Internet Engineering Task Force C. E. 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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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scalability
Wide applicability of a protocol to large as well as small
populations of nodes participating in the protocol.
scenario
The tuple <laydown, pathloss matrix, mobility factor, traffic>
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.
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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.
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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
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