| For Americans to have full E1 communications with their European counterparts, they need to multiplex (time division) two T1s. All twenty four channels on the first T1 is used and only 8 channels on the second T1. What a waste of bandwidth. Can't we all get on one standard?
E1
E1, as mentioned in the previous writeup, is a communications standard developed in Europe. It, like the metric system, has been adopted by the majority of the developed world.
At full bandwidth E1 is 32 64-Kbps channels (2.048 Mbps). The usable bandwidth, depending on the point of view you take, is 31 or 30 channels. From the service providers point of view, it is 31 channels because they are providing 31 data capable channels to the customer. One channel is used for their overhead. From the client's perspective, only 30 channels are capable of carrying data. An additional channel is consumed for customer overhead.
T1
T1 is an older competing standard originally developed in the United States. It was the brainchild of AT&T and Bell Labs. Currently it is used by the United States, Mexico, and a few Asian, Central and South American courtries.
A T1 at full bandwidth is 1.544 Mbps. The actual usable bandwith is 1.536 Kbps. The additional 8 bits are used for timing. 1.536 Kbps translates to 24 64-Kbps channels.
Competing Standards
Comparable to the U.S. stance on metric system, its refusal to adopt the much more widely accepted E1 standard has global ramifications. With the U.S. being such a force in the world economy, the increase in importance of global communications, and the advent of the Internet, the consequences are not trivial.
Wasted Bandwidth
The amount of bandwidth wasted per E1 connection on the US domestic side can approach 1.04 Mbps or approximately 34%. While some of the bandwidth can be scavenged for other purposes, logistics typically prevents it from being so.
Schematic Diagram
-------------------------------------------------------------------------------------------
| | | | | |
| | |------------------| | |
| | /| T1 |\ -- -- | |
| | / | | \ / \/ \ | |
| --- ---/ | | \--- | | ----- E1 -- |
||CPE|------|MUX| | | |MUX|----| Cloud |----|CS/ES|---------|FE||
| --- ---\ | | /--- | | ----- -- |
| | \ | | / \ /\ / | |
| | \| |/ -- -- | |
| | |------------------| | |
| | | T1 | | |
| | | 3.088 Mbps Reserved | |
|<-2.048 Mbps>|<----------------------2.048 Mbps Used--------------------->|<--2.048 Mbps-->|
| | | 1.040 Mbps Wasted | |
| | | | | |
|<-Customer Premise->|<---Local Loop--->|<------------Carrier------------->|<----Foreign--->|
| Demark End |
-------------------------------------------------------------------------------------------
| 
