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7.4 OSPF area

OSPF Command: area a.b.c.d range a.b.c.d/m
OSPF Command: area <0-4294967295> range a.b.c.d/m
OSPF Command: no area a.b.c.d range a.b.c.d/m
OSPF Command: no area <0-4294967295> range a.b.c.d/m

Summarize intra area paths from specified area into one Type-3 summary-LSA announced to other areas. This command can be used only in ABR and ONLY router-LSAs (Type-1) and network-LSAs (Type-2) (ie. LSAs with scope area) can be summarized. Type-5 AS-external-LSAs can’t be summarized - their scope is AS. Summarizing Type-7 AS-external-LSAs isn’t supported yet by Quagga.

router ospf
 network 192.168.1.0/24 area 0.0.0.0
 network 10.0.0.0/8 area 0.0.0.10
 area 0.0.0.10 range 10.0.0.0/8

With configuration above one Type-3 Summary-LSA with routing info 10.0.0.0/8 is announced into backbone area if area 0.0.0.10 contains at least one intra-area network (ie. described with router or network LSA) from this range.

OSPF Command: area a.b.c.d range IPV4_PREFIX not-advertise
OSPF Command: no area a.b.c.d range IPV4_PREFIX not-advertise

Instead of summarizing intra area paths filter them - ie. intra area paths from this range are not advertised into other areas. This command makes sense in ABR only.

OSPF Command: area a.b.c.d range IPV4_PREFIX substitute IPV4_PREFIX
OSPF Command: no area a.b.c.d range IPV4_PREFIX substitute IPV4_PREFIX

Substitute summarized prefix with another prefix.

router ospf
 network 192.168.1.0/24 area 0.0.0.0
 network 10.0.0.0/8 area 0.0.0.10
 area 0.0.0.10 range 10.0.0.0/8 substitute 11.0.0.0/8

One Type-3 summary-LSA with routing info 11.0.0.0/8 is announced into backbone area if area 0.0.0.10 contains at least one intra-area network (ie. described with router-LSA or network-LSA) from range 10.0.0.0/8. This command makes sense in ABR only.

OSPF Command: area a.b.c.d virtual-link a.b.c.d
OSPF Command: area <0-4294967295> virtual-link a.b.c.d
OSPF Command: no area a.b.c.d virtual-link a.b.c.d
OSPF Command: no area <0-4294967295> virtual-link a.b.c.d
OSPF Command: area a.b.c.d shortcut
OSPF Command: area <0-4294967295> shortcut
OSPF Command: no area a.b.c.d shortcut
OSPF Command: no area <0-4294967295> shortcut

Configure the area as Shortcut capable. See RFC3509. This requires that the ’abr-type’ be set to ’shortcut’.

OSPF Command: area a.b.c.d stub
OSPF Command: area <0-4294967295> stub
OSPF Command: no area a.b.c.d stub
OSPF Command: no area <0-4294967295> stub

Configure the area to be a stub area. That is, an area where no router originates routes external to OSPF and hence an area where all external routes are via the ABR(s). Hence, ABRs for such an area do not need to pass AS-External LSAs (type-5s) or ASBR-Summary LSAs (type-4) into the area. They need only pass Network-Summary (type-3) LSAs into such an area, along with a default-route summary.

OSPF Command: area a.b.c.d stub no-summary
OSPF Command: area <0-4294967295> stub no-summary
OSPF Command: no area a.b.c.d stub no-summary
OSPF Command: no area <0-4294967295> stub no-summary

Prevents an ospfd ABR from injecting inter-area summaries into the specified stub area.

OSPF Command: area a.b.c.d default-cost <0-16777215>
OSPF Command: no area a.b.c.d default-cost <0-16777215>

Set the cost of default-summary LSAs announced to stubby areas.

OSPF Command: area a.b.c.d export-list NAME
OSPF Command: area <0-4294967295> export-list NAME
OSPF Command: no area a.b.c.d export-list NAME
OSPF Command: no area <0-4294967295> export-list NAME

Filter Type-3 summary-LSAs announced to other areas originated from intra- area paths from specified area.

router ospf
 network 192.168.1.0/24 area 0.0.0.0
 network 10.0.0.0/8 area 0.0.0.10
 area 0.0.0.10 export-list foo
!
access-list foo permit 10.10.0.0/16
access-list foo deny any

With example above any intra-area paths from area 0.0.0.10 and from range 10.10.0.0/16 (for example 10.10.1.0/24 and 10.10.2.128/30) are announced into other areas as Type-3 summary-LSA’s, but any others (for example 10.11.0.0/16 or 10.128.30.16/30) aren’t.

This command is only relevant if the router is an ABR for the specified area.

OSPF Command: area a.b.c.d import-list NAME
OSPF Command: area <0-4294967295> import-list NAME
OSPF Command: no area a.b.c.d import-list NAME
OSPF Command: no area <0-4294967295> import-list NAME

Same as export-list, but it applies to paths announced into specified area as Type-3 summary-LSAs.

OSPF Command: area a.b.c.d filter-list prefix NAME in
OSPF Command: area a.b.c.d filter-list prefix NAME out
OSPF Command: area <0-4294967295> filter-list prefix NAME in
OSPF Command: area <0-4294967295> filter-list prefix NAME out
OSPF Command: no area a.b.c.d filter-list prefix NAME in
OSPF Command: no area a.b.c.d filter-list prefix NAME out
OSPF Command: no area <0-4294967295> filter-list prefix NAME in
OSPF Command: no area <0-4294967295> filter-list prefix NAME out

Filtering Type-3 summary-LSAs to/from area using prefix lists. This command makes sense in ABR only.

OSPF Command: area a.b.c.d authentication
OSPF Command: area <0-4294967295> authentication
OSPF Command: no area a.b.c.d authentication
OSPF Command: no area <0-4294967295> authentication

Specify that simple password authentication should be used for the given area.

OSPF Command: area a.b.c.d authentication message-digest
OSPF Command: area <0-4294967295> authentication message-digest

Specify that OSPF packets must be authenticated with MD5 HMACs within the given area. Keying material must also be configured on a per-interface basis (see ip ospf message-digest-key).

MD5 authentication may also be configured on a per-interface basis (see ip ospf authentication message-digest). Such per-interface settings will override any per-area authentication setting.


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