MVPN mLDP Partitioned MDT

The MVPN mLDP partitioned MDT feature uses Upstream Multicast Hop-Provider Multicast Service Interface (UMS-PMSI), a subset of provider edge routers (PEs) to transmit data to other PEs; similar to the usage of multiple selective-PMSI (S-PMSI) by data multicast distribution tree (MDT). In the partitioned MDT approach, egress PE routers that have interested receivers for traffic from a particular ingress PE joins a point-to-point (P2P) connection rooted at that ingress PE. This makes the number of ingress PE routers in a network to be low resulting in a limited number of trees in the core.

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Prerequisites for MVPN mLDP Partitioned MDT

MVPN BGP auto discovery should be configured.

Restrictions for MVPN mLDP Partitioned MDT

  • PIM Dense mode (except for Auto-RP) and PIM-Bidir in the VRF are not supported.

  • BGP multicast signaling is supported and PIM signaling is not supported.

  • Only point-to-multi point (P2MP) mLDP label switch path is supported.

  • Same VRF (for which mLDP in-band signaling is configured) needs to be configured on IPv4

  • Rosen mLDP recursive FEC is not supported. Partitioned MDT is applicable to inter-AS VPN (Inter AS option B and option C are not supported).

  • mLDP filtering is not supported.

  • Only interface-based strict RPF is supported with partitioned MDT.

Information About MVPN mLDP Partitioned MDT

Overview of MVPN mLDP Partitioned MDT

MVPN allows a service provider to configure and support multicast traffic in an MPLS VPN environment. This type supports routing and forwarding of multicast packets for each individual VPN routing and forwarding (VRF) instance, and it also provides a mechanism to transport VPN multicast packets across the service provider backbone. In the MLDP case, the regular label switch path forwarding is used, so core does not need to run PIM protocol. In this scenario, the c-packets are encapsulated in the MPLS labels and forwarding is based on the MPLS Label Switched Paths (LSPs).

The MVPN mLDP service allows you to build a Protocol Independent Multicast (PIM) domain that has sources and receivers located in different sites.

To provide Layer 3 multicast services to customers with multiple distributed sites, service providers look for a secure and scalable mechanism to transmit customer multicast traffic across the provider network. Multicast VPN (MVPN) provides such services over a shared service provider backbone, using native multicast technology similar to BGP/MPLS VPN.

MVPN emulates MPLS VPN technology in its adoption of the multicast domain (MD) concept, in which provider edge (PE) routers establish virtual PIM neighbor connections with other PE routers that are connected to the same customer VPN. These PE routers thereby form a secure, virtual multicast domain over the provider network. Multicast traffic is then transmitted across the core network from one site to another, as if the traffic were going through a dedicated provider network.

Separate multicast routing and forwarding tables are maintained for each VPN routing and forwarding (VRF) instance, with traffic being sent through VPN tunnels across the service provider backbone.

In the Rosen MVPN mLDP solution, a multipoint-to-multipoint (MP2MP) default MDT is setup to carry control plane and data traffic. A disadvantage with this solution is that all PE routers that are part of the MVPN need to join this default MDT tree. Setting up a MP2MP tree between all PE routers of a MVPN is equivalent to creating N P2MP trees rooted at each PE (Where N is the number of PE routers). In an Inter-AS (Option A) solution this problem is exacerbated since all PE routers across all AS’es need to join the default MDT. Another disadvantage of this solution is that any packet sent through a default MDT reaches all the PE routers even if there is no requirement.

In the partitioned MDT approach, only those egress PE routers that receive traffic requests from a particular ingress PE join the PMSI configured at that ingress PE. This makes the number of ingress PE routers in a network to be low resulting in a limited number of trees in the core.

How to Configure MVPN mLDP Partitioned MDT

Configuring MVPN mLDP Partitioned MDT

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    ip multicast-routing vrf vrf-name

    4.    ip vrf vrf-name

    5.    rd route-distinguisher

    6.    route target export route-target-ext-community

    7.    route target import route-target-ext-community

    8.    mdt strict-rpf interface

    9.    mdt partitioned mldp p2mp

    10.    mdt auto-discovery mldp [inter-as]

    11.    exit

    12.    show ip pim mdt

    13.    show ip pim vrf mdt [send | receive]

    14.    show ip multicast mpls vif


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example: 
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example: 
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 ip multicast-routing vrf vrf-name


    Example: 
    Device(config)# ip multicast-routing vrf VRF
     

    Enables IP multicast routing for the MVPN VRF specified for the vrf-name argument.

     
    Step 4 ip vrf vrf-name


    Example: 
    Device(config-vrf)# ip vrf VRF
     

    Defines a VRF instance and enters VRF configuration mode.

     
    Step 5 rd route-distinguisher


    Example: 
    Device(config-vrf)# rd 50:11
     

    Creates a route distinguisher (RD) (in order to make the VRF functional).

    • Creates the routing and forwarding tables, associates the RD with the VRF instance, and specifies the default RD for a VPN.

     
    Step 6 route target export route-target-ext-community


    Example: 
    Device(config-vrf)# route target export 100:100
     

    Creates an export route target extended community for the specified VRF.

     
    Step 7 route target import route-target-ext-community


    Example: 
    Device(config-vrf)# route target import 100:100
     

    Creates an import route target extended community for the specified VRF.

     
    Step 8 mdt strict-rpf interface


    Example: 
    Device(config-vrf)# mdt strict-rpf interface
     

    Creates per-PE LSPVIF interface to implement strict-RPF check.

     
    Step 9 mdt partitioned mldp p2mp


    Example: 
    Device(config-vrf)# mdt partitioned mldp p2mp
     

    Configures partitioned MDT.

     
    Step 10 mdt auto-discovery mldp [inter-as]


    Example: 
    Device(config-vrf)# mdt auto-discovery mldp inter-as
     

    Enables inter-AS operation with BGP A-D.

     
    Step 11 exit


    Example: 
    Device(config-vrf)# exit
     

    Exits the VRF configuration mode and returns to privileged EXEC mode.

     
    Step 12 show ip pim mdt


    Example: 
    Device# show ip pim mdt
     

    Displays information on wildcard S-PMSI A-D route.

     
    Step 13 show ip pim vrf mdt [send | receive]


    Example: 
    Device# show ip pim vrf mdt send
     

    Displays information on wildcard S-PMSI A-D route along with MDT group mappings received from other PE routers or the MDT groups that are currently in use.

     
    Step 14 show ip multicast mpls vif


    Example: 
    Device# end
     

    Displays the LSPVIFs created for all the PEs.

     

    Configuration Examples for MVPN mLDP Partitioned MDT

    Example: MVPN mLDP Partitioned MDT

    
ip multicast-routing vrf VRF
   ip vrf VRF
   rd 50:11
   route target export 100:100
   route target import 100:100
   mdt strict-rpf interface
   mdt partitioned mldp p2mp
   mdt auto-discovery mldp inter-as  
  !
 !

    Additional References for MVPN mLDP Partitioned MDT

    Related Documents

    Related Topic

    Document Title

    Cisco IOS commands

    Cisco IOS Master Commands List, All Releases

    IP multicast commands

    Cisco IP Multicast Command Reference

    Configuring Multicast VPN Inter-AS Support

    IP Multicast: MVPN Configuration Guide

    Configuring MLDP-based MVPN

    IP Multicast: LSM Configuration Guide

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    Feature Information for MVPN mLDP Partitioned MDT

    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 MVPN mLDP Partitioned MDT

    Feature Name

    Releases

    Feature Information

    MVPN mLDP Partitioned MDT

    15.4(1)T

    In the partitioned MDT approach, only those egress PE routers that receive traffic requests from a particular ingress PE join a S-PMSI configured at that ingress PE. Typically the number of ingress PE routers in a network is low resulting in a limited number of trees in the core.

    No commands were introduced or modified.