| EFCI | Explicit Forward Congestion Indication. A 1-bit field in the PTI that contains information whether congestion at an intermediate node has been experienced. The EFCI bit is set when, i.e., a buffer threshold has been exceeded. |
| ELAN | Emulated Local Area Network. |
| EMI | Electromagnetic Interference |
| ENR | Enterprise Network Roundtable. An ATM Forum associated group of ATM users to provide feedback on ATM-related issues and also present the users with completed interoperable capabilities and functionality. |
| EOM | End of Message |
| ER | Explicit Rate. A field in the RM cell header specifying the cell rate a user should use for transmission over a virtual connection (VC), as it is dictated by the RM (see also CCR). |
| ETAG | End Tag |
| ETE | End-to-End |
| EXM | Exit Message |
| FC | Feedback Control |
| FCS | Fast Circuit Switching |
| FCS | Frame Check Sequence |
| FDDI | Fiber Distributed Data Interface. An ANSI-defined standard for implementing a high-speed (100 Mbps) LAN over fiber. |
| FEBE | Far End Block Error |
| FEC | Forward Error Correction. An error correction technique where there are no retransmissions and therefore the receiver is responsible for correcting any errors in the packets. |
| FERF | Far End Receive Failure |
| FRS | Frame Relay Service |
| FUNI | Frame User Network Interface |
| GAP | Generic Address Parameter |
| GCID | Global Call Identifier |
| GCID-IE | Global Call Identifier- Information Element |
| GCRA | Generic Cell Rate Algorithm |
| GFC | Generic Flow Control. A 4-bit field in the ATM cell header in order to support multiplexing functions. Its default value is '0000', when the GFC protocol is not enforced. The GFC mechanism is intended to support simple flow control in ATM connections. |
| GRC | Generic Reference Configuration |
| HDB3 | High Density Bipolar 3 |
| HDLC | High Level Data Link Control |
| HEC | Header Error Check or Header Error Control. A 1-byte field in the cell header used for the header error correction and detection. Due to the information contained in the header, HEC is quite significant. |
| HEC | Header Error Check |
| HEL | Header Extension Length |
| HLPI | Higher Layer Protocol Identifier |
| HOL | Head-of-Line. The head position of a buffer (i.e. inside a switch). A blocking phenomenon is associated with the HOL which refers to the fact that cells in the queue have to wait for the HOL cell to depart first. |
| IAA | Initial Address Acknowledgment |
| IAM | Initial Address Message |
| IAR | Initial Address Reject |
| IC | Initial Cell Rate |
| ICD | International Code Designator |
| ICMP | Internet Control Message Protocol |
| IDU | Interface Data Unit |
| IE | Information Element |
| IEC | Inter-exchange Carrier |
| IEEE | Institute of Electrical and Electronic Engineers. A standards and specification organization with extensive activities in the areas of computers and electronics. |
| IETF | Internet Engineering Task Force. A body, which was initially responsible for developing specifications required for the interoperable implementation of IP. One of the issues IETF has been focusing on is the implementation of Classical IP over ATM. |
| IISP | Interim Interswitch Signaling Protocol. A protocol that uses UNI-based signaling for switch-to-switch communication (see also NNI). |
| ILMI | Interim Link Management Interface |
| ILMI | Interim Local Management Interface. An ATM Forum-defined Network Management System (NMS) based on SNMP that can provide configuration, performance and fault management information concerning virtual circuits (VC) connections available at its UNI (public and private). It operates over AAL3/4 and AAL5 and will be eventually replaced once it becomes standardized by ITU-T. |
| IOP | Interoperability |
| IP | Internet Protocol. A networking protocol for providing a connectionless (datagram) service to the higher transport protocol. It is responsible for discovering and maintaining topology information and for routing packets across homogeneous or heterogeneous networks. Combined with TCP, it is commonly known as the TCP/IP platform. |
| Ipng | Internet Protocol Next Generation |
| IPX | Novell Internetwork Packet Exchange. A protocol similar to IP that was developed by Novell |
| ISO | International Organization for Standardization |
| ITU | International Telecommunications Union-Telecommunications Standards Sector. A formal international standards, specifications and recommendations body, formerly known as CCITT. ITU-T is part of the International Telecommunications Union (ITU) founded in 1948 and sponsored by the U.N. to promote telephone and telegraphy issues. |
| IUT | Implementation Under Test |
| IWF | Interworking Function |
| IWU | Interworking Unit |
| JPEG | Joint Photographic Experts Group |