DsLam

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DSLAM forms a large area LAN
A Dslam connects via TwistedPair copper wire to Adsl modems upto a distance of 5km. The wireing for a DSLAM are laid via TelephoneNetworkRollout. A DSLAM is one of the most powerful network and communications devices on a cost performance basis. That is why http://www.telkom.co.za uses it.

DSLAM is Point-to-Multipoint device
* DSLAM: Digital Subscriber line access multiplexer * A DSLAM is a Point-to-Multipoint device or Router and Switch combination. * It has ATM protocol based ports functioning as a SwiTch at the back and a Router port at the front. * An ADSL modem is an ATM-to-Ethernet protocol converter. * DSLAM sizes vary between eight and 200 ports. * The eight port uses eight RJ-45 telephone jack connectors. * The larger port sizes use a Telco-50 connector cable. * A single DSLAM port connects via TwistedPair(AWG24) to a single ADSL modem. * The DSLAM can drop and pass network protocols such as P2P. * It has QOS, bandwidth increments of 32k and other management features. * Downstream bandwidth 24meg(Adsl2+), 24meg(VDSL), 50meg(VDSL2+) * Upstream bandwidth 1.6meg(ADSL2+), 10meg(VDSL), 50meg(VDSL2+) * Downstream distances ~ 0,626m(VDSL2+), 1km(VDSL), 5km(ADSL2+ * The ADSL modem hands out a DHCP lease to an Ethernet device. * Holiday Inn uses a DSLAM to stream video on demand to their hotel rooms.

Role of the DSLAM
The word subscriber confuses the role of a DSLAM. Human beings subscribe to a certain world view. A DSLAM and a network SwiTch are not subscribing to anything, they are interfacing via a communications protocol: Either Ethernet or ATM to another device using the same protocol.

Digital subscriber line access multiplexer can also rephrased as: ADSL modems router. BR The word 'Multiplex' obscures the fact that the Ethernet Gigabit upload port at the back of the dslam Routes the ADSL modems connected to its ATM protocol ports over any network via the Ethernet protocol. So a Dslam should be visualized as a longdistance communicating switch connected to a Router. A RouTer connected to a SwiTch can also be described as ,,multiplexing,, the SwiTch data via it's Gigabit Ethernet port unto an Ethernet based network. As far as RouTers and DSLAMs are concerned their Gigabit Ethernet ports multiplexes or routes their data via the Ethernet protocol unto a computer network that also uses the Ethernet protocol. This has got nothing to do with telephone company backbones, ServingAreaInterface and DigtalLoopCarriers. Backbones and ServingAreaInterface can also be formed using Ethernet based RouTers and SwiTch but because of the distance limitation of 100m over copper with Ethernet, telephone exchanges use a DSLAM.DigitalLoopCarriers, Backbones and CentralOffice are jargon terms that only have any semblance of meaning once the various protocols as used by DSLAMs, RouTers, SwiTch and hubs are understood. Upto eight DSALMs can be daisy chained. Dslam1 connects via one of it's ATM ports to Dslams2's ATM port. These two Dslams then communicate via the ATM protocol. View a Dslam as forming a huge LAN. These large DSLAM LANs link into a WAN and view a Telephone company as a WAN operator. A Dslam just like a Router, Hub, Bridge and Switch per se has got nothing to do with a Telephone company. All Telcos just happen to use Ethernet based RouTers, SwiTch bridges and the ATM based switch/router combination known as a DSLAM. A community setting up their own telephone exchange via a DSLAM is really just setting up a large area LAN than can radiate out to 5km.

A DSLAM functioning as a SwiTch and RouTer, receives the ADSL modem data on an ATM port, converts it to Ethernet and streams this data via the single Ethernet gigabit link that physically plugs into the DSLAM itself unto an Ethernet based network. The data uploaded to the DSLAM via it's Gigibit Ethernet port is converted to the ATM protocol and streamed out to each ADSL modem. Each ADSL modem converts the ATM protocol data to Ethernent data. As far as the end user is concerned he is using the IP protocol from end-to-end. A DSLAM can stream video to all its ADSL modems at the same time. This allows for See http://en.wikipedia.org/wiki/Triple_play_%28telecommunications%29 The DSLAM has QOS and bandwidth control in increments of 32k, allowing bandwidth management to each ADSL modem. Download the http:/www.versatek.com Pdf document on their ADSL2+ DSLAMS. A DSLAM overcomes the distance limitation of 100m over copper wire that limits Ethernet usage. The ATM protocol uses fixed packet widths. The Ethernet protocol uses variable data rates. As the distance of a wire increases, its resitance increases hence the the need for the ATM protocol between the DSLAM port and the ADSL modem. For FiberOptics the prefered protocol is Ethernet due to its simplicity. ATM is a complex protocol but has to be used for long distance communication over copper.

ADSL2+ speeds and reach
Price: $530 for eight port or $67/port * Upload speed from an ADSL modem to it's DSLAM port: 1meg ~ 1.6km * Download speeds from a single DSLAM port to it's ADSL modem: * 25meg at 1000 feet * 24meg at 2000 feet * 23meg at 3000 feet * 22meg at 4000 feet * 21meg at 5000 feet * 19meg at 6000 feet * 16meg at 7000 feet

VDSL speeds and reach
* Price $900 for 16-port or $56/port * Upload: 10megs upto 1km * Download: 24meg upto 1km

VDSL2+ speeds and reach
* Upload: 50megs at 650m * Download: 50megs at 650m As the distance of the ADSL modem from the DSLAM increases the throughput will drop. At any distance where the speed becomes unacceptable, connect a Fiber/Ethernet module to the ADSL modem's ethernet port. The Fiber/Ethernet module is essentially a two-port SwiTch. A DSLAM is a viable alternative to many Fiber deployments, it allows people to build their own private telephone exchanges via telephone poles and underground cabling in the exact same manner that a Telco builds their exchanges. The mini-Dslam uses 10 way terminiation Krono-bloks to connect the modems to the Dslam.

Pricing of DSLAMs and VDSL-Ethernet bridges
* Retail price for eight-port mini-DSLAM - $540 : http://www.versatek.com/products/vx1000md.html * ADSL2+ modems: $29 * VDSL/Ethernet bridge: $85 * Versatek sales Engineer: Mr.Hui - USA Tel: 909-591-8891 ext122 * See DslamDistributors for other manufacturers

(in the links below find the M-ANNEXURE which allows 3.5meg upstream)

VDSL Ethernet bridges viewed as single port DSLAM
A VDSL bridge bridges or connects two Ethernet based devices upto 1km over TwitedPair. VDSL is an ATM based protocol. One can view a VDSL bridge as a one-port based DSLAM. The VDSL(CPE) converts Ethernet to ATM and transmits it to the other VDSL(CO) who converts the data back to Ethernet. As far as the user is concerned he is transparently interfacing with an Ethernet device on the other end. http://www.versatek.us/products/html/veb150-buy.html. They retail for $85 and achieve 10meg in both directions over TwistedPair upto 3000feet with a range of 7500feet on reduced throughput. This will reduce fiber usage and costs considerably. VDSL/Ethernet bridges can be used instead of DSLAMs depending on the application and datashaping that needs to be done. The VDSL bridge installed at the customer is known as CPE(Customer Premise Equipment). The CPE bridge connects to the CO(CentralOffice) bridge. See TelephoneNetworkRollout for more info on using VDSL-Ethernet bridges to build a community telephone exchange.

Combine VDSL bridge with DSLAMs
Multiple users either open streets, closed villages, shopping malls and business premises connects their ZoneMinder box to a CPE VDSL bridge. The CPE VDSL streams the CCTV footage to the VDSL(CO) at ServingAreaInterface. The SAI houses a SwiTch,RouTer and DsLam. Each VDSL CO connects to the SwiTch. The SwiTch interfaces with a RouTer. The RouTer connects the the DsLam Gigabit upload port. The DsLam streams the video to the ADSL modems at the CentralOffice.