Internet Engineering Task Force C. Perkins INTERNET DRAFT Sun Microsystems 17 November 1998 Mobile Ad Hoc Networking Terminology draft-ietf-manet-term-01.txt Status of This Memo This document is a submission by the Mobile Ad Hoc Networking Working Group of the Internet Engineering Task Force (IETF). Comments should be submitted to the manet@itd.nrl.navy.mil mailing list. Distribution of this memo is unlimited. This document is an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as ``work in progress.'' To view the entire list of current Internet-Drafts, please check the ``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). Abstract This document presents conventional definitions for many terms to be used during the discussion of various algorithms for enabling ad hoc networks of mobile computers, particularly over wireless media. Perkins Expires 17 May 1999 [Page i] Internet Draft Ad Hoc Network Terminology 17 November 1998 1. Introduction This document presents conventional definitions for many terms to be used during the discussion of various algorithms for enabling ad hoc networks of mobile computers, particularly over wireless media. With commonly agreed definitions, it is expected that protocol designers will be able to discuss more clearly the advantages and disadvantages of their algorithms. 2. Definitions for Mobile Ad Hoc Network Terms asymmetric link A link with transmission characteristics which are different depending upon the relative position or design characteristics of the transmitter and the receiver of data on the link. For instance, the range of one transmitter may be much higher than the range of another transmitter on the same medium. bandwidth The total capacity of a link to carry information (typically bits). bandwidth utilization The actual amount of information delivered over a link, expressed as a percent of the available bandwidth on that link. base station A centralized node coordinating the channel access of a population of mobile nodes within its transmission range. beacon A control message issued by a node (especially, a base station) informing all the other nodes in its neighborhood of the continuing presence of the node, possibly along with additional status information. channel A subdivision of the physical medium allowing possibly shared independent uses of the medium. Channels may be made available by subdividing the medium into distinct time slots, or distinct spectral bands, or decorrelated coding sequences. Perkins Expires 17 May 1999 [Page 1] Internet Draft Ad Hoc Network Terminology 17 November 1998 channel access protocol A protocol for mediating access to, and possibly allocation of, the various channels available within the physical communications medium. Nodes participating in the channel access protocol can communicate only when they have uncontested access to the medium, so that there will be no interference. cluster A group of nodes located within close physical proximity, typically all within range of one another, which can be grouped together for the purpose of limiting the production and propogation of routing information. cluster head A cluster head is a node (often elected in the cluster formation process) that has complete knowledge about group membership and link state information in the cluster. Each cluster should have one and only one cluster head. cluster member All nodes within a cluster EXCEPT the cluster head are called members of that cluster. communications medium A communication channel such as free space, cable or fiber through which data can be transmitted communications technology The means employed by two nodes to transfer data control message Information passed between two or more network nodes for maintaining protocol state which is not associated to any specific application. convergence The process of approaching a state of equilibrium in which all nodes in the network agree on a consistent collection of state about the topology of the network, and in which no further control messages are needed to establish the consistency of the network topology. Perkins Expires 17 May 1999 [Page 2] Internet Draft Ad Hoc Network Terminology 17 November 1998 convergence time The time which is required for a network to reach convergence after an event (typically, the movement of a mobile node) which changes the network topology. distance vector A style of routing protocol in which, for each desired destination, a node maintains information about the distance to that destination, and a vector (next hop) towards that destination. fairness A property of channel access protocols whereby a medium is made fairly equal to all eligible nodes on the link. Fairness does not strictly imply equality, especially in cases where nodes are given link access according to unequal priority or classification. flooding The process of delivering data or control messages to every node within the ad hoc network. forwarding node A node within an ad hoc network which performs the function of forwarding datagrams from one of its neighbors to another. goodput The total bandwidth used, less the volume of control messages and protocol overhead from the data packets. hidden-terminal problem The problem whereby a transmitting node can fail in its attempt to transmit data because of destructive interference which is only detectable at the receiving node, not the transmitting node. home address An IP address that is assigned for an extended period of time to a mobile node. It remains unchanged regardless of where the node is attached to the Internet [9]. If a node has more Perkins Expires 17 May 1999 [Page 3] Internet Draft Ad Hoc Network Terminology 17 November 1998 than one home address, it SHOULD select and use a single home address when participating in the ad hoc network. host Any node that is not a router. interface A node's attachment to a link. interface index An 8-bit quantity which uniquely identifies an interface among a given node's interfaces. laydown The relative physical location of the nodes within the ad hoc network. link A communication facility or physical medium that can sustain data communications between multiple network nodes, such as an Ethernet (simple or bridged). A link is the layer immediately below IP. link-layer address A link-layer identifier for an interface, such as IEEE 802 addresses on Ethernet links. link state A style of routing protocol in which every node within the network is expected to maintain information about every link within the network topology. link-level acknowledgement A protocol strategy, typically employed over wireless media, requiring neighbors to acknowledge receipt of packets (typically unicast only) from the transmitter. Such strategies aim to avoid packet loss or delay resulting from lack of, or unwanted characteristics of, higher level protocols. Perkins Expires 17 May 1999 [Page 4] Internet Draft Ad Hoc Network Terminology 17 November 1998 local broadcast The delivery of data to every node on a link (i.e., within range of the transmitter). loop-free A property of routing protocols whereby the path taken by a data packet from source to destination never transits the same intermediate node twice before arrival at the destination. MAC-layer address An address (sometimes called the link address) associated with the link interface of a node on a physical link. mobility factor The relative frequency of node movement, compared to the convergence time of the routing protocols used in the ad hoc network. mobility security association A collection of security contexts, between a pair of routers, which may be applied to protocol messages exchanged between them. neighbor a "neighbor" is any other node to which data may be propagated directly over the communications medium without relying the assistance of any other forwarding node neighborhood All the nodes which can receive data on the same link from one node whenever it transmits data. next hop A neighbor which has been designated to forward packets along the way to a particular destination. node A device that implements IP. Perkins Expires 17 May 1999 [Page 5] Internet Draft Ad Hoc Network Terminology 17 November 1998 packet An IP header plus payload. pathloss A reduction in signal strength caused by traversing the physical medium constituting the link. pathloss matrix A matrix of coefficients describing the pathloss between any two nodes in an ad hoc network. When the links are asymmetric, the matrix is also asymmetric. payload The actual data within a packet, not including network protocol headers which were not inserted by an application. prefix A bit string that consists of some number of initial bits of an address. route table The table where ad hoc nodes keep routing (including next hop) information for various destinations. route entry An entry for a specific destination (unicast or multicast) in the route table. route establishment The process of setting up a route between a source and a destination. route activation The process of putting a route into use after it has been set up. router A node that forwards IP packets not explicitly addressed to itself. Perkins Expires 17 May 1999 [Page 6] Internet Draft Ad Hoc Network Terminology 17 November 1998 scalability Wide applicability of a protocol to large as well as small populations of nodes participating in the protocol. scenario The tuple characterizing a class of ad hoc networks. security context A security context between two routers defines the manner in which two routers choose to mutually authentication each other, and indicates an authentication algorithm and mode. Security Parameter Index (SPI) An index identifying a security context between a pair of routers among the contexts possible in the mobility security association. signal strength The detectable power of the signal carrying the data bits, as seen by the receiver of the signal. source route A source route from node A to node B is an ordered list of home addresses, starting with the home address of node A and ending with the home address of the node B. Between A and B, the source route includes an ordered list of all the intermediate hops between A and B, as well as the interface index of the interface through which the packet should be transmitted to reach the next hop. spatial re-use Simultaneous use of channels with identical or close physical characteristics, but located spatially far enough apart to avoid interference (i.e., co-channel interference) system-wide broadcast Same as flooding, but used in contrast to local broadcast. Perkins Expires 17 May 1999 [Page 7] Internet Draft Ad Hoc Network Terminology 17 November 1998 throughput The amount of data from a source to a destination processed by the protocol for which throughput is to be measured for instance, IP, TCP, or the MAC protocol. topology A network can be viewed abstractly as a "graph" whose "topology" at any point in time is defined by set of "points" connected by "edges." triggered update An unsolicited route update transmitted by an router along a path to a destination. Perkins Expires 17 May 1999 [Page 8] Internet Draft Ad Hoc Network Terminology 17 November 1998 Chair's Address The working group can be contacted via the current chairs: M. Scott Corson Joseph Macker Institute for Systems Research Information Technology Division University of Maryland Naval Research Laboratory College Park, MD 20742 Washington, DC 20375 Phone: +1-301-405-6630 +1-202-767-2001 E-mail: corson@isr.umd.edu macker@itd.nrl.navy.mil Author's Address Questions about this memo can be directed to: Charles E. Perkins Advanced Network Development Sun Microsystems Laboratories 901 San Antonio Rd. Palo Alto, CA 94303 +1-650-786-6464 +1-650-786-6445 charles.perkins@sun.com Perkins Expires 17 May 1999 [Page 9]