Labels and label switching, Computer Networking

An ATM network is created from interconnected ATM switches. The attachment ports or points can be connected to computers or other ATM switches. As cells reach at an ATM switch, their VPI/VCI is changed using a forwarding table that produced the new VPI/VCI for the next leg of the cell's trip.

The forwarding table is necessarily indexed by the incoming cell's VPI/VCI and the message yield the new VPI/VCI.


The placement of the incoming cell's VPI/VCI with a probably distinct VPI/VCI is called rewriting.

ATM is thus known a label switching or label rewriting system. Thus two devices with a connection through an ATM network will likely have distinct VPI/VCI numbers for every end of the connection as given in the figure below.


2496_label rewritting.png



2327_label rewritting1.png



 As an example, in the diagram we see that the sending computer S needs a VPI/VCI of 3 and transmits a cell.

 Switch A accepts the cell and looks up 3, then rewrites the VPI/VCI as 4, and transmits the cell out of its port 2.

 Switch B accepts the cell and looks up 4 then rewrites the VPI/VCI as 1 and transmits the cell at its port 2.

 Switch C accepts the cell and looks up 1 then rewrites the VPI/VCI as 6 and transmits the cell out of its port 2.

 The receiver computer R accepts the cell with a VPI/VCI of 6, which is the number it is using for the connection. Forwarding tables in every switch must be coordinated to describe meaningful 'paths' through the network.

Posted Date: 7/31/2012 7:24:18 AM | Location : United States

Related Discussions:- Labels and label switching, Assignment Help, Ask Question on Labels and label switching, Get Answer, Expert's Help, Labels and label switching Discussions

Write discussion on Labels and label switching
Your posts are moderated
Related Questions

Question : a) Give three examples of vulnerable services which are among the overwhelming majority of successful attacks. b) Name the five outside sources which can be the

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4 What is overlapping

Error Detection- Check Sum The Checksum generator are subdivides the data unit into equal segments of "n" bits (usually 16) These segments are added utilizing one's c

Question: a) The cpio utility has three operating modes. What are they? b) The characters of the permission string are broken up into three groups of three characters. Ex

By utilizing measurements of the so-called pseudo range between an object and each of several earth orbiting GPS satellites, the object can be very accurately located in space. A g

What is the role of IEEE in computer networking? IEEE, or the Institute of Electrical and Electronics Engineers, is an organization composed of engineers that issues and manage

Challenge Handshake Authentication Protocols (CHAP) CHAP as its an implies implements  a form of authentication that  requires a challenge  and a response. A CHAP authenticator

Q. Which steps are used at receiver end by check sum? The receiver follows these steps: The unit is divided into "k" sections each of "n" bits All sections are

What are the different technologies involved in establishing WAN links? Analog connections - using conventional telephone lines; Digital connections - using digital-grade telep