Router Glossary

Call Agents 

Also called a media gateway controller, the media gateway controller is a system used in some VoIP architectures. MGC handles the registration and management of resources at the media gateway. A media gateway controller exchanges messages with central office switches via a signaling gateway. A media gateway controller is sometimes called a call agent, call controller, or softswitch. 


The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on Internet Protocol networks whereby a DHCP server dynamically assigns an IP address and other network configuration parameters to each device on a network so they can communicate with other IP networks. 


Plain Ordinary Telephone Service was the standard service offering from telephone companies from 1876 until 1988[3] in the United States when the Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) was introduced, followed by cellular telephone systems, and Voice over IP (VoIP).  

Quality of Service (QoS) 

QoS prioritizes mission-critical traffic and control network congestion at various layers of the OSI model. On the LAN, NetVanta and Total Access routers offer 802.1p and DiffServ Class of Service (CoS). To assign priority to traffic, Weighted Round Robin and Strict Priority Queuing is used with four egress queues per port. For the WAN, DiffServ marking, Low Latency Queuing, Weighted Fair Queuing (WFQ), and Class-based WFQ provide priority for IP packets routed over the WAN. Together these features offer a powerful end-to-end QoS story. 


The NetVanta and Total Access routers provide a powerful, high-performance stateful inspection firewall to stop intruders and common Denial of Service (DoS) attacks. In addition, a variety of data security features, including MAC-based port security, SSH and SSL for encrypted user login, and user authentication using TACACS+, RADIUS or RSA SecurID. For data integrity and added security, the NetVanta 1335 supports 500 IPSec VPN tunnels using DES, 3DES or AES encryption.  

Session Border Controller 

A session border controller (SBC) is a network element deployed to protect SIP-based Voice over Internet Protocol (VoIP) networks. The SBC provides network security, connectivity between elements in the network, quality of service (QoS), emergency call prioritization and lawful intercept, media services, statistics and billing information. 

Static vs. Dynamic IP address 

A static IP is an IP address assigned to a user and it does not change. A dynamic IP is an IP address that is constantly changing. 


A software switch (softswitch) is a call switching node in a telecommunications network, based not on the specialized switching hardware of the traditional telephone exchange but implemented in software running on a general-purpose computing platform. Like its traditional counterparts, it connects telephone calls between subscribers or other switching systems across a telecommunication network. Often a softswitch is implemented to switch calls using Voice over IP (VoIP) technologies,[1] but hybrid systems exist. 

Although the term softswitch technically refers to any such device, it is conventionally applied to a device that handles IP-to-IP phone calls, while the phrase access server or “media gateway” is used to refer to devices that either originate or terminate traditional land line phone calls. In practice, such devices can often do both. An access server might take a mobile call or a call originating from a traditional telephone line, convert it to IP traffic, then send it over an IP network to another such device, which terminates the call by reversing the process and converting the Voice over IP call to circuit-switched digital systems using traditional digital time-division multiplexing (TDM) or analog POTS protocols. 

The call agents are the software switching elements of the softswitch. Other components handle functions for billing, directory services and network signaling. The network elements that convert voice streams between VoIP links and traditional media technologies, such as analog telephone lines, pair-gain devices, carrier systems, are called media gateways. A call agent may control many different media gateways in geographically dispersed areas via an IP network. 


Virtual Local Area (VLAN) is a subnetwork, which can group together collections of devices on separate physical local area networks (LANs). A LAN is a group of computers and devices that share a communications line or wireless link to a server within the same geographical area. 

VLANs make it easy for network administrators to partition a single switched network to match the functional and security requirements of their systems without having to run new cables or make major changes in their current network infrastructure. VLANs are often set up by larger businesses to re-partition devices for better traffic management. 

VLANs are also important because they can help improve the overall performance of a network by grouping together devices that communicate most frequently. VLANs also provide security on larger networks by allowing a higher degree of control over which devices have access to each other. VLANs tend to be flexible because they are based on logical connections, rather than physical. 

One or more network switches may support multiple, independent VLANs, creating Layer 2 (data link) implementations of subnets. A VLAN is associated with a broadcast domain. It is usually composed of one or more network switches. 


Voice over IP (VoIP) converts voice into a digital signal. 


NetVanta and Total Access routers concurrently provides an 802.11b/g and 802.11a radio support at speed up to 54Mbps. Standard wireless security features apply, with advanced business class needs, including multiple SSIDs, disabled SSID broadcasts, 802.1x for user-based authentication, WPA and WPA2 pre-shared keys, with TKIP and AES encryption. NetVanta and Total Access Wi-Fi also employs Virtual Access Points (VAPs), the equivalent of wireless Virtual LANs (VLANs). VAPs allow customers to securely segment their wireless network like that of their wired network. 

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