I could write quite a long essay on why this wouldn't work, either on the site whose network I used to manage until a few years ago, or on the intranet of my current employer. It's a neat trick, but it just doesn't match the realities of network management and operations. It implies, for example, that if you have to change a NIC in a router, or swap a faulty router, subnet renumbering will occur, with all its consequences for DNS, SNMP, security policy and key distribution, and asset management databases.
In any case, that size of network will need the same subnet numbering plan for globals and locals, to avoid driving the network operators crazy during fault analysis. There may be a class of smallish unmanaged networks where this would work, but even there I think there's a big DNS problem. Brian Aidan Williams wrote: > > A draft is in the pipeline. > > Michel, you and Brian are missing the point that there > is *no* administration of SLAs if we can use a MAC address > to automatically number *each* *link* in a site with a > site-local address. > > All this needs is a new addressing format. > I think this addresses your GUSL requirements. > > There is no numbering plan to administer, new or old. > This has no effect on the numbering plan you might use for globals. > There is no common site-local prefix shared across the site. > Site-local addresses prefixes are constructed without manual > configuration. > > For each link, a router may automatically assign a site-local > address from an EUI-48 (ie a MAC address) using the following > address format: > > | 12 bits | 48 bits | 4 bits | 64 bits | > +---------+------------------+----------+----------------------+ > | fef | router device ID | sub ID | machine interface ID | > +---------+------------------+----------+----------------------+ > Figure 1: Address Format: fef0::/12 > > There is no 16 bit SLA subnet number to be managed! > > A router gets 16 subnets per EUI-48. It can use those to number > links without ethernet or similar chips with 48 bit MAC addresses. > > Links with more than one router can have more than one automatically > allocated site-local prefix. IPv6 supports that just fine. > > If you don't like sharing the existing site-local space with non-/48 > addressing format we can use a different prefix, say fe00::/10. > That has the advantage of increasing to 6 the number of sub ID bits. > > - aidan > > Michel Py wrote: > > Administrative nightmare. This one of these things in IPv6 where there > > is an explicit trade-off between allocation efficiency and simplicity. > > > > I agree that the 54 subnet bits we have for site-locals today is > > overkill, but anything less than 16 subnet bits is not good. > > > > In the case you have both site-local and global at the same time, you > > want to maintain subnet numbers: > > > > 2001:YOUR:BLOC:BEEF:INTE:RFAC:E_IDE:NTIF > > FEC0:0000:0000:BEEF:INTE:RFAC:E_IDE:NTIF > > ^^^^ > > Maintain subnet number > > > > Given the room we have in FEC0::/10, I don't see a reason to do > > otherwise. > > > > Michel. -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
