* 802.11 group to examine fast, secure roaming
As noted last time, a new IEEE 802.21 committee will begin work next March to enable seamless inter-network roaming among the various 802-based networks.
There are reportedly two primary types of information that need to be communicated from Layer 2, 802-based networks to Mobile IP or other Layer 3 roaming protocols to enable both fast and seamless roaming among dissimilar network types.
David Johnston, interim chair of the emerging 802.21 working group and a senior communications engineer at Intel, describes them this way:
* Network detection and selection
If a laptop has an 802.11, 802.16 and 802.3 connection available (and possibly others), how does the device know which network to choose?
The client must be able to identify the type of network available, determine whether it can authenticate to it and find out how much the connection costs. If equipment such as access points and base stations provide this information, client devices can make good handover decisions in selecting the most appropriate network.
* Layer 2 triggers
This involves Layer 2 (802) providing Layer 3 (IP) with useful information about network conditions. This information could include alerting Layer 3 of degradation in a wireless signal, for example, indicating that a link might fail.
In addition to 802 network advocates, the cellular industry will be represented in 802.21, since dual-mode 3G/802.11 handsets and other multi-interface devices are emerging.
Meanwhile, roaming within homogeneous network types isn’t yet a fait accompli. Basic 802.11 standards do not address access points sharing information with one another.
Brace yourself for another “letter” joining the 802.11 alphabet soup of standards. An as-yet unnamed working group – currently called the Fast Roaming Study Group – is looking into how to standardize handoffs among wireless LAN access points such that security is optimized while latency is minimized.
“Currently, the state of 802.11 networks is that they are fast or secure. In the future, they will be fast and secure,” Johnston says.
Meanwhile, the 802.11f effort for standardizing an Inter-Access Point Protocol is at a virtual standstill. 802.11f is meant to specify a protocol used by access points to communicate with each other.
