What Is a Leased Line?

In general terms, a dedicated network line is an independent network cable for an organization, that is, an independent local area network, such as military, banks, etc., to make users' data transmission reliable and reliable. The advantages of dedicated lines are good security and QoS. Can be guaranteed. However, leased line prices are relatively high, and management also requires professionals.

Network line

In general terms, a dedicated network line is an independent network cable for an organization, that is, an independent local area network, such as military, banks, etc., to make users' data transmission reliable and reliable. The advantages of dedicated lines are good security and QoS. Can be guaranteed. However, leased line prices are relatively high, and management also requires professionals.

Chinese name

Network line

Foreign name

Dedicated network

Solid

Independent LAN

There are two main types of network leased lines

1. Physical dedicated channel. The physical dedicated channel is a dedicated line that is laid between the service provider and the user. The line is only used by the user independently. Other data cannot enter this line. The general line allows multiple users to share the channel;

2. Virtual dedicated channel. A virtual private channel is to reserve a certain bandwidth for users on a general channel, so that users can enjoy this part of the bandwidth, just like opening another channel on the public channel, and only the corresponding user is used, and the user's data is encrypted To ensure reliability and safety;

Main dedicated lane

Frame Relay

A packet-oriented communication method for connecting computer systems. It is mainly used for LAN interconnection on public or private networks and

ATM ATM

ATM features high bandwidth, low latency, or high data bursts.

X.25 (Packet Switched Service Network): X. The 25 protocol is a protocol recommended by CCITT (ITU), which defines the connection of terminals and computers to a packet-switched network. A packet-switched network selects a route for a data packet to a destination on a network. X. 25 is a well-implemented packet switching service. Traditionally, it is used to connect remote terminals to the host system. This service provides any point-to-point connection for simultaneous users. Signals from multiple users on a network can be routed through X. 25 interfaces into the packet-switched network and distributed to different remote locations. A communication channel called a virtual circuit connects endpoint sites across a network on a predefined path. Although X. 25. The main part of the throughput is used for error checking overhead. The 25 interface cannot support lines up to 64Kbps. CCITT re-established this standard in 1992 and increased the rate to 2Mbps.

ATM

In X. In 25, the concept of virtual circuits is very important. A virtual circuit establishes a temporary or permanent "logical" communication channel between two locations across a packet-switched network. Using a circuit guarantees that packets arrive in order because they are all transmitted along the same path. It provides a reliable way for data to be transmitted over the network.

In X. There are two types of virtual circuits in 25: temporary virtual circuits will establish call-based virtual circuits and then be removed at the end of the data transmission session; permanent virtual circuits maintain a fixed connection between the two endpoints.

ADSL ADSL

ADSL is an asymmetric DSL technology. The so-called asymmetric means that the uplink rate of the subscriber line is different from the downlink rate, and the uplink rate is low. And other interactive businesses. ADSL supports an uplink rate of 512Kbps ~ 1Mbps and a downlink rate of 1Mbps ~ 8Mbps on a pair of copper wires, and the effective transmission distance is within the range of 3 ~ 5 kilometers.

ADSL leased line

The first generation of ADSLDSLAM required a lot of ATM network resources during construction. In addition, the high cost of ATM equipment itself directly led to the high cost of comprehensive construction. Therefore, the first generation of ADSLDSLAM was not widely used in access services. . The second-generation ADSLDSLAM, based on the original DSLAM of the ATM core, provides IP upstream through protocol conversion, thus solving the weakness of the first-generation ADSLDSLAM that relies entirely on the ATM network. However, the second-generation ADSLDSLAM can only be regarded as a transition product, and its structural characteristics cause the device to consume a lot of resources when performing ATM and IP conversion. At the same time, because the conversion of ATM and IP is centralized on the uplink interface board, this undoubtedly makes the uplink interface a bottleneck. In addition, the second generation ADSLDSLAM uses the ATM core, and its cascading method is to cascade through the ATM internal bus using a dedicated cable. In addition, the second-generation ADSLDSLAM uses an ATM core and can only support a small amount of 802.1Q VLANs, generally no more than 32. Therefore, it is impossible to map each PVC to a VLAN one by one, and it is difficult to guarantee the QoS of dedicated line users. Drawing on the design experience of the first-generation pure ATM structure and the second-generation ATM core IP upstream ADSLDSLAM, Harbour Networks has adopted an advanced pure Ethernet technology core in the design of the Hammer10000 IPDSLAM third-generation broadband IP access switch, using a patent The technology completely terminates the ATM feature on the ADSL interface board. It has a backplane bandwidth of up to 30G and full wire-speed L2 / L3 switching capabilities, ensuring that all ports have wire-speed forwarding capabilities, which greatly improves the adaptability of ADSL technology applications.

Virtual Private Network

Virtual Private Network (VPN Virtual Private Network): The English full name of VPN is "Virtual Private Network", which translates to "Virtual Private Network". As the name suggests, we can understand the virtual private network as a virtual private internal line. It can establish a proprietary communication line between two or more intranets in different places connected to the Internet through a special encrypted communication protocol. It is like setting up a dedicated line, but it does not Need to really lay physical lines like optical cables. This is like going to a telecommunications bureau to apply for a dedicated line, but there is no need to pay for the laying of the line, nor to purchase hardware equipment such as routers. VPN technology was originally one of the important technologies of routers. At present, VPN functions are also supported in software such as switches, firewalls, and Windows 2000. In short, the core of VPN is to use public networks to establish virtual private networks.

Virtual private network

E1: 30-channel pulse code modulation PCM in Europe is referred to as E1, and the rate is 2.048Mbit / s. A time division multiplexed frame of E1 (its length T = 125us) is divided into 32 equal time slots, and the time slot numbers are CH0 ~ CH31. The time slot CH0 is used for frame synchronization, the time slot CH16 is used to transmit signaling, and the remaining 30 time slots CH1 ~ CH15 and CH17 ~ CH31 are used as 30 speech channels. Each time slot transmits 8 bits, so 256 bits are shared. 8000 frames are transmitted per second, so the data rate of the PCM group E1 is 2.048Mbit / s.

E1 is another standard for high-speed transmission. An E1 can have multiple concurrent channels at the same time, and each channel is an independent connection. E1 service and its corresponding equipment are more expensive than ISDN and ordinary telephones, but E1 service is relatively less expensive.