louis-6wind · louis-6wind · Dec 11, 2021 · Dec 11, 2021 · Dec 11, 2021 · Dec 18, 2021
diff --git a/doc/user/isisd.rst b/doc/user/isisd.rst
@@ -295,12 +295,12 @@ Showing ISIS information
    Show the ISIS database globally, for a specific LSP id without or with
    details.
 
-.. clicmd:: show isis topology [level-1|level-2]
+.. clicmd:: show isis topology [level-1|level-2] [algorithm (128-255)]
 
    Show topology IS-IS paths to Intermediate Systems, globally, in area
    (level-1) or domain (level-2).
 
-.. clicmd:: show isis route [level-1|level-2] [prefix-sid|backup]
+.. clicmd:: show isis route [level-1|level-2] [prefix-sid|backup] [algorithm (128-255)]
 
    Show the ISIS routing table, as determined by the most recent SPF
    calculation.
@@ -368,8 +368,7 @@ Traffic Engineering
 
    :ref:`ospf-traffic-engineering`
 
-
-.. _debugging-isis:
+.. _isis-segment-routing:
 
 Segment Routing
 ===============
@@ -402,7 +401,7 @@ Known limitations:
    MPLS dataplane. E.g. for Linux kernel, since version 4.13 the maximum value
    is 32.
 
-.. clicmd:: segment-routing prefix <A.B.C.D/M|X:X::X:X/M> <absolute (16-1048575)|index (0-65535) [no-php-flag|explicit-null] [n-flag-clear]
+.. clicmd:: segment-routing prefix <A.B.C.D/M|X:X::X:X/M> [algorithm (128-255)] <absolute (16-1048575)|index (0-65535) [no-php-flag|explicit-null] [n-flag-clear]
 
    prefix. The 'no-php-flag' means NO Penultimate Hop Popping that allows SR
    node to request to its neighbor to not pop the label. The 'explicit-null'
@@ -411,10 +410,164 @@ Known limitations:
    clear the Node flag that is set by default for Prefix-SIDs associated to
    loopback addresses. This option is necessary to configure Anycast-SIDs.
 
-.. clicmd:: show isis segment-routing node
+.. clicmd:: show isis segment-routing node [algorithm (128-255)]
 
    Show detailed information about all learned Segment Routing Nodes.
 
+.. _isis-flex-algo:
+
+Flex-Algos (Flex-Algo)
+===============================
+
+*isisd* supports some features of :t:`draft-ietf-lsr-Flex-Algo` on an MPLS
+Segment-Routing dataplane. The compatibility has been tested against Cisco.
+
+IS-IS uses by default the `Shortest-Path-First` algorithm that basically
+calculates paths based on the shortest total metric to the destinations.
+Flex-Algo allows new algorithms to run in parallel to compute paths in different
+manners, based on metrics (IGP metric or a new type of metrics such as Traffic
+Engineering (TE) metric and minimum delay...) and constraints. New metric types
+are not yet implemented but constraints are already operational. Constraints can
+restrict paths to links with specific affinities or avoid links with specific
+affinities. Combinations of these are also possible.
+
+The administrator can configure up to 128 Flex-Algos in an IS-IS area.
+To do so, it defines a set of Flex-Algo Definitions (FAD) which
+have the following characteristics:
+
+- a numeric identifier (ID) between 128 and 255 inclusive
+- a set of constraints (basically, include or exclude a certain given set of
+	links, designated by a admin-group)
+- the calculation type (only the `Shortest-Path-First` is currently supported)
+- the metric type (only the IGP inherited metric type is currently supported)
+- some additional flags (not supported for the moment).
+
+A subset of routers advertises the Flex-Algo Definitions (FAD) to the other
+routers within an area. In order to use a common set of FADs, each router runs a
+FAD election process for each locally configured algorithm, using the following
+rules:
+
+- If a locally configured FAD is not advertised to the area, the router does not
+	participate in the particular flex algorithm.
+- If a given flex algorithm is running, the participation in this particular
+	flex algorithm stops when its advertisements are over.
+- A router includes its own FAD in the election process if and only if it is
+	advertised to the other routers.
+- If only one router advertises the FAD, the FAD is elected.
+- If several FADs are advertised with different priorities, the one with the
+	highest priority value is selected.
+- If there are multiple advertisements of the FAD with the same highest
+	priority, the FAD of the router with the highest IS-IS system-ID is
+	selected.
+
+
+Routers only use the specifications of the elected FAD regardless of the locally
+configured definitions. If a router does not support one of the FAD
+characteristics, it stops participating in the Flex-Algo.
+
+For each running Flex-Algo, the Segment-Routing SIDs must be
+configured with values unique to the algorithm. It allows routers to identify
+which flex algorithm they must use for a given packet.
+
+The following commands configure Flex-Algo at the 'router isis' configuration
+level. Segment-Routing prefixes must be configured for the Flex-Algo.
+
+.. clicmd:: flexible-algorithm (128-255)
+
+   Add a Flex-Algo Definition (FAD) and enter the FAD configuration
+   level. The algorithm ID value is in the range of 128 to 255 inclusive.
+
+.. clicmd:: no flexible-algorithm (128-255)
+
+   Unconfigure a Flex-Algo Definition.
+
+.. clicmd:: affinity-map NAME bit-position (0-255)
+
+   Add the specified 'affinity-map'. Affinity-map definitions are used in
+   FADs and in interfaces admin-group definition.
+
+   Affinity-maps format in advertisement TLVs use the extended admin-group
+   format defined in the RFC7308 section 2.2. The extended admin-group uses a
+   256 bits field. If an affinity-map is set, the bit at the extended
+   admin-group 'bit-position' is set 1, else it is set to 0.
+
+The following commands configure Flex-Algo at the 'router isis' and
+'flexible-algorithm (128-255)' configuration level.
+
+.. clicmd:: advertise-definition
+
+   Advertise the current FAD to other IS-IS routers by using specific IS-IS
+   TLVs. By default, the definition is is not shared with other routers.
+
+   A router can advertise a FAD without participating in the Flex-Algo.
+
+.. clicmd:: priority (0-255)
+
+   Set the specified 'priority' in the current FAD advertisements .
+
+.. clicmd:: metric-type [igp|te|delay]
+
+   Set the 'metric-type' for the current FAD. 'igp' is
+   the default value and refers to the classic 'Shortest-Path-First' algorithm.
+   If the 'te' or the 'delay' metric is selected, the value is advertised but
+   the flex algorithm is disabled locally because these types are not currently
+   supported.
+
+.. clicmd:: no metric-type
+
+   Reset the 'metric-type' to the default 'igp' metric.
+
+.. clicmd:: affinity exclude-any NAME
+
+   Add the specified affinity to the list of exclude-any affinities. The
+   Flex-Algo will compute paths that exclude the segments with any of
+   the specified affinities.
+
+.. clicmd:: no affinity exclude-any NAME
+
+   Remove the specified affinity to the list of exclude-any affinities.
+
+.. clicmd:: affinity include-all NAME
+
+   Add the specified affinity to the list of include-all affinities. The
+   Flex-Algo will compute paths that include the segments with all
+   the specified affinities.
+
+.. clicmd:: no affinity include-all NAME
+
+   Remove the specified affinity to the list of include-all affinities.
+
+.. clicmd:: affinity include-any NAME
+
+   Add the specified affinity to the list of include-any affinities. The
+   Flex-Algo will compute paths that include the segments with any of
+   the specified affinities.
+
+.. clicmd:: no affinity include-any NAME
+
+   Remove the specified affinity to the list of include-any affinities.
+
+The following commands configure Flex-Algo at the 'interface' configuration
+level.
+
+.. clicmd:: isis affinity flex-algo NAME
+
+	Add the specified affinity to the interface.
+
+.. clicmd:: no isis affinity flex-algo NAME
+
+	Remove the specified affinity from the interface.
+
+The following command show Flex-Algo information:
+
+.. clicmd:: show isis flex-algo [(128-255)]
+
+	Show information about the elected FADs
+
+'show isis route', 'show isis topology' and 'show isis segment-routing node'
+includes an 'algorithm (128-255)' optional argument. See
+:ref:`showing-isis-information` and :ref:`isis-segment-routing`.
+
 Debugging ISIS
 ==============
 

diff --git a/isisd/fabricd.c b/isisd/fabricd.c
@@ -220,10 +220,10 @@ struct fabricd *fabricd_new(struct isis_area *area)
 	rv->area = area;
 	rv->initial_sync_state = FABRICD_SYNC_PENDING;
 
-	rv->spftree =
-		isis_spftree_new(area, &area->lspdb[IS_LEVEL_2 - 1],
-				 area->isis->sysid, ISIS_LEVEL2, SPFTREE_IPV4,
-				 SPF_TYPE_FORWARD, F_SPFTREE_HOPCOUNT_METRIC);
+	rv->spftree = isis_spftree_new(
+		area, &area->lspdb[IS_LEVEL_2 - 1], area->isis->sysid,
+		ISIS_LEVEL2, SPFTREE_IPV4, SPF_TYPE_FORWARD,
+		F_SPFTREE_HOPCOUNT_METRIC, SR_ALGORITHM_SPF);
 	rv->neighbors = skiplist_new(0, neighbor_entry_list_cmp,
 				     neighbor_entry_del_void);
 	rv->neighbors_neighbors = hash_create(neighbor_entry_hash_key,

diff --git a/isisd/isis_circuit.c b/isisd/isis_circuit.c
@@ -177,6 +177,7 @@ struct isis_circuit *isis_circuit_new(struct interface *ifp, const char *tag)
 	circuit_mt_init(circuit);
 	isis_lfa_excluded_ifaces_init(circuit, ISIS_LEVEL1);
 	isis_lfa_excluded_ifaces_init(circuit, ISIS_LEVEL2);
+	circuit->affinity_flex_algo = list_new();
 
 	circuit->ldp_sync_info = ldp_sync_info_create();
 	circuit->ldp_sync_info->enabled = LDP_IGP_SYNC_ENABLED;
@@ -212,6 +213,7 @@ void isis_circuit_del(struct isis_circuit *circuit)
 	circuit_mt_finish(circuit);
 	isis_lfa_excluded_ifaces_clear(circuit, ISIS_LEVEL1);
 	isis_lfa_excluded_ifaces_clear(circuit, ISIS_LEVEL2);
+	list_delete(&circuit->affinity_flex_algo);
 
 	list_delete(&circuit->ip_addrs);
 	list_delete(&circuit->ipv6_link);

diff --git a/isisd/isis_circuit.h b/isisd/isis_circuit.h
@@ -179,6 +179,14 @@ struct isis_circuit {
 				    */
 	struct list *snmp_adj_list; /* List in id order */
 
+	/*
+	 * ASLA for Flex-Algo
+	 * It records affinity color names as "const char *" used by the
+	 * circuit. The resulting bitmap of interface admin group is
+	 * generated on-demand when the lsp_build with affinity maps.
+	 */
+	struct list *affinity_flex_algo;
+
 	QOBJ_FIELDS;
 };
 DECLARE_QOBJ_TYPE(isis_circuit);