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6. Usage Examples

6.1. IPv4 over IPv6 Core​

The extensions defined in this document may be used as discussed in [RFC5565] for the interconnection of IPv4 islands over an IPv6 backbone. In this application, Address Family Border Routers (AFBRs; as defined in [RFC4925]) advertise IPv4 NLRI in the MP_REACH_NLRI along with an IPv6 next hop.

The MP_REACH_NLRI is encoded with:

  • AFI = 1

  • SAFI = 1

  • Length of Next Hop Address field = 16 (or 32)

  • Next Hop Address = IPv6 address of the next hop

  • NLRI = IPv4 routes

During BGP Capability Advertisement, the PE routers would include the following fields in the Capabilities Optional Parameter:

  • Capability Code set to "Extended Next Hop Encoding"

  • Capability Value containing

6.2. IPv4 VPN Unicast over IPv6 Core​

The extensions defined in this document may be used for support of IPv4 VPNs over an IPv6 backbone. In this application, PE routers would advertise VPN-IPv4 NLRI in the MP_REACH_NLRI along with an IPv6 next hop.

The MP_REACH_NLRI is encoded with:

  • AFI = 1

  • SAFI = 128

  • Length of Next Hop Address field = 24 (or 48)

  • Next Hop Address = VPN-IPv6 address of a next hop whose RD is set to zero

  • NLRI = IPv4-VPN routes

During BGP Capability Advertisement, the PE routers would include the following fields in the Capabilities Optional Parameter:

  • Capability Code set to "Extended Next Hop Encoding"

  • Capability Value containing

6.3. IPv4 VPN Multicast over IPv6 Core​

The extensions defined in this document may be used for support of IPv4 multicast VPNs over an IPv6 backbone. In this application, PE routers would advertise VPN-IPv4 NLRI in the MP_REACH_NLRI along with an IPv6 next hop.

The MP_REACH_NLRI is encoded with:

  • AFI = 1

  • SAFI = 129

  • Length of Next Hop Address field = 24 (or 48)

  • Next Hop Address = VPN-IPv6 address of a next hop whose RD is set to zero

  • NLRI = IPv4-VPN routes

During BGP Capability Advertisement, the PE routers would include the following fields in the Capabilities Optional Parameter:

  • Capability Code set to "Extended Next Hop Encoding"

  • Capability Value containing

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