Routers, LANs, MANs, and VLANs Routers have long been an important component in a network beginning with the transmission of data traffic. With VoIP on its way it will also evolve to support voice traffic as well. It does so today in a lab and test environment as well as limited VoIP deployment.

What security functions does a router provide and are these functions adequate for securing the LAN or MAN?

Internet Voice, also known as Voice over Internet Protocol (VoIP), is a technology that allows a caller to make telephone calls using a broadband Internet connection instead of a regular (or analog) phone line. Some services using VoIP only allow a caller to reach other people using the same service. Other services allow calls to anyone with a telephone number, including local, long distance, mobile, and international numbers. Some services only work over a computer or a special VoIP phone. Other services allow a traditional phone connection through an adaptor. The one feature all VoIP technologies share is that for the individual calling out, the caller must be equipped with a broadband or high speed Internet connection, usually through a cable modem, or high speed services such as DSL or a local area network. (VoIP, 2003)

Routers have always been necessary for making connections between different networking standards such as...

These connections will be necessary for VoIP as well as to continue current connections via text. But how to make this secure, when a user hooks up an inexpensive microphone to a computer and sends his or her voice through a cable modem or connect a phone directly to a telephone adaptor?
Firstly, one must understand that a router is generally an OSI layer 3 device that use an IP address instead of MAC address for the destination of a data packet. Therefore, it is hardware independent and gives network designer more flexibility. A router can divide network into different subnets, thus making Internet sharing possible. Because routers use software method to control the network traffic, they are generally slower than switches. Therefore, the use of routers for most business is limited to Internet connection sharing through NAT routers. In a wide area network (WAN), routers are necessary for connections between different networking standards such as the connection between Ethernet and ATM. (Yeh, 2002) A MAN (Metropolitan Area Network) is defined as a network that connects different LANs within the same Metropolis. Examples include campus networks and industrial networks that connect factories and office buildings together. (Newman, 2003)

The most popular MAN standard today is ATM. ATM was created during the…