Concept
The application gateway can be located in the application layer or transport layer. The application layer gateway is located, also known as the proxy server. The called transport layer gateway is located in the transport layer. Protocol conversion on the application layer.
Examples 1:
A host is executed is an ISO email standard, and another host is executive is an Internet email standard. If these two hosts need to exchange emails, then The protocol conversion is performed by an email gateway. This email gateway is an application gateway.
Example 2:
In the context of the Novell NetWare network interactive operation, the gateway used by the server information block (SMB) protocol used in the Windows network and the NetWare core protocol used by NetWare networks. (NCP) The role of the bridge is placed. NCP is a protocol working in the OSI seventh floor to control interactions between clients and servers, mainly to turn on, close, and read functions in different ways.
Detailed classification
The current gateway product classification is getting fine, there is a signaling gateway, a relay gateway, and an access gateway.
Application Protocol
Gateway at the seven-layer protocol of the application network:
OSI is an open traffic system interconnect reference model, he is a definition Very good agreement. The OSI model has a 7-layer structure, and there are several sub-layers per layer.
I simply introduce these 7 layers and its functions.
OSI 7 layers from top to bottom are
7 application layer
6 representation layer
5 session layer
4 Transportation Layer
3 Network Layer
2 Data Link Layer
1 Physical Layer
Among them, The 7, 6, 5, and 4 layers define the functions of the application, the following 3, ie 3, 2, 1 layer mainly facing the end-to-end data stream through the network.
The current gateway has a firewall figure on the application layer and the network layer, and can also see the VPN role on the third floor. The safe gateway of the anti-drug wall acts in the second layer. According to the seven-layer level limit, the high-level agreement can take the principle of the low-level agreement, and the development of the security gateway is going to the line of the high-level agreement.
Gateway and router Difference:
Service Gateway is an IP of the router, other The computer must access the router with an IP segment of the gateway. For example, the IP of the router is 192.168.0.1 (this is the gateway) is also the address necessary to enter the router, and other hosts must also be 192.168.0.x (in the same network segment) This is to access the router to say that in order to go online, the gateway address on the computer will be filled in 192.168.0.1.
Application advantages
Intelligent access, perfect and reliable
Products Support ADSL, fiber, etc. Wideband access scheme, realizing flexible expansion bandwidth and cheap Access. Enter the company to solve the flexible expansion of bandwidth and inexpensive access. Access to the company via routing, NAT, multi-link multiplexing and detection.
Health network, application security
products provide a full range of local area network access security to enterprises through its own firewall, anti-virus, intrusion detection, user access, active certification, etc. Management plan. Provide a full range of local area network management solutions through its own DHCP server, ARP firewall, DDNS and other functions.
Mobile Office, Fast Safety
The VPN function included in the product, can make the user pass through a one-touch operation, convenient and easy to build a low price Wide area online private network provides enterprises to provide wide area network security business transmission channels, facilitating corporate headquarters and mobile staff, branches, partners, product suppliers, customers, improvement, customers, customers, suppliers And partners carry out business skills.
Suppressing bandwidth abuse, guaranteeing key business
Dynamic smart bandwidth management function, only one-time setting, automatic suppression of bandwidth users, easy to solve BT, P2P and video movie downloads, etc. Bandwidth problem.