ospfd: add support for suppress_fa

This command will trigger the OSPF forwarding address suppression in
translated type-5 LSAs, causing a NSSA ABR to use 0.0.0.0 as a forwarding
address instead of copying the address from the type-7 LSA

Example: In a topology like: R1 --- R2(ABR) --- R3(ASBR)

R3 is announcing a type-7 LSA that is translated to type-5 by the R2 ABR.
The forwarding address in the type-5 is by default copied from the type-7

    r1# sh ip os da external

                    AS External Link States

      LS age: 6
      Options: 0x2  : *|-|-|-|-|-|E|-
      LS Flags: 0x6
      LS Type: AS-external-LSA
      Link State ID: 3.3.3.3 (External Network Number)
      Advertising Router: 10.0.25.2
      LS Seq Number: 80000001
      Checksum: 0xcf99
      Length: 36

      Network Mask: /32
            Metric Type: 2 (Larger than any link state path)
            TOS: 0
            Metric: 20
            Forward Address: 10.0.23.3    <--- address copied from type-7 lsa
            External Route Tag: 0

    r2# sh ip os database

                    NSSA-external Link States (Area 0.0.0.1 [NSSA])

    Link ID         ADV Router      Age  Seq#       CkSum  Route
    3.3.3.3         10.0.23.3          8 0x80000001 0x431d E2 3.3.3.3/32 [0x0]

                    AS External Link States

    Link ID         ADV Router      Age  Seq#       CkSum  Route
    3.3.3.3         10.0.25.2          0 0x80000001 0xcf99 E2 3.3.3.3/32 [0x0]

    r2# conf t
    r2(config)# router ospf
    r2(config-router)# area 1 nssa suppress-fa
    r2(config-router)# exit
    r2(config)# exit

    r2# sh ip os database

                    NSSA-external Link States (Area 0.0.0.1 [NSSA])

    Link ID         ADV Router      Age  Seq#       CkSum  Route
    3.3.3.3         10.0.23.3         66 0x80000001 0x431d E2 3.3.3.3/32 [0x0]

                    AS External Link States

    Link ID         ADV Router      Age  Seq#       CkSum  Route
    3.3.3.3         10.0.25.2         16 0x80000002 0x0983 E2 3.3.3.3/32 [0x0]

    r1# sh ip os da external

           OSPF Router with ID (11.11.11.11)

                    AS External Link States

      LS age: 34
      Options: 0x2  : *|-|-|-|-|-|E|-
      LS Flags: 0x6
      LS Type: AS-external-LSA
      Link State ID: 3.3.3.3 (External Network Number)
      Advertising Router: 10.0.25.2
      LS Seq Number: 80000002
      Checksum: 0x0983
      Length: 36

      Network Mask: /32
            Metric Type: 2 (Larger than any link state path)
            TOS: 0
            Metric: 20
            Forward Address: 0.0.0.0       <--- address set to 0
            External Route Tag: 0

    r2# conf t
    r2(config)# router ospf
    r2(config-router)# no area 1 nssa suppress-fa
    r2(config-router)# exit

    r1# sh ip os da external

           OSPF Router with ID (11.11.11.11)

                    AS External Link States

      LS age: 1
      Options: 0x2  : *|-|-|-|-|-|E|-
      LS Flags: 0x6
      LS Type: AS-external-LSA
      Link State ID: 3.3.3.3 (External Network Number)
      Advertising Router: 10.0.25.2
      LS Seq Number: 80000003
      Checksum: 0xcb9b
      Length: 36
      Network Mask: /32
            Metric Type: 2 (Larger than any link state path)
            TOS: 0
            Metric: 20
            Forward Address: 0.0.0.0       <--- address set to 0
            External Route Tag: 0

    r2# conf t
    r2(config)# router ospf
    r2(config-router)# no area 1 nssa suppress-fa
    r2(config-router)# exit

    r1# sh ip os da external

           OSPF Router with ID (11.11.11.11)

                    AS External Link States

      LS age: 1
      Options: 0x2  : *|-|-|-|-|-|E|-
      LS Flags: 0x6
      LS Type: AS-external-LSA
      Link State ID: 3.3.3.3 (External Network Number)
      Advertising Router: 10.0.25.2
      LS Seq Number: 80000003
      Checksum: 0xcb9b
      Length: 36

      Network Mask: /32
            Metric Type: 2 (Larger than any link state path)
            TOS: 0
            Metric: 20
            Forward Address: 10.0.23.3    <--- address copied from type-7 lsa
            External Route Tag: 0

Signed-off-by: ckishimo <carles.kishimoto@gmail.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/ospfd/ospfd.c b/ospfd/ospfd.c
index 9856e6013..f126577ae 100644
--- a/ospfd/ospfd.c
+++ b/ospfd/ospfd.c
@@ -1672,6 +1672,7 @@ int ospf_area_nssa_set(struct ospf *ospf, struct in_addr area_id)
 
 		/* set NSSA area defaults */
 		area->no_summary = 0;
+		area->suppress_fa = 0;
 		area->NSSATranslatorRole = OSPF_NSSA_ROLE_CANDIDATE;
 		area->NSSATranslatorState = OSPF_NSSA_TRANSLATE_DISABLED;
 		area->NSSATranslatorStabilityInterval =
@@ -1693,6 +1694,7 @@ int ospf_area_nssa_unset(struct ospf *ospf, struct in_addr area_id, int argc)
 		ospf->anyNSSA--;
 		/* set NSSA area defaults */
 		area->no_summary = 0;
+		area->suppress_fa = 0;
 		area->NSSATranslatorRole = OSPF_NSSA_ROLE_CANDIDATE;
 		area->NSSATranslatorState = OSPF_NSSA_TRANSLATE_DISABLED;
 		area->NSSATranslatorStabilityInterval =
@@ -1708,6 +1710,32 @@ int ospf_area_nssa_unset(struct ospf *ospf, struct in_addr area_id, int argc)
 	return 1;
 }
 
+int ospf_area_nssa_suppress_fa_set(struct ospf *ospf, struct in_addr area_id)
+{
+	struct ospf_area *area;
+
+	area = ospf_area_lookup_by_area_id(ospf, area_id);
+	if (area == NULL)
+		return 0;
+
+	area->suppress_fa = 1;
+
+	return 1;
+}
+
+int ospf_area_nssa_suppress_fa_unset(struct ospf *ospf, struct in_addr area_id)
+{
+	struct ospf_area *area;
+
+	area = ospf_area_lookup_by_area_id(ospf, area_id);
+	if (area == NULL)
+		return 0;
+
+	area->suppress_fa = 0;
+
+	return 1;
+}
+
 int ospf_area_nssa_translator_role_set(struct ospf *ospf,
 				       struct in_addr area_id, int role)
 {