C H A P T E R  7

Feedback OSPF

OSPF protocol is an IGP used to distribute routing information within a single autonomous system. Routers use link-state algorithms to send routing information to all nodes in an inter-network by calculating the shortest path to each node based on topography of the Internet constructed by each node. Each router sends that portion of the routing table (keeps track of routes to particular network destinations), which describes the state of its own links, and it also sends the complete routing structure (topography).

The advantage of shortest-path-first algorithms is that they result in smaller, more frequent updates everywhere. They converge quickly, thus preventing such problems as routing loops and count-to-infinity (when routers continuously increment the hop count to a particular network). This makes for a stable network.

All OSPF interface related configurations can be done only when the global OSPF is enabled.

The multiple instances feature is not supported.


7.1 OSPF Commands

The list of CLI commands for the configuration of OSPF is as follows:

7.1.1 router ospf

Enables OSPF routing process. The no form of the command disables OSPF routing process.


router ospf


no router ospf


Mode

Global Configuration

Example

SEFOS(config)# router ospf

Notes

The command no router ospf disables the OSPF router admin status to terminate the OSPF process.


Related Commands

7.1.2 router ospf - process-id

Note - This command is not supported.

Enables the OSPF routing process. The no form of the command disables the OSPF routing process. This command operates similarly to the command router ospf.


router ospf process-id_1-65535


no router ospf process-id_1-65535


Syntax Description

process-id_1-65535 - OSPF process identifier. This value ranges between 1 and 65535. This parameter is not currently supported.

Mode

Global Configuration

The no form of the command can also be executed in Router Configuration.

Example

SEFOS(config)# router ospf 1


Related Commands

7.1.3 router-id

Sets the router identifier for the OSPF process.


router-id <router ip address>


Syntax Description

router ip address - Specifies the OSPF router ID as an IP address.

Mode

Router Configuration

Example

SEFOS(config-router)# router-id 10.0.0.1

Notes

An arbitrary value for the IP address for each router can be configured. However, each router ID must be unique. To ensure uniqueness, the router identifier must match one of the router’s IP interface addresses.


Related Commands

7.1.4 area - stability interval

Configures the stability interval NSSA. The no form of the command configures default stability interval for NSSA.


area area-id stability-interval interval-value_0-0x7fffffff


no area area-id stability-interval


Syntax Description

area-id - Area associated with the OSPF address range. It is specified as an IP address.

stability-interval - The number of seconds after an elected translator determines its services are no longer required, during which time it must continue to perform its translation duties.

Mode

Router Configuration

Defaults

40

Example

SEFOS(config-router)# area 10.0.0.1 stability-interval 10000

Notes

Area identifier 0.0.0.0 is used for the OSPF backbone.

The OSPF sequence number is a 32-bit signed integer. It starts with the value ’80000001’h, -- or -’7FFFFFFF’h, and increments until ’7FFFFFFF’h. Thus, a typical sequence number will be very negative.


Related Commands

7.1.5 area - translation-role

Configures the translation role for the NSSA. The no form of the command configures the default translation role for the NSSA.


area area-id translation-role {always | candidate}


no area area-id translation-role


Syntax Description

area-id - Area associated with the OSPF address range. It is specified as an IP address.

translation-role - An NSSA Border router’s ability to perform NSSA Translation of Type-7 LSAs to Type-5 LSAs.

Mode

Router Configuration

Defaults

candidate

Example

SEFOS(config-router)# area 10.0.0.1 translation-role always

Notes

Type-5 LSAs - Originated by AS boundary routers, and flooded throughout the AS. Each AS-external-LSA describes a route to a destination in another autonomous system. Default routes for the AS can also be described by AS-external-LSAs.


Related Commands

7.1.6 compatible rfc1583

Sets the OSPF compatibility list compatible with RFC 1583. The no form of the command disables RFC 1583 compatibility.


compatible rfc1583


no compatible rfc1583


Mode

Router Configuration

Defaults

compatible rfc1583

Example

SEFOS(config-router)# compatible rfc1583

Notes

  • This command enables support of RFC1583 compatibility in products that support later standards.
  • It controls the preference rules, when choosing among multiple AS external LSAs advertising the same destination. When set to compatible rfc1583, the preference rules remain those specified by RFC 1583. When set to no compatible rfc1583, the preference rules are those stated in RFC 2178.
  • To minimize the chance of routing loops, all OSPF routers in an OSPF routing domain must have RFC compatibility set identically.

7.1.7 abr-type

Sets the alternative ABR type.


abr-type {standard | cisco | ibm}


Syntax Description

standard - Standard ABR type as defined in RFC 2328.

cisco - CISCO ABR type as defined in RFC 3509.

ibm - IBM ABR type as defined in RFC 3509.

Mode

Router Configuration

Defaults

standard

Example

SEFOS(config-router)# abr-type standard

Notes

  • RFC 2328 - OSPF version 2.
  • RFC-3509 - Alternative implementations of OSPF area border routers.

Related Commands

7.1.8 neighbor

Specifies a neighbor router and its priority. The no form of the command removes the neighbor set default value for the neighbor priority.


neighbor neighbor-id [priority 0-255]


no neighbor neighbor-id [priority]


Syntax Description

neighbor-id - Neighbor router identifier.

priority - A number value that specifies the router priority.

poll-interval seconds - A number value that represents the poll interval time.

cost 1-65535 - Assigns a cost value to the neighbor. This value ranges between 1 and 65535.

database-filter all - Filters the outgoing link-state advertisements provided to an OSPF neighbor.

Mode

Router Configuration

Defaults

priority

Example

SEFOS(config-router)# neighbor 20.0.0.1 priority 25

Notes

The value 0 signifies that the neighbor is not eligible to become the designated router on this particular network.


Related Commands

7.1.9 area area-id default-cost

Specifies a cost for the default summary route sent into a stub or NSSA. The no form of the command removes the assigned default route cost.


area area-id default-cost cost [tos 0-30]


no area area-id default-cost cost [tos 0-30]


Syntax Description

area-id - Area associated with the OSPF address range. It is specified as an IP address.

default-cost - Cost for the default summary route used for a stub area.

tos - Type of service of the route being configured.

Mode

Router Configuration

Defaults

default-cost - 10

tos - 0

Example

SEFOS(config-router)# area 10.0.0.1 default-cost 5

Notes

  • A default cost can be defined only for a valid area.
  • The only supported tos value is 0.
  • In the area 0.0.0.0, the default-cost and the tos must be set at the same time. If setting only the default-cost, SEFOS does not accept the command and a message similar to the following is displayed: Invalid Metric.Exceeded the range
  • The tos range of 0-30 is also not accepted.

Related Commands

7.1.10 area area-id nssa

Configures an area as a NSSA and other parameters related to that area.


area area-id nssa [{no-summary | default-information-originate [metric value] [metric-type type_1-3] [tos 0-30]]


Syntax Description

area-id - Area associated with the OSPF address range. It is specified as an IP address.

nssa - Configures an area as a not-so-stubby area (NSSA).

no-summary - Allows an area to be a not-so-stubby area without requiring injection of summary routes.

default-information-originate - Default route into OSPF. Possible values:

  • metric - The Metric value applied to the route before it is advertised into the OSPF domain.
  • metric-type - The metric type applied to the route before it is advertised into the OSPF domain.
  • tos - Type of service of the route being configured. The only supported tos value is 0.

Mode

Router Configuration

Defaults

metric - 10

metric-type - 1

tos - 0

Example

SEFOS(config-router)# area 40.0.0.1 nssa

SEFOS(config-router)# area 40.0.0.1 nssa no-sum

SEFOS(config-router)# area 40.0.0.1 nssa default-information-originate metric 8

Notes

The no area area-id [{stub | nssa}] command removes an area or converts stub or nssa to normal area.


Related Commands

7.1.11 area area-id stub

Specifies an area as a stub area and other parameters related to that area. The no form of the command removes an area or converts stub/nssa to normal area.


area area-id stub [no-summary]


no area area-id [{stub [no-summary] | nssa [no-redistribution] [default-information-originate [metric value] [metric-type type_1-3]] [no-summary]}]]


Syntax Description

area-id - Area associated with the OSPF address range. It is specified as an IP address.

stub - Configures an area as a stub area.

no-summary - The router will neither originate nor propagate summary LSAs into the stub area. This option is not currently supported with the no form of the command.

nssa - Configures an area as a not-so-stubby area (NSSA).

no-redistribution - Imports routes only into the normal areas, but not into the NSSA area.

default-information-originate - Default route into OSPF.

metric - The metric value applied to the route before it is advertised into the OSPF domain.

metric-type - The metric type applied to the route before it is advertised into the OSPF domain.

Mode

Router Configuration

Example

SEFOS(config-router)# area 10.0.0.1 stub

Notes

The command must be configured on all routers and access servers in the stub area.


Related Commands

7.1.12 default-information originate always

Enables generation of a default external route into an OSPF routing domain and other parameters related to that area. The no form of the command disables generation of a default external route into an OSPF routing domain.


default-information originate always [metric metric-value_0-0xffffff] [metric-type type_1-2]


no default-information originate always [metric metric-value_0-0xffffff] [metric-type type_1-2]


Syntax Description

metric - The metric value applied to the route before it is advertised into the OSPF domain.

metric-type - The metric type applied to the route before it is advertised into the OSPF domain.

Mode

Router Configuration

Defaults

metric - 10

metric-type - 2

Example

SEFOS(config-router)# default-information originate always metric 1 metric-type 1

Notes

The [route-map route-map-name] option is not supported.


Related Commands

7.1.13 default-information originate

Enables the generation of a default external route into an OSPF routing domain. The no form of the command disables the generation of a default external route into an OSPF routing domain. This command operates similarly to the command default-information originate always.


default-information originate {[always] [metric metric-value_0-0xffffff] [metric-type type_1-2] [route-map route-map-name]}


no default-information originate {[always] [metric metric-value_0-0xffffff] [metric-type type_1-2] [route-map route-map-name]}


Syntax Description

always - Always advertises the default route regardless of whether the software has a default route.

metric metric-value - Metric value to be applied to the route before it is advertised into the OSPF Domain. This value ranges between 0 and 0xffffff.

metric-type - Metric type to be applied to the route before it is advertised into the OSPF Domain. The type can be as follows:

  • 1 - Type 1 external route.
  • 2 - Type 2 external route.

route-map - Route map name to be satisfied for the routing process to generate the default route.

Mode

Router Configuration

Defaults

metric - 10

metric-type - 2

Example

SEFOS(config-router)# default-information originate always metric 1 metric-type 1

Notes

The [route-map route-map-name] option is not supported.


Related Commands

7.1.14 area - virtual-link

Defines an OSPF virtual link and its related parameters. The no form of removes an OSPF virtual link.


area area-id virtual-link router-id [authentication {simple | message-digest | null}] [hello-interval 1-65535] [retransmit-interval 0-3600] [transmit-delay 0-3600] [dead-interval value] [{authentication-key key_8 | message-digest-key key-id_0-255 md5 key_16}]


no area area-id virtual-link router-id [authentication] [hello-interval] [retransmit-interval] [transmit-delay] [dead-interval] [{authentication-key | message-digest-key key-id_0-255}]


Syntax Description

area-id - The Transit Area that the Virtual Link traverses. It is specified as an IP address.

virtual-link - The Router ID of the Virtual Neighbor.

authentication - The authentication type for an interface.

hello-interval - The interval between hello packets that the software sends on the OSPF virtual link interface.

retransmit-interval - The time between link-state advertisement (LSA) retransmissions for adjacencies belonging to the OSPF virtual link interface.

transmit-delay - The time the router will stop using this key for packets generation.

dead-interval - The interval at which hello packets must not be seen before its neighbors declare the router down. (The range of values for the dead interval is 0-0x7fffffff.)

authentication-key - Identifies the secret key used to create the message digest appended to the OSPF packet.

message-digest-key - OSPF MD5 authentication. Enables Message Digest 5 (MD5) authentication on the area specified by the area-id.

md5 - The secret key which is used to create the message digest appended to the OSPF packet.

Mode

Router Configuration

Defaults

authentication - null

hello-interval - 10

retransmit-interval - 5

transmit-delay - 1

dead-interval - 40

Example

SEFOS(config-router)# area 10.0.0.1 virtual-link 20.0.0.1 authentication message-digest hello-interval 100 retransmit-interval 100 transmit-delay 50 dead-interval 200 authentication-key asdf

Notes

  • In OSPF, all areas must be connected to a backbone area. If the connection to the backbone is lost, it can be repaired by establishing a virtual link.
  • hello-interval and dead-interval: The value must be the same for all routers and access servers on a specific network.

Related Commands

7.1.15 asbr router

Specifies this router as ASBR. The no form of the command disables this router as ASBR.


asbr router


no asbr router


Mode

Router Configuration

Example

SEFOS(config-router)# asbr router

Notes

Routers that act as gateways (redistribution) between OSPF and other routing protocols (IGRP, EIGRP, RIP, BGP, Static) or other instances of the OSPF routing process are called (ASBR).


Related Commands

7.1.16 area - range

Consolidates and summarizes routes at an area boundary. The no form of the command deletes the summary address.


area area-id range network mask {summary | type7} [{advertise | not-advertise}] [tag value]


no area area-id range network mask [{advertise | not-advertise}] [tag tag-value] [cost value]


Syntax Description

area-id - Area associated with the OSPF address range. It is specified as an IP address.

range - OSPF address range.

network - The IP address of the Net indicated by the range.

Mask - The subnet mask that pertains to the range.

summary - Summary LSAs.

type7 - Type-7 LSA.

advertise - When associated area identifier (area-id) is 0.0.0.0, aggregated Type-5 are generated. Otherwise if associated area-id is x.x.x.x (other than 0.0.0.0) aggregated Type-7 is generated in NSSA x.x.x.x.

not-advertise - When associated area-id is 0.0.0.0, Type-5 is not generated for the specified range, while aggregated Type-7 are generated in all attached NSSA. While if associated area-id is x.x.x.x (other than 0.0.0.0), Type-7 are not generated in NSSA x.x.x.x for the specified range.

tag - The Tag Type describes whether Tags will be automatically generated or will be manually configured This parameter is currently not supported in the no form of the command.

cost - Metric or cost for a summary route, which is used during OSPF SPF (Shortest Path First) calculation to determine the shortest paths to the destination. This value ranges between 0 and 16777215.

Mode

Router Configuration

Defaults

tag - 2

Example

SEFOS(config-router)# area 10.0.0.1 range 10.0.0.0 255.0.0.0 summary advertise tag 10

Notes

The mask indicates the range of addresses being described by the particular route. For example, a summary-LSA for the destination 128.185.0.0 with a mask of 0xffff0000 actually is describing a single route to the collection of destinations 128.185.0.0 - 128.185.255.255.

This command is used only with Area Border Routers (ABRs). It is used to consolidate or summarize routes for an area. The result is that a single summary route is advertised to other areas by the ABR.


Related Commands

7.1.17 area - range - cost

Consolidates and summarizes routes at an area boundary. This command operates similarly to the command area - range.


area area-id range network mask [{advertise | not-advertise}] [tag value] [cost value]


Syntax Description

area-id - Area associated with the OSPF address range. This is specified as an IP address.

network - The IP address of the network indicated by the range.

mask - The subnet mask that pertains to the range. The mask indicates the range of addresses described by the particular route. For example, a summary-LSA for the destination 128.185.0.0 with a mask of 0xffff0000 is actually describing a single route to the collection of destinations 128.185.0.0 - 128.185.255.255.

advertise - When associated area-id is 0.0.0.0, aggregated Type-5 LSAs are generated. Otherwise if associated area-id is x.x.x.x (other than 0.0.0.0) aggregated Type-7 LSA is generated in NSSA x.x.x.x.

not-advertise - When associated area-id is 0.0.0.0, Type-5 LSA is not generated for the specified range, while aggregated Type-7 LSAs are generated in all attached NSSA. If associated area-id is x.x.x.x (other than 0.0.0.0), Type-7 LSAs are not generated in NSSA x.x.x.x for the specified range.

tag - Specifies whether the tags will be automatically generated or manually configured.

cost - Metric or cost for a summary route, which is used during OSPF SPF calculation to determine the shortest paths to the destination. This value ranges between 0 and 16777215.

Mode

Router Configuration

Defaults

tag - 2

Example

SEFOS(config-router)# area 10.0.0.1 range 10.0.0.0 255.0.0.0 advertise tag 10


Related Commands

7.1.18 summary-address

Creates aggregate addresses for OSPF. The no form of the command deletes the external summary address.


summary-address network mask area-id [{allowAll | denyAll |  advertise | not-advertise}] [Translation {enabled | disabled}]


no summary-address network mask area-id [not-advertise]


Syntax Description

network - The IP address of the Net indicated by the range.

mask - The subnet mask that pertains to the range.

area-id - Area associated with the OSPF address range. It is specified as an IP address.

allowAll - When set to allowAll and associated area-id is 0.0.0.0 aggregated Type-5 are generated for the specified range. In addition aggregated Type-7 are generated in all attached NSSA, for the specified range.

denyAll - When set to denyAll neither Type-5 nor Type-7 will be generated for the specified range.

advertise - When associated area-id is 0.0.0.0, aggregated Type-5 are generated. Otherwise if associated area-id is x.x.x.x (other than 0.0.0.0) aggregated Type-7 is generated in NSSA x.x.x.x.

not-advertise - When associated area-id is 0.0.0.0, Type-5 is not generated for the specified range, while aggregated Type-7 are generated in all attached NSSA. While associated area-id is x.x.x.x (other than 0.0.0.0), Type-7 are not generated in NSSA x.x.x.x for the specified range.

Translation - Indicates how an NSSA Border router is performing NSSA translation of Type-7 to into Type-5 LSAs. When set to enabled, P Bit is set in the generated Type-7 LSA. When set to disabled P Bit is cleared in the generated Type-7 LSA for the range.

Mode

Router Configuration

Defaults

summary-address - advertise

translation - disabled

Example

SEFOS(config-router)# summary-address 10.0.0.6 255.0.0.0 10.0.0.0 allowAll Translation enabled

Notes

  • The router with the highest router_id becomes and remains the default router regardless of whether it has the highest priority or not. The router with the hightest priority becomes the default router only after the VLAN interface of the router is brought down and back up.
  • When translation is set to enabled, the NSSA border router’s futOspfAreaNssaTranslatorRole is set to always. When this object is set to disabled, a candidate NSSA border router does not perform translation.
  • This commnd indicates whether Type-5/Type-7 will be aggregated or not generated for the specified range.
  • allowAll and denyAll are not valid for area-id other than 0.0.0.0.
  • Routes learned from other routing protocols can be summarized. The metric used to advertise the summary is the smallest metric of all the more specific routes.
  • This command helps reduce the size of the routing table.

Related Commands

7.1.19 redistribute

Configures the protocol from which the routes have to be redistributed into OSPF. The no form of the command disables redistribution of routes from the given protocol into OSPF.


redistribute {static | connected | rip | bgp | all} [route-map name_1-20]


no redistribute {static | connected | rip | bgp | all} [route-map name_1-20]


Syntax Description

static - Redistributes routes, configured statically, to the OSPF routing protocol.

connected - Redistributes directly connected network routes, to the OSPF routing protocol.

rip - Redistributes routes, that are learned by the RIP process, to the OSPF routing protocol.

bgp - Redistributes routes, that are learned by the BGP process, to the OSPF routing protocol.

all - Redistributes all routes to the OSPF routing protocol.

route-map - Identifies the specified route-map in the list of route-maps. The length of the name ranges from 1 to 20.

Mode

Router Configuration

Example

SEFOS(config-router)# redistribute static

Notes

The ASBR Router command must be configured prior to the execution of this command.


Related Commands

7.1.20 redist-config

Configures the information to be applied to routes learned from RTM. The no form of the command deletes the information applied to routes learned from RTM.


redist-config network mask [metric-value metric_1-16777215] [metric-type {asExttype1 | asExttype2}]  [tag tag-value}


no redist-config network mask


Syntax Description

network - IP Address of the destination route.

mask - Mask of the destination route.

metric-value - The metric value applied to the route before it is advertised into the OSPF domain.

metric-type - The metric type applied to the route before it is advertised into the OSPF domain.

tag - The tag type describes whether tags will be automatically generated or will be manually configured.

Mode

Router Configuration

Defaults

metric-value - 10

metric-type - asExttype2

tag - manual

Example

SEFOS(config-router)# redist-config 10.0.0.0 255.0.0.0 metric-value 100 metric-type asExttype1 tag 10

Notes

tag tag-value: This is not used by OSPF protocol itself. It may be used to communicate information between AS boundary routers. The precise nature of this information is outside the scope of OSPF. If tags are manually configured, the futospfRRDRouteTag MIB has to be set with the Tag value needed.


Related Commands

7.1.21 network

Defines the interfaces on which OSPF runs and the area identifier for those interfaces. The no form of the command disables OSPF routing for interfaces defined and to remove the area ID of that interface.


network network-number area area-id [unnum Vlan port-number]


no network network-number area area-id [unnum Vlan port-number]


Syntax Description

network-number - Network type.

area - Area associated with the OSPF address range. It is specified as an IP address.

unnum Vlan - VLAN identifier for which no IP address is configured.

Mode

Router Configuration

Example

SEFOS(config-router)# network 20.0.0.1 area 20.0.0.0 unnum Vlan 1

Notes

  • When a more specific OSPF network range is removed, interfaces belonging to that network range will be retained and remain active if and only if a less specific network range exists.
  • There is no limit to the number of network commands that can be used on the router.

Related Commands

7.1.22 network - wildcard-mask

Defines the interfaces on which OSPF runs, and the area identifier for those interfaces. The no form of the command disables OSPF routing for interfaces defined, and removes the area identifier of that interface. This command operates similarly to the command network.


network network number wildcard-mask area area-id [unnum Vlan port-number]


no network network number wildcard-mask area area-id [unnum Vlan port-number]


Syntax Description

network-number - IP address of the network.

wildcard-mask - IP-address-type mask that includes don’t care bits.

area-id - Area associated with the OSPF address range. This is specified as an IP address.

unnum Vlan - VLAN identifier for which no IP address is configured.

Mode

Router Configuration

Example

SEFOS(config-router)# network 20.0.0.1 255.0.0.0 area 20.0.0.0 unnum Vlan 1

Notes

  • When a more specific OSPF network range is removed, interfaces belonging to that network range will be retained and will remain active only if a less specific network range exists.
  • There is no limit to the number of network commands that can be used on the router.

Related Commands

7.1.23 set nssa asbr-default-route translator

Enables or disables setting of P bit in the default Type-7 LSA generated by NSSA internal ASBR.


set nssa asbr-default-route translator {enable | disable}


Syntax Description

enable - When set to enabled, P-Bit is set in the generated Type-7 default LSA.

disable - When set disabled, P-Bit is clear in the generated default LSA.

Mode

Router Configuration

Defaults

Disabled.

Example

SEFOS(config-router)# set nssa asbr-default-route translator enable

Notes

Specifies the P-Bit setting for the default Type-7 LSA generated by ASBR (which is not ABR).


Related Commands

7.1.24 passive-interface vlan

Suppresses routing updates on an interface. The no form of the command enables routing updates on an interface.


passive-interface {vlan 1-4094 | interface-type interface-id}


no passive-interface {vlan 1-4094 | interface-type interface-id}


Syntax Description

vlan-id - LSA retransmissions for adjacencies belonging to the VLAN interface.

interface-type - Interface type. The keyword interface-type is not supported.

interface-id - Interface identifier. The keyword interface-id is not supported.

Mode

Router Configuration

Example

SEFOS(config-router)# passive-interface vlan 1

Notes

OSPF routing information is neither sent nor received through the specified router interface. The specified interface address appears as a stub network in the OSPF domain.


Related Commands

7.1.25 passive-interface default

Suppresses routing updates on all interfaces. The no form of the command enables routing updates on all interfaces.


passive-interface default


no passive-interface default


Mode

Router Configuration

Example

SEFOS(config-router)# passive-interface default

Notes

All the OSPF interfaces created after the execution of this command will be passive. This is useful in Internet service provider (ISP) and large enterprise networks where many of the distribution routers have more than 200 interfaces.


Related Commands

7.1.26 timers spf

Sets OSPF SPF delay and hold timers. The no form of the command resets OSPF SPF delay and hold timers to the default value.


timers spf spf-delay_1-100 spf-holdtime_1-1000


no timers spf


Syntax Description

spf-delay_1-100 - Delay time (in seconds) in starting a SPF calculation after receiving a topology change. This value ranges between 1 and 100 seconds. A value of 0 means that there is no delay. That is, the SPF calculation is started immediately.

spf-holdtime_1-1000 - Minimum time (in seconds) between two consecutive SPF calculations. This value ranges between 1 and 1000 seconds.

Mode

Router Configuration

Defaults

spf-delay_1-100 - 5 seconds.

spf-holdtime_1-1000 - 10 seconds.

Example

SEFOS(config-router)# timers spf 10 20


7.1.27 ip ospf demand-circuit

Configures OSPF to treat the interface as an OSPF demand circuit. The no form of the command removes the demand circuit designation from the interface.


ip ospf demand-circuit


no ip ospf demand-circuit


Mode

Interface Configuration

TApplicable only in VLAN Interface.

Example

SEFOS(config-if)# ip ospf demand-circuit

Notes

  • It indicates whether demand OSPF procedures (hello suppression to FULL neighbors and setting the DoNotAge flag on prorogated LSAs) must be performed on this interface.
  • On point-to-point interfaces, only one end of the demand circuit must be configured with this command. Periodic hello messages are suppressed and periodic refreshes of LSAs do not flood the demand circuit.

Related Commands

7.1.28 ip ospf retransmit-interval

Specifies the time between LSA retransmissions for adjacencies belonging to the interface. The no form of the command uses the default time between LSA retransmissions for adjacencies belonging to the interface.


ip ospf retransmit-interval seconds_0-3600


no ip ospf retransmit-interval


Mode

Interface Configuration

Applicable only in VLAN interface.

Defaults

5

Example

SEFOS(config-if)# ip ospf retransmit-interval 300

Notes

This value is also used while retransmitting database description and link-state request packets.


Related Commands

7.1.29 ip ospf transmit-delay

Sets the estimated time it takes to transmit a link state update packet on the interface. The no form of the command sets the default estimated time it takes to transmit a link state update packet on the interface.


ip ospf transmit-delay seconds_0-3600


no ip ospf transmit-delay


Mode

Interface Configuration

Applicable only in VLAN Interface.

Defaults

1

Example

SEFOS(config-if)# ip ospf transmit-delay 50

Notes

Link-state advertisements (LSAs) in the update packet must have their ages incremented by the amount specified in the seconds argument before transmission.


Related Commands

7.1.30 ip ospf priority

Sets the router priority.


ip ospf priority 0-255


no ip ospf priority


Mode

Interface Configuration

This command is applicable only in VLAN interface.

Defaults

1

Example

SEFOS(config-if)# ip ospf priority 25

Notes

When two routers attached to a network attempt to become the designated router, the one with the higher router priority takes precedence. If there is a tie, the router with the higher router identifier takes precedence.


Related Commands

7.1.31 ip ospf hello-interval

Specifies the interval between hello packets sent on the interface. The no form of the command sets default value for, interval between hello packets sent on the interface.


ip ospf hello-interval seconds_1-65535


no ip ospf hello-interval


Mode

Interface Configuration

Applicable only in VLAN Interface.

Defaults

10

Example

SEFOS(config-if)# ip ospf hello-interval 75

Notes

This value must be the same for all routers attached to a common network.


Related Commands

7.1.32 ip ospf dead-interval

This command sets the interval at which hello packets must not be seen before neighbors declare the router down and the no form of the command sets default value for the interval at which hello packets must not be seen before neighbors declare the router down.


ip ospf dead-interval seconds_0-0x7fffffff


no ip ospf dead-interval


Mode

Interface Configuration

Applicable only in VLAN interface.

Defaults

40

Example

SEFOS(config-if)# ip ospf dead-interval 1000

Notes

This value must be the same for all routers and access servers on a specific network.


Related Commands

7.1.33 ip ospf cost

Explicitly specifies the cost of sending a packet on an interface. The no form of the command resets the path cost to the default value.


ip ospf cost cost_1-65535 [tos tos-value_0-30]


no ip ospf cost [tos tos-value_0-30]


Syntax Description

cost - Type 1 external metrics which is expressed in the same units as OSPF interface cost, that is in terms of the OSPF link state metric.

tos - TOS of the route being configured. The only tos value you can enter is 0. because TOS is not supported.

Mode

Interface Configuration

This command is applicable only in VLAN Interface.

Defaults

cost - 10

Example

SEFOS(config-if)# ip ospf cost 10

Notes

  • In general, the path cost is calculated using the following formula:

108 / bandwidth .

  • Using this formula, the default path costs are calculated.

Example: Ethernet-Default cost is 10.


Related Commands

7.1.34 ip ospf network

Configures the OSPF network type to a type other than the default for a given media. The no form of the command sets the OSPF network type to the default type.


ip ospf network {broadcast | non-broadcast | point-to-multipoint | point-to-point}


no ip ospf network


Syntax Description

broadcast - Networks supporting many (more than two) attached routers, together with the capability to address a single physical message to all of the attached routers (broadcast).

non-broadcast - Networks supporting many (more than two) routers, but having no broadcast capability.

point-to-multipoint - Treats the non-broadcast network as a collection of point-to-point links.

point-to-point - A network that joins a single pair of routers.

Mode

Interface Configuration

This command is applicable only in VLAN Interface.

Defaults

broadcast

Example

SEFOS(config-if)# ip ospf network broadcast

Notes

Each pair of routers on a broadcast network is assumed to be able to communicate directly. An Ethernet is an example of a broadcast network. A 56Kb serial line is an example of a point-to-point network.


Related Commands

7.1.35 ip ospf authentication-key

Specifies a password to be used by neighboring routers that are using the OSPF simple password authentication. The no form of the command removes a previously assigned OSPF password.


ip ospf authentication-key password_8


no ip ospf authentication-key


Mode

Interface Configuration

Applicable only in VLAN interface.

Example

SEFOS(config-if)# ip ospf authentication-key asdf123

Notes

  • The password string can contain from 1 to 8 uppercase and lowercase alphanumeric characters.
  • A separate password can be assigned to each network on a per-interface basis. All neighboring routers on the same network must have the same password to be able to exchange OSPF information.

Related Commands

7.1.36 ip ospf authentication

Specifies the authentication type for an interface. The no form of the command removes the authentication type for an interface and set it to NULL authentication.


ip ospf authentication [{message-digest | null}]


no ip ospf authentication


Syntax Description

message-digest - Message Digest authentication.

null - NULL authentication.

Mode

Interface Configuration

Applicable only in VLAN Interface.

Defaults

null

Example

SEFOS(config-if)# ip ospf authentication

Notes

  • Before using the ip ospf authentication command, a password for the interface must be configured using the ip ospf authentication-key command.
  • If the authentication type is ’message digest’ then key will be selected from the md-5 table.

Related Commands

7.1.37 ip ospf message-digest-key

Enables OSPF MD5 authentication. The no form of the command removes an old MD5 key.


ip ospf message-digest-key key-id_0-255 md5 md5-key_16


no ip ospf message-digest-key key-id_0-255


Syntax Description

key-id_0-255 - Identifies the secret key, which is used to create the message digest appended to the OSPF packet.

md5 - Secret key, which is used to create the message digest appended to the OSPF packet.

Mode

Interface Configuration

This command is applicable only in VLAN Interface.

Example

SEFOS(config-if)# ip ospf message-digest-key 5 md5 abcd123

Notes

  • Message Digest authentication is a cryptographic authentication. A key (password) and key-id are configured on each router. The router uses an algorithm based on the OSPF packet, the key, and the key-id to generate a "message digest" that gets appended to the packet.
  • Usually, one key per interface is used to generate authentication information when sending packets and to authenticate incoming packets. The same key identifier on the neighbor router must have the same key value.

Related Commands

7.1.38 debug ip ospf

Sets the OSPF debug level. The no form of the command removes an old MD5 key.


debug ip ospf {pkt {hp | ddp | lrq | lsu | lsa} | module {adj-formation | ism | nsm | config | interface}}


no debug ip ospf {pkt {hp | ddp | lrq | lsu | lsa} | module {adj-formation | ism | nsm | config | interface} | all}


Syntax Description

pkt - Packet high level dump debug messages.

hp - Hello packet debug messages.

ddp - DDP packet debug messages.

lrq - Link state Request Packet debug messages.

lsu - Link state Update Packet debug messages.

lsa - Link state Acknowledge Packet debug messages.

module - RTM module debug messages.

adj-formation - Adjacency formation debug messages.

ism - Interface state machine debug messages.

nsm - Neighbor state machine debug messages.

config - Configuration debug messages.

interface - Interface.

Mode

Privileged EXEC

Example

SEFOS# debug ip ospf pkt hp

Notes

The information displayed by the show ip ospf retransmission-list command is useful in debugging OSPF routing operations.


Related Commands

7.1.39 show ip ospf interface

Displays OSPF interface information.


show ip ospf interface [vlan 1-4094]


Syntax Description

vlan - LSA retransmissions for adjacencies belonging to the VLAN interface.

Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf interface

vlan4 is up line protocol is up

Internet Address 10.1.4.1, Mask 255.255.255.0, Area 0.0.0.5

AS 1, Router ID 10.1.100.1, Network Type BROADCAST, Cost 1

Transmit Delay is 1 sec, State 4, Priority 1

Designated RouterId 10.1.100.1, Interface address 10.1.4.1

No backup designated router on this network

Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Hello due in 6 sec

Neighbor Count is 0, Adjacent neighbor count is 0

Connected to VRF default

vlan100 is up line protocol is up

Internet Address 10.1.100.1, Mask 255.0.0.0, Area 33.0.0.12

AS 1, Router ID 10.0.0.1, Network Type BROADCAST, Cost 1

Transmit Delay is 1 sec, State 5, Priority 1

Designated RouterId 10.1.100.2, Interface address 10.1.100.2

Backup Designated RouterId 10.1.100.1, Interface address 10.1.100.1

Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Hello due in 6 sec

Neighbor Count is 1, Adjacent neighbor count is 1

Adjacent with the neighbor 10.1.100.2

Connected to VRF default


Related Commands

7.1.40 show ip ospf neighbor

Displays OSPF neighbor information list.


show ip ospf neighbor [vlan 1-4094] [neighbor-id] [detail]


Syntax Description

vlan - LSA retransmissions for adjacencies belonging to the VLAN interface.

neighbor-id - Neighbor router identifier.

detail - OSPF neighbor information in detail.

Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf neighbor

Vrf default

 

Neighbor-ID Pri State DeadTime Address Interface

---------- --- -------- ------- ------- ---------

10.1.100.2 1 FULL/DR 33 10.1.100.2 vlan100


Related Commands

7.1.41 show ip ospf request-list

Displays OSPF Link state request list information.


show ip ospf request-list [neighbor-id] [vlan 1-4094]


show ip ospf [vrf name] request-list [neighbor-id] [vlan 1-4094]


Syntax Description

neighbor-id - Neighbor router ID.

vlan - LSA retransmissions for adjacencies belonging to the VLAN interface.

Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf request-list

 

OSPF Router with ID (10.1.100.1) (Vrf default)

Neighbor 10.1.100.2, interface - address 10.1.100.2

Type LS-ID ADV-RTR SeqNo Age Checksum

---- ---- ------- ----- --- --------


Related Commands

7.1.42 show ip ospf retransmission-list

Displays OSPF Link state retransmission list information.


show ip ospf retransmission-list [neighbor-id] [vlan 1-4094]


show ip ospf [vrf name] retransmission-list [neighbor-id] [vlan [vlan 1-4094]


Syntax Description

neighbor-id - Neighbor router identifier.

vlan - LSA retransmissions for adjacencies belonging to the VLAN interface.

Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf retransmission-list

OSPF Router with ID (10.1.100.1) (Vrf default)

Notes

This value is also used while retransmitting database description and link-state request packets.


Related Commands

7.1.43 show ip ospf virtual-links

Displays OSPF virtual link information.


show ip ospf virtual-links


Mode

Privileged EXEC

Example

Single Instance:

 

SEFOS# show ip ospf virtual-links

 

Vrf default

 

Virtual Link to router 10.1.100.2, Interface State is POINT_TO_POINT

Transit Area 0.0.0.1

Transmit Delay is 1 sec, Neighbor State FULL

Timer intervals configured, Hello 10, Dead 40, Retransmit 5


Related Commands

7.1.44 show ip ospf border-routers

Displays OSPF border and boundary router information.


show ip ospf border-routers


Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf border-routers

 

Vrf default

 

OSPF Process Border Router Information

 

Destination TOS Type NextHop Cost Rt.Type Area

----------- --- ---- ------- ---- ------- ----

10.1.100.2 0 ABR 10.1.100.2 1 intraArea 0.0.0.1


Related Commands

7.1.45 show ip ospf - summary address

Displays OSPF summary-address redistribution information.


show ip ospf {area-range | summary-address}


Syntax

area-range - Area associated with the OSPF address range. It is specified as an IP address.

summary-address - Aggregate addresses for OSPF.

Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf area-range

Display of Summary addresses for Type3 and Translated Type5

Summary Address

----------------------------------------------

Network Mask LSAType Area Effect Tag

------- ------- ---- ------ ---

10.0.0.0 255.0.0.0 Summary 33.0.0.12 Advertise 1074636208

SEFOS# show ip ospf summary-address

Display of Summary addresses for Type5 and Type7 from redistributed routes

OSPF External Summary Address Configuration Information

-----------------------------------------------------

Network Mask Area Effect TranslationSt

------- ---- ---- ------ ------------

10.0.0.1 255.0.0.0 33.0.0.12 advertiseMatching enabled


Related Commands

7.1.46 show ip ospf

Displays general information about the OSPF routing process.


show ip ospf


Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf

OSPF Router with ID(10.1.100.1) (Vrf default)

Supports only single TOC(TOS0) route

ABR Type supported is Standard ABR

It is an Area Border Router

Number of Areas in this router is 3

Area is 0.0.0.5

Number of interfaces in this area is 1

SPF algorithm executed 35 times

Area is 0.0.0.1

Number of interfaces in this area is 1

SPF algorithm executed 44 times

Area is 0.0.0.0

Number of interfaces in this area is 1

SPF algorithm executed 20 times


Related Commands

7.1.47 show ip ospf route

Displays routes learned by OSPF process.


show ip ospf route


Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf route

Vrf default

OSPF Routing Table

Dest/Mask TOS NextHop/Interface Cost Rt.Type Area

--------- --- -------/--------- ---- ------- ----

10.1.4.0/255.255.255.0 0 0.0.0.0/vlan4 1 IntraArea 0.0.0.5

10.1.11.0/255.255.255.0 0 10.1.100.2/vlan1002 2 InterArea 0.0.0.0

10.1.100.0/255.255.255.0 0 0.0.0.0/vlan100 1 IntraArea 0.0.0.1


Related Commands

7.1.48 show ip ospf - database summary

Displays OSPF LSA Database summary.


show ip ospf area-id database [{database-summary | self-originate | adv-router ip-address}]


Syntax Description

area-id - Area associated with the OSPF address range. It is specified as an IP address.

database - Displays how many of each type of LSA for each area there are in the database.

database-summary - Displays how many of each type of LSA for each area there are in the database, and the total number of LSA types.

self-originate - Displays only self-originated LSAs (from the local router).

adv-router - Displays all the specified router link-state advertisements (LSAs). If no IP address is included, the information is about the local router itself.

Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf database

OSPF Router with ID (10.1.100.1) (Vrf default)

Router Link States (Area 0.0.0.0)

---------------------------------

Link ID ADV Router Age Seq# Checksum Link Count

------- ---------- --- ---- -------- ----------

10.1.100.2 10.1.100.2 32769 0x80000026 0x7aa4 2

10.1.100.1 10.1.100.1 1626 0x80000036 0x1e1a 1

Summary Link States (Area 0.0.0.0)

----------------------------------

 

Link ID ADV Router Age Seq# Checksum

------- ---------- --- ---- --------

10.1.100.0 10.1.100.1 566 0x80000031 0x2dfe

10.1.4.0 10.1.100.1 566 0x80000030 0x533a

10.1.100.0 10.1.100.2 33600 0x80000001 0x87d3

Router Link States (Area 0.0.0.1)

---------------------------------

Link ID ADV Router Age Seq# Checksum Link Count

------- ---------- --- ---- -------- ----------

10.1.100.2 10.1.100.2 135 0x8000000b 0x5609 1

10.1.100.1 10.1.100.1 1626 0x8000003d 0xf33c 1

Network Link States (Area 0.0.0.1)

----------------------------------

 

Link ID ADV Router Age Seq# Checksum

------- ---------- --- ---- --------

10.1.100.1 10.1.100.1 673 0x80000009 0xff6e

Summary Link States (Area 0.0.0.1)

----------------------------------

Link ID ADV Router Age Seq# Checksum

------- ---------- --- ---- --------

10.1.4.0 10.1.100.1 755 0x80000030 0x533a

10.1.11.0 10.1.100.2 882 0x80000008 0x505d

Router Link States (Area 0.0.0.5)

---------------------------------

Link ID ADV Router Age Seq# Checksum Link Count

------- ---------- --- ---- -------- ----------

 

10.1.100.1 10.1.100.1 755 0x80000038 0xf118 1

Summary Link States (Area 0.0.0.5)

----------------------------------

Link ID ADV Router Age Seq# Checksum

------- ---------- --- ---- --------

10.1.100.0 10.1.100.1 755 0x80000009 0x7dd6

10.1.11.0 10.1.100.1 1621 0x80000008 0x604d


7.1.49 show ip ospf - database

Displays OSPF Database summary for the LSA type.


show ip ospf [area-id] database {asbr-summary | external | network | nssa-external | opaque-area | opaque-as | opaque-link | router | summary } [link-state-id] [{adv-router ip-address | self-originate}]


Syntax Description

area-id - Area associated with the OSPF address range. It is specified as an IP address.

database - Displays how many of each type of LSA for each area there are in the database.

asbr-summary - Displays information only about the ASBR summary LSAs.

external - Displays information only about the external LSAs.

network - Displays information only about the network LSAs.

nssa-external - Displays information about the NSSA external LSAs.

opaque-area - Displays information about the Type-10 LSAs.

opaque-as - Displays information about the Type-11 LSAs.

opaque-link - Displays information about the Type-9 LSAs.

router - Displays information only about the router LSAs.

summary - Displays information only about the summary LSAs.

link-state-id - Portion of the Internet environment that is being described by the advertisement. The value entered depends on the type of the LSA. The value must be entered in the form of an IP address.

adv-router - Displays all the specified router link-state advertisements (LSAs). If no IP address is included, the information is about the local router itself.

self-originate - Displays only self-originated LSAs (from the local router).

Mode

Privileged EXEC

Example

Single Instance:

SEFOS# show ip ospf database summary

 

OSPF Router with ID (10.0.100.1) (Vrf default)

 

SEFOS# show ip ospf database network

 

OSPF Router with ID (10.0.100.1) (Vrf default)


Related Commands

 

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