Frame Relay Virtual Circuits

by Leon Tufallo.
Share
|
Homepage | Submit your article | Contact | TOS
More articles on network security  

You are here: Categories » Electronics and communication » Network security

One reason for Frame Relay's popularity is its capability to logically create multiple connection-oriented data link layer communication paths between two devices across a single physical interface. These VCs provide you with a bidirectional communications path that can exist between a single pair of equipment, commonly called a point-to-point connection, or between multiple pairs of equipment, also known as a partial or full mesh. Each of these VCs is identified by a unique data link connection identifier (DLCI) that differentiates the communications between different devices.

VCs can be mapped across any service provider's Frame Relay network without regard for the number of hops the connection will cross. A VC is not limited to three devices, two DTEs, and a DCE when traveling from source to destination. Just remember that each hop adds to your circuit's overall delay because of the processing that each device needs to do to read the packet and send the packet toward its destination.

VCs can be divided into two separate categorizesswitched virtual circuits (SVCs) or permanent virtual circuits (PVCs).

SVCs

The SVC gives you a way to automatically create temporary connections between DTE devices in the Frame Relay network that can be used in on-demand situations, such as those requiring only sporadic data transfer. An SVC's communication component consists of the following four operational states:

  • Call setup Indicates that the establishment of the SVC between two Frame Relay DTE devices is currently being negotiated.

  • Data transfer Indicates that data is being transmitted between DTE devices over an SVC.

  • Idle Indicates that the SVC between DTE devices is still active, but no data is currently being transferred.

  • Call termination Indicates that the SVC between DTE devices is being terminated.

NOTE

When an SVC remains in an idle state for a defined period of time, the SVC can be torn down and the call terminated.


After the termination of an SVC is complete, if additional data needs to be transmitted between the DTE devices, a new SVC is established. Cisco devices use the same signaling protocols used by ISDN to establish, maintain, and terminate SVCs.

PVCs

The PVC, unlike the SVC, establishes a permanent connection between your DTE devices. This type of circuit is typically used for frequent and consistent data transfers across the Frame Relay network. Because PVC establishment does not require call setup or termination, it is always up. PVCs have only two operational states:

  • Data transfer Indicates that data is currently being transmitted between the DTE devices over the PVC.

  • Idle Indicates that the connection between DTE devices is active, but no data is currently being transferred between DTE devices.

NOTE

Because a PVC connection has no call setup or termination, it is not terminated under any circumstances when in an idle state, unlike the SVC idle state. SVCs encounter startup delays after an idle period.

As soon as the PVC is established, your DTE devices may transfer data whenever they are ready, without the delay associated with the establishment of an SVC.

Share
Leave a comment or ask a question
Total comments: 0

Network security Disclaimer

  • The e-articles directory is not responsible for any and all copyright infringements by writers and authors. If you suspect the information contained by this page for any copyright infringements, please contact us to investigate the issue
Layer 1 Wireless Security Basics - Let's build on the more technical aspects of the discussed policy considerations. We'll start from physical layer security. The physical layer security of wireless networks encompasses avoiding (more...)
Network Vulnerability Analysis - Vulnerability analysis, sometimes called vulnerability scanning, is the act of determining which security holes and vulnerabilities may be applicable to the target network. In order to do this, (more...)
Wireless attacks at Corporations Small Companies and Home Users - There is a general misconception that only large enterprises are at risk from cracking, wireless cracking included. This is a myth, but it is very prevalent. Large corporations are where the mo (more...)
Practical Use of Asymmetric Cryptography: Key distribution Authentication and Digital signatures - The basic idea of using asymmetric cryptography is distributing public keys while keeping the private keys private and using a person's public key to encrypt data sent to this particular indivi (more...)
Deploying a Linux Based Custom Built Hardened Wireless Gateway - We have to ensure the security of the gateway that separates our AP or bridge or wireless-connected VLAN from the wired side. Such gateways are nothing more (or less) than a flexible stat (more...)
Network Isolation - Isolation of networks affects the flow of network data, which services run on particular systems, and where they are located. It does not affect any of the internal or external network data f (more...)
Ethernet specification - The progenitor of all of today's networks was the Ethernet system originally developed in the 1970s at the Xerox Corporation's Palo Alto Research Center for linking its Alto workstations to lase (more...)
Network Topologies - The topology of a network is the lay of the cables across the land. Most networks involve cables, lots of them, with at least one leading to every PC. Like the proverbial can of worms, they can (more...)
Network Hierarchies - Topology describes only one physical aspect of a network. The connections between the various PCs in a network also can fit one of two logical hierarchies. The alternatives form a class system a (more...)
Wireless Networks and Security Vulnerabilities - The use of wireless networks is increasing at very fast rates worldwide, largely owing to the relative ease of use and the attendant convenience, as well as the relatively lower and ever falling co (more...)
 
free content
    Copyright © 2006 - 2012 e-articles.info.
The texts, articles and tutorials in the directory are property of their respective owners and authors.