MIP (mobile IP) is a means of maintaining seamless IP connectivity when a client workstation or PDA moves from subnet to subnet. Although it was devised as long ago as October 1996, mobility support for the Internet Protocol (IP) has only just become fashionable. This delay is hardly surprisingly, though, given that it’s only the advent of wireless LANs and GPRS mobile telephony that has caused manufacturers to want to jump on the mobile IP bandwagon.

ReefEdge’s Connect Server range (in our case a CS100) is the server end of an MIP implementation. It is a rack-sized black box running a stripped-down Linux kernel, on top of which the manufacturer has built a MIP implementation. Although the unit has its own internal user database facility, most users will want to use its other authentication mechanisms, which include interfaces to RADIUS servers and the obligatory LDAP connectivity. You can, in fact, mix and match your authentication schemes, so you could have your corporate users authenticated via LDAP (potentially to a number of separate repositories across the corporate WAN) and guest accounts residing in the CS100’s internal database.

If you’re just using a Connect Server (CS), each of your client computers needs a MIP-capable driver (or, as ReefEdge call it, a Mobile Domain Utility or MDU). This allows you to authenticate over whatever network connection you have into the CS, which can then deal with the forwarding of packets when you roam to other IP networks. In fact, it’s quite a useful little VPN tool as well. Even if you’re not roaming with it, you can have it handle both your network logon and the setup of your IPSec VPN connection.

The cutting edge
ReefEdge’s claim to fame, though, is that it gives you the option of building MIP networks without the need for client software on your workstations. It does this via a network of Edge Controllers (ECs) – units that link into the LAN and into which the wireless access points connect. The idea is that the MIP cleverness happens between the EC and the CS, so the client computer doesn’t even have to know it’s going on. It’s a neat idea, as it certainly removes the need for a lot of software installations, and it means that your MIP installation will work even with WLAN-enabled devices that you can’t get a MIP driver for.

The ECs are built as intelligent devices, and so most of the roaming negotiations happen between ECs, without need for reference to the central Connect Server. This is a useful way to make sure the CS isn’t a hideous bottleneck in your nice new MIP network. The CS’s role when used with ECs is to manage and distribute configuration information to the various ECs and let them get on with the actual packet forwarding.

All of the CS products are able to run in resilient pairs, with the backup unit taking over should the master turn up its toes. The initial configuration of IP address information and hot-spare setup is done via a character-based VT100 interface. Once you’ve set the addresses and rebooted you have a secure HTTP-based web interface to work with.

If you want to run a number of disparate but connected networks, you can have multiple sets of CS units managed centrally, via a recently-announced Multi-Site Manager application that allows you to configure all your toys under one roof.

ReefEdge has come up with an interesting and innovative take on Mobile IP technology. The idea of confining the MIP capability to the network infrastructure, instead of insisting on client-side drivers etc., is an excellent one. However, if you do want to take your PC out of range of a wireless access point you still have the choice of installing the MDU. The CS100, in particular, is easy to get to grips with and the web-based user interface is comprehensive and usable. We only had one problem with our unit and that was a minor terminal issue that the vendors are already aware of and will presumably sort out before long.


In a MIP system you want something that will be able to service all the client platforms you use, either with custom drivers or, as in ReefEdge’s case, by dealing with the special MIP technology within the infrastructure devices themselves.