IPv6 和 L2TP 隧道 — Truman Boyes

最近有人向我请教有关批发场景或案例，其中服务提供商运行 L2TP LAC，而各个 ISP 在宽带环境中运行 LNS。当使用 IPv6 时，可以在 LAC 与 LNS 之间使用 IPv4 L2TP 隧道来承载 IPv6CP（NCP），进而为客户住宅网关上的 IPv6 主机/网络分配地址。

根据 RFC 4779：

6.2.3.1.  IPv6 Related Infrastructure Changes

   In this scenario, the BRAS is forwarding the PPP sessions initiated
   by the subscriber over the L2TPv2 tunnel established to the L2TP
   Network Server (LNS), the aggregation point in the ISP network.  The
   L2TPv2 tunnel between the L2TP Access Concentrator (LAC) and LNS can
   run over IPv6 or IPv4.  These capabilities have to be supported on
   the BRAS.  The following devices have to be upgraded to dual stack:
   Host, Customer Router, and Edge Router.  If the tunnel is set up over
   IPv6, then the BRAS must be upgraded to dual stack.

最初发表于 truman.net。查看存档副本。