Re: [dhcwg] DHCPv6 router option

[Stig Venaas <stig.venaas at uninett.no>]

David W. Hankins wrote:
[...]
> So long as we're talking about me;
> 
> I have also been thinking that I would drop the router lifetime
> values, preferring instead for the fields contents to be "valid
> as long as the client holds its current lease (basically the longest
> valid lifetime of any addresses granted)", but I don't know if
> this interferes with some intention to support these options via
> Information-Request messages, so I have been witholding comment.  I
> planned to wait and see the presentation before suggesting
> alterations.

Not sure which is best, but for Information-Request you could also
consider the Information Refresh Time Option (RFC 4242).

Stig

> I do know that our software, as it operates at userspace and not in
> kernel space, does not seem to have reliable mechanisms to store
> router lifetimes to the kernel (depends on architecture, on some it
> is merely undocumented), and we probably would on some platforms tie
> the insertion and removal of any routes to IP address lifetimes
> instead until such time as kernel keepers make this configuration
> possible.
> 
> I would prefer not to have to add extra complexity to track the router
> lifetime separately, at any rate.
> 
> The idea is that this follows the same way we use or invalidate other
> configuration state in the lease - such as nameservers or domain
> search.  They are valid until the last address expires, and they are
> updated (old-removed, new-inserted) upon every Renew or Rebind.

Right, I thought you would add/update/remove routes just like other
information like nameserver info where you have no notion of lifetime
external to the DHCP client.

I think using DHCP for default router config is mostly useful where
you have a fixed address for the default router. Router failover can
be done using VRRP, HSRP or whatever (just like many people do for IPv4
today) without changing the router address. In that case you don't
really care much about lifetimes.

Stig

> 
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