Being in the "CLEC" business I can tell you that we typically refer to T3 when discussing "Transport only" type ciruits of 45Mbps from point to point. When we refer to putting services on it, such as Frame Relay, ATM, PPP, voice (PRI, Trunks, etc) then we usually refer to them as DS3.
However, they are certainly used interchangibly by most. A T1 or T3 is a "Carrier" as explained below: To see the relationship between T-carrier, E-carrier, and DS0 multiples, see digital signal X. The T-carrier system, introduced by the Bell System in the U.S. in the 1960s, was the first successful system that supported digitized voice transmission. The original transmission rate (1.544 Mbps) in the T-1 line is in common use today in Internet service provider (ISP) connections to the Internet. Another level, the T-3 line, providing 44.736 Mbps, is also commonly used by Internet service providers. Another commonly installed service is a fractional T-1, which is the rental of some portion of the 24 channels in a T-1 line, with the other channels going unused. The T-carrier system is entirely digital, using pulse code modulation and time-division multiplexing. The system uses four wires and provides duplex capability (two wires for receiving and two for sending at the same time). The T-1 digital stream consists of 24 64-Kbps channels that are multiplexed. (The standardized 64 Kbps channel is based on the bandwidth required for a voice conversation.) The four wires were originally a pair of twisted pair copper wires, but can now also include coaxial cable, optical fiber, digital microwave, and other media. A number of variations on the number and use of channels are possible. In the T-1 system, voice signals are sampled 8,000 times a second and each sample is digitized into an 8-bit word. With 24 channels being digitized at the same time, a 192-bit frame (24 channels each with an 8-bit word) is thus being transmitted 8,000 times a second. Each frame is separated from the next by a single bit, making a 193-bit block. The 192 bit frame multiplied by 8,000 and the additional 8,000 framing bits make up the T-1's 1.544 Mbps data rate. The signaling bits are the least significant bits in each frame. A DS0/1/3 is a Digital signal carried by the "T" carrier as explained below: Digital signal X is a term for the series of standard digital transmission rates or levels based on DS0, a transmission rate of 64 Kbps, the bandwidth normally used for one telephone voice channel. Both the North American T-carrier system system and the European E-carrier systems of transmission operate using the DS series as a base multiple. The digital signal is what is carried inside the carrier system. DS0 is the base for the digital signal X series. DS1, used as the signal in the T-1 carrier, is 24 DS0 (64 Kbps) signals transmitted using pulse-code modulation (PCM) and time-division multiplexing (TDM). DS2 is four DS1 signals multiplexed together to produce a rate of 6.312 Mbps. DS3, the signal in the T-3 carrier, carries a multiple of 28 DS1 signals or 672 DS0s or 44.736 Mbps. Digital signal X is based on the ANSI T1.107 guidelines. The ITU-TS guidelines differ somewhat. > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of > MADMAN > Sent: Thursday, March 20, 2003 4:32 PM > To: [EMAIL PROTECTED] > Subject: Re: DS3 bandwidth issues [7:65790] > > > six of one half dozen of the other, they both describe the same > thing. I "think" T is a Bellcore name and DS is a some standards > body name. > > Dave > > Scott Roberts wrote: > > why do people refer to a DS3 as a DS3 and not a T3? is there > something I'm > > missing? > > > > scott > > > > ""Nate"" wrote in message > > news:[EMAIL PROTECTED] > > > >>We've run a bandwidth test on our DS3 with nothing connected to it but a > >>workstation (and obviously a router/pix). We went to testmyspeed.com as > >>well as dslreports.com. We both got very good bandwidth tests (upward > > > > 6m/s) > > > >>however in transferring a 200m file to/from a workstation behind the > >>connection, we got over 30 minutes while our existing T1 got 26 minutes. > >>Anyone mind explaining this phenomenon? Just a side note, we have no > >>encryption between GRE tunnels. Thanks in advanced. > >> > >>-Nate > -- > David Madland > CCIE# 2016 > Sr. Network Engineer > Qwest Communications > 612-664-3367 > > I would rather have a German division in front of me than a French one > behind me." > --- General George S. Patton Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=65893&t=65790 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
