Protocol for internet:
Asynchronous Transfer Mode (ATM) of Protocol for internet is a switching technique for networks of telecommunication . Protocol for internet uses the asynchronous time-division of the multiplexing, it encodes data into cells of small, fixed-sized. This differs from networks such as the Internet or Ethernet LANsthat use variable sized packets or frames. ATM of Protocol for internet provides data link layer services that run over OSI Layer 1 physical links. ATM of Protocol for internet has functional similarity with both circuit switched networking, small packet switched networking. and its makes it a good choice for a network that must handle both traditional high-speed data traffic (e.g., file transfers), and real-time, low-latency content such as voice and video. ATM uses a connection-oriented model in which a virtual circuit must be established between two endpoints before the actual data exchange begins.
ATM or Protocol for internet evolved from the B-ISDN development efforts
– Frame Relay: high-speed WAN (1.5+ Mbps)
– ATM or Protocol for internet : very high speed WAN (155 Mbps and 622Mbps)
ATM or Protocol for internet , like Frame Relay, was built on the assumption that the underlying physical media was reliable and flexible
– minimal error ,flow control capabilities
– even more streamlined, so faster, than Frame Relay
Specifications developed by the ITU-T and ATM or Protocol for internet Forum
ATM Protocol Architecture
Fixed-size packets called cells
– “cell switching”
two primary protocol layers relate to ATM or Protocol for internet functions:
– Common layer providing packet transfers, logical connections (ATM)
– Service dependent ATM or Protocol for internet adaptation layer (AAL)
AAL maps other protocols to ATM or Protocol for internet
– like IP (AAL5)
VCC (Virtual Channel Connection): a logical connection analogous to a virtual circuit in the X.25, that is Frame Relay data link connection
– full-duplex flow between end users
– user-network control signaling
– network-network management/routing
VPC (Virtual Path Connection): a bundle of VCCs with the same end points (not necessarily same end-users)
– and switched along the same path
ATM or Protocol for internet cell:
The ATM cell is the basic unit of information transfer in the B-ISDN ATM communication. cell is comprised of 53 bytes. Five of the bytes make up the header field and the remaining 48 bytes form the user information field.
Generic Flow Control (GFC):
Although the primary function of this header is the physical access control, it is often used to reduce cell jitters in the CBR services, and assign fair capacity for theVBR services, to control traffic for the VBR flows. functionality requires the power to control any UNI structure, be it a ring, a star, some bus configuration, or any combination of these.
Virtual Path Identifier / Virtual Channel Identifier (VPI/VCI):
The role of the VPI/VCI fields is to indicate Virtual Path or Virtual Channel identification numbers, so that the cells belonging to the same connection can be distinguished. A unique and separate the VPI/VCI identifier is assigned in the advance to indicate which type of cell is following, unassigned cells, physical layer cells of OAM , metasignalling channel or a generic broadcast signaling channel.
Payload Type (PT) / Cell Loss Priority (CLP) / Header Error Control (HEC):
When user information is present or the ATM cell has suffered traffic congestion then the PT field will yield this information.
The CLP bit is used to tell the system whether the corresponding byte is to be discarded during network congestion . ATM cells or Protocol for internet with CLP=0 have a priority in regard to cell loss than ATM cells with CLP=1. Therefore, during resource congestions, CLP=1 cells are dropped before any CLP=0 cell is dropped.
HEC is a CRC byte for the cell header field and is used for sensing and correcting cell errors and in delineating the cell header.
Q1: Protocol Model of Protocol for internet has how many planes
Ans: 3 planes
User – provides for user information transfer and associated controls (flow control, congestion control)
Control – performs call control and connection control functions (signalling)
Management – provides plane management and layer management and coordination .
Q2: function VCC (logical connection) of Protocol fot internet Uses what?
Ans: Exchange between end users
– user data
– control signalling
Exchange between an end user and a network entity
– control signalling
Exchange between 2 network entities
– traffic management
– routing functions
Q3: What are the 2 advantages of virtual path of Protocol for internet ?
Ans: Increased network performance and reliability – network consists of fewer aggregated entities
Reduced processing and short connection setup time.
Q4: How many Control Signalling does here of Protocol for internet?
Q5: What a re the 2 Control Signalling does of Protocol for internet?
A mechanism to establish from Protocol for internet and release VPCs and VCCs per ITU-T Rec. I.150
– four methods for yhe VCCs Semi-permanent VCC: no control signalling required
– Meta-signalling channel: permanent, low data rate channel for setting up signalling channels
– User-to the network signalling virtual channel: set up between user and network
– User-to-user signalling virtual channel: set up between users within the VPC, allowing users to set up and VCCs tear down , without network intervention