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 the connections with LAN or a MAN. 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 80s to meet the demand of Telecom companies and service providers for high-speed backbone connection. LAN (Local Area Network), MAN (Metropolitan Area Network), or WAN (Wide Area Network) according to its distance and structure. A LAN is defined as a network built within four-kilometer distance on the same building complex. It is the most basic structure of the network. Basically, a connection between at least two computers will constitute a LAN. The most popular standard for LAN today is the Ethernet. (Yeh, 2002)

Security is maintained on the Ethernet through password protections, and security is maintained through MAN by the use of passwords that require first a user to enter the system, occasionally only on specific terminals, and then to make use of a password or other validating device. However, the transmission of voice technology means that systems are open to other security permutations; similar to those that threatens cellular telephone users. A combination of devices used to scramble vocal transmissions as well as traditional computer protections will be necessary to fully ensure that the resulting technology is secure for future users.

How are VLANs protected from attackers and intruders?

VLANs are computers that behave as if they are connected to the same wire even though they may actually be physically located on different segments of a LAN. (Webopedia, 2004) VLANs are configured through software rather than hardware, adding to their flexibility as systems. “One of the biggest advantages of VLANs is that when a computer is physically moved to another location, it can stay on the same VLAN without any hardware reconfiguration.” (“VLAN Information,” 2004) Thus, virtual LANs (VLANs) can be viewed as a group of devices on different physical LAN segments that can communicate with each other as if they were all on the same physical LAN segment. The more flexible the system, however, the more open it is to security incursions. One potential way to secure VLANs has been through making use of its ability to be distanced from hardware, and thus giving it potential protection from viruses that encroach upon a system using its hardware, however worms that do not make use of systemic hardware still pose a potential security danger.

Works Cited

Newman, Robert C. (2003). Enterprise Security. Upper Saddle River, New Jersey: Prentice Hall.

VLAN — Definition.” (2004) Webopedia. Retrieved on July 15, 2004 at http://net21.ucdavis.edu/newvlan.htm

VLAN Information.” (2004) Retrieved on July 15, 2005 at http://net21.ucdavis.edu/newvlan.htm

VoIP. (2003) Retrieved on July 15, 2005 at http://www.fcc.gov/voip/

Yeh, Albert. (2002). “Introduction To LAN and Switches.” Ovislink. Retrieved on July 15, 2005 at http://www.ovislink.com.tw/lanintro.htm