Glossary of Terms

BT’s 21st Century Network

3rd Generation Mobile data network

4th Generation Mobile Technology

ATM Adaptation Layer 5 This most typically encountered as an ADSL thing but if you need to know about it and you don’t already then you have problems.

Broadband Remote Access Server A device which accepts PPP connections from end users and forwards them on to an LNS. Also used for holding boobies.

Basic Rate Interface (BRI, 2B+D, 2B1D) or Basic Rate Access is an Integrated Services Digital Network (ISDN) configuration intended primarily for use in subscriber lines similar to those that have long been used for voice-grade telephone service. As such, an ISDN BRI connection can use the existing telephone infrastructure at a business. The BRI configuration provides 2 data (bearer) channels (B channels) at 64 kbit/s each and 1 control (delta) channel (D channel) at 16 kbit/s. The B channels are used for voice or user data, and the D channel is used for any combination of data, control/signaling, and X.25 packet networking. The 2 B channels can be aggregated by channel bonding providing a total data rate of 128 kbit/s. The BRI ISDN service is commonly installed for residential or small business service (ISDN PABX) in many countries. Two modes of presentation are possible in the UK being MSN or System the latter is used for phone systems and DDI number blocks.

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A DSLAM (Digital Subscriber Line Access Multiplexer) allows telephone lines to make faster connections to the Internet. The network device is located in telephony exchanges connecting multiple customer DSLs to a high-speed Internet backbone using where multiple signals are combined into one signal over a shared medium.

Interleaving is a method of protecting the data transmitted from burst errors, with interleaving enabled should an error occur the idea is that enough error control bits can piece back enough of the transmission to retain the information from corruption. For example; Original transmitted: ThisIsAnExampleOfInterleaving Received after burst without Interleaving: ThisIs______pleOfInterleaving Received after burst with Interleaving: T_isI_AnE_amp_eOfInterle_vin_ The disadvantage of enabling Interleaving is the increase of latency, and so ping response times will be higher with page load taking longer.

ISDN service types The Integrated Services Digital Network (ISDN) prescribes two levels of service: Basic Rate Interface (BRI): two 64-kbit/s B channels and one 16-kbit/s D channel, intended for small enterprises and residential service. Primary Rate Interface (PRI) for large organizations, with one 64-kbit/s D channel and 23 (1.536 Mbit/s T1, a.k.a. "23B + D") or 30, 64-kbit/s B channels (2.048 Mbit/s E1, a.k.a. "30B + 2D"). Each B-channel carries data, voice, and other services. The D-channel carries control and signaling information. Larger connections are possible using PRI pairing. A dual T1-PRI could have 24 + 23 = 47 B-channels and 1 D-channel (often called "47B + D"), but more commonly has 46 B-channels and 2 D-channels thus providing a backup signaling channel. The concept applies to E1s as well and both can include more than 2 PRIs. When configuring multiple T1’s as ISDN-PRI’s, it’s possible to use NFAS (non-facility associated signalling) to enable one or two D-channels to support additional B-channels on separate T1 circuits.

In computer networking, Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs) or as part of the delivery of services by ISPs. It does not provide any encryption or confidentiality by itself. Rather, it relies on an encryption protocol that it passes within the tunnel to provide privacy. https://en.wikipedia.org/wiki/Layer_2_Tunneling_Protocol

L2TP Network Server- a router which terminates the broadband connections from customer routers. IC’s LNS devices provide constant quality monitoring of your broadband connections - you don’t get that from SKY or BT - you can see the graphs within the my.ic.uk portal.

Multi Protocol Label Switching but that does not help much really in understanding. IC use this to provide super fast private networks for both ourselves and for customers. IC provides 2 main types of MPLS network. Layer 2 (switched) private point to point or point to multi-point networks called VPLS and Later 3 (routed) private networks which function like a large single private distributed router.

The Primary Rate Interface (PRI) is a telecommunications interface standard used on an Integrated Services Digital Network (ISDN) for carrying multiple voice and data transmissions between the network and a user. PRI is the standard for providing telecommunication services to enterprises and offices. It is based on T-carrier (T1) transmission in the US, Canada, and Japan, while the E-carrier (E1) is common in Europe and Australia. The T1 line consists of 23 bearer (B) channels and one data (D) channel for control purposes,[1] for a total bandwidth of 24x64-kbit/s or 1.544 Mbit/s. The E1 carrier provides 30B- and two D-channels for a bandwidth of 2.048 Mbit/s.[2] The first timeslot on the E1 is used for synchronization purposes and is not considered to be a B- or D-channel. The D-channel typically uses timeslot 16 on an E1, while it is timeslot 24 for a T1. Fewer active bearer channels, sometimes called user channels, may be used in fractional T1 or E1 services.

Repetitive Electrical Impulse Noise (REIN) is a term applied to some interference found on problematic DSL internet connections. The interference can be detected as electrical impulses on the physical telephone line on which the internet connection operates. REIN is particularly problematic as it can cause DSL modems to lose synchronisation and drop connection

VC-MUX, (Virtual Circuit Multiplexing) is one of the two mechanisms for identifying the protocol carried. When configuring a router to be used with an Internet Central connection it is essential to specify VC-MUX as opposed to LLC for the Encapsulation.