E1
Transmitting data over a telephone network at 2.048 Mbps. Europe equivalent of T1.

E2
Europe. Transmitting data over a telephone network at 8.848 Mbps.

E3
Europe. Transmitting data over a telephone network at 34 Mbps.

E4
Europe. Transmitting data over a telephone network at 139.264 Mbps.

EBCDIC
Extended Binary Coded Decimal Interchange Code. IBM ¨ - 8 bits character code 
8 bits character code. 

EC
Echo Canceling

ECC
Error Checking and Correcting 
The general rule of thumb in deciding what type of memory you need is to look at what's already installed in your system. To find out if you have ECC, parity, or non-parity memory, count the number of chips on the module. Divide the total number of chips by three. If you can evenly divide the number of chips by three, the module is ECC or parity, if not, then it is a non-parity module. 
So what if your system does have ECC or parity memory - the chips are evenly divisible by three - how do you know which one you have? One way is to look at the part numbers on the chips of your module. If each chip has the same part number, you have ECC. If one chip is different, you have parity.
If you are building a PC and deciding which type to use, the following guidelines should help. If you plan to use your system as a server or a similar mission critical type machine, it is to your advantage to use ECC. If you plan to use your PC for regular home, office, or gaming applications, you are better off with non-parity. 
Using ECC decreases your PC's performance by about 2%. Current technology DRAM is very stable and memory errors are rare, so unless you have a need for ECC, you are better served with non-parity SDRAM.
Most motherboards that do not have an ECC function within the BIOS are still able to use a module with ECC, but the module will run in non-ECC mode. Keep in mind, there are some cases where the motherboard will not accept an ECC module, depending on the BIOS programming. The only sure-fire way to test this is to place the module in the motherboard and see if the BIOS will recognize the memory addition. 

The general rule of thumb in deciding what type of memory you need is to look at what's already installed in your system. To find out if you have ECC, parity, or non-parity memory, count the number of chips on the module. Divide the total number of chips by three. If you can evenly divide the number of chips by three, the module is ECC or parity, if not, then it is a non-parity module. 
If you already have a PC and are unsure which type you have, count the number of small, black, IC chips mounted on one of your existing DIMMs. If the number of chips is evenly divisible by three, then you need ECC. If the number of chips is NOT evenly divisible by three, you have non-parity memory. 
If you are building a PC and deciding which type to use, the following guidelines should help. If you plan to use your system as a server or a similar mission critical type machine, it is to your advantage to use ECC. If you plan to use your PC for regular home, office, or gaming applications, you are better off with non-parity. 
ECC performs "double bit detection and single bit correction." This means that if you have a single bit memory error, the chipset and memory will find and repair the error on the fly without you knowing that it happened. If you have a double bit memory error, it will detect and report it. Using ECC decreases your PC's performance by about 2%. Current technology DRAM is very stable and memory errors are rare, so unless you have a need for ECC, you are better served with non-parity SDRAM.
DDR memory modules support both ECC - error correction code, typically used in servers - and non-ECC -used on desktops/laptops - DDR is also available in both registered - typically used in servers- and unbuffered - typically used in PCs - versions.
When adding new memory, you need to match what is already in your system. Parity modules have an extra chip that detects if data was correctly read or written by the memory module, depending on the type of error. However, a parity module will not correct the error.
You can determine if your system has parity by simply counting the number of black memory chips on each module. Parity - and ECC - memory modules have a chip count divisible by 3. Any chip count not divisible by 3 indicates a non-parity memory module.

ECF
Echo Frame. A type of station mgnt. frame in FDDI that allows a station to perform loopback testing.

ECM
Entity Coordination Management 
Part of the FDDI station management specification. The ECM resides within the PHY sub-layer and is responsible for the media interface to the FDDI network. 

EDBFA
Erbium Doped Fiber Amplifiers. See DWDM

EECM
End to End Call Manager - Cisco ¨

E&M
recEive and transMit /or Ear & Mouth. Standard signaling method used over interoffice and toll trunks. 
E&M is a trunking arrangement generally used for two-way switch-to-switch or switch-to-network connections.

EFCI
Explicit Forward Congestion Indication

EFR
Early life Failure Rate

EFS
End of Frame Sequence, In FDDI frame and token format blocks, consists of ending delimiter -ED- and frame status -FS- fields. 

EFT
Electronic Funds Transfer

EGP
Exterior Gateway Protocol - RFC 904 
ARPA - DoD
An internet protocol for exchanging routing information between autonomous systems. 
A protocol in the IP suite used to exchange network reachability information between routers in different autonomous systems. Routers establish EGP neighbor relationships in order to periodically exchange reliable reachability information. 

E-GPRS
Enhanced General Packet Radio Service. See EDGE

EHF
Extremely High Frequency

EIGRP
Enhanced Interior Gateway Protocol

EIP
Enterprise Information Portal

EKTS
Electronic Key Telephone Service

ELAN
Education Language

ELAN
Emulated LAN-ATM. Emulated LANs make connection-oriented ATM networks look like connectionless local area networks. 

EMP
Electromagnetic Pulse

EN
End Node - APPN PU2.1 - IBM ¨

EOC
Embedded Operations Channel

EOM
End Of Message - ATM

EON
End Of Transmission / End Of Text

EPD
Early Packet Discard - ATM

EP-L
Electro Photographic Laser

ER
Explicit Rate / Route - ATM 

ERLANG
Telephony - Measurement unit giving the intensity of the traffic on a total group of lines during the most used hour.

ERM
Enterprise Relationship Management 
Solutions that enable the enterprise to share comprehensive, up-to-date customer, product, competitor and market information; for the end goals of long-term customer satisfaction, increased revenues, and higher profitability. 


ERMS
Enhanced Rotary Mechanical Splices

ESAF
Ethernet Sync Adapter with Filter

ESCON
Enterprise System Connection - IBM ¨ 17 Mbps channel for attaching mainframe to peripherals. 

ESMTP
Extended Simple Mail Transfer Protocol - RFC 1869

ETDMA
Extended Time Division Multiple Access

ETHERNET
A baseband LAN specification invented by Xerox¨ Corporation and developed jointly by Xerox, Intel¨, and Digital¨ Equipment Corporation.
Widely used LAN technology defined by the IEEE 802.3 specification. Ethernet networks run at a data rate of 10 Mb/s, 100 Mb/s, or 1000 Mb/s, using baseband transmission and CSMA/CD access or full duplex. The IEEE/ISO standard provides for integration into the OSI reference model and extends the physical layer and media with repeaters and implementations that operate on fiber optics, broadband, and unshielded twisted pair cable. 
- IEEE 802.3
- Up to 1024 nodes
- 10 M-bits
- Using the OSI layers 1 and 2
- Ethernet address A 48-bit number usually expressed as a 12-digit hexadecimal number that uniquely identifies a workstation, server, or other device on a network. 
Ethernet and 802.3 frames



Extranet
A method, using the Internet, by which remote users and multiple LANs can be connected to a corporate intranet.