IP and ATM convergence

---- With the explosive growth of data and information, the development of computer networks as a media of information transmission is also a rapid development. Computer-based Internet), using the IP technology of Routing ). The core of the traditional digital network B-ISDN for broadband integrated business, which is mainly developed by China Telecom, is the ATM exchange technology. The rise of IP addresses poses a challenge to ATM.
---- IP is the technical basis of the Internet network layer protocol. It adopts the connectionless and end-to-end TCP/IP protocol. It has a simple structure and is easy to achieve ing between different types of networks. It has a unified addressing system and strong network scalability. It can run on almost any high-level data link and is widely used. IP protocols are dominant in data business procedures and become the core of various businesses. IP address addressing Resolution Protocol ARP) and routing may lead to broadcast storms in the network, resulting in a bottleneck effect of router processing capabilities. Therefore, the connection-free feature makes the IP address unable to meet the requirements of some new service quality QoS.
---- ATM is an information reuse and exchange technology. It divides information into fixed-unit-units (cells) for transmission, and features high bandwidth of 622 Mbit/s, fast speed, large capacity and high scalability, it can provide corresponding QoS for different levels of services. It can provide different types of services for different transmission. ATM is connection-oriented and can carry any information flow, including data, voice, and image. ATM divides the information into small groups, called cell) and transmits the information through pre-established channels. However, because the ATM uses the signaling protocol, the interconnection capability with other networks is poor.
---- As mentioned above, IP and ATM are essentially different. IP addresses are non-connected and have corresponding address and routing functions. Before any data transmission, an end-to-end connection must be established between two communication entities. ATM is connection-oriented, it has its own address structure, routing mode, and signaling. It does not need to be set as a group cell on each intermediate Node switch). Before any data exchange, the network path between two communication entities has been calculated and remains unchanged throughout the connection. Although there is no association between ATM and IP, there are many different technologies and protocols between the two, as shown in Table 1), but there is no confrontation between IP and ATM. IP addresses require ATM technically, however, ATM needs IP addresses for commercial applications. Thus, various IP and ATM fusion technologies are generated.
Table 1 Comparison of ATM and IP performance
2 ATMIP
Protocol structure lane lan simulation), MPOA, Q.2931FTP File Transfer Protocol), SMTP Simple Mail Transfer Protocol)
2 TCP File Transfer Protocol), UDP User Datagram Protocol)
AALATM Adaptation Layer) IP network protocol), ARP Address Resolution Protocol), ICMP network layer)
ATM2
ATM physical layer Ethernet and other physical layers
Transmission connections of all possible local network activities in the forwarding status
Maximum matching address prefix of tags with a fixed forwarding Length
Bidirectional Multi-direction Routing
Dynamic change of path fixed during call
Broadcast one-to-multiple
Signaling?
Fixed group length variable cell length
Stateful non-stateful
Connection-oriented connection-free
QoS?
Information data, voice, and image data
Connect to establish a group
---- Based on the relationship between the IP protocol and the ATM Protocol, there are two models for the technology that integrates IP and ATM: the first model is called the overlap model. It treats the IP address as a network that is interconnected with the ATM network, without modifying the protocol module of the ATM network, and adds the functions of the IP protocol to the ATM. That is to say, in the overlap model, the IP protocol runs on the ATM. It needs to define two sets of address structures and routing protocols, and two sets of maintenance and management functions at the same time, the ATM system needs to allocate both IP addresses and ATM addresses. All protocols working on the ATM network need to parse the protocol and associate the high-level IP addresses with the corresponding ATM addresses. The second model is called the integration model. It divides the ATM unit entity into the ATM Network Address Allocation Policy and the routing selection protocol, and the ATM network entity adopts the same protocol system and address allocation policy as the IP protocol, the ATM system only needs to identify the IP address, and the network no longer needs the ATM address resolution procedure. A simple comparison of the two models is shown in table 2.
Table 2 Comparison of overlay models and integration models
Project overlay model Integration Model
LANE
LAN simulation) IPOA
IPoverATM) MPOA
ATM supports multiple protocols) IP address switching Label Switching IP navigation MPLS
The interconnection IP address is superimposed on the ATM to integrate Layer 2 and Layer 2 of the IP protocol with the ATM layer.
Scalability, low, high, and high
The IP routing protocol is placed in the IP router or in the ATM switch.
No use of the ATM Routing Protocol
Address Resolution requirements are not required
Modification to the ATM control software is not required
QoS Assurance not guaranteed
Multicast support not supported
Low broadcast/Multi-Transmission Efficiency
Support for ATM services, whether it is yes or not
Support for VLAN Virtual LAN) No Yes
Network Environment LAN Wan
---- The combination of IP and ATM has many technologies, and their applicability is also different. However, they all use ATM hardware exchange to improve IP routing performance and reduce network transmission latency, it also makes use of the features that the IP address is simple, practical, and can communicate with other networks. Integration of Route Selection and exchange allows you to gain strengths and complement each other to achieve flexibility and efficiency.
---- Using an ATM network to transmit IP addresses has the following advantages:
---- 1) scalability. Complex routing is implemented at the edge of the network, while the switched virtual circuit SVC is implemented by the network core.
No core route becomes the bottleneck. Route operations are distributed throughout the network to achieve multi-service customer operations.
---- 2) Business quality assurance. Allows you to manage and monitor QoS attributes for a large number of connections to support SLA ).
---- 3) efficient information transmission. The exchange route enables IP information to be directly routed to the destination.
---- 4) efficient space bandwidth usage. The ATM switching structure integrates the space-based IP protocol to provide efficient bandwidth applications.
---- 5) Excessive reservation of network resources. ATM information shapers can eliminate IP information bursts, which not only maximizes the utilization of network resources. It also supports service level protocols to minimize packet loss.
---- 6) reduces interference with network operators. The use of switched virtual circuits reduces the management of set connections and maintenance of connections.