LAPB (Link Access Procedure, Balanced)

Pronounced lap bee. A bit-oriented protocol that is part

of the X.25 protocol suite, LAPB runs at Layer 2, the Data Link Layer, of the OSI Reference Model.The LAPB frame comprises a header and trailer that encapsulate the packet formed by the X.25 packet layer protocol (PLP) at the Network Layer. The LAPB frame provides a mechanism for transporting packets across a link, ensuring that frames of data are ordered correctly and are free from error. LAPB is a balanced protocol that operates in asynchronous balanced mode (ABM), referring to the fact that the devices have a balanced, rather than a master/slave, relationship. LAPB is a derivative of the High-level Data Link Control (HDLC) protocol, which, in turn, is based on the IBM Synchronous Data Link Control (SDLC) frame. Figure L-1 illustrates the LAPB frame and its component fields.

1

1

1

Variable

2

1

Flag

Address Control

Frame Check

Packet

Flag

Sequence

Header

Trailer

• 10 Gigabit Ethernet (10GbE)
• 10 Gigabit Ethernet (IEEE 802.3ae) Media Specifications
• 10GigE (10 Gbps Ethernet)
• 10XXX
• 11
• 12
• 128-QAM
• 13
• 1394
• 1/3 FEC
• 14
• 15
• 1.5-way paging
• 16
• 16-QAM
• 16-QPSK
• 18
• 1:8 Splitter
• 1A
• 1A1
• 1A2
• 1Base5 (1 Mbps; Baseband; 500 meters)
• 1B+D
• 1. Domain Name System. The naming convention that divides the Internet into logical domains identified in Internet Protocol version 4 (IPv4) as a 32-bit portion of the total address.The standard convention is user@organization.domain, where user is the name of the end user, organization is the name of the enterprise or other organization owning or sponsoring the address, and domain is the type of entity owning or sponsoring the address.The administration of the DNS is the responsibility of Internet Corporation for Assigned Names and Numbers (ICANN). See also domain, ICANN, Internet, and IPv4. 2.
• 1. In storage, irrelevant material, usually zero (0) bits, added to a data block in order to fill it to a minimum size, to force certain fields of control data or user data into certain positions or sizes, or to prevent the user data from duplicating a bit pattern that has a specific control meaning. See also block. 2.