OSPFv3

ospf6d is a daemon support OSPF version 3 for IPv6 network. OSPF for IPv6 is described in RFC 2740.

OSPF6 router

router ospf6 [vrf NAME]
ospf6 router-id A.B.C.D

Set router’s Router-ID.

timers throttle spf (0-600000) (0-600000) (0-600000)

This command sets the initial delay, the initial-holdtime and the maximum-holdtime between when SPF is calculated and the event which triggered the calculation. The times are specified in milliseconds and must be in the range of 0 to 600000 milliseconds.

The delay specifies the minimum amount of time to delay SPF calculation (hence it affects how long SPF calculation is delayed after an event which occurs outside of the holdtime of any previous SPF calculation, and also serves as a minimum holdtime).

Consecutive SPF calculations will always be separated by at least ‘hold-time’ milliseconds. The hold-time is adaptive and initially is set to the initial-holdtime configured with the above command. Events which occur within the holdtime of the previous SPF calculation will cause the holdtime to be increased by initial-holdtime, bounded by the maximum-holdtime configured with this command. If the adaptive hold-time elapses without any SPF-triggering event occurring then the current holdtime is reset to the initial-holdtime.

router ospf6
 timers throttle spf 200 400 10000

In this example, the delay is set to 200ms, the initial holdtime is set to 400ms and the maximum holdtime to 10s. Hence there will always be at least 200ms between an event which requires SPF calculation and the actual SPF calculation. Further consecutive SPF calculations will always be separated by between 400ms to 10s, the hold-time increasing by 400ms each time an SPF-triggering event occurs within the hold-time of the previous SPF calculation.

auto-cost reference-bandwidth COST

This sets the reference bandwidth for cost calculations, where this bandwidth is considered equivalent to an OSPF cost of 1, specified in Mbits/s. The default is 100Mbit/s (i.e. a link of bandwidth 100Mbit/s or higher will have a cost of 1. Cost of lower bandwidth links will be scaled with reference to this cost).

This configuration setting MUST be consistent across all routers within the OSPF domain.

maximum-paths (1-64)

Use this command to control the maximum number of parallel routes that OSPFv3 can support. The default is 64.

write-multiplier (1-100)

Use this command to tune the amount of work done in the packet read and write threads before relinquishing control. The parameter is the number of packets to process before returning. The default value of this parameter is 20.

clear ipv6 ospf6 process [vrf NAME]

This command clears up the database and routing tables and resets the neighborship by restarting the interface state machine. This will be helpful when there is a change in router-id and if user wants the router-id change to take effect, user can use this cli instead of restarting the ospf6d daemon.

clear ipv6 ospf6 [vrf NAME] interface [IFNAME]

This command restarts the interface state machine for all interfaces in the VRF or only for the specific interface if IFNAME is specified.

ASBR Summarisation Support in OSPFv3

External routes in OSPFv3 are carried by type 5/7 LSA (external LSAs). External LSAs are generated by ASBR (Autonomous System Boundary Router). Large topology database requires a large amount of router memory, which slows down all processes, including SPF calculations. It is necessary to reduce the size of the OSPFv3 topology database, especially in a large network. Summarising routes keeps the routing tables smaller and easier to troubleshoot.

External route summarization must be configured on ASBR. Stub area do not allow ASBR because they don’t allow type 5 LSAs.

An ASBR will inject a summary route into the OSPFv3 domain.

Summary route will only be advertised if you have at least one subnet that falls within the summary range.

Users will be allowed an option in the CLI to not advertise range of ipv6 prefixes as well.

The configuration of ASBR Summarisation is supported using the CLI command

summary-address X:X::X:X/M [tag (1-4294967295)] [{metric (0-16777215) | metric-type (1-2)}]

This command will advertise a single External LSA on behalf of all the prefixes falling under this range configured by the CLI. The user is allowed to configure tag, metric and metric-type as well. By default, tag is not configured, default metric as 20 and metric-type as type-2 gets advertised. A summary route is created when one or more specific routes are learned and removed when no more specific route exist. The summary route is also installed in the local system with Null0 as next-hop to avoid leaking traffic.

no summary-address X:X::X:X/M [tag (1-4294967295)] [{metric (0-16777215) | metric-type (1-2)}]

This command can be used to remove the summarisation configuration. This will flush the single External LSA if it was originated and advertise the External LSAs for all the existing individual prefixes.

summary-address X:X::X:X/M no-advertise

This command can be used when user do not want to advertise a certain range of prefixes using the no-advertise option. This command when configured will flush all the existing external LSAs falling under this range.

no summary-address X:X::X:X/M no-advertise

This command can be used to remove the previous configuration. When configured, tt will resume originating external LSAs for all the prefixes falling under the configured range.

aggregation timer (5-1800)

The summarisation command takes effect after the aggregation timer expires. By default the value of this timer is 5 seconds. User can modify the time after which the external LSAs should get originated using this command.

no aggregation timer (5-1800)

This command removes the timer configuration. It reverts back to default 5 second timer.

show ipv6 ospf6 summary-address [detail] [json]

This command can be used to see all the summary-address related information. When detail option is used, it shows all the prefixes falling under each summary-configuration apart from other information.

OSPF6 area

area A.B.C.D range X:X::X:X/M [<advertise|not-advertise|cost (0-16777215)>]
area (0-4294967295) range X:X::X:X/M [<advertise|not-advertise|cost (0-16777215)>]

Summarize a group of internal subnets into a single Inter-Area-Prefix LSA. This command can only be used at the area boundary (ABR router).

By default, the metric of the summary route is calculated as the highest metric among the summarized routes. The cost option, however, can be used to set an explicit metric.

The not-advertise option, when present, prevents the summary route from being advertised, effectively filtering the summarized routes.

area A.B.C.D nssa [no-summary] [default-information-originate [metric-type (1-2)] [metric (0-16777214)]]
area (0-4294967295) nssa [no-summary] [default-information-originate [metric-type (1-2)] [metric (0-16777214)]]
area A.B.C.D nssa range X:X::X:X/M [<not-advertise|cost (0-16777215)>]
area (0-4294967295) nssa range X:X::X:X/M [<not-advertise|cost (0-16777215)>]

Summarize a group of external subnets into a single Type-7 LSA, which is then translated to a Type-5 LSA and avertised to the backbone. This command can only be used at the area boundary (NSSA ABR router).

By default, the metric of the summary route is calculated as the highest metric among the summarized routes. The cost option, however, can be used to set an explicit metric.

The not-advertise option, when present, prevents the summary route from being advertised, effectively filtering the summarized routes.

area A.B.C.D export-list NAME
area (0-4294967295) export-list NAME

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

router ospf6
 area 0.0.0.10 export-list foo
!
ipv6 access-list foo permit 2001:db8:1000::/64
ipv6 access-list foo deny any

With example above any intra-area paths from area 0.0.0.10 and from range 2001:db8::/32 (for example 2001:db8:1::/64 and 2001:db8:2::/64) are announced into other areas as Type-3 summary-LSA’s, but any others (for example 2001:200::/48) aren’t.

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

area A.B.C.D import-list NAME
area (0-4294967295) import-list NAME

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

area A.B.C.D filter-list prefix NAME in
area A.B.C.D filter-list prefix NAME out
area (0-4294967295) filter-list prefix NAME in
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.

OSPF6 interface

ipv6 ospf6 area <A.B.C.D|(0-4294967295)>

Enable OSPFv3 on the interface and add it to the specified area.

ipv6 ospf6 cost COST

Sets interface’s output cost. Default value depends on the interface bandwidth and on the auto-cost reference bandwidth.

ipv6 ospf6 hello-interval HELLOINTERVAL

Sets interface’s Hello Interval. Default 10

ipv6 ospf6 dead-interval DEADINTERVAL

Sets interface’s Router Dead Interval. Default value is 40.

ipv6 ospf6 graceful-restart hello-delay HELLODELAYINTERVAL

Set the length of time during which Grace-LSAs are sent at 1-second intervals while coming back up after an unplanned outage. During this time, no hello packets are sent.

A higher hello delay will increase the chance that all neighbors are notified about the ongoing graceful restart before receiving a hello packet (which is crucial for the graceful restart to succeed). The hello delay shouldn’t be set too high, however, otherwise the adjacencies might time out. As a best practice, it’s recommended to set the hello delay and hello interval with the same values. The default value is 10 seconds.

ipv6 ospf6 retransmit-interval RETRANSMITINTERVAL

Sets interface’s Rxmt Interval. Default value is 5.

ipv6 ospf6 priority PRIORITY

Sets interface’s Router Priority. Default value is 1.

ipv6 ospf6 transmit-delay TRANSMITDELAY

Sets interface’s Inf-Trans-Delay. Default value is 1.

ipv6 ospf6 network (broadcast|point-to-point)

Set explicitly network type for specified interface.

OSPF6 route-map

Usage of ospfd6’s route-map support.

set metric [+|-](0-4294967295)

Set a metric for matched route when sending announcement. Use plus (+) sign to add a metric value to an existing metric. Use minus (-) sign to substract a metric value from an existing metric.

Redistribute routes to OSPF6

redistribute <bgp|connected|isis|kernel|ripng|static|table> [metric-type (1-2)] [metric (0-16777214)] [route-map WORD]
default-information originate [{always|metric (0-16777214)|metric-type (1-2)|route-map WORD}]

Graceful Restart

graceful-restart [grace-period (1-1800)]

Configure Graceful Restart (RFC 5187) restarting support. When enabled, the default grace period is 120 seconds.

To perform a graceful shutdown, the “graceful-restart prepare ipv6 ospf” EXEC-level command needs to be issued before restarting the ospf6d daemon.

When Graceful Restart is enabled and the ospf6d daemon crashes or is killed abruptely (e.g. SIGKILL), it will attempt an unplanned Graceful Restart once it restarts.

graceful-restart helper enable [A.B.C.D]

Configure Graceful Restart (RFC 5187) helper support. By default, helper support is disabled for all neighbours. This config enables/disables helper support on this router for all neighbours. To enable/disable helper support for a specific neighbour, the router-id (A.B.C.D) has to be specified.

graceful-restart helper strict-lsa-checking

If ‘strict-lsa-checking’ is configured then the helper will abort the Graceful Restart when a LSA change occurs which affects the restarting router. By default ‘strict-lsa-checking’ is enabled”

graceful-restart helper supported-grace-time (10-1800)

Supports as HELPER for configured grace period.

graceful-restart helper planned-only

It helps to support as HELPER only for planned restarts. By default, it supports both planned and unplanned outages.

graceful-restart prepare ipv6 ospf

Initiate a graceful restart for all OSPFv3 instances configured with the “graceful-restart” command. The ospf6d daemon should be restarted during the instance-specific grace period, otherwise the graceful restart will fail.

This is an EXEC-level command.

Showing OSPF6 information

show ipv6 ospf6 [vrf <NAME|all>] [json]

Show information on a variety of general OSPFv3 and area state and configuration information. JSON output can be obtained by appending ‘json’ to the end of command.

show ipv6 ospf6 [vrf <NAME|all>] database [<detail|dump|internal>] [json]

This command shows LSAs present in the LSDB. There are three view options. These options helps in viewing all the parameters of the LSAs. JSON output can be obtained by appending ‘json’ to the end of command. JSON option is not applicable with ‘dump’ option.

show ipv6 ospf6 [vrf <NAME|all>] database adv-router A.B.C.D linkstate-id A.B.C.D [json]

The LSAs additinally can also be filtered with the linkstate-id and advertising-router fields. We can use the LSA type filter and views with this command as well and visa-versa. JSON output can be obtained by appending ‘json’ to the end of command.

show ipv6 ospf6 [vrf <NAME|all>] database self-originated [json]

This command is used to filter the LSAs which are originated by the present router. All the other filters are applicable here as well.

show ipv6 ospf6 [vrf <NAME|all>] interface [json]

To see OSPF interface configuration like costs. JSON output can be obtained by appending “json” in the end.

show ipv6 ospf6 [vrf <NAME|all>] neighbor [json]

Shows state and chosen (Backup) DR of neighbor. JSON output can be obtained by appending ‘json’ at the end.

show ipv6 ospf6 [vrf <NAME|all>] interface traffic [json]

Shows counts of different packets that have been received and transmitted by the interfaces. JSON output can be obtained by appending “json” at the end.

show ipv6 route ospf6

This command shows internal routing table.

show ipv6 ospf6 zebra [json]

Shows state about what is being redistributed between zebra and OSPF6. JSON output can be obtained by appending “json” at the end.

show ipv6 ospf6 [vrf <NAME|all>] redistribute [json]

Shows the routes which are redistributed by the router. JSON output can be obtained by appending ‘json’ at the end.

show ipv6 ospf6 [vrf <NAME|all>] route [<intra-area|inter-area|external-1|external-2|X:X::X:X|X:X::X:X/M|detail|summary>] [json]
show ipv6 ospf6 [vrf <NAME|all>] route X:X::X:X/M match [detail] [json]

The additional match option will match the given address to the destination of the routes, and return the result accordingly.

show ipv6 ospf6 [vrf <NAME|all>] interface [IFNAME] prefix [detail|<X:X::X:X|X:X::X:X/M> [<match|detail>]] [json]

This command shows the prefixes present in the interface routing table. Interface name can also be given. JSON output can be obtained by appending ‘json’ to the end of command.

show ipv6 ospf6 [vrf <NAME|all>] spf tree [json]

This commands shows the spf tree from the recent spf calculation with the calling router as the root. If json is appended in the end, we can get the tree in JSON format. Each area that the router belongs to has it’s own JSON object, with each router having “cost”, “isLeafNode” and “children” as arguments.

show ipv6 ospf6 graceful-restart helper [detail] [json]

This command shows the graceful-restart helper details including helper configuration parameters.

OSPFv3 Debugging

The following debug commands are supported:

debug ospf6 abr

Toggle OSPFv3 ABR debugging messages.

debug ospf6 asbr

Toggle OSPFv3 ASBR debugging messages.

debug ospf6 border-routers {router-id [A.B.C.D] | area-id [A.B.C.D]}

Toggle OSPFv3 border router debugging messages. This can be specified for a router with specific Router-ID/Area-ID.

debug ospf6 flooding

Toggle OSPFv3 flooding debugging messages.

debug ospf6 interface

Toggle OSPFv3 interface related debugging messages.

debug ospf6 lsa

Toggle OSPFv3 Link State Advertisements debugging messages.

debug ospf6 lsa aggregation

Toggle OSPFv3 Link State Advertisements summarization debugging messages.

debug ospf6 message

Toggle OSPFv3 message exchange debugging messages.

debug ospf6 neighbor

Toggle OSPFv3 neighbor interaction debugging messages.

debug ospf6 nssa

Toggle OSPFv3 Not So Stubby Area (NSSA) debugging messages.

debug ospf6 route

Toggle OSPFv3 routes debugging messages.

debug ospf6 spf

Toggle OSPFv3 Shortest Path calculation debugging messages.

debug ospf6 zebra

Toggle OSPFv3 zebra interaction debugging messages.

debug ospf6 graceful-restart

Toggle OSPFv3 graceful-restart helper debugging messages.

OSPF6 Configuration Examples

Example of ospf6d configured on one interface and area:

interface ge0
 ipv6 ospf6 area 0.0.0.0
 ipv6 ospf6 instance-id 0
!
router ospf6
 ospf6 router-id 212.17.55.53
 area 0.0.0.0 range 2001:770:105:2::/64
!

Larger example with policy and various options set:

debug ospf6 neighbor state
!
interface ge0
 ipv6 ospf6 area 0.0.0.0
 ipv6 ospf6 cost 1
 ipv6 ospf6 hello-interval 10
 ipv6 ospf6 dead-interval 40
 ipv6 ospf6 retransmit-interval 5
 ipv6 ospf6 priority 0
 ipv6 ospf6 transmit-delay 1
 ipv6 ospf6 instance-id 0
!
interface loopback0
 ipv6 ospf6 cost 1
 ipv6 ospf6 hello-interval 10
 ipv6 ospf6 dead-interval 40
 ipv6 ospf6 retransmit-interval 5
 ipv6 ospf6 priority 1
 ipv6 ospf6 transmit-delay 1
 ipv6 ospf6 instance-id 0
!
router ospf6
 router-id 255.1.1.1
 redistribute static route-map static-ospf6
!
!
ipv6 prefix-list test-prefix seq 1000 deny any
!
route-map static-ospf6 permit 10
 match ipv6 address prefix-list test-prefix
 set metric-type type-2
 set metric 2000
!