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GLOSSARY

OC-1, OC-1, OC-3, OC-12, OC-24, OC-48, OC-128, OC-192, OC-256, OC-768
OLTP - ONLINE TRANSACTION PROCESSING
ONLINE
ODI - OPEN DATA-LINK INTERFACE
OPEN RELAY


• OCxThe Synchronous Optical Network (SONET) includes a set of signal rate multiples for transmitting digital signals on optical fiber. The base rate (OC-1) is 51.84 Mbps. Certain multiples of the base rate are provided as shown in the following table. Asynchronous transfer mode (ATM) makes use of some of the Optical Carrier levels.
                           Optical Carrier       Level Data Rate
                                OC-1                       51.84 Mbps
                                OC-3                     155.52 Mbps
                                OC-12                   622.08 Mbps
                                OC-24                      1.244 Gbps
                                OC-48                      2.488 Gbps
                                OC-192                         10 Gbps
                                OC-256                  13.271 Gbps
                                OC-768                         40 Gbps
  
  

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• OLTP Online Transaction Processing, is a class of program that facilitates and manages transaction-oriented applications, typically for data entry and retrieval transactions in a number of industries, including banking, airlines, mailorder, supermarkets, and manufacturers. Probably the most widely installed OLTP product is IBM's CICS (Customer Information Control System).
  

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• ONLINE is the condition of being connected to a network of computers or other devices. The term is frequently used to describe someone who is currently connected to the Internet.
  

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• ODI Open Data-Link Interface is a software interface that allows different Data-Link layer protocols to share the same driver or adapter in a computer. ODI was introduced by Novell. For example, using ODI, both TCP/IP and IPX/SPX can share the same device adapter. The Data-Link Layer, part of the Open Systems Interconnect (OSI) model, provides a way to move data across a physical link.
  

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• OPEN RELAY (sometimes called an insecure relay or a third-party relay) is an SMTP e-mail server that allows third-party relay of e-mail messages. By processing mail that is neither for nor from a local user, an open relay makes it possible for an unscrupulous sender to route large volumes of spam . In effect, the owner of the server -- who is typically unaware of the problem -- donates network and computer resources to the sender's purpose. In addition to the financial costs incurred when a spammer hijacks a server, an organization may also suffer system crashes, equipment damage, and loss of business.
  Open relays are sometimes used legitimately: they are frequently used to support mobile users connecting to a corporate network through an ISP or to support multiple domains within an organization, and are sometimes used for debugging connectivity or to circumvent a known routing problem. However, other mechanisms can be used to route an authorized user around a closed relay.
  The Mail Abuse Prevention System (MAPS) is one of several organizations that seeks to control the problem of open relays, though educating the public about the danger, and through publishing a blacklist of organizations whose mail hosts allow third-party relays. The relay feature is a part of all SMTP-based servers, which means that most modern e-mail servers, if unprotected, are vulnerable. According to MAPS, because spammers use automated tools to search the Internet for vulnerable servers, an open relay will eventually be found and used. To avoid allowing spammers free access to their resources -- and to help stem the Internet's flow of spam -- MAPS urges administrators to turn off the relay option on their servers.
  

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