_spaces(struct isis_spftree *spftree_pc,
const struct lfa_protected_resource *resource)
{
struct isis_spftree *spftree;
struct isis_spftree *spftree_reverse;
struct isis_spf_nodes *adj_nodes;
struct isis_spf_node *adj_node;
/* Obtain pre-failure SPTs and list of adjacent nodes. */
spftree = spftree_pc->lfa.old.spftree;
spftree_reverse = spftree_pc->lfa.old.spftree_reverse;
adj_nodes = &spftree->adj_nodes;
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: computing P-space (self)");
lfa_calc_reach_nodes(spftree, spftree, adj_nodes, true, resource,
&spftree_pc->lfa.p_space);
RB_FOREACH (adj_node, isis_spf_nodes, adj_nodes) {
if (spf_adj_node_is_affected(adj_node, resource,
spftree->sysid)) {
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: computing Q-space (%s)",
print_sys_hostname(adj_node->sysid));
/*
* Compute the reverse SPF in the behalf of the node
* adjacent to the failure.
*/
adj_node->lfa.spftree_reverse =
isis_spf_reverse_run(adj_node->lfa.spftree);
lfa_calc_reach_nodes(adj_node->lfa.spftree_reverse,
spftree_reverse, adj_nodes, false,
resource,
&spftree_pc->lfa.q_space);
} else {
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: computing P-space (%s)",
print_sys_hostname(adj_node->sysid));
lfa_calc_reach_nodes(adj_node->lfa.spftree, spftree,
adj_nodes, true, resource,
&adj_node->lfa.p_space);
}
}
}
/**
* Compute the TI-LFA backup paths for a given protected interface.
*
* @param area IS-IS area
* @param spftree IS-IS SPF tree
* @param spftree_reverse IS-IS Reverse SPF tree
* @param resource Protected resource
*
* @return Pointer to the post-convergence SPF tree
*/
struct isis_spftree *isis_tilfa_compute(struct isis_area *area,
struct isis_spftree *spftree,
struct isis_spftree *spftree_reverse,
struct lfa_protected_resource *resource)
{
struct isis_spftree *spftree_pc;
struct isis_spf_node *adj_node;
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: computing TI-LFAs for %s",
lfa_protected_resource2str(resource));
/* Populate list of nodes affected by link failure. */
if (resource->type == LFA_NODE_PROTECTION) {
isis_spf_node_list_init(&resource->nodes);
RB_FOREACH (adj_node, isis_spf_nodes, &spftree->adj_nodes) {
if (spf_adj_node_is_affected(adj_node, resource,
spftree->sysid))
isis_spf_node_new(&resource->nodes,
adj_node->sysid);
}
}
/* Create post-convergence SPF tree. */
spftree_pc = isis_spftree_new(area, spftree->lspdb, spftree->sysid,
spftree->level, spftree->tree_id,
SPF_TYPE_TI_LFA, spftree->flags);
spftree_pc->lfa.old.spftree = spftree;
spftree_pc->lfa.old.spftree_reverse = spftree_reverse;
spftree_pc->lfa.protected_resource = *resource;
/* Compute the extended P-space and Q-space. */
lfa_calc_pq_spaces(spftree_pc, resource);
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: computing the post convergence SPT w.r.t. %s",
lfa_protected_resource2str(resource));
/* Re-run SPF in the local node to find the post-convergence paths. */
isis_run_spf(spftree_pc);
/* Clear list of nodes affeted by link failure. */
if (resource->type == LFA_NODE_PROTECTION)
isis_spf_node_list_clear(&resource->nodes);
return spftree_pc;
}
/**
* Run forward SPF on all adjacent routers.
*
* @param spftree IS-IS SPF tree
*
* @return 0 on success, -1 otherwise
*/
int isis_spf_run_neighbors(struct isis_spftree *spftree)
{
struct isis_lsp *lsp;
struct isis_spf_node *adj_node;
lsp = isis_root_system_lsp(spftree->lspdb, spftree->sysid);
if (!lsp)
return -1;
RB_FOREACH (adj_node, isis_spf_nodes, &spftree->adj_nodes) {
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: running SPF on neighbor %s",
print_sys_hostname(adj_node->sysid));
/* Compute the SPT on behalf of the neighbor. */
adj_node->lfa.spftree = isis_spftree_new(
spftree->area, spftree->lspdb, adj_node->sysid,
spftree->level, spftree->tree_id, SPF_TYPE_FORWARD,
F_SPFTREE_NO_ADJACENCIES | F_SPFTREE_NO_ROUTES);
isis_run_spf(adj_node->lfa.spftree);
}
return 0;
}
/* Find Router ID of PQ node. */
static struct in_addr *rlfa_pq_node_rtr_id(struct isis_spftree *spftree,
const struct isis_vertex *vertex_pq)
{
struct isis_lsp *lsp;
lsp = isis_root_system_lsp(spftree->lspdb, vertex_pq->N.id);
if (!lsp)
return NULL;
if (lsp->tlvs->router_cap->router_id.s_addr == INADDR_ANY)
return NULL;
return &lsp->tlvs->router_cap->router_id;
}
/* Find PQ node by intersecting the P/Q spaces. This is a recursive function. */
static const struct in_addr *
rlfa_find_pq_node(struct isis_spftree *spftree_pc,
struct isis_vertex *vertex_dest,
const struct isis_vertex *vertex,
const struct isis_vertex *vertex_child)
{
struct isis_area *area = spftree_pc->area;
int level = spftree_pc->level;
struct isis_vertex *pvertex;
struct listnode *node;
bool is_pnode, is_qnode;
if (!vertex_child)
goto parents;
if (vertex->type != VTYPE_NONPSEUDO_IS
&& vertex->type != VTYPE_NONPSEUDO_TE_IS)
goto parents;
if (!VTYPE_IS(vertex_child->type))
vertex_child = NULL;
/* Check if node is part of the extended P-space and/or Q-space. */
is_pnode = lfa_ext_p_space_check(spftree_pc, vertex_dest, vertex);
is_qnode = lfa_q_space_check(spftree_pc, vertex);
if (is_pnode && is_qnode) {
const struct in_addr *rtr_id_pq;
uint32_t max_metric;
struct prefix_list *plist = NULL;
rtr_id_pq = rlfa_pq_node_rtr_id(spftree_pc, vertex);
if (!rtr_id_pq) {
if (IS_DEBUG_LFA) {
char buf[VID2STR_BUFFER];
vid2string(vertex, buf, sizeof(buf));
zlog_debug(
"ISIS-LFA: tentative PQ node (%s %s) doesn't have a router-ID",
vtype2string(vertex->type), buf);
}
goto parents;
}
max_metric = spftree_pc->lfa.remote.max_metric;
if (max_metric && vertex->d_N > max_metric) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: skipping PQ node %pI4 (maximum metric)",
rtr_id_pq);
goto parents;
}
plist = area->rlfa_plist[level - 1];
if (plist) {
struct prefix p;
p.family = AF_INET;
p.prefixlen = IPV4_MAX_BITLEN;
p.u.prefix4 = *rtr_id_pq;
if (prefix_list_apply(plist, &p) == PREFIX_DENY) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: PQ node %pI4 filtered by prefix-list",
rtr_id_pq);
goto parents;
}
}
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: found PQ node: %pI4", rtr_id_pq);
return rtr_id_pq;
}
parents:
for (ALL_LIST_ELEMENTS_RO(vertex->parents, node, pvertex)) {
const struct in_addr *rtr_id_pq;
rtr_id_pq = rlfa_find_pq_node(spftree_pc, vertex_dest, pvertex,
vertex);
if (rtr_id_pq)
return rtr_id_pq;
}
return NULL;
}
int rlfa_cmp(const struct rlfa *a, const struct rlfa *b)
{
return prefix_cmp(&a->prefix, &b->prefix);
}
static struct rlfa *rlfa_add(struct isis_spftree *spftree,
struct isis_vertex *vertex,
struct in_addr pq_address)
{
struct rlfa *rlfa;
assert(VTYPE_IP(vertex->type));
rlfa = XCALLOC(MTYPE_ISIS_RLFA, sizeof(*rlfa));
rlfa->prefix = vertex->N.ip.p.dest;
rlfa->vertex = vertex;
rlfa->pq_address = pq_address;
rlfa_tree_add(&spftree->lfa.remote.rlfas, rlfa);
return rlfa;
}
static void rlfa_delete(struct isis_spftree *spftree, struct rlfa *rlfa)
{
rlfa_tree_del(&spftree->lfa.remote.rlfas, rlfa);
XFREE(MTYPE_ISIS_RLFA, rlfa);
}
static struct rlfa *rlfa_lookup(struct isis_spftree *spftree,
union prefixconstptr pu)
{
struct rlfa s = {};
s.prefix = *pu.p;
return rlfa_tree_find(&spftree->lfa.remote.rlfas, &s);
}
static int isis_area_verify_routes_cb(struct thread *thread)
{
struct isis_area *area = THREAD_ARG(thread);
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: updating RLFAs in the RIB");
isis_area_verify_routes(area);
return 0;
}
static mpls_label_t rlfa_nexthop_label(struct isis_spftree *spftree,
struct isis_vertex_adj *vadj,
struct zapi_rlfa_response *response)
{
struct isis_spf_adj *sadj = vadj->sadj;
struct isis_adjacency *adj = sadj->adj;
/*
* Special case to make unit tests work (use implicit-null labels
* instead of artifical ones).
*/
if (CHECK_FLAG(spftree->flags, F_SPFTREE_NO_ADJACENCIES))
return MPLS_LABEL_IMPLICIT_NULL;
for (unsigned int i = 0; i < response->nexthop_num; i++) {
switch (response->nexthops[i].family) {
case AF_INET:
for (unsigned int j = 0; j < adj->ipv4_address_count;
j++) {
struct in_addr addr = adj->ipv4_addresses[j];
if (!IPV4_ADDR_SAME(
&addr,
&response->nexthops[i].gate.ipv4))
continue;
return response->nexthops[i].label;
}
break;
case AF_INET6:
for (unsigned int j = 0; j < adj->ipv6_address_count;
j++) {
struct in6_addr addr = adj->ipv6_addresses[j];
if (!IPV6_ADDR_SAME(
&addr,
&response->nexthops[i].gate.ipv6))
continue;
return response->nexthops[i].label;
}
break;
default:
break;
}
}
return MPLS_INVALID_LABEL;
}
int isis_rlfa_activate(struct isis_spftree *spftree, struct rlfa *rlfa,
struct zapi_rlfa_response *response)
{
struct isis_area *area = spftree->area;
struct isis_vertex *vertex = rlfa->vertex;
struct isis_vertex_adj *vadj;
struct listnode *node;
for (ALL_LIST_ELEMENTS_RO(vertex->Adj_N, node, vadj)) {
mpls_label_t ldp_label;
struct mpls_label_stack *label_stack;
size_t num_labels = 0;
size_t i = 0;
ldp_label = rlfa_nexthop_label(spftree, vadj, response);
if (ldp_label == MPLS_INVALID_LABEL) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: failed to activate RLFA: missing LDP label to reach PQ node through %s",
sysid_print(vadj->sadj->id));
return -1;
}
if (ldp_label != MPLS_LABEL_IMPLICIT_NULL)
num_labels++;
if (response->pq_label != MPLS_LABEL_IMPLICIT_NULL)
num_labels++;
if (vadj->sr.present
&& vadj->sr.label != MPLS_LABEL_IMPLICIT_NULL)
num_labels++;
/* Allocate label stack. */
label_stack =
XCALLOC(MTYPE_ISIS_NEXTHOP_LABELS,
sizeof(struct mpls_label_stack)
+ num_labels * sizeof(mpls_label_t));
label_stack->num_labels = num_labels;
/* Push label allocated by the nexthop (outer label). */
if (ldp_label != MPLS_LABEL_IMPLICIT_NULL)
label_stack->label[i++] = ldp_label;
/* Push label allocated by the PQ node (inner label). */
if (response->pq_label != MPLS_LABEL_IMPLICIT_NULL)
label_stack->label[i++] = response->pq_label;
/* Preserve the original Prefix-SID label when it's present. */
if (vadj->sr.present
&& vadj->sr.label != MPLS_LABEL_IMPLICIT_NULL)
label_stack->label[i++] = vadj->sr.label;
vadj->label_stack = label_stack;
}
isis_route_create(&vertex->N.ip.p.dest, &vertex->N.ip.p.src,
vertex->d_N, vertex->depth, &vertex->N.ip.sr,
vertex->Adj_N, true, area,
spftree->route_table_backup);
spftree->lfa.protection_counters.rlfa[vertex->N.ip.priority] += 1;
thread_cancel(&area->t_rlfa_rib_update);
thread_add_timer(master, isis_area_verify_routes_cb, area, 2,
&area->t_rlfa_rib_update);
return 0;
}
void isis_rlfa_deactivate(struct isis_spftree *spftree, struct rlfa *rlfa)
{
struct isis_area *area = spftree->area;
struct isis_vertex *vertex = rlfa->vertex;
struct route_node *rn;
rn = route_node_lookup(spftree->route_table_backup, &rlfa->prefix);
if (!rn)
return;
isis_route_delete(area, rn, spftree->route_table_backup);
spftree->lfa.protection_counters.rlfa[vertex->N.ip.priority] -= 1;
thread_cancel(&area->t_rlfa_rib_update);
thread_add_timer(master, isis_area_verify_routes_cb, area, 2,
&area->t_rlfa_rib_update);
}
void isis_rlfa_list_init(struct isis_spftree *spftree)
{
rlfa_tree_init(&spftree->lfa.remote.rlfas);
}
void isis_rlfa_list_clear(struct isis_spftree *spftree)
{
while (rlfa_tree_count(&spftree->lfa.remote.rlfas) > 0) {
struct rlfa *rlfa;
rlfa = rlfa_tree_first(&spftree->lfa.remote.rlfas);
isis_rlfa_deactivate(spftree, rlfa);
rlfa_delete(spftree, rlfa);
}
}
void isis_rlfa_process_ldp_response(struct zapi_rlfa_response *response)
{
struct isis *isis;
struct isis_area *area;
struct isis_spftree *spftree;
struct rlfa *rlfa;
enum spf_tree_id tree_id;
uint32_t spf_run_id;
int level;
if (response->igp.protocol != ZEBRA_ROUTE_ISIS)
return;
isis = isis_lookup_by_vrfid(response->igp.vrf_id);
if (!isis)
return;
area = isis_area_lookup(response->igp.isis.area_tag,
response->igp.vrf_id);
if (!area)
return;
tree_id = response->igp.isis.spf.tree_id;
if (tree_id != SPFTREE_IPV4 && tree_id != SPFTREE_IPV6) {
zlog_warn("ISIS-LFA: invalid SPF tree ID received from LDP");
return;
}
level = response->igp.isis.spf.level;
if (level != ISIS_LEVEL1 && level != ISIS_LEVEL2) {
zlog_warn("ISIS-LFA: invalid IS-IS level received from LDP");
return;
}
spf_run_id = response->igp.isis.spf.run_id;
spftree = area->spftree[tree_id][level - 1];
if (spftree->runcount != spf_run_id)
/* Outdated RLFA, ignore... */
return;
rlfa = rlfa_lookup(spftree, &response->destination);
if (!rlfa) {
zlog_warn(
"ISIS-LFA: couldn't find Remote-LFA %pFX received from LDP",
&response->destination);
return;
}
if (response->pq_label != MPLS_INVALID_LABEL) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: activating/updating RLFA for %pFX",
&rlfa->prefix);
if (isis_rlfa_activate(spftree, rlfa, response) != 0)
isis_rlfa_deactivate(spftree, rlfa);
} else {
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: deactivating RLFA for %pFX",
&rlfa->prefix);
isis_rlfa_deactivate(spftree, rlfa);
}
}
void isis_ldp_rlfa_handle_client_close(struct zapi_client_close_info *info)
{
struct isis *isis = isis_lookup_by_vrfid(VRF_DEFAULT);
struct isis_area *area;
struct listnode *node;
if (!isis)
return;
/* Check if the LDP main client session closed */
if (info->proto != ZEBRA_ROUTE_LDP || info->session_id == 0)
return;
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: LDP is down, deactivating all RLFAs");
for (ALL_LIST_ELEMENTS_RO(isis->area_list, node, area)) {
for (int tree = SPFTREE_IPV4; tree < SPFTREE_COUNT; tree++) {
for (int level = ISIS_LEVEL1; level <= ISIS_LEVELS;
level++) {
struct isis_spftree *spftree;
spftree = area->spftree[tree][level - 1];
isis_rlfa_list_clear(spftree);
}
}
}
}
/**
* Check if the given SPF vertex needs protection and, if so, attempt to
* compute a Remote LFA for it.
*
* @param spftree_pc The post-convergence SPF tree
* @param vertex IS-IS SPF vertex to check
*/
void isis_rlfa_check(struct isis_spftree *spftree_pc,
struct isis_vertex *vertex)
{
struct isis_spftree *spftree_old = spftree_pc->lfa.old.spftree;
struct rlfa *rlfa;
const struct in_addr *rtr_id_pq;
char buf[VID2STR_BUFFER];
if (!lfa_check_needs_protection(spftree_pc, vertex)) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: %s %s unaffected by %s",
vtype2string(vertex->type),
vid2string(vertex, buf, sizeof(buf)),
lfa_protected_resource2str(
&spftree_pc->lfa.protected_resource));
return;
}
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: computing repair path(s) of %s %s w.r.t %s",
vtype2string(vertex->type),
vid2string(vertex, buf, sizeof(buf)),
lfa_protected_resource2str(
&spftree_pc->lfa.protected_resource));
/* Find PQ node. */
rtr_id_pq = rlfa_find_pq_node(spftree_pc, vertex, vertex, NULL);
if (!rtr_id_pq) {
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: no acceptable PQ node found");
return;
}
/* Store valid RLFA and store LDP label for the PQ node. */
rlfa = rlfa_add(spftree_old, vertex, *rtr_id_pq);
/* Register RLFA with LDP. */
if (isis_zebra_rlfa_register(spftree_old, rlfa) != 0)
rlfa_delete(spftree_old, rlfa);
}
/**
* Compute the Remote LFA backup paths for a given protected interface.
*
* @param area IS-IS area
* @param spftree IS-IS SPF tree
* @param spftree_reverse IS-IS Reverse SPF tree
* @param max_metric Remote LFA maximum metric
* @param resource Protected resource
*
* @return Pointer to the post-convergence SPF tree
*/
struct isis_spftree *isis_rlfa_compute(struct isis_area *area,
struct isis_spftree *spftree,
struct isis_spftree *spftree_reverse,
uint32_t max_metric,
struct lfa_protected_resource *resource)
{
struct isis_spftree *spftree_pc;
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: computing remote LFAs for %s",
lfa_protected_resource2str(resource));
/* Create post-convergence SPF tree. */
spftree_pc = isis_spftree_new(area, spftree->lspdb, spftree->sysid,
spftree->level, spftree->tree_id,
SPF_TYPE_RLFA, spftree->flags);
spftree_pc->lfa.old.spftree = spftree;
spftree_pc->lfa.old.spftree_reverse = spftree_reverse;
spftree_pc->lfa.remote.max_metric = max_metric;
spftree_pc->lfa.protected_resource = *resource;
/* Compute the extended P-space and Q-space. */
lfa_calc_pq_spaces(spftree_pc, resource);
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: computing the post convergence SPT w.r.t. %s",
lfa_protected_resource2str(resource));
/* Re-run SPF in the local node to find the post-convergence paths. */
isis_run_spf(spftree_pc);
return spftree_pc;
}
/* Calculate the distance from the root node to the given IP destination. */
static int lfa_calc_dist_destination(struct isis_spftree *spftree,
const struct isis_vertex *vertex_N,
uint32_t *distance)
{
struct isis_vertex *vertex, *vertex_best = NULL;
switch (spftree->family) {
case AF_INET:
for (int vtype = VTYPE_IPREACH_INTERNAL;
vtype <= VTYPE_IPREACH_TE; vtype++) {
vertex = isis_find_vertex(
&spftree->paths, &vertex_N->N.ip.p.dest, vtype);
if (!vertex)
continue;
/* Pick vertex with the best metric. */
if (!vertex_best || vertex_best->d_N > vertex->d_N)
vertex_best = vertex;
}
break;
case AF_INET6:
for (int vtype = VTYPE_IP6REACH_INTERNAL;
vtype <= VTYPE_IP6REACH_EXTERNAL; vtype++) {
vertex = isis_find_vertex(
&spftree->paths, &vertex_N->N.ip.p.dest, vtype);
if (!vertex)
continue;
/* Pick vertex with the best metric. */
if (!vertex_best || vertex_best->d_N > vertex->d_N)
vertex_best = vertex;
}
break;
default:
break;
}
if (!vertex_best)
return -1;
assert(VTYPE_IP(vertex_best->type));
vertex_best = listnode_head(vertex_best->parents);
*distance = vertex_best->d_N;
return 0;
}
/* Calculate the distance from the root node to the given node. */
static int lfa_calc_dist_node(struct isis_spftree *spftree,
const uint8_t *sysid, uint32_t *distance)
{
struct isis_vertex *vertex, *vertex_best = NULL;
for (int vtype = VTYPE_PSEUDO_IS; vtype <= VTYPE_NONPSEUDO_TE_IS;
vtype++) {
vertex = isis_find_vertex(&spftree->paths, sysid, vtype);
if (!vertex)
continue;
/* Pick vertex with the best metric. */
if (!vertex_best || vertex_best->d_N > vertex->d_N)
vertex_best = vertex;
}
if (!vertex_best)
return -1;
*distance = vertex_best->d_N;
return 0;
}
/*
* Check loop-free criterion (RFC 5286's inequality 1):
* - Dist_opt(N, D) < Dist_opt(N, S) + Dist_opt(S, D)
*/
static bool clfa_loop_free_check(struct isis_spftree *spftree,
struct isis_vertex *vertex_S_D,
struct isis_spf_adj *sadj_primary,
struct isis_spf_adj *sadj_N,
uint32_t *lfa_metric)
{
struct isis_spf_node *node_N;
uint32_t dist_N_D;
uint32_t dist_N_S;
uint32_t dist_S_D;
node_N = isis_spf_node_find(&spftree->adj_nodes, sadj_N->id);
assert(node_N);
/* Distance from N to D. */
if (lfa_calc_dist_destination(node_N->lfa.spftree, vertex_S_D,
&dist_N_D)
!= 0)
return false;
/* Distance from N to S (or PN). */
if (CHECK_FLAG(sadj_primary->flags, F_ISIS_SPF_ADJ_BROADCAST)) {
static uint8_t pn_sysid[ISIS_SYS_ID_LEN + 1];
memcpy(pn_sysid, sadj_primary->id, ISIS_SYS_ID_LEN + 1);
if (lfa_calc_dist_node(node_N->lfa.spftree, pn_sysid, &dist_N_S)
!= 0)
return false;
} else {
static uint8_t root_sysid[ISIS_SYS_ID_LEN + 1];
memcpy(root_sysid, spftree->sysid, ISIS_SYS_ID_LEN);
LSP_PSEUDO_ID(root_sysid) = 0;
if (lfa_calc_dist_node(node_N->lfa.spftree, root_sysid,
&dist_N_S)
!= 0)
return false;
}
/* Distance from S (or PN) to D. */
vertex_S_D = listnode_head(vertex_S_D->parents);
dist_S_D = vertex_S_D->d_N;
if (CHECK_FLAG(sadj_primary->flags, F_ISIS_SPF_ADJ_BROADCAST))
dist_S_D -= sadj_primary->metric;
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: loop-free check: %u < %u + %u", dist_N_D,
dist_N_S, dist_S_D);
if (dist_N_D < (dist_N_S + dist_S_D)) {
*lfa_metric = sadj_N->metric + dist_N_D;
return true;
}
return false;
}
/*
* Check loop-free criterion (RFC 5286's inequality 2):
* - Distance_opt(N, D) < Distance_opt(S, D)
*/
static bool clfa_downstream_check(struct isis_spftree *spftree,
struct isis_vertex *vertex_S_D,
struct isis_spf_adj *sadj_N)
{
struct isis_spf_node *node_N;
uint32_t dist_N_D;
uint32_t dist_S_D;
node_N = isis_spf_node_find(&spftree->adj_nodes, sadj_N->id);
assert(node_N);
/* Distance from N to D. */
if (lfa_calc_dist_destination(node_N->lfa.spftree, vertex_S_D,
&dist_N_D)
!= 0)
return false;
/* Distance from S (or PN) to D. */
vertex_S_D = listnode_head(vertex_S_D->parents);
dist_S_D = vertex_S_D->d_N;
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: downstream check: %u < %u", dist_N_D,
dist_S_D);
if (dist_N_D < dist_S_D)
return true;
return false;
}
/*
* Check loop-free criterion (RFC 5286's inequality 3):
* - Dist_opt(N, D) < Dist_opt(N, E) + Dist_opt(E, D)
*/
static bool clfa_node_protecting_check(struct isis_spftree *spftree,
struct isis_vertex *vertex_S_D,
struct isis_spf_adj *sadj_N,
struct isis_spf_adj *sadj_E)
{
struct isis_spf_node *node_N, *node_E;
uint32_t dist_N_D;
uint32_t dist_N_E;
uint32_t dist_E_D;
node_N = isis_spf_node_find(&spftree->adj_nodes, sadj_N->id);
assert(node_N);
node_E = isis_spf_node_find(&spftree->adj_nodes, sadj_E->id);
assert(node_E);
/* Distance from N to D. */
if (lfa_calc_dist_destination(node_N->lfa.spftree, vertex_S_D,
&dist_N_D)
!= 0)
return false;
/* Distance from N to E. */
if (lfa_calc_dist_node(node_N->lfa.spftree, node_E->sysid, &dist_N_E)
!= 0)
return false;
/* Distance from E to D. */
if (lfa_calc_dist_destination(node_E->lfa.spftree, vertex_S_D,
&dist_E_D)
!= 0)
return false;
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: node protecting check: %u < %u + %u",
dist_N_D, dist_N_E, dist_E_D);
return (dist_N_D < (dist_N_E + dist_E_D));
}
static struct list *
isis_lfa_tiebreakers(struct isis_area *area, struct isis_spftree *spftree,
struct lfa_protected_resource *resource,
struct isis_vertex *vertex,
struct isis_spf_adj *sadj_primary, struct list *lfa_list)
{
struct lfa_tiebreaker *tie_b;
int level = spftree->level;
struct list *filtered_lfa_list;
struct list *tent_lfa_list;
filtered_lfa_list = list_dup(lfa_list);
filtered_lfa_list->del = NULL;
if (listcount(filtered_lfa_list) == 1)
return filtered_lfa_list;
/* Check tiebreakers in ascending order by index. */
frr_each (lfa_tiebreaker_tree, &area->lfa_tiebreakers[level - 1],
tie_b) {
struct isis_vertex_adj *lfa;
struct listnode *node, *nnode;
uint32_t best_metric = UINT32_MAX;
tent_lfa_list = list_dup(filtered_lfa_list);
switch (tie_b->type) {
case LFA_TIEBREAKER_DOWNSTREAM:
for (ALL_LIST_ELEMENTS(tent_lfa_list, node, nnode,
lfa)) {
if (clfa_downstream_check(spftree, vertex,
lfa->sadj))
continue;
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: LFA %s doesn't satisfy the downstream condition",
print_sys_hostname(
lfa->sadj->id));
listnode_delete(tent_lfa_list, lfa);
}
break;
case LFA_TIEBREAKER_LOWEST_METRIC:
/* Find the best metric first. */
for (ALL_LIST_ELEMENTS_RO(tent_lfa_list, node, lfa)) {
if (lfa->lfa_metric < best_metric)
best_metric = lfa->lfa_metric;
}
/* Remove LFAs that don't have the best metric. */
for (ALL_LIST_ELEMENTS(tent_lfa_list, node, nnode,
lfa)) {
if (lfa->lfa_metric == best_metric)
continue;
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: LFA %s doesn't have the lowest cost metric",
print_sys_hostname(
lfa->sadj->id));
listnode_delete(tent_lfa_list, lfa);
}
break;
case LFA_TIEBREAKER_NODE_PROTECTING:
for (ALL_LIST_ELEMENTS(tent_lfa_list, node, nnode,
lfa)) {
if (clfa_node_protecting_check(spftree, vertex,
lfa->sadj,
sadj_primary))
continue;
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: LFA %s doesn't provide node protection",
print_sys_hostname(
lfa->sadj->id));
listnode_delete(tent_lfa_list, lfa);
}
break;
}
/*
* Decide what to do next based on the number of remaining LFAs.
*/
switch (listcount(tent_lfa_list)) {
case 0:
/*
* Ignore this tie-breaker since it excluded all LFAs.
* Move on to the next one (if any).
*/
list_delete(&tent_lfa_list);
break;
case 1:
/* Finish tie-breaking once we get a single LFA. */
list_delete(&filtered_lfa_list);
filtered_lfa_list = tent_lfa_list;
return filtered_lfa_list;
default:
/*
* We still have two or more LFAs. Move on to the next
* tie-breaker (if any).
*/
list_delete(&filtered_lfa_list);
filtered_lfa_list = tent_lfa_list;
break;
}
}
return filtered_lfa_list;
}
void isis_lfa_compute(struct isis_area *area, struct isis_circuit *circuit,
struct isis_spftree *spftree,
struct lfa_protected_resource *resource)
{
struct isis_vertex *vertex;
struct listnode *vnode, *snode;
int level = spftree->level;
resource->type = LFA_LINK_PROTECTION;
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: computing local LFAs for %s",
lfa_protected_resource2str(resource));
for (ALL_QUEUE_ELEMENTS_RO(&spftree->paths, vnode, vertex)) {
struct list *lfa_list;
struct list *filtered_lfa_list;
struct isis_spf_adj *sadj_N;
struct isis_vertex_adj *vadj_primary;
struct isis_spf_adj *sadj_primary;
bool allow_ecmp;
uint32_t best_metric = UINT32_MAX;
char buf[VID2STR_BUFFER];
if (!VTYPE_IP(vertex->type))
continue;
vid2string(vertex, buf, sizeof(buf));
if (!spf_vertex_check_is_affected(vertex, spftree->sysid,
resource)) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: %s %s unaffected by %s",
vtype2string(vertex->type), buf,
lfa_protected_resource2str(resource));
continue;
}
if (IS_DEBUG_LFA)
zlog_debug("ISIS-LFA: checking %s %s w.r.t %s",
vtype2string(vertex->type), buf,
lfa_protected_resource2str(resource));
if (vertex->N.ip.priority
> area->lfa_priority_limit[level - 1]) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: skipping computing LFAs due to low prefix priority");
continue;
}
vadj_primary = listnode_head(vertex->Adj_N);
sadj_primary = vadj_primary->sadj;
/*
* Loop over list of SPF adjacencies and compute a list of
* preliminary LFAs.
*/
lfa_list = list_new();
lfa_list->del = isis_vertex_adj_free;
for (ALL_LIST_ELEMENTS_RO(spftree->sadj_list, snode, sadj_N)) {
uint32_t lfa_metric;
struct isis_vertex_adj *lfa;
struct isis_prefix_sid *psid = NULL;
bool last_hop = false;
/* Skip pseudonodes. */
if (LSP_PSEUDO_ID(sadj_N->id))
continue;
/*
* Skip nexthops that are along a link whose cost is
* infinite.
*/
if (CHECK_FLAG(sadj_N->flags,
F_ISIS_SPF_ADJ_METRIC_INFINITY))
continue;
/* Skip nexthops that have the overload bit set. */
if (spftree->mtid != ISIS_MT_IPV4_UNICAST) {
struct isis_mt_router_info *mt_router_info;
mt_router_info =
isis_tlvs_lookup_mt_router_info(
sadj_N->lsp->tlvs,
spftree->mtid);
if (mt_router_info && mt_router_info->overload)
continue;
} else if (ISIS_MASK_LSP_OL_BIT(
sadj_N->lsp->hdr.lsp_bits))
continue;
/* Skip primary nexthop. */
if (spf_adj_check_is_affected(sadj_N, resource, NULL,
false))
continue;
/* Skip excluded interfaces as per the configuration. */
if (circuit
&& isis_lfa_excluded_iface_check(
circuit, level,
sadj_N->adj->circuit->interface->name))
continue;
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: checking candidate LFA %s",
print_sys_hostname(sadj_N->id));
/* Check loop-free criterion. */
if (!clfa_loop_free_check(spftree, vertex, sadj_primary,
sadj_N, &lfa_metric)) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: LFA condition not met for %s",
print_sys_hostname(sadj_N->id));
continue;
}
if (lfa_metric < best_metric)
best_metric = lfa_metric;
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: %s is a valid loop-free alternate",
print_sys_hostname(sadj_N->id));
if (vertex->N.ip.sr.present) {
psid = &vertex->N.ip.sr.sid;
if (lfa_metric == sadj_N->metric)
last_hop = true;
}
lfa = isis_vertex_adj_add(spftree, vertex, lfa_list,
sadj_N, psid, last_hop);
lfa->lfa_metric = lfa_metric;
}
if (list_isempty(lfa_list)) {
if (IS_DEBUG_LFA)
zlog_debug(
"ISIS-LFA: no valid local LFAs found");
list_delete(&lfa_list);
continue;
}
SET_FLAG(vertex->flags, F_ISIS_VERTEX_LFA_PROTECTED);
/* Check tie-breakers. */
filtered_lfa_list =
isis_lfa_tiebreakers(area, spftree, resource, vertex,
sadj_primary, lfa_list);
/* Create backup route using the best LFAs. */
allow_ecmp = area->lfa_load_sharing[level - 1];
isis_route_create(&vertex->N.ip.p.dest, &vertex->N.ip.p.src,
best_metric, vertex->depth, &vertex->N.ip.sr,
filtered_lfa_list, allow_ecmp, area,
spftree->route_table_backup);
spftree->lfa.protection_counters.lfa[vertex->N.ip.priority] +=
1;
list_delete(&filtered_lfa_list);
list_delete(&lfa_list);
}
}
static void isis_spf_run_tilfa(struct isis_area *area,
struct isis_circuit *circuit,
struct isis_spftree *spftree,
struct isis_spftree *spftree_reverse,
struct lfa_protected_resource *resource)
{
struct isis_spftree *spftree_pc_link;
struct isis_spftree *spftree_pc_node;
/* Compute node protecting repair paths first (if necessary). */
if (circuit->tilfa_node_protection[spftree->level - 1]) {
resource->type = LFA_NODE_PROTECTION;
spftree_pc_node = isis_tilfa_compute(area, spftree,
spftree_reverse, resource);
isis_spftree_del(spftree_pc_node);
}
/* Compute link protecting repair paths. */
resource->type = LFA_LINK_PROTECTION;
spftree_pc_link =
isis_tilfa_compute(area, spftree, spftree_reverse, resource);
isis_spftree_del(spftree_pc_link);
}
/**
* Run the LFA/RLFA/TI-LFA algorithms for all protected interfaces.
*
* @param area IS-IS area
* @param spftree IS-IS SPF tree
*/
void isis_spf_run_lfa(struct isis_area *area, struct isis_spftree *spftree)
{
struct isis_spftree *spftree_reverse = NULL;
struct isis_circuit *circuit;
struct listnode *node;
int level = spftree->level;
/* Run reverse SPF locally. */
if (area->rlfa_protected_links[level - 1] > 0
|| area->tilfa_protected_links[level - 1] > 0)
spftree_reverse = isis_spf_reverse_run(spftree);
/* Run forward SPF on all adjacent routers. */
isis_spf_run_neighbors(spftree);
/* Check which interfaces are protected. */
for (ALL_LIST_ELEMENTS_RO(area->circuit_list, node, circuit)) {
struct lfa_protected_resource resource = {};
struct isis_adjacency *adj;
static uint8_t null_sysid[ISIS_SYS_ID_LEN + 1];
if (!(circuit->is_type & level))
continue;
if (!circuit->lfa_protection[level - 1]
&& !circuit->tilfa_protection[level - 1])
continue;
/* Fill in the protected resource. */
switch (circuit->circ_type) {
case CIRCUIT_T_BROADCAST:
if (level == ISIS_LEVEL1)
memcpy(resource.adjacency,
circuit->u.bc.l1_desig_is,
ISIS_SYS_ID_LEN + 1);
else
memcpy(resource.adjacency,
circuit->u.bc.l2_desig_is,
ISIS_SYS_ID_LEN + 1);
/* Do nothing if no DR was elected yet. */
if (!memcmp(resource.adjacency, null_sysid,
ISIS_SYS_ID_LEN + 1))
continue;
break;
case CIRCUIT_T_P2P:
adj = circuit->u.p2p.neighbor;
if (!adj)
continue;
memcpy(resource.adjacency, adj->sysid, ISIS_SYS_ID_LEN);
LSP_PSEUDO_ID(resource.adjacency) = 0;
break;
default:
continue;
}
if (circuit->lfa_protection[level - 1]) {
/* Run local LFA. */
isis_lfa_compute(area, circuit, spftree, &resource);
if (circuit->rlfa_protection[level - 1]) {
struct isis_spftree *spftree_pc;
uint32_t max_metric;
/* Run remote LFA. */
assert(spftree_reverse);
max_metric =
circuit->rlfa_max_metric[level - 1];
spftree_pc = isis_rlfa_compute(
area, spftree, spftree_reverse,
max_metric, &resource);
listnode_add(spftree->lfa.remote.pc_spftrees,
spftree_pc);
}
} else if (circuit->tilfa_protection[level - 1]) {
/* Run TI-LFA. */
assert(spftree_reverse);
isis_spf_run_tilfa(area, circuit, spftree,
spftree_reverse, &resource);
}
}
if (spftree_reverse)
isis_spftree_del(spftree_reverse);
}
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