Overview

This article describes the implementation of WAN protocols on political business environments today HDLC network, DSL, SONET, DWDM and DLSW +

High level Data Link Control (HDLC)

HDLC is a Cisco proprietary protocol designed for sending data over serial links. It defines an encapsulation for the level of data link layer for transporting data over a public network or a private network. This protocol is used for rentalOnline TDM circuits. TDM connections are probably the oldest type of circuit-switching technology of the telephone network, the telephone traffic has relied. The difference is that companies require the transport of data traffic speeds ranging from 256 Kbps to 45 Mbps This is a type of data connection, the devices at both ends of what is a phone, calls for the preparation and formatting of data for these speeds.

The network operator TDM with stepscalled digital signal zero (DS-0). A DS-0 is a channel to 64 Kbps (56 Kbps when) in-band signaling, which is part of DS-1 specific industry standard. A DS-1 defines a standard for the design of the transmission on a T1 circuit at 1.544 Mbps, with 24 channels DS-0. A DS-3 defines a standard form for transmission via a T3 circuit to 44.736 Mbit / s with 28 channels DS-1. Some service providers offer what is fractional T1 (Frac T1). This is a path that runs at speeds of less than 1.544Mbit / s, as it is a part of the group of 24 channels.

The common fractional T1 speeds of 384 kbit / s, from 6 DS-0 channels is included. Many routers serial interfaces which offer a split-channel or T1 circuit. This is useful if you do not want for a complete circuit from T1 to pay. This is done to differentiate each channel from the complete circuit T1. Europe uses standard a bit 'different speed circuit called E1and E3. Circuit E1 has 30 channels DS-0 and includesoperates at 2.048 Mbps, while E3 is running from 20 channels T1 and, at 34.368 Mbit / s covers.

Digital Subscriber Line (DSL)

Digital Subscriber Line is a new broadband technology, used for dial-up access and connectivity in the office. It 'very cost-effective than ISDN and T1circuits because it is faster and less expensive. The problem with DSL is that you no longer than 18,000 feet must be placed by the service center. Questionfor high-speed Internet access service provider has installed terminals in many DSL central offices. That the possibilities for availability in your area will increase if it is not an option today. The current specification defines three main technologies that are) the asymmetric DSL (ADSL, Very High Data Rate DSL (VDSL) and Symmetric DSL (SDSL).

ADSL (Asymmetric DSL), as the name suggests, is the ADSL technology enables the rapidSpeed downstream service provider customers to speed ahead of the customer to the provider. The design reflects the flow of the Internet and video applications, because they generally download more information than the client has sent. Depending on the distance from the headquarters of the service provider, the downstream speed can be faster than 6 Mbps and upstream speed can be up to 640 Kbps His conservative with bridge taps and wire diameter increases(Gauge) will increase the flow of traffic to and from the customer to the provider.

The ADSL modem or router at the interface of the client with a standard telephone line pair 2 is solved for the service provider DSL access multiplexer (DSLAM). At this point, the cross-connect their DSLAM service with a variety of different devices, such as T1, T3, SONET, Frame Relay, ATM, or DSL lines for transmission over the Internet or to another central office. As mentionedSome customers are sharing the ADSL line using their mobile phones, as well as calls. The DSLAM is opened to traffic from voice traffic data, and a switch to class 5, where it is sent routed through the PSTN via a protocol such as SS7. Many business customers have a line of data, but with rising costs, when the number is not available, that there is no impact on their Internet connection or better.

Very high rate DSL (VDSL) is a specific more than DSLdata will be transmitted at distances between 1,000 m and 4,500 m over copper telephone lines. Distances of 1000 meters of a speed of 55 Mb / s support, while the distances of 4,500 feet at a speed of about 12 Mbit / s support. There are some technical differences in the encoding of line, but the modem is split, telephone service and ADSL for calls.

Symmetric DSL (SDSL) is something new, and as the name suggests, the transfer of data in bothDirections speed T1. The specific distance from headquarters to 21,000 feet, and it should be noted that there will be a separate phone line for telephone traffic SDSL should not be divided. This is currently a problem and needs to be addressed this year. SDSL is an "always-on service, which reduces problems with the connection. That and the rise in input prices makes it better for web hosting applications, since the downloading of files sent with appropriate downstreamTraffic is passed through their upstream traffic. There are huge opportunities for suppliers of services to low-cost high-speed Internet access for many customers in the United States to sell today. Telecommuters and business customers can lower costs with higher speed circuits for sending voice and data out of the house, access and sales offices via the Internet.

SONET / SDH

The Synchronous Optical Network (SONET)-specification describes a highSpeed-fiber technology will be of service for the transport of voice and data traffic. A SONET network is a series of segments, the ring will be built together. Each segment is twice the number SONET rings include rotate left for diversity should be one of the rings is not available. The standard OC-1 interface is 51.8 Mbps SONET ring network with add / drop multiplexer (ADM) to terminate the SONET signal for various city and national sites to build. You TimeDivision Multiplexer that / demux mux signals from a SONET OC-12 to OC-48 traffic flow. Every Apple has an active role and a connection in standby mode and SONET Ring. When a network failure with the active connection is detected, the connection of waiting is activated immediately. The SONET frame is 810 bytes, there is a byte of overhead and payload. The overhead is the section and line level exists. The byte payload are combined with the signaling path and the payload. Router as a Clientas the Cisco 7507, which support OC-3 interfaces, with an interface ADM.

Dense Wave Division Multiplexing (DWDM)

Dense Wave Division Multiplexer (DWDM), are used for optical signals on different wavelengths over a single fiber strand in the multiplex transmission through an optical network with speeds up to OC-48 OC-192. Each wavelength may be at a speed of up to 10 Gbit / s run. Current optical systems can be up to 100 wavelengths or channels per fiber, the multiplex sectionis close to 1 terabit (1000 Gbit / s) at full speed. The effort now is on developing multi-terabit traffic on 1 Fiber Strand concentrated. This technology is a sort of demarcation between the networks faster core business and long-term core ISP networks, for a total of hundreds of corporate customers. The client company is able, in collaboration with DWDM networks with ATM switches and IP routers with OC-48 interfaces. Public and private network operators have SONET rings, in conjunction withDevices with interfaces running at OC-48 speeds as well. 12,016 Cisco Gigabit Switch Router is equipped with OC-48 interfaces. Companies today use 400 OC-48 router interfaces with the 12,016 to build a WAN-terabit core.

Data Link Switching (DLSw +)

Switching data link is a layer 2 protocol to encapsulate SNA frame on a WAN IP. This is a method that integrates SNA workstations and servers with the IP encapsulation, IP –Corporate network. Encapsulation of SNA is necessary because it does not define a Layer 3 address the protocol stack. Routers that are configured with DLSW + stable peer relationships with local and remote DLSW + router. Each SNA frame is encapsulated in an IP packet, before being sent across the WAN to a router configured peer DLSW +. Each local router close LLC2 data link layer of images from any workstation and send confirmations for each local workstation as a localPackets are sent and received. Problems LLC2 timeout that occurs between the workstation and server, if confirmation is necessary in a WAN to stay the course to be done will be deleted.

SNA is connection-oriented and have the data link confirmations every few seconds, the session timeout. Protocols Bridge as source route bridge (SRB), the number of bridges and rings, you can span a package SNA. There are problems with the number of rings with DLSW used as a RIF +Field is set to the router. DLSW + incorporates many different data link technologies like Ethernet, Token Ring, SDLC and Frame Relay. This is a translation as well as between different types of frames, such as Ethernet and Token Ring to each router for data connectivity technologies. Promiscuous mode is configured DLSW + router, which for many connections from remote peer router allows. An example would be the 7500 data center routers that peer connections have been distributed by manyOffices.