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ers, it can connect to several city or country, or across several chau and can provide telecommunication, forming an international long distance network.
WAN is present on the network, a division of the most common network division is according to the scope of computer network and the distance between Internet division, have wan, LAN and metropolitan three types. WAN is relatively wide range covers geography of the data communication network, it often provide conditions using public carrier transmission. The Internet is a huge wan. Usually at the router will have a WAN ports, also refers to access the Internet such relatively wider data communications network of port.
3.3.1WAN interface:
RJ - 45 port
Using RJ - 45 port can also build wan and LAN VLAN (between virtual local area network), and establish and remote network or the Internet connection. If use routers for different VLAN provide routing, can use directly twisted-pair cable connected to different VLAN port. But take note here - 45 port RJ which connected network is generally not is the maximum distance that 10base-t, but 100Mbps fast Ethernet above. If you must through fiber connection to the long distance network, or connection is other types of port, when they need to resort to transceiver repeater can realize the connection between each other. As shown in figure for Fast Ethernet (Fast Ethernet) port.
AUI port
AUI port is used with coarse coaxial cable connected network interface, actually AUI port is also often used with wan connection, but this kind of interface type in wan USES it is less. In Cisco2600 series routers, provided with AUI RJ - 45 two wan connection, user can choose according to their own needs proper type.
3.3.2High-speed synchronous serial interface
On a router wan connection, application of port will calculate most synchronous SERIAL "(" high-speed *), the port is mainly used to connect currently applied extensively DDN, Frame Relay (Frame Relay), x.25, PSTN (simulated telephone lines) and other network connection modes. In corporate network between sometimes through DDN or x.25 etc wan connection technique for special connection. This synchronization port general requirement rate is very high, because generally speaking through this port the connected network at both ends of the real-time synchronization request. As shown in figure for high-speed synchronous serial interface.
3.3.3Asynchronous serial interface
Asynchronous serial port (ASYNC) is mainly applied in Modem or Modem pool connection, used to realize the remote computer via PSTN dialed network. This kind of asynchronous port relative to the introduction of synchronous port is required in loose in rate, because it does not require many network at both ends of the real-time synchronization, only asked to keep continuous can. So we can see when using the Internet is not necessarily website real-time content, but this is not important, because after all this delay is very small, it is essential to browse the web page when can maintain normal download. As shown in figure for asynchronous serial interface.
ISDN BRI port
ISDNBRI port for ISDN lines through Internet or other routers and remote network connection, which can realize 128Kbps communications rate. ISDN have two rates connections, one kind is ISDN BRI (basic rate interface), another kind is ISDN PRI (the group of rate interface), ISDN BRI port is usi