VT1.5
Encyclopedia
VT1.5 is a type of virtual tributary in SONET
.
SONET bandwidth
is defined in multiples of an OC-1/STS-1, each of which can transport up to 51.84 Mbit/s. However, it is frequently desirable to address much smaller portions of bandwidth. To meet this need, sub-STS-1 facilities called Virtual Tributaries have been defined. In North America
and Japan
, the VT1.5 is the most common virtual tributary because it can carry 1.728 Mbit/s; just enough room for a DS1/T1
signal. In Europe
, the VT2 (with a data rate of 2.304 Mbit/s) is used to transport E1s.
Some SONET manufacturers offer products that can switch at the VT1.5 level. Such equipment is able to re-arrange the data payloads so that inbound VT1.5s are placed into a completely different set of outbound STS's than the ones they arrived in. Among other things, this allows the bandwidth usage to be optimized and facilitates a cleaner network design.
The following is provided via Network Infrastructure/Design Student:
Four types of VT’s defined in SONET
7 VT groups (VTG) per STS-1.
Sonet
Sonet may refer to:* Sonet Records, European record label* Synchronous optical networking * Saab Sonett...
.
SONET bandwidth
Bandwidth (computing)
In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...
is defined in multiples of an OC-1/STS-1, each of which can transport up to 51.84 Mbit/s. However, it is frequently desirable to address much smaller portions of bandwidth. To meet this need, sub-STS-1 facilities called Virtual Tributaries have been defined. In North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, the VT1.5 is the most common virtual tributary because it can carry 1.728 Mbit/s; just enough room for a DS1/T1
Digital Signal 1
Digital signal 1 is a T-carrier signaling scheme devised by Bell Labs. DS1 is a widely used standard in telecommunications in North America and Japan to transmit voice and data between devices. E1 is used in place of T1 outside North America, Japan, and South Korea...
signal. In Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, the VT2 (with a data rate of 2.304 Mbit/s) is used to transport E1s.
Some SONET manufacturers offer products that can switch at the VT1.5 level. Such equipment is able to re-arrange the data payloads so that inbound VT1.5s are placed into a completely different set of outbound STS's than the ones they arrived in. Among other things, this allows the bandwidth usage to be optimized and facilitates a cleaner network design.
The following is provided via Network Infrastructure/Design Student:
Four types of VT’s defined in SONET
- VT 1.5 (DS-1: 1.544 Mbit/s)
- VT 2 (E-1: 2.048 Mbit/s)
- VT 3 (DS-1C: 3.152 Mbit/s)
- VT 6 (DS-2: 6.312 Mbit/s)
7 VT groups (VTG) per STS-1.
- Four DS-1s map into one VTG.
- One STS-1 frame can carry 28 DS-1s
- DS-3 Maps directly to STS-1. VT are not needed.