To overcome the problems with their original WLAN and reap the potential
benefits listed earlier earlier in this case study, ST. Luke's made two
changes[CONR03]. First, the hospital phased out the Proxim APs and replaced
them with Cisco Aironet (WWW.aironet.com) APs. The Cisco APs, using IEE
802.11b, operate at11Mbps. Also, the Cisco APs use direct sequence spread
spectrum (DSSS), which is more reliable than the frequency-hopping technique
used in the Proxiom APs.
The second measure taken by St Luke's was to acquire a software solution from
NetMotion Wireless(netmotionwireless.com) called Mobility. The basic layout
of the Mobility solution is shown in Figure V.1. Mobility software is
installed in each wireless client device (typically a laptop or handheld) and
in two NetMotion servers whose task is maintain connections. The two severs
provide a backup capability in case one sever fails. The Mobility software
maintains the sate of an application even is a wireless device moves out of
range, experiences interference, or switches to standby mode. When a user
comes back into ranger or switches into active mode, the user's application
resumes where it left off.
In essence, Mobility works as follows. Upon connecting, each Mobility client
is assigned a virtual IP address by the Mobility server on the wired network.
The Mobility sever manages network traffic on behalf of the client,
intercepting packets destined the client's virtual address and the client,
intercepting packets destined for the client's virtual address and forwarding
them to the client's current POP (point of presence) address. While the POP
address may change when the device moves to a different subnet, from one
converage area to another, or even from one network to another, the virtual
address remains constant while any connections are active.
是先用DR.EYE跑過一次....
已經修改過很多~.~
DR.EYE跑完的結果根本不能看
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