Hi Vijayrajan,
On Oct 7, 2009, at 12:25 PM, Vijayrajan ranganathan wrote:
Hi Everyone, Is there a notion that auto-configured IPv6 addresses based on globally unique prefixes are transient compared to manually configured ones?
Auto-configured global IPv6 addresses are "leased" to an interface for a specified "lifetime". They expire at the end of that lifetime if the lifetime is not renewed.
As an IPv6 application developer, would I have to factor in this "transiency" of autoconf addresses in my design all the time? How safe & normal is it to replace all manual IPv6 address configuration with auto-configuration in a large IPv6 deployment esp in an environment that is very sensitive to non-availability of addresses?
Typically, IPv6 router advertisements will advertise fairly long (at least several hour) lifetimes for their prefixes, and those lifetimes are renewed each time a hosts receives another router advertisement, which should happen quite often.
Also, when the address lifetime expires, the addresses do not go away, they are merely deprecated. They will continue to be used for ongoing communication, and may be used for new communication if no other addresses are available. So, prefix lifetimes offer a way to replace an existing address with a new address when the network configuration changes, but they do not prevent continued local communication if the only router (or every router) goes down for an extended period, for example.
Another related question, is it common for a site's global prefix(es) to change? In this regard, are they any different from an IANA assigned IPv4 network-id for example?
Most global prefixes in IPv6 are provider-assigned, so they would change if you change ISPs, or perhaps if your ISP changes their network configuration. Some registries do seem to over provider- independent IPv6 addresses, but I don't know all of the details about how you would get one of those and/or how you would get an ISP to route it. You'd need to contact a registry and your ISP to work that out.
Margaret -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
