DS3 Mux

A DS3 multiplexer (mux), typically called an M13, is a Telecom term for the device required by either Telcos or large business users to break down the DS3 signal into DS1 (T1) level connections which are required by most PBXs. While each DS3 has a capacity to carry 28 DS1s, it is not required that it carry all 28. A DS3 is also known as a T3. For termination, a DS3 mux is placed between the DS3 facility and those devices requiring DS1 (T1) connections, and a mux card is used to decode the DS3 time slot for each respective DS1 of service being carried by the DS3.

Usage of DS3 Multiplexers. DS3s are high capacity circuits, typically used by Telephone companies and large business users that require more than a DS1 (T1 or 1.544Mb) of connectivity. In terms of capacity, a DS3 is equal to 28 DS1s (T1s) of capacity. Due to equipment multiplexing limitations, most business users that need more than a few T1s of capacity opt for the next "level" of service as a DS3, because access costs on NxT1 vs. a DS3 will typically break-even at about 4 T1s (6mb). Once the DS3 facility is leased, adding T1 capacity requires very little lead-time, and no additional monthly cost for the access facility.

Common Names / Muxing Levels:

• DS0 = Digital Service Level 0 (64kb)
• DS1 = T1 = Digital Service Level 1 (1.544mb) = 24 DS0s
• DS3 = T3 = Digital Service Level 3 (45mb) = 28 DS1s or 672 DS0s
• M13 = Typical name for a multiplexer that combines 28 DS1s into a DS3 (i.e.: DS1 to DS3)

Typical Mux Applications . When M13 muxes are used, they may be used solely to de-mux DS1s for digital termination at the DS1 level directly into a PBX, or CSU (for data services), or may be followed by Channel Banks, which are used to break the resulting DS1 signals down further into DS0 circuits.

Please see our multiplexing page for an in-depth tutorial about multiplexing schemes.

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