OTV Loopback Join Interface

This chapter describes the Overlay Transport Virtualization (OTV) Loopback Join Interface feature on Cisco NX-OS devices.

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Information About OTV Loopback Join Interface

The Overlay Transport Virtualization (OTV) Loopback Join interface feature, for the Cisco Nexus 7000 and Nexus 7700 platforms, adds the capability of an Overlay using a loopback interface as the Join interface. The Loopback Join Interface adds a PIM-based control plane, where the Loopback interface has PIM configured and acts as a first-hop/last-hop multicast router into the multicast core. This gives the capability for the Loopback Join interface to have multiple Uplinks into the provider Multicast core.

Prior to Release 8.0(1), OTV supports only one uplink interface to connect to the core, which is an IGMP host interface. PIM cannot be enabled on this join-interface. Beginning with Release 8.0(1), PIM routing is supported on the core uplinks through the loopback interfaces. Therefore, the OTV edge device behaves as a first hop or last hop multicast router towards the core device. This enables multiple core uplinks to be operational concurrently for OTV traffic. The PIM Routing support on uplinks utilizes the dynamic unicast routing-based convergence on the core network topology changes. This feature facilitates support for a loopback interface for sourcing OTV traffic; and therefore, the core physical topology changes does not impact Overlay states, negating the control place churn for OTV databases. PIM on OTV supports the loopback join interface loopback configuration under Overlay mode, similar to the existing join interface. You must configure PIM in Sparse mode on the loopback interface to use the interface for transmitting and receiving OTV traffic.

The loopback join-interface is used to facilitate the following:

  • to source the OTV traffic from the edge device into the core device.

  • to source multicast traffic into the core device, in order to receive OTV traffic from the core device.

The loopback will be operational irrespective of the physical network topology changes.


Note

A physical Layer 3 interface cannot be used with the PIM method as an OTV join interface.

The same loopback can be used by multiple Overlays to source their traffic. For a given Overlay, if the join interface changes to a physical interface, Ethernet, then the behavior for that Overlay will revert to the older IGMP-host model.

Guidelines and Limitationsfor OTV Loopback Join Interface

Guidelines for OTV Loopback Join Interface

Loopback Join Interface has the following configuration guidelines:

  • For optimal configuration, ensure that you use the multiple uplink interfaces.

  • If all the uplink interfaces are down, the OTV connectivity to the core will be broken. You must ensure that the connection to the core is operational always.

  • If the loopback join interface configuration is modified, all the OTV overlay states will be altered, which impacts the traffic.

Limitations for OTV Loopback Join Interface

Loopback Join Interface has the following configuration limitations:

  • This feature is available only on the Nexus 70xx Series and Nexus 77xx Series Switches.

  • Unicast and Adjacency Server features are not supported on Loopback Join Interface.

  • PIM bidirectional mode is not supported for loopback join interface for Release 8.0(1).

  • Loopback join interface IP address cannot be the same as AnyCast-Rp IP address.

  • If two OTV overlays are configured on the same Layer 3 join interface and packet flow is enabled, IPv6 packets will loop between the OTV overlay interfaces. This is applicable to scenarios in which the OTV overlays are stitched to VXLAN overlays.

Prerequisites for OTV Loopback Join Interface

Loopback Join Interface has the following prerequisites:

  • The transport network must support the Protocol Independent Multicast (PIM) sparse mode (Any Source Multicast [ASM]) for the provider multicast group and Source Specific Multicast (SSM) for the delivery group.

How to Configure OTV Loopback Join Interface

Configuring Uplink Interfaces

To configure uplink interfaces, perform the steps below.

Procedure

Step 1

Enter global configuration mode.

switch# configure terminal

Step 2

Create an uplink interface and enter interface configuration mode.

switch(config)# interface interface_type slot/port

Step 3

Configure the uplink interface.

switch(config-if)# ip address ip_address

Step 4

Add the interface to the OSPFv2 instance and area.

switch(config-if)# ip router ospf instance-tag area area-id

Step 5

Enable PIM sparse mode on loopback interface and on the uplink Layer3 interface. The default is disabled.

switch(config-if)# ip pim sparse-mode

Note

 

You must configure PIM in sparse-mode on the uplink Layer3 interfaces, to use it for transmitting and receiving OTV traffic.

Step 6

Enable the interface.

switch(config-if)# no shutdown

Example: Configuring Uplink Interfaces

This example shows a running configuration, followed by a verification command that displays the Cisco Uplink Interfaces configuration details. Replace the placeholders with relevant values for your setup. 

configure terminal
feature pim

interface Ethernet1/2
  ip address 2.2.2.2/24
  ip router ospf 100 area 0.0.0.0
  ip pim sparse-mode
  no shutdown

interface Ethernet1/3
  ip address 5.5.5.2/24
  ip router ospf 100 area 0.0.0.0
  ip pim sparse-mode
  no shutdown

Configuring Loopback Interface

To configure loopback interface, perform the steps below.

Before you begin

By default, the OTV feature is disabled on the device. You must explicitly enable the OTV feature to access the configuration and verification commands.

Procedure

Step 1

Enter global configuration mode.

switch# configure terminal

Step 2

Create a loopback interface and enter interface configuration mode.

switch(config)# interface loopback_interface

Step 3

Configure the loopback interface.

switch(config-if)# ip address ip_address

Step 4

Add the interface to the OSPFv2 instance and area.

switch(config-if)# ip router ospf instance-tag area area-id

Step 5

Enable PIM sparse mode on loopback interface and on the uplink Layer3 interface. The default is disabled.

switch(config-if)# ip pim sparse-mode

Note

 

You must configure PIM in sparse-mode on the uplink Layer3 interface, to use it for transmitting and receiving OTV traffic.

Step 6

Enable the interface.

switch(config-if)# no shutdown

Example: Configuring Loopback Interface

This example shows a running configuration, followed by a verification command that displays the Cisco Loopback interface configuration details. Replace the placeholders with relevant values for your setup. 

configure terminal
feature pim

interface loopback1
  ip address 10.10.10.2/32
  ip router ospf 100 area 0.0.0.0
  ip pim sparse-mode

Configuring Interface Overlay

To configure interface overlay, perform the steps below.

Before you begin

By default, the OTV feature is disabled on the device. You must explicitly enable the OTV feature to access the configuration and verification commands.

Procedure

Step 1

Enter global configuration mode.

switch# configure terminal

Step 2

Enable OTV.

switch(config)# feature otv

Step 3

Create an OTV overlay interface and enter interface configuration mode. The range is from 0 to 65535.

switch(config)# interface overlay interface_number

Step 4

Join the OTV overlay interface with a loopback interface.

switch(config-if)# otv join-interface loopback1_interface

Step 5

Configure a multicast group address for the OTV control plane for this OTV overlay network.

switch(config-if)# otv control-group multicast-address

Step 6

Configure one or more ranges of local IPv4 multicast group prefixes used for multicast data traffic.

switch(config-if)# otv data-group multicast-address/mask

  • Enable SSM for the groups by using the ip pim ssm command in global configuration mode.

  • Use SSM multicast groups 232.0.0.0/8.

  • The multicast group address is an IPv4 address in dotted decimal notation.

  • A subnet mask is used to indicate ranges of addresses.

  • You can define up to 8 data-group ranges.

Step 7

Extend the OTV Overlay to the VLAN interface, use the following command.

switch(config-if)# otv extend-vlan range

Step 8

Enable the interface.

switch(config-if)# no shutdown

Example: Configuring OTV Loopback Join Interface

This example shows a running configuration, followed by a verification command that displays the Cisco OTV Loopback Join Interface configuration details. Replace the placeholders with relevant values for your setup. 

configure terminal
feature otv
Interface Overlay config:
interface Overlay1
  otv join-interface loopback1
  otv control-group 224.1.1.1
  otv data-group 232.1.1.0/24
  otv extend-vlan 201-205
  no shutdown



switch(config)# show otv overlay1
  VPN name : Overlay1
  VPN state : UP
  Extended vlans : 200 (Total:1)
  Control group : 224.1.1.1
  Data group range(s) : 232.0.0.1/24
  Broadcast group : 224.0.0.1
  Join interface(s) : Lo1 (10.10.10.2)
  Site vlan : 1 (up)
  AED-Capable : Yes
  Capability : Multicast-Reachable

Additional References for OTV Loopback Join Interface

Related Documents

Related Topic

Document Title

command syntax

Cisco Nexus 7000 Series Command Reference

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http://www.cisco.com/go/mibs

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Feature Information for OTV Loopback Join Interface

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 https://cfnng.cisco.com/. An account on Cisco.com is not required.
Table 1. Feature Information for OTV Loopback Join Interface

Feature Name

Releases

Feature Information

OTV Loopback Join Interface

8.0(1)

The Overlay Transport Virtualization (OTV) Loopback Join interface feature adds the capability of an Overlay using a loopback interface as the Join interface. Loopback Join Interface adds a PIM-based control plane, where the Loopback interface has PIM configured and acts as a first-hop/last-hop multicast router into the multicast core.

The following commands were modified by this feature: otv join-interface command has been expanded to allow for 'loopbackx' under overlay configuration .