Re: [DNA-BOF] Using L2 to provide Instantaneous Movement

[Alper Yegin <alper@docomolabs-usa.com>]

> The problem is understanding the right L2 frames to include this
> information in.  The Beacon and Probe Response are not secured, and also
> are relatively early in the process so that they might not reflect the
> actual VLAN that the station is assigned to.  So probably the best that
> can be achieved in prior to association is to advertise *all* the prefixes
> associated with a given BSSID.  This might be a single prefix (in the case
> where the BSSID/SSID corresponds to a single VLAN) or it might be multiple
> (in the case where the VLAN is dynamically assigned and can vary).  The
> station can make its decision as to which AP to associate based on the
> advertisements, but they are only a "hint" because it is possible that the
> actual prefix to which the station is connected may not be the expected
> one. The station will do a reachability test on the assumption that the
> prefix is the expected one, but if this fails it must be prepared to
> obtain an address by conventional means (DHCPv4, RS/RA, DHCPv6, etc.).

If the STA is going to perform a reachability test in any case, what is the
functionality of learning the possible prefixes? In the case of addr
autoconf, router discovery can be used for the test and learning the
prefixes in advance is not needed. In the case of DHCP, do you assume the
client may have more than one IP address with an unexpired lease and which
ones to test for depends on the prefixes?

Btw, I think looking at the prefixes is not straight forward in IPv4. Use of
RFC1918 address space can overlap between two different subnets.

Alper