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T1s used in point-to-point connections are often viable solutions. T1s can be used for point-to-point T1 services in two categories: voice or data. Contrary to the T1 being used for access to the local carrier, a point-to-point T1 line carries traffic from one customer location to another, only using the telecommunications network to transport the T1 itself. The service provider sells a point-to-point service without any switching, routing, or any carrier-based services other than provisioning a "private line" T1. Any circuit that is provisioned by a carrier for only a customer's use, and connects two locations together, is considered a private line. Point-to-Point Voice Applications. Popular in the 80's and 90's, when long distance charges were much higher, many company's linked major locations together with voice tie trunks. In a tie-trunk configuration, PBXs at both locations were "tied together" with interconnect trunks so that any traffic bound from location A to B, traveled over a tie trunk, avoiding metered long distance charges. Point-to-Point Data Applications. Data applications are the most common for private line point-to-point services. Generally, these link two Local Area Networks together, and the private line link is considered the WAN (wide area network). Since T1s can be provisioned linking locations across the street or across the country, there's no theoretical limit to the distance. Only data application sensitivity may dictate that latency be no greater than a designed limit. Latency is a measure of how long it takes to send a packet from one location to another, and return a response. Also known as round-trip delay, data applications will typically accommodate a point-to-point T1, no matter the distance. When considering migrating from this service to either a Frame Relay or pure IP environment, much closer attention must be paid to applications and the effects of latency. Point-to-Point Voice Equipment Choices. In either the access or tie line configuration, T1s can terminate to PBXs either via analog or digital interfaces. Typically, analog interfaces on PBXs have 4 ports, requiring 6 trunk cards to terminate a T1, plus for the digital to analog conversion, a channel bank with the appropriate cards per channel is required. A much simpler equipment option to terminate a T1 of phone service is using a DTI (Direct Termination Interface) card, which is an option for today's digital PBXs. A DTI card will terminate the T1 directly, eliminating any analog conversions (until the call reaches the telephone handset) and the extra space required for channel banks. Point-to-Point Data Equipment Choices. In most cases, if the point-to-point service is carrying only data, both ends will terminate either into a multiplexer , or more likely a router. By terminating into a router, the point-to-point T1 becomes part of the company's enterprise network, extending their existing LAN (local area network) beyond the facility's doors, and linking the second location as if it were collocated. |
Point to Point T1
