Internet Architecture Board


IAB IPv6 Multi-Homing BOF

IAB IPv6 Multi-Homing BOF

Dave Meyer, Cisco, moderator

With the advent of the growing and widespread deployment of IPv6, many familiar operational issues have arisen. Among the current IPv6 “hot topics” are RIR policy (including the HD ratio discussion) and site multi-homing. This BOF focuses on the multi-homing issue, since multi-homing is a one of the significant drivers of the growth and dynamic properties of Default Free Zone (DFZ). In particular, there is concern that the amount of multi-homing will grow beyond the organizations who use it today in the IPv4 Internet and that we need new mechanisms to handle the potential growth (both in terms of the size of the DFZ, and its dynamic properties).

The current direction that the IETF is taking is being defined by the shim6
working group. Briefly, shim6 seeks to find a mechanism which provides most the functional benefits of multi-homing while still allowing reasonable scalability of the DFZ. More precisely, shim6 seeks to find scalable solutions that allow sites to multi-home for the purposes of redundancy, traffic engineering, or other policy.

However, there has been quite a bit of discussion in various venues as to whether shim6 actually accomplishes what most might traditionally think of as traffic engineering. In particular, traffic engineering can be thought of as the practice and mechanisms needed to place traffic where capacity exists (in contrast to capacity planning, which puts capacity where traffic exists). One can note that in order to accomplish site-wide inbound traffic engineering under shim6, some control mechanism would be required that is capable of causing all of the hosts within the site to change the destination address that their correspondents are using. Some feel that this is overly complex. In the outbound traffic engineering case, a similar capability would require a control mechanism that has knowledge of the site’s external routing tables and can affect the destination addresses used by the site’s hosts, which has also raised concerns about its potential complexity.

The purpose of this BOF for the IAB is to solicit community feedback on the progress and direction of the IPv6 multi-homing work in the IETF, and to help the IAB determine if there is meaningful work that the IETF (and the IAB in particular) can do to address any problem(s) that may be perceived with the current direction. The BOF is IAB-sponsored, and is the first in a series held at the various NOGs (NANOG, RIPE, APRICOT, etc) in support of this effort. A possible outcome might be an IAB workshop on multi-homing in IPv6.