The goal of this exercise is to study 6PE (IPv6 Provider Edge) transition mechanism described in draft-ooms-v6ops-bgp-tunnel-00.txt (now published as RFC 4798, since the draft is very old, the solution proposed here are not exactly what have been standardized). This principle is implemented by many major router manufacturers. This proposal combines one IGP, MPLS and BGP to allow an ISP to carry efficiently IPv6 traffic without modifying core routers. Only edge routers have to be modified to understand IPv6 protocol. In the rest of this exercise we will study progressively the Internet Draft and the different elements of this proposal.
A company has a site in Europe and another one in Mexico. They are interconnected by a private leased line. Each site is locally connected to an ISP (ISP-EU in Europe and ISP-MX in mexico). Border routers are respectively ER-EU in Europe and ER-MX in Mexico. Providers have allocated prefixes α in Europe and β in Mexico. Providers are doing in-gress filtering (i.e. a packet with a source address non allocated by a provider is discarded by the first provider router).
In the rest of the document, a host A (resp. B) will designate a host in Internet (outside company network) close to the ISP-MX (resp. ISP-EU) with a metric linked to BGP announcement. C (resp. D) will represent an equipment in the Mexican (resp. european) part of the company network.
Inside the site, an IGP routing protocol allows all routers to know all internal prefixes.