Modem Signal and Line States

Signal and Line State Diagrams

Configuring a Line to Disconnect Automatically

To configure automatic line disconnect, use the following command in line configuration mode:

Command

Purpose

 

 

Router(config-line)# autohangup

Configures automatic line disconnect.

 

 

The autohangup command causes the EXEC facility to issue the exit command when the last connection closes. This feature is useful for UNIX-to-UNIX copy program (UUCP) applications because UUCP scripts cannot issue a command to hang up the telephone. This feature is not used often.

Supporting Reverse Modem Connections and Preventing Incoming Calls

In addition to initiating connections, the Cisco IOS software can receive incoming connections. This capability allows you to attach serial and parallel printers, modems, and other shared peripherals to the router or access server and drive them remotely from other modem-connected systems. The Cisco IOS software supports reverse TCP, XRemote, and local-area transport (LAT) connections.

The specific TCP port or socket to which you attach the device determines the type of service that the Cisco IOS software provides on a line. When you attach the serial lines of a computer system or a data terminal switch to the serial lines of the access server, the access server can act as a network front-end device for a host that does not support the TCP/IP protocols. This arrangement is sometimes called front-endingor reverse connection mode.

The Cisco IOS software supports ports connected to computers that are connected to modems. To configure the Cisco IOS software to function somewhat like a modem, use the following command in line configuration mode. This command also prevents incoming calls.

Command

Purpose

 

 

Router(config-line)# modem callout

Configures a line for reverse connections and prevents incoming

 

calls.

 

 

Figure 29 illustrates the modem callout process. When the Cisco IOS software receives an incoming connection, it raises the DTR signal and waits to see if the CTS signal is raised to indicate that the host has noticed the router DTR signal. If the host does not respond within the interval set by the modem answer-timeoutline configuration command, the software lowers the DTR signal and drops the connection.

Cisco IOS Dial Technologies Configuration Guide

DC-163

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Cisco Systems DC-157 manual Configuring a Line to Disconnect Automatically, DC-163
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DC-157 specifications

Cisco Systems DC-157 is a robust solution designed to cater to the evolving demands of data center environments. Aimed at enhancing network efficiency and providing an optimal infrastructure for cloud-based applications, the DC-157 is noted for its exceptional scalability, reliability, and performance. With an increasing reliance on digital transformations, Cisco has strategically positioned the DC-157 as an essential component for businesses seeking to modernize their data centers.

The DC-157 integrates advanced technologies that streamline data operations and ensure seamless connectivity. One of its main features is the support for high-density configurations, which allows organizations to maximize their data center space while minimizing energy consumption. This is facilitated through a highly efficient power management system that not only optimizes energy use but also contributes to a greener data center environment.

In terms of networking, the DC-157 leverages Cisco’s renowned routing and switching technologies that guarantee low-latency connections and rapid data processing. The device supports various protocols, ensuring compatibility with a diverse range of networking equipment and enhancing interoperability across different platforms.

Management of the DC-157 is significantly simplified through Cisco's advanced network management tools, which provide comprehensive monitoring and analytics capabilities. Administrators can easily track performance metrics, manage traffic flow, and swiftly identify potential bottlenecks, ensuring consistent and reliable service delivery.

Security is a cornerstone of the DC-157’s architecture. The device is equipped with built-in security features that protect data integrity and prevent unauthorized access. With end-to-end encryption and automated threat detection, organizations can confidently deploy applications and services without the fear of data breaches.

Additionally, the DC-157 supports virtualization technologies that allow for the dynamic allocation of resources. This flexibility is essential for businesses that require rapid deployment of applications and services, enabling them to adapt quickly to changing market demands.

In summary, Cisco Systems DC-157 stands out with its combination of scalability, reliability, and advanced features. By integrating cutting-edge technologies and strong security measures, Cisco provides a data center solution that not only meets current needs but is also future-ready, ensuring organizations can thrive in a constantly evolving digital landscape. As businesses continue to leverage data as a strategic asset, the DC-157 proves to be an indispensable resource for optimizing data center operations.
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