ISP Information:
This is created when a bunch of physically connected ports are grouped together by network hardware that supports VLANs. These VLANs are each treated as completely separate entities, and can only be joined together by a router. This scheme is useful for grouping departments together for security and minimizing network traffic.
ISP Glossary:
Virtual LAN - By Guy KewneySome time today, the GPRS world will reveal that it has a securityvulnerability which has seen an undisclosed number of its customersripped off. They've been trapped into connecting to malicious contentservers, by hackers penetrating the billing system.The first international phone company to admit that they haveinstalled a solution -- offered by Check Point -- will be theGerman phone provider, E-Plus.The scam is called "the over-billing attack." It works quite simplybecause of a link from the Internet world -- unregulated -- to thenormally tightly regulated GSM planet. "Network administrators face anexponential onslaught of attacks that to date have traditionally beenconfined to the world of wire line data," was the summary from CheckPoint.There are lots of potential issues, but the one which has forced thephone networks to acknowledge that there is a problem, is a scam wherea company obtains IP addresses that the GPRS operators own, in the"cellular pool" and start pinging those addresses.When one of them responds, the scam operator knows that a user hasbeen assigned the address. And, unbelievably, there was nothing tostop them simply providing services direct to that IP address -- andtaking the money out of the GPRS billing system to pay for it.http://www.newswireless.net/articles/031002-scam.html
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