The OSPF Support for MTR feature provides Open Shortest Path First (OSPF) support for multiple logical topologies over a single physical network. This module describes how to configure OSPF for Multitopology Routing (MTR).
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
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Prerequisites for OSPF Support for MTR
Be familiar with the concepts documented in the" Routing Protocol Support for MTR" section.
Configure and activate a global topology configuration.
Check your Open Shortest Path First (OSPF) device configuration and enter the topology-aware device configuration commands in router address family configuration mode.
Several OSPF configuration commands need to be topology-aware. Before you configure OSPF Multitopology Routing (MTR), you need to enter the following commands in router address family configuration mode if they are used in your original OSPF device configuration.
You must enable IP routing on the router for MTR to operate. MTR supports static and dynamic routing in Cisco IOS software. You can enable dynamic routing per-topology to support inter-domain and intra-domain routing. Route calculation and forwarding are independent for each topology. MTR support is integrated into Cisco IOS software for the following protocols:
Integrated Intermediate System-to-Intermediate System (IS-IS)
Open Shortest Path First (OSPF)
You apply the per-topology configuration in router address family configuration mode of the global routing process (router configuration mode). The address family and subaddress family are specified when entering address-family configuration mode. You specify the topology name and topology ID by entering the
topology command in address-family configuration mode.
You configure each topology with a unique topology ID under the routing protocol. The topology ID is used to identify and group NLRI for each topology in updates for a given protocol. In OSPF, EIGRP, and IS-IS, you enter the topology ID during the first configuration of the
topology command for a class-specific topology. In BGP, you configure the topology ID by entering the
bgp tid command under the topology configuration.
You can configure class-specific topologies with different metrics than the base topology. Interface metrics configured on the base topology can be inherited by the class-specific topology. Inheritance occurs if no explicit inheritance metric is configured in the class-specific topology.
You configure BGP support only in router configuration mode. You configure Interior Gateway Protocol (IGP) support in router configuration mode and in interface configuration mode.
By default, interfaces are not included in non-base topologies. For routing protocol support for EIGRP, IS-IS, and OSPF, you must explicitly configure a non-base topology on an interface. You can override the default behavior by using the
all-interfaces command in address family topology configuration mode. The
all-interfaces command causes the non-base topology to be configured on all interfaces of the router that are part of the default address space or the VRF in which the topology is configured.
Interface Configuration Support for MTR
The configuration of a Multitopology Routing (MTR) topology in interface configuration mode allows you to enable or disable MTR on a per-interface basis. By default, a class-specific topology does not include any interfaces.
You can include or exclude individual interfaces by configuring the
topology interface configuration command. You specify the address family and the topology (base or class-specific) when entering this command. The subaddress family can be specified. If no subaddress family is specified, the unicast subaddress family is used by default.
You can include globally all interfaces on a device in a topology by entering the
all-interfaces command in routing topology configuration mode. Per-interface topology configuration applied with the
topology command overrides global interface configuration.
The interface configuration support for MTR has these characteristics:
Per-interface routing configuration: Interior Gateway Protocol (IGP) routing and metric configurations can be applied in interface topology configuration mode. Per-interface metrics and routing behaviors can be configured for each IGP.
Open Shortest Path First (OSPF) interface topology configuration: Interface mode OSPF configurations for a class-specific topology are applied in interface topology configuration mode. In this mode, you can configure an interface cost or disable OSPF routing without removing the interface from the global topology configuration.
Enhanced Interior Gateway Routing Protocol (EIGRP) interface topology configuration: Interface mode EIGRP configurations for a class-specific topology are applied in interface topology configuration mode. In this mode, you can configure various EIGRP features.
Intermediate System-to-Intermediate System (IS-IS) interface topology configuration: Interface mode IS-IS configurations for a class-specific topology are applied in interface topology configuration mode. In this mode, you can configure an interface cost or disable IS-IS routing without removing the interface from the global topology configuration.
Be familiar with the concepts documented in the Routing Protocol Support for MTR section.
Configure and activate a global topology configuration.
Check your OSPF router configuration and enter the topology-aware router configuration commands in router address family configuration mode.
Several OSPF router configuration commands need to be topology-aware. Before you configure OSPF MTR, you need to enter these commands in router address family configuration mode if they are used in your original OSPF router configuration.
7.show ip ospf [process-id]
topology-info [multicast] [topology {topology-name |
base}]
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Router> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configure terminal
Example:
Router# configure terminal
Enters global configuration mode.
Step 3
router ospfprocess-id [vrfvrf-name]
Example:
Router(config)# router ospf 1
Enables an OSPF routing process and enters router configuration mode.
Step 4
address-family ipv4 [multicast |
unicast]
Example:
Router(config-router)# address-family ipv4
Enter router address family configuration mode to configure an OSPF address family session.
Currently, only the base topology can be configured under the multicast subaddress family.
Step 5
topology {base |
topology-nametidnumber}
Example:
Router(config-router-af)# topology VOICE tid 10
Configures OSPF support for the topology and assigns a TID number for each topology. Enters router address family topology configuration mode.
Use the
tidnumber keyword and argument to configure a topology ID. The topology ID must be configured in the first configuration of the specified topology. It is optional for subsequent configuration.
Note
The
base keyword is accepted only for IPv4 multicast. The
tid keyword is accepted only for IPv4 or IPv6 unicast.
Step 6
end
Example:
Router(config-router-af-topology)# end
Exits router address family topology configuration mode and returns to privileged EXEC mode.
Step 7
show ip ospf [process-id]
topology-info [multicast] [topology {topology-name |
base}]
Example:
Router# show ip ospf topology-info topology VOICE
(Optional) Displays OSPF information about the specified topology.
If an EIGRP topology configuration is required, proceed to the next task. If an IS-IS topology configuration is required proceed to the Activating an MTR Topology by Using IS-IS section.
Activating an MTR Topology in Interface Configuration Mode by Using OSPF
Before You Begin
Define a topology globally before performing the per-interface topology configuration.
Enters interface topology configuration mode to configure MTR.
Note
Entering this command with the
disable keyword disables the topology instance on the interface. This form is used to exclude a topology configuration from an interface.
Step 5
ip ospf costnumber
Example:
Router(config-if-topology)# ip ospf cost 100
Applies a cost to the interface in a topology instance.
The lowest cost number has the highest preference.
Step 6
ip ospf topology disable
Example:
Router(config-if-topology)# ip ospf topology disable
Prevents OSPF from advertising the interface as part of the topology without disabling the OSPF process or the topology on the interface.
Step 7
end
Example:
Router(config-if-topology)# end
Exits interface topology configuration mode and returns to privileged EXEC mode.
Step 8
show ip ospf [process-id]
interface [interface-type interface-number] [brief] [multicast] [topology {topology-name |
base}]
Displays OSPF and interface information about the specified topology when the
topology keyword is entered.
Monitoring Interface and Topology IP Traffic Statistics for MTR
Use any of the following commands in any order to monitor interface and topology IP traffic statistics for Multitopology Routing (MTR).
SUMMARY STEPS
1.enable
2.show ip interface [type number] [topology {name |
all |
base}] [stats]
3.show ip traffic [topology {name |
all |
base}]
4.clear ip interfacetype number [topology {name |
all |
base}] [stats]
5.clear ip traffic [topology {name |
all |
base}]
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Device> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
show ip interface [type number] [topology {name |
all |
base}] [stats]
Example:
Device# show ip interface FastEthernet 1/10 stats
(Optional) Displays IP traffic statistics for all interfaces or statistics related to the specified interface.
If you specify an interface type and number, information for that specific interface is displayed. If you specify no optional arguments, information for all the interfaces is displayed.
If the
topologyname keyword and argument are used, statistics are limited to the IP traffic for that specific topology.
The
base keyword displays the IPv4 unicast base topology.
Step 3
show ip traffic [topology {name |
all |
base}]
Example:
Device# show ip traffic topology VOICE
(Optional) Displays global IP traffic statistics (an aggregation of all the topologies when MTR is enabled) or statistics related to a particular topology.
The
base keyword is reserved for the IPv4 unicast base topology.
Step 4
clear ip interfacetype number [topology {name |
all |
base}] [stats]
Example:
Device# clear ip interface FastEthernet 1/10 topology all
(Optional) Resets interface-level IP traffic statistics.
If the
topology keyword and a related keyword are not used, only the interface-level aggregate statistics are reset.
If all topologies need to be reset, use the
all keyword as the topology name.
Step 5
clear ip traffic [topology {name |
all |
base}]
Example:
Device# clear ip traffic topology all
(Optional) Resets IP traffic statistics.
If no topology name is specified, global statistics are cleared.
The following example shows how to configure the VOICE topology in an OSPF routing process and set the priority of the VOICE topology to the highest priority:
router ospf 1
address-family ipv4
topology VOICE tid 10
priority 127
end
In the following example, the showipospf command is used with the topology-infoandtopology keywords to display OSPF information about the topology named VOICE.
Router# show ip ospf 1 topology-info topology VOICE
OSPF Router with ID (10.0.0.1) (Process ID 1)
VOICE Topology (MTID 66)
Topology priority is 64
Redistributing External Routes from,
isis
Number of areas transit capable is 0
Initial SPF schedule delay 5000 msecs
Minimum hold time between two consecutive SPFs 10000 msecs
Maximum wait time between two consecutive SPFs 10000 msecs
Area BACKBONE(0) (Inactive)
SPF algorithm last executed 16:45:18.984 ago
SPF algorithm executed 3 times
Area ranges are
Area 1
SPF algorithm last executed 00:00:21.584 ago
SPF algorithm executed 1 times
Area ranges are
Examples MTR OSPF Topology in Interface Configuration Mode
The following example shows how to disable OSPF routing on interface Ethernet 0/0 without removing the interface from the global topology configuration:
interface Ethernet 0/0
topology ipv4 VOICE
ip ospf cost 100
ip ospf topology disable
end
In the following example, the
show ip ospf interface command is used with the
topology keyword to display information about the topologies configured for OSPF in interface configuration mode.
Router# show ip ospf 1 interface topology VOICE
VOICE Topology (MTID 66)
Serial3/0 is up, line protocol is up
Internet Address 10.0.0.5/30, Area 1
Process ID 1, Router ID 44.44.44.44, Network Type POINT_TO_POINT
Topology-MTID Cost Disabled Shutdown Topology Name
4 77 no no grc
Transmit Delay is 1 sec, State POINT_TO_POINT
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:05
Supports Link-local Signaling (LLS)
Cisco NSF helper support enabled
IETF NSF helper support enabled
Index 1/4, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 10.2.2.2
Suppress hello for 0 neighbor(s)
In the following example, the
show ip ospf interface command is used with the
brief and the
topology keywords to display information about the topologies configured for OSPF in interface configuration mode.
Router# show ip ospf 1 interface brief topology VOICE
VOICE Topology (MTID 66)
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Se3/0 1 1 10.0.0.5/30 1 UP 0/0
Se2/0 1 1 10.0.0.1/30 1 UP 0/0
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The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1
Feature Information for OSPF Support for MTR
Feature Name
Releases
Feature Information
OSPF Support for MTR
12.2(33)SRB
This feature provides Open Shortest Path First (OSPF) support for multiple logical topologies over a single physical network.
The following commands were introduced or modified:
address-family ipv4,
area capability default-exclusion,
ip ospf cost,
ip ospf topology disable,
priority,
router ospf,
show ip ospf interface,
show ip ospf topology-info,
topology.
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