Internet DRAFT - draft-bush-vnc-mib
draft-bush-vnc-mib
Internet Draft Stephen Bush
Expires in June 1997 Sunil Jagannath
<draft-bush-vnc-mib-00.txt> ITTC
January 13, 1997
The Definition of Managed Objects for Virtual Network Configuration
Status of this Memo
This document is a submission by the Information and Telecommunica-
tions Technologies Center (ITTC) at the University of Kansas. Com-
ments should be submitted to sbush@tisl.ukans.edu.
Distribution of this memo is unlimited.
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Abstract
This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in TCP/IP-based internets.
In particular, it describes managed objects used for managing Virtual
Network Configuration (VNC) of the Rapidly Deployable Radio Network
(RDRN) Network Control Protocol (NCP).
The Network Management Framework
The Internet-standard Network Management Framework consists of three
components. They are:
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STD 16/RFC 1155 which defines the SMI, the mechanisms used for
describing and naming objects for the purpose of management. STD
16/RFC 1212 defines a more concise description mechanism, which is
wholly consistent with the SMI.
STD 17/RFC 1213 which defines MIB-II, the core set of managed
objects for the Internet suite of protocols.
STD 15/RFC 1157 which defines the SNMP, the protocol used for net-
work access to managed objects.
The Framework permits new objects to be defined for the purpose of
experimentation and evaluation.
Objects
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. Objects in the MIB are
defined using the subset of Abstract Syntax Notation One (ASN.1) [3]
defined in the SMI. In particular, each object type is named by an
OBJECT IDENTIFIER, an administratively assigned name. The object
type together with an object instance serves to uniquely identify a
specific instantiation of the object. For human convenience, we
often use a textual string, termed the descriptor, to refer to the
object type.
Format of Definitions
Section 5 contains the specification of all object types contained in
this MIB module. The object types are defined using the conventions
defined in the SMI, as amended by the extensions specified in [5,6].
Overview
Network Control Protocol Terminology
This section defines some of the terminology used in the Description
of the Network Control Protocol [11] and [12] operation.
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o "AX.25"
Asynchronous X.25 Protocol (See [1]).
o "Callsign"
The packet radio callsign is assigned by the FCC and
identifies the packet radio operator.
o "Edge Switch" (ES)
A node which either resides within the wireless
network or at the edge of the fixed and
wireless network and which serves as a base station.
o "Global Positioning System" (GPS)
Satellite system which provides location and time.
o "Remote Node" (RN)
A host with the ability to connect via a beamforming
antenna to an edge switch (ES).
Virtual Network Configuration
Virtual Network Configuration (VNC) allows future states of a system
to be predicted and used efficiently. VNC is used for the configura-
tion of a wireless mobile Asynchronous Transfer Mode (ATM) network
known as the Rapidly Deployable Radio Network (RDRN). Configuration
in a mobile network must be a dynamic and continuous process. Fac-
tors such as load, distance, capacity and topology are all constantly
changing in a mobile environment. The VNC algorithm anticipates con-
figuration changes and speeds the reconfiguration process by pre-
computing and caching results. The Global Positioning System (GPS)
is a key element in the implementation of this algorithm because it
provides location information and accurate time for each node. The
effort required to enhance network configuration with Virtual Network
Configuration is minimal. New fields are added to each existing mes-
sage and additional structures are added to existing processes. The
benefit of prediction is gained at the cost of additional traffic and
processing.
Virtual Network Configuration Algorithm
The Virtual Network Configuration (VNC) algorithm is an application
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of a more general mechanism called Time Warp Emulation (TWE). Time
Warp Emulation is a modification of Time Warp. The motivation behind
TWE is to allow the actual components of a real-time system to work
ahead in time in order to predict future behavior and adjust them-
selves when that behavior does not match reality. This is accom-
plished by realizing that there are now two types of false messages,
those which arrive in the past relative to the process's Local Vir-
tual Time (LVT) and those messages which have been generated which
are time-stamped with the current real time, but whose values exceed
some tolerance from the component's current value.
The basic Time Warp mechanism is modified by adding a verification
query phase. This phase occurs when real time matches the receive
time of a message in the output queue of a process. In this phase,
the physical device being emulated in time is queried and the results
compared with the value of the message. A value exceeding a prespeci-
fied tolerance will cause a rollback of the process.
The Virtual Network Configuration (VNC) algorithm can be explained by
an example. A remote node's direction, velocity, bandwidth used,
number of connections, past history and other factors can be used to
approximate a new configuration sometime into the future. All actual
configuration processes can begin to work ahead in time to where the
remote node is expected to be at some point in the future. If the
prediction is incorrect, but not far off, only some processing will
have to be rolled back in time. For example, the beamsteering process
results may have to be adjusted, but the topology and many higher
level requirements will still be correct. Working ahead and rolling
back to adjust for error with reality is an on-going process, which
depends on the tradeoff between allowable risk and amount of process-
ing time allowed into the future.
Virtual Network Configuration Implementation
The effort required to enhance the network configuration algorithm to
include Virtual Network Configuration is minimal. Three new fields
are added to each existing message: antimessage toggle, send time,
and receive time. Physical processes include beamforming, topology
acquisition, table updates, and all processing required for configu-
ration. Each physical process is assigned a tolerance. When the value
of a real message exceeds the tolerance of a predicted message stored
in the send queue, the process is rolled back.
Also, an additional packet type was created for updating an approxi-
mation of the Global Virtual Time (GVT). Because the system is com-
posed of asynchronously executing logical processes, each working
ahead as quickly as possible with its own local notion of time, it is
necessary to calculate the time of the system as a whole. This
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system-wide time is the GVT. The difference between GVT and current
time is the amount of lookahead, Lambda. Although GVT >= t where t is
real time, Lambda is required because it is used to control the effi-
ciency and accuracy of the system. Since the network configuration
system uses a master node as described in the physical layer setup,
this is a natural centralized location for a centralized GVT update
method. RNs transmit their LVT to the master, the master calculates
an approximate GVT and returns the result.
The Rapidly Deployable Radio Network (RDRN) consists of links formed
by beamforming antennas. While beamforming allows improved spectrum
usage through spatial reuse, it poses a challenge to configure. Each
mobile node and base station contains a GPS receiver and is aware of
its current location. This information is shared among nodes and an
optimal topology for beamformed links is determined. The protocol
which carries this information is known as the network control proto-
col (NCP). The NCP is carried over an omni-directional packet radio
overlay network. See reference [8] and [9] for detailed information
about the operation of NCP.
Virtual Network Configuration MIB Overview
A very brief overview of VNC components and operation will be pro-
vided in this section. The VNC algorithm is an extension of opti-
mistic parallel simulation [10] and accomplishes configuration of a
mobile wireless ATM network including handoff. A driving process
injects virtual messages into the VNC system. Virtual messages are
similar to real messages except that they exist in the future and are
thus predictions of future events.
VNC consists of Logical Processes (LP) which communicate via mes-
sages. An LP is comprised of a State Queue, Receive Queue, and Send
Queue. Each LP State has an associated tolerance. If messages arrive
out of order or beyond the given tolerance, a rollback occurs. Roll-
backs produce anti-messages which cancel the effects of causality
violations and inaccurate VNC predictions. The system may contain a
global virtual time calculation (GVT) and global lookahead parameter
(LA). The MIB objects described below manage each of these compo-
nents. The GvtUpdate MIB object manages the rate at which a simple
polling algorithm for GVT calculation is performed. The StepSize
object controls the rate of virtual messages generation from the
driving process.
Definitions
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RDRN-VNC-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, OBJECT-TYPE,
enterprises, Counter32, Integer32, TimeTicks, Unsigned32
FROM SNMPv2-SMI
DisplayString, RowStatus, DateAndTime, TruthValue, TimeStamp,
TAddress
FROM SNMPv2-TC;
RdrnVncMIB MODULE-IDENTITY
ORGANIZATION "KU TISL"
CONTACT-INFO
" Steve Bush
sbush@tisl.ukans.edu"
DESCRIPTION
"Experimental MIB modules for the Rapidly Deployable
Radio Networks (RDRN) Project Network Control
Protocol (NCP) enhanced with the Virtual Network
Configuration."
::= { 1 3 6 1 3 ncp(75) 2 }
vnc OBJECT IDENTIFIER ::= { ncp(75) 2 }
--
-- Logical Process Table
--
logicalProcess OBJECT IDENTIFIER ::= { vnc 1 }
logicalProcessTable OBJECT-TYPE
SYNTAX SEQUENCE OF LogicalProcessEntry
ACCESS read-only
STATUS mandatory
DESCRIPTION
"Table of VNC LP information."
::= { logicalProcess 1 }
logicalProcessEntry OBJECT-TYPE
SYNTAX LogicalProcessEntry
ACCESS read-only
STATUS mandatory
::= { logicalProcessTable 1 }
LogicalProcessEntry ::= SEQUENCE {
logicalProcessID
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DisplayString,
logicalProcessLVT
INTEGER,
logicalProcessQRSize
INTEGER,
logicalProcessQSSize
INTEGER,
logicalProcessRollbacks
INTEGER,
logicalProcessSQSize
INTEGER,
logicalProcessTolerance
INTEGER,
logicalProcessGVT
INTEGER,
logicalProcessLookAhead
INTEGER,
logicalProcessGvtUpdate
INTEGER,
logicalProcessStepSize
INTEGER
}
logicalProcessID OBJECT-TYPE
SYNTAX DisplayString
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The LP identifier."
::= { logicalProcessEntry 1 }
logicalProcessLVT OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is the LP Local Virtual Time."
::= { logicalProcessEntry 2 }
logicalProcessQRSize OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is the LP Receive Queue Size."
::= { logicalProcessEntry 3 }
logicalProcessQSSize OBJECT-TYPE
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SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is the LP send queue size."
::= { logicalProcessEntry 4 }
logicalProcessRollbacks OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is the number of rollbacks this LP has suffered."
::= { logicalProcessEntry 5 }
logicalProcessSQSize OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is the LP state queue size."
::= { logicalProcessEntry 6 }
logicalProcessTolerance OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is the allowable deviation between process's
predicted state and the actual state."
::= { logicalProcessEntry 7 }
logicalProcessGVT OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is this system's notion of Global Virtual Time."
::= { logicalProcessEntry 8 }
logicalProcessLookAhead OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is this system's maximum time into which it can
predict."
::= { logicalProcessEntry 9 }
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logicalProcessGvtUpdate OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is the GVT update rate."
::= { logicalProcessEntry 10 }
logicalProcessStepSize OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This is the time until next virtual message."
::= { logicalProcessEntry 11 }
END
Security Considerations
None.
References
[1] Rose M., and K. McCloghrie, "Structure and Identification of
Management Information for TCP/IP-based internets", STD 16, RFC
1155, Performance Systems International, Hughes LAN Systems, May
1990.
[2] McCloghrie K., and M. Rose, Editors, "Management Information Base
for Network Management of TCP/IP-based internets", STD 17, RFC
1213, Performance Systems International, March 1991.
[3] Information processing systems - Open Systems Interconnection -
Specification of Abstract Syntax Notation One (ASN.1),
International Organization for Standardization, International
[4] Information processing systems - Open Systems Interconnection -
Specification of Basic Encoding Rules for Abstract Notation One
(ASN.1), International Organization for Standardization,
International Standard 8825, December 1987.
[5] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions",
STD 16, RFC 1212, Performance Systems International, Hughes LAN
Systems, March 1991.
[6] Rose, M., Editor, "A Convention for Defining Traps for use with
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the SNMP", RFC 1215, Performance Systems International, March
1991.
[7] McCloghrie, K., "Extensions to the Generic-Interface MIB", RFC
1229, Hughes LAN Systems, Inc., May 1991.
[8] Stephen F. Bush, Sunil Jagannath, Joseph B. Evans, and Victor
Frost, "A Control and Management Network for Wireless ATM
Systems" in Proceedings of the International Communications
Conference '96, p. 459,463 (1996 June). Online version
available at: http://www.tisl.ukans.edu/~sbush/pspapers/icc96.ps
[9] Stephen F. Bush, Sunil Jagannath, Ricardo Sanchez, Joseph B.
Evans, Victor Frost, and K. Sam Shanmugan, Rapidly Deployable
Radio Networks (RDRN) Network Architecture, Telecommunications
Information Sciences Laboratory (1995 July). Online version
available at:
http://www.tisl.ukans.edu/~sbush/pspapers/network_arch.ps
[10] D. R. Jefferson and H. A. Sowizral, Fast Concurrent Simulation
Using The Time Warp Mechanism, Part I: Local Control, pp. 27-53,
The Rand Corporation (1982).
[11] Network Control Protocol for the Configuration of Mobile
Wireless Beamformed GPS-Based Networks,
<draft-bush-ncp-config-00.txt>, Stephen F. Bush, Sunil Jagan-
nath.
[12] The Definition of Managed Objects for the Configuration of
Mobile Wireless Beamformed GPS-Based Networks,
<draft-bush-rdrn-mib-00.txt>, Stephen F. Bush, Sunil Jagannath.
Author's Address
Stephen F. Bush
Sunil Jagannath
Information and Telecommunications Technologies Center (ITTC)
University of Kansas
Lawrence, Kansas 66045
Phone: (913) 864-7761
EMail: sbush@tisl.ukans.edu
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