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IPv6 Site Renumbering

Document Charter IPv6 Site Renumbering WG (6renum)
Title IPv6 Site Renumbering
Last updated 2011-06-14
State Approved
WG State Concluded
IESG Responsible AD Joel Jaeggli
Charter edit AD (None)
Send notices to (None)

As outlined in RFC 5887, renumbering, especially for medium to large 
  sites and networks, is currently viewed as an expensive, painful, and 
  error-prone process, avoided by network managers as much as possible.
  As that RFC describes, there are triggers that mean some cases of 
  renumbering are unavoidable, so it should be considered a given that a 
  site may need partial or complete renumbering at some stage. It is thus 
  important to implement and deploy techniques that facilitate simpler 
  IPv6 site renumbering, so that as IPv6 becomes universally deployed, 
  renumbering can be viewed as a more routine event. This includes 
  consideration of how the initial assignment and subsequent management of 
  address information is performed, as this will affect future renumbering 
  If IPv6 site renumbering continues to be considered difficult, network 
  managers will turn to PI addressing for IPv6 to attempt to minimise the 
  need for future renumbering. However, widespread use of PI may create 
  very serious BGP4 scaling problems. It is thus desirable to develop 
  tools and practices that may make renumbering a simpler process to 
  reduce demand for IPv6 PI space.
  Renumbering, or partial renumbering, can be complicated in an enterprise 
  site where a short prefix is divided into subnets with longer prefixes.  
  Aggregation, synchronisation, coordination, etc., need to be carefully 
  managed, and the use of manually inserted address literals minimised.
  Other factors such as applications binding long-term to low level IP 
  addresses may add constraints to what can be realistically achieved, but 
  identifying and documenting such factors is a useful objective.  In some 
  scenarios, consideration may also need to be made for 'flag day' 
  renumbering (in contrast to the procedure described in RFC4192). 
  The task of the 6RENUM working group is to document existing renumbering 
  practices for enterprise site networks and to identify specific 
  renumbering problems or 'gaps' in the context of partial or site-wide 
  renumbering.  Completion of these tasks should provide a basis for 
  future work to identify and develop point solutions or system solutions 
  to address those problems or to stimulate such development in other 
  working groups as appropriate. 
  6RENUM is chartered to perform an analysis of IPv6 site renumbering. If 
  the analysis leads to conclusions that are also applicable to IPv4 that 
  will be an advantage, but it is not an objective of the WG to make its 
  outputs more widely available than IPv6. Similarly the WG is targeting 
  enterprise networks, but the analysis may also be applicable to SOHO or 
  other (e.g. ad-hoc) scenarios.
  It may be that for site renumbering to become more routine, a systematic 
  address management approach will be required. By documenting current 
  practices and undertaking a gap analysis, we should become better 
  informed of the requirements of such an approach. Post-analysis 
  rechartering may lead to further work in this area. RFC 4192, RFC 5887, 
  and draft-jiang-ipv6-site-renum-guideline are starting points for this 
  The goals of the 6RENUM working group are:
  1. To undertake scenario descriptions, including documentation of 
  current capability inventories and existing BCPs, for enterprise 
  networks, including managed and unmanaged elements. These texts should 
  contribute towards a gap analysis and provide an agreed basis for 
  subsequent WG rechartering towards development of solutions (which may 
  be more appropriate for other WGs to undertake) and improved practices. 
  Operator input will be of high value for this text.
  2. To perform a gap analysis for renumbering practices, to identify 
  generic issues for network design, network management, address 
  management and renumbering operations. The methodology for the WG will 
  be to begin building the enterprise scenario description while in 
  parallel constructing an initial gap analysis drawing on existing work 
  in (at least) RFC4192 and RFC5887. As the scenario text hardens, its 
  contributions will be incorporated into the more detailed gap analysis, 
  which can be published once the scenario text is completed. The 
  deliverables are thus the scenario and gap analysis texts.
  The following topics are out of scope for the working group:
  1. Renumbering avoidance; this can perhaps be considered by appropriate 
  IRTF groups. As documented in RFC5887, renumbering cannot be completely 
  avoided. The WG is limited to dealing with how to renumber when it is 
  2. IPv4 renumbering. While many sites are likely to run dual-stack, IPv6 
  is the future and, especially given concerns over extensive use of IPv6 
  PI, the most appropriate place to focus effort.
  3. ISP renumbering; this is potentially the most complex renumbering 
  case. However, more benefit can be achieved by focusing effort on site 
  renumbering. The enterprise site analysis should include the ISP's role 
  in the site's renumbering events.
  4. Neither SOHO nor manet networks are targeted by the WG. However, if 
  outputs from the WG are applicable to those scenarios, that would be an 
  A recharter of the WG will be possible once the gap analysis and 
  scenario description are completed and published. Such rechartering 
  would identify more specific work items within the 6RENUM WG or 
  appropriate protocol WGs, and may include a proposal for work on a 
  systematic address management approach.