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.

LABEL REWRITING:

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

 

EXAMPLE:

 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) Define what is a software agent? (b) An intelligent agent is known to exhibit several characteristics or properties that distinguish it from another piece of so

It treats all processors as equivalent. Any processor can do the work of any other processor. Applications are separated into threads that can run simultaneously on any available p

LAN Topologies The term topology explains the geographic arrangement of networking devices. It explains the actual layout of the network hardware. Given the location of worksta

Control Flow: Once the client has established a network connection with a server, the server must instantiate a new, empty, BasicEnrollmentManager implementation for this client,



Gateway A gateway  is an internetwork  device which  joins different  network  protocols  together. It woods on all  seven  layers of OSI model. Gateways are also known as  pro

Token Ring Implementation Sequence of 150-ohm shielded twisted-pairs sections Output port on every station connected to input port on the next Frame is passed to

Monitor Stations Lost tokens - timer is issued each time a frame or token is generated If no frame is received in time period new token is generated by a monitor stat

OpenMP is a compiler directive based standard developed in the late 1990s jointly by a group of main computer hardware and software vendors. It is portable across a lot of popular