[bess] Regarding the Next Hop Network Address coding for IPv4 VPN over IPv6 Core in RFC5549

[Zhuangshunwan <[e-mail]>]

Dear authors and WGs,

RFC5549 Section 6.2 says:

. 6.2.  IPv4 VPN 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:
.
.    o  AFI = 1
.
.    o  SAFI = 128
.
.    o  Length of Next Hop Network Address = 16 (or 32)
.
.    o  Network Address of Next Hop = IPv6 address of Next Hop
.
.    o  NLRI = IPv4-VPN routes


Regarding IPv4-VPN routes, RFC4634 Section 4.3.2 says:

. 4.3.2.  Route Distribution Among PEs by BGP
[snip]
.    When a PE router distributes a VPN-IPv4 route via BGP, it uses its
.    own address as the "BGP next hop".  This address is encoded as a
.    VPN-IPv4 address with an RD of 0.  ([BGP-MP] requires that the next
.    hop address be in the same address family as the Network Layer
.    Reachability Information (NLRI).)  It also assigns and distributes an
.    MPLS label.  (Essentially, PE routers distribute not VPN-IPv4 routes,
.    but Labeled VPN-IPv4 routes.  Cf. [MPLS-BGP].)  When the PE processes
.    a received packet that has this label at the top of the stack, the PE
.    will pop the stack, and process the packet appropriately.
[snip]


Question:
RFC5549 defines "IPv4 VPN over IPv6 Core", When a PE router distributes a VPN-IPv4 route with an IPv6 Next-Hop via BGP, should the IPv6 Next-Hop be encoded as an VPN-IPv6 address with an RD of 0 ?


Thanks,
Shunwan