Monitor and manage the transmission of the cell in the network called transmission control. It is important to do it, especially for delay
Sensitive video data. Different types of communications require different levels of services. An ATM network for different communication types
For different QoS (service quality) levels.
1. ATM communication type We can follow the three features of the ATM network: bandwidth, wait time, and cell delay variations to the communication type
class. The bandwidth is to support a network capacity size of a connection. Waiting time is the amount of delay related to the connection. If it is low
Waiting time means that the cell needs to quickly pass from a point in the network to another. Cell latency changes are every relevant letter
The delay range experienced by the tuple. Low cell delay changes means that a set of cells must be less far from each other.
Via the network.
The ATM network has three communication types: CRB (Constant Bit Rate constant positioning rate), VRB (Variable Bit)
Rate Change Bit Rate) and ARB (Available Bit Rate available space). CRB communications include sounds and videos.
To accomplish this communication, ATM provides a constant bandwidth, low wait time, and low signal delay. VRB communication
Different bandwidths are similar to CRB. ABR communication does not need to determine bandwidth or delay parameters and are applied by many data applications
Accept.
2. The ATM connection requests an ATM network with the other end by issuing a connection request that leads to an ATM network negotiation.
Connect. This process is called a connection establishment program. Most of you must negotiate can be specified by ATM Forum Uni 3.0,
Includes communication type, constant and peak bandwidth, signal sequence length, and QoS level. This process guarantees the ATM network and endpoint construction
Establish a Treaty. The network promise submits a QoS, and the ATM endpoint is committed to not sending more than the connection process.
Many traffic.
When the blocking occurs, the transmission control providing mechanism restores the network. ATM network uses three transmission control technology: biography
Transmission control, transfer shaping and blocking control:
(1) Traffic Policing ATM Network To ensure that communication in each connection does not exceed the negotiation parameters, the ATM switch uses a "leakless bucket"
Algorithm to manage communication. Imagine with a hole in the bottom of the wooden bucket, water in a fixed rate (negotiated rate) from the barrel (slow
The flushing area flows out. When the information flow exceeds the negotiation rate and buffer overflow, it is necessary to perform transmission control. Every ATM letter
The header has a CLP (Cell Loss Priority) bit, that is, the cell loss attribute bit, is used to indicate whether the cell is related to the contract
Consisten to the same. For example, if the cell is inconsistent with the contract, it means that there may be more cells allowed by the contract, ATM
The switching CLP bit is 1. This cell can only be transmitted through the network when there is enough network capacity, if not
Sufficient bandwidth is available, and the CLP bit is inconsistent, and the cells need to be re-transmitted. CBR communication
A single "drain" is required because it is mostly a fixed rate in its network protocol. VBR communication use double
"Vulnerable Bucket", on the one hand, in some discrete time intervals, the fixed rate is monitored, on the other hand, monitor the largest
(Peak) bandwidth. If any one value exceeds the protocol parameter, the ATM switch manages VBR communication by controlling the CLP bit.
(2) Traffic shaping is similar to the transmission control, and the transfer is completed on the user-network interface. Use dual "drain" algorithm control
Communication makes the flow rate complies with the agreement. The device that completes the transfer shaping is typical for PC or workstation, bridge,
The ATM network adapter in the router and DSUS (Digital Services Unit).
(3) Blocking control occurs in any network, occurs when the data sent by a user is greater than the network in the network, occurs, occurs. When more users send data to the same network, the bandwidth to any user can also be obtained over time.
Change. Most networks cannot tell users how much bandwidth can be obtained in any given instant. Result user
There is no basis to control the amount of data sent. When the data sent is greater than the data that the network can process, the network is slow
The rush is filled and overflowing, and the data must be retransmitted, which further increasing traffic makes the network congestion. ATM network
The blocked control is performed so that the ABR communication can effectively use bandwidth. Effective blocking control reduces due to blocking
Reissue data needs.
ATM expands network capabilities to support a wide range of applications and help network managers. Use ATM technology as a base
Basis to ensure a acceptable interface with WAN (WAN) to meet the high broadband business needs of LANs. Transmission management
Make the user gets the quality of the service they need.
