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TI-LFA is a modern fast-reroute (FRR) solution that leverages Segment Routing to pre-compute backup nexthops for all destinations in the network, helping to reduce traffic restoration times whenever a failure occurs. The backup nexthops are expected to be installed in the FIB so that they can be activated as soon as a failure is detected, making sub-50ms recovery possible (assuming an hierarchical FIB). TI-LFA is a huge step forward compared to prior IP-FRR solutions, like classic LFA and Remote LFA, as it guarantees 100% coverage for all destinations. This is possible thanks to the source routing capabilities of SR, which allows the backup nexthops to steer traffic around the failures (using as many SIDs as necessary). In addition to that, the repair paths always follow the post-convergence SPF tree, which prevents transient congestions and suboptimal routing from happening. Deploying TI-LFA is very simple as it only requires a single configuration command for each interface that needs to be protected (both link protection and node protection are available). In addition to IPv4 and IPv6 routes, SR Prefix-SIDs and Adj-SIDs are also protected by the backup nexthops computed by the TI-LFA algorithms. Signed-off-by: Renato Westphal <renato@opensourcerouting.org>
80 lines
2.8 KiB
C
80 lines
2.8 KiB
C
/*
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* IS-IS Rout(e)ing protocol - isis_spf.h
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* IS-IS Shortest Path First algorithm
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*
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* Copyright (C) 2001,2002 Sampo Saaristo
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* Tampere University of Technology
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* Institute of Communications Engineering
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public Licenseas published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; see the file COPYING; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _ZEBRA_ISIS_SPF_H
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#define _ZEBRA_ISIS_SPF_H
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#include "isisd/isis_lfa.h"
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struct isis_spftree;
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enum spf_type {
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SPF_TYPE_FORWARD = 1,
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SPF_TYPE_REVERSE,
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SPF_TYPE_TI_LFA,
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};
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struct isis_spf_adj {
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uint8_t id[ISIS_SYS_ID_LEN + 1];
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struct isis_adjacency *adj;
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uint32_t metric;
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struct isis_ext_subtlvs *subtlvs;
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struct {
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uint8_t desig_is_id[ISIS_SYS_ID_LEN + 1];
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struct isis_lsp *lsp_pseudo;
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} lan;
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uint8_t flags;
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#define F_ISIS_SPF_ADJ_BROADCAST 0x01
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#define F_ISIS_SPF_ADJ_OLDMETRIC 0x02
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};
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struct isis_spftree *isis_spftree_new(struct isis_area *area,
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struct lspdb_head *lspdb,
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const uint8_t *sysid, int level,
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enum spf_tree_id tree_id,
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enum spf_type type, uint8_t flags);
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void isis_spf_invalidate_routes(struct isis_spftree *tree);
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void isis_spf_verify_routes(struct isis_area *area,
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struct isis_spftree **trees);
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void isis_spftree_del(struct isis_spftree *spftree);
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void spftree_area_init(struct isis_area *area);
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void spftree_area_del(struct isis_area *area);
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struct isis_lsp *isis_root_system_lsp(struct lspdb_head *lspdb,
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const uint8_t *sysid);
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#define isis_spf_schedule(area, level) \
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_isis_spf_schedule((area), (level), __func__, \
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__FILE__, __LINE__)
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int _isis_spf_schedule(struct isis_area *area, int level,
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const char *func, const char *file, int line);
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void isis_print_spftree(struct vty *vty, struct isis_spftree *spftree);
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void isis_print_routes(struct vty *vty, struct isis_spftree *spftree,
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bool backup);
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void isis_spf_init(void);
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void isis_spf_print(struct isis_spftree *spftree, struct vty *vty);
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void isis_run_spf(struct isis_spftree *spftree);
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struct isis_spftree *isis_run_hopcount_spf(struct isis_area *area,
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uint8_t *sysid,
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struct isis_spftree *spftree);
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#endif /* _ZEBRA_ISIS_SPF_H */
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