Internet DRAFT - draft-lee-insignia
draft-lee-insignia
INTERNET-DRAFT Seoung-Bum Lee and Andrew T. Campbell
Columbia University
<draft-lee-insignia-00.txt> November 1998
Expires May 1999
INSIGNIA
Status of this Memo
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 learn the current status of any Internet-Draft, please check the
``1id- abstracts.txt'' listing contained in the Internet- Drafts
Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or
ftp.isi.edu (US West Coast).
Distribution of this memo is unlimited.
Abstract
This document specifies INSIGNIA, an in-band signaling system for
supporting quality of service (QOS) in mobile ad hoc networks. The
term `in-band signaling` refers to the fact that control information
is carried along with data in IP packets. We argue that in-band
signaling is more suitable than explicit out-of-band approaches
(e.g., RSVP) when supporting end-to-end quality of service in highly
dynamic environments such as mobile ad hoc networks where network
topology, node connectivity and end-to-end quality of service are
strongly time-varying. INSIGNIA is designed to support the delivery
of adaptive real-time services and includes fast session/flow/
microflow reservation, restoration and adaptation algorithms
between source/destination pairs. In this memo we discuss how
INSIGNIA fits into our broader vision of a wireless flow management
model for mobile ad hoc networks and how it interfaces to the
proposed MANET Working Group routing algorithms and IMEP
specification.
Lee and Campbell Expires May 1999 [Page 1]
INTERNET DRAFT INSIGNIA November, 1998
Table of Contents
1. INTRODUCTION .................................................. 2
1.1 TERMINOLOGY .............................................. 3
1.2 ASSUMPTIONS .............................................. 5
2. A WIRELESS FOW MANAGEMENT MODEL FOR MOBILE AD HOC NETWORKING .. 5
2.1 PACKET FORWARDING MODULE ................................. 7
2.2 ROUTING MODULE ........................................... 7
2.3 INSIGNIA MODULE .......................................... 7
2.4 ADMISSION CONTROL MODULE ................................. 7
2.5 PACKET SCHEDULING MODULE ................................. 8
2.6 MEDIUM ACCESS CONTROLLER MODULE .......................... 8
3. INSIGNIA PROTOCOL ............................................. 8
3.1 INSIGNIA IP OPTIONS ...................................... 8
3.2 RESERVATION MODE ......................................... 9
3.3 SERVICE TYPE ............................................. 10
3.4 PAYLOAD INDICATOR ........................................ 10
3.5 BANDWIDTH INDICATOR ...................................... 10
3.6 BANDWIDTH REQUEST ........................................ 11
4. INSIGNIA OPERATIONS ........................................... 12
4.1 FLOW SETUP ............................................... 12
4.2 QOS REPORTING ............................................ 14
4.3 SOFT-STATE MANAGEMENT .................................... 15
4.4 FLOW RESTROATION ......................................... 16
4.5 ADAPTATION ............................................... 17
5. INTEROPERABILITY WITH IMEP .................................... 21
6. SECURITY ISSUES ............................................... 21
7. APPLICATION ................................................... 22
8. ACKNOWLEDGMENT ................................................ 22
9. REFERENCE ..................................................... 22
10. AUTHOR'S ADDRESSES ............................................ 24
1. INTRODUCTION
The introduction of real-time audio, video and data services into
mobile ad hoc networks presents number of technical barriers that
are due to the time-varying nature of the network topology, node
connectivity and end-to-end quality of service (QOS). In such
networks, mobile nodes function as hosts and routers. As hosts they
represent source and destination nodes in the network while as
routers they represent intermediate nodes between a source and
Lee and Campbell Expires May 1999 [Page 2]
INTERNET DRAFT INSIGNIA November, 1998
destination providing store-and-forward services to neighboring
nodes. The wireless topology that interconnects mobile hosts/routers
can change rapidly in unpredictable ways or remain relatively static
over long periods of time. Another technical issue that needs to be
addressed is associated with the wireless link level performance.
Mobile ad hoc networks are bandwidth constrained and time-varying
due to radio link characteristics and impairments.
The end-to-end communications abstraction between two communicating
mobile hosts can be viewed as a complex channel. Due to node
mobility and wireless link impairments, user-to-user sessions may
need to be rerouted in the network while preserving the session
connectivity and quality. Network algorithms need to be strongly
adaptive and responsive to the time-varying and location dependent
topological changes, resource availability, quality of service
degradation and session connectivity.
In order to provide adaptive quality of service support for real-
time service in mobile ad hoc networks, 'flow-states' (i.e.,
reservation states at nodes associated with flows or microflows)
need to be managed. A flow needs to be established, restored,
adapted and removed over the course of a user-to-user session in
response to time-varying topology, connectivity and end-to-end
quality of service conditions.
Since wireless and computational resources are limited in mobile ad
hoc networks, any signaling overhead needed for wireless flow
management must be kept to a bare minimum. Future signaling systems
should be capable of restoring reservations and associated flow-
states along a new path in response to topological changes with
minimum noticeable degradation at the user session level.
This memo provides an overview of wireless flow management model
that supports the delivery of adaptive real-time services in dynamic
mobile ad hoc networks. A key component of wireless flow management
is INSIGNIA, an in-band signaling system that supports fast flow
reservation, restoration and adaptation algorithms that are
specifically designed to deliver adaptive real-time services in
mobile ad hoc networking environments. INSIGNIA is designed to be
lightweight and highly responsive to changes in network topology,
node connectivity and end-to-end quality of service conditions.
1.1 TERMINOLOGY
Mobile Ad Hoc Networks:
Represent autonomous distributed systems that comprise a
number of mobile nodes connected by wireless links forming
arbitrary time-varying wireless network topologies [20].
Lee and Campbell Expires May 1999 [Page 3]
INTERNET DRAFT INSIGNIA November, 1998
Adaptive real-time flows:
This type of flow represents delay sensitive traffic, e.g., voice
and video which can sustain some loss. Real time data flows are
assumed to be somewhat loss tolerant and delay sensitive.
These types of flows typically require flow setup procedures,
resource reservation provided by INSIGNIA.
Microflows:
Micro flows represent short-lived flows, e.g. web style
client/server interactions that comprises a limited train of data
packets. These types of flows may require resource assurances in
the network and, therefore, typically require some form of in-
band support for fast resource allocation. We use the terms
session/flow and microflow interchangeably. INSIGNIA has been
designed to transparently support the requirements of both flows
and microflows in mobile ad hoc networks.
Flow Setup:
A Source initiates a flow set up by transmitting a request packet
with its minimum and maximum bandwidth requirements. Intermediate
mobiles receiving request packets, processes the requests and
forward them to the next appropriate mobile host. A flow setup is
complete when a source receives a QOS report from its peer
destination.
Restoration:
When a reserved flow is rerouted and its associated states
(e.g., reservation) are successfully created along the new route.
Three types of restoration (viz. `max to max`, `max to min` and
`min to max`) may be observed along the new path.
Enhancement Layer (EL) Degradation:
When a reserved flow is rerouted and its EL restoration fails,
then a flow/sessions enhancement layer packets are degraded
to best effort service. In a such case, only base layer (BL)
packets are forwarded/received as reserved packets.
Flow Degradation:
When a reserved flow is rerouted and both EL and BL restoration
fails. No resource allocation or associated states are created
and all packets are treated as best effort after re-routing.
Adaptation:
When EL degradation persists for an unacceptable period, a
destination mobile notifies its source to drop the EL packets
at the source host (scaling down). The destination can also
initiates an EL resource recovery (scaling up) procedure when a
monitored flow state at the destination indicate that sufficient
resources exist along the path to support a better quality level.
Lee and Campbell Expires May 1999 [Page 4]
INTERNET DRAFT INSIGNIA November, 1998
Adaptation Policy:
Describes the bandwidth adaptation characteristics of a flow and
the actions to be taken based on the observed network conditions
experienced by a flow and its ability to adapt to those
conditions. The decision to trigger adaptation mechanisms (i.e.,
scaling flows up/down)is based on application-specific adaptation
policy.
Adaptation Handler:
A module that stores the adaptation policy that interacts with
flow monitoring and QOS report modules.
Monitoring Module:
A module that keeps track of the incoming INSIGNIA flow state.
Typically the packet type, resource availability and QOS
are periodically monitored.
QOS reports:
These are periodic messages that are generated by destinations
to inform peer sources of reception state/status of adaptive
real-time flows. The periodicity depends on the sensitivity of a
flow. Best effort flows do not, typically, generate QOS reports.
Soft-state management:
Each mobile host creates, stores and updates the state
information for each adaptive real-time flow and its reservation
status. This state information requires subsequent packets to
refresh the flow state otherwise the flow state is considered old
and automatically removed after a soft-state interval.
Soft-state timer:
The soft-state timer value defines the holding time for real-time
reservation state for adaptive real-time flows/flows. If the
mobile soft-state is not refreshed within the soft-state timer
interval then the state is automatically removed. (Note that the
treatment of flows and microflows may differ in terms of the
setting of this state variable. Typically, flows would call for
extremely fast reservation and release that may be more aggressive
than the dynamics and timescales associated with longer lived
flows. This issue is under experimentation and for further study.)
1.2 ASSUMPTIONS
INSIGNIA assumes that link status sensing and access schemes are
provided by lower layer entities/protocols.
2. A WIRELESS FLOW MANAGEMENT MODEL FOR MOBILE AD HOC NETWORKING
The goal of wireless flow management is to support the delivery of
adaptive real-time services in mobile ad hoc hosts under time-
Lee and Campbell Expires May 1999 [Page 5]
INTERNET DRAFT INSIGNIA November, 1998
varying conditions. An adaptive service model allows packet audio,
video and real-time data applications to specify their maximum and
minimum bandwidth needs. INSIGNIA plays a central role in the
resources allocation and management between source and destination
mobiles. Based on availability of end-to-end resources, wireless
flow management attempts to provide assurances for the minimum or
maximum bandwidth needs depending of resource availability. In
addition to supporting adaptive real-time services the service model
also supports IP best-effort packet delivery.
adaptive mobile
applications
^
+--------------------------------------------------------------+
| | |
| +---------------+ | +-----------------+ +-----------+ |
| | MANET routing | | | INSIGNIA |<---> | admission | |
| | protocol | | | | | control | |
| +---------------+ | +-----------------+ +-----------+ |
| | \ | | | | | |
| | \ | | | control | |
| --------- \ | | --------- | --------- |
| routing \ | | mobile | channel |
| table \ | | soft-state | state |
| --------- \ | | --------- | --------- |
| \ \ | signal / \ | packet / \ |
| \ \ v -ing / \ | drop / \ |
| \ +------------+ +-----------+ \ |
| +-----+ \| packet | | packet | +-----+ |
===>| MAC |===>| forwarding |======>| scheduling|====>| MAC |===>
| +-----+ +------------+ +-----------+ +-----+ |
|IP packet in data packets IP packet out|
+--------------------------------------------------------------+
Figure 1. Wireless Flow Management Model at a Mobile Host/Router
Realizing wireless flow management in mobile ad hoc networks
presents a number of technical challenges. First, flows and
microflows should be rapidly established without the penalty of a
round trip delay and with minimal overhead due to signaling. Second,
active flows should be maintained and restored in case of routing
changes or link failure. Wireless flow management should be capable
of rapidly responding to dynamic topology changes by adapting and
re-establishing affected flows with minimal service disruption.
Third, flow-state set up during flow establishment should be
automatically removed when an application session terminates. Flow-
state should also be automatically removed at routers no longer on
Lee and Campbell Expires May 1999 [Page 6]
INTERNET DRAFT INSIGNIA November, 1998
the new path after re-routing has occurred due to topological
changes.
The main modules of the wireless flow management model are
illustrated in Figure 1).
2.1 PACKET FORWARDING MODULE
The packet forwarding module [15] classifies incoming packets
and forwards them to the appropriate module (viz. MANET routing,
INSIGNIA, local applications, wireless packet scheduling modules).
Signaling messages are processed by INSIGNIA and data packets
delivered locally or forwarded to the packet scheduling module.
2.2 ROUTING MODULE
The routing module dynamically tracks changes in ad hoc network
topology making the routing table visible (via APIs) to all
intermediate packet forwarding module (e.g., INSIGNIA, packet
forwarding). Wireless flow management assumes the availability of
MANET routing protocol [2] (e.g. Temporally Ordered Routing
Algorithm (TORA) [1], Dynamic Source Routing [7], Zone Routing
Protocol [5], Ad Hoc On demand Distance Vector Routing Protocol
[6]).
2.3 INSIGNIA MODULE
The INSIGNIA module establishes, restores, adapts and tears down
real-time flows. Flow restoration algorithms respond to dynamic
route changes due to mobility. Adaptation algorithms respond to
changes in available bandwidth. Based on an in-band signaling
approach that explicitly carries control information in the IP
packet header, flows can be rapidly established, restored, adapted
and released in response wireless impairments and topology changes.
Because of this dynamic environment, network state management is
based on soft-state [3], which is well suited to managing
reservation flow-state in mobile ad hoc networks.
2.4 ADMISSION CONTROL MODULE
The admission control module is responsible for allocating bandwidth
to flows based on the maximum/minimum bandwidth requested. Once
resources have been allocated they are periodically refreshed by a
mobile soft-state mechanism through the reception of data packets.
Admission control testing is based on the measured channel
capacity/utilization and requested bandwidth. To keep the protocol
simple and lightweight, new reservation requests do not affect
existing flow reservations. Rerouted or new flows may be degraded if
resources are unavailable.
Lee and Campbell Expires May 1999 [Page 7]
INTERNET DRAFT INSIGNIA November, 1998
2.5 PACKET SCHEDULING MODULE
The packet scheduling module responds to location dependent channel
conditions experienced in wireless networks [22]. The scheduling
mechanism is implementation and QOS model dependent. Currently, we
have implemented a simple Weighted Round-Robin (WRR) service
discipline which takes location dependent channel conditions into
account. It should be noted that a wide variety of scheduling
disciplines can be used to realize the packet scheduling module.
2.6 MEDIUM ACCESS CONTROLLER MODULE
The medium access controller module (possibly) provides quality of
service driven access to the shared wireless media for adaptive
real-time services and best-effort services. The wireless flow
management is designed to be transparent to any underlying media
access control protocols. However, the performance of the MANET is
strongly coupled to the provisioning of QOS support at the MAC
layer. Nevertheless, our approach is to investigate the performance
of INSIGNIA using both non QOS-capable and QOS-capable MACs.
3. INSIGNIA PROTOCOL
Mobile ad hoc signaling systems should be lightweight in terms of
the amount of bandwidth they consume and be capable of reacting to
fast network dynamics close to call/session and packet transmission
time scales. Future signaling systems should be highly responsive to
flow re-routing and be capable of re-establishing active
reservations along the new path with minimum disruption to on-going
services.
In-band signaling systems are capable of operating close to packet
transmission time scales and are therefore well suited toward
managing fast time-scale dynamics found in mobile ad hoc
environments. In contrast, out-of-band signaling systems (e.g.
Internet's RSVP, ATM's UNI, etc.) are incapable of responding to
such fast time-scale dynamics. Based on an in-band approach,
INSIGNIA is designed to restore 'flow-state' (i.e., a reservation)
in response to topology changes within the interval of two
consecutive IP packets under ideal conditions.
3.1 IP OPTIONS
To establish an adaptive real-time flows, INSIGNIA uses a new IP
option to setup, restore and adapt resources between source-
destination pairs. When intermediate nodes receive packets with the
these IP options set they attempt to reserve, restore or adapt
resources forwarding date packets toward the destination.
By coding control information in the INSIGNIA IP option (in each IP
Lee and Campbell Expires May 1999 [Page 8]
INTERNET DRAFT INSIGNIA November, 1998
header), we support the notion of in-band control which we believe
is called for to support QOS in ad-hoc mobile networks. The INSIGNIA
IP option supports flow reservation, restoration and adaptation
control. Best effort and adaptive real-time services are supported
by INSIGNIA and are indicated by the reservation mode and service
type fields in the IP options as illustrated in Figure 2. Flows are
represented as having a discrete base layer (BL) with a minimum
bandwidth and an enhancement layer, which requires the maximum
bandwidth. This characterization is commonly used for multi-
resolution traffic (e.g., MPEG audio and video) and more generally
for real-time data that has discrete max-min requirements.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| IHL |Type of Service| Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |Flags| Fragment Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time to Live | Protocol | Header Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options (Used for INSIGNIA IP Options) | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2a. IP Header
reservation payload bandwidth request
mode indicator
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
+-------+-----+-----+-------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|REQ/RES|RT/BE|BL/EL|max/min| max_bandwidth | min_bandwidth |
+-------+-----+-----+-------+---------------+---------------+
service bandwidth
type indicator
|<----->|<--->|<--->|<----->|<----------------------------->|
1 bit 1 bit 1 bit 1 bit 16 bits
Figure 2b. INSIGNIA IP Options
3.2 RERSERVATION MODE
To establish an adaptive real-time flow, a source node sets the
request (REQ) bit in the IP option of a data packet to initiate a
reservation request. On reception of a REQ packet, the intermediate
nodes execute admission control and accept or deny the request. If
the request is accepted, resources are committed and subsequent
Lee and Campbell Expires May 1999 [Page 9]
INTERNET DRAFT INSIGNIA November, 1998
packets are scheduled accordingly. Otherwise, packets are treated as
best effort packets if resources are unavailable.
Packets that are received by nodes with their reservation mode set
to reserved (RES) indicate that the session has previously passed
admission control and resources have been reserved. In the case
where a RES packet is received and no resources have been allocated
the admission controller immediately attempts to make a reservation.
This condition commonly occurs when reserved flows are rerouted
during the lifetime of an active session due to mobility of sources,
intermediate router nodes or destinations.
3.3 SERVICE TYPE
The interpretation of the service type, which indicates either a
real-time (RT) or best-effort (BE) packet, is dependent on the
reservation mode. A packet with the reservation mode set to REQ and
service type to RT is attempting to setup a real-time flow with the
bandwidth requirements of the flow specified in the bandwidth
request field. A packet with RES/RT set indicates that an end-to-end
reservation has previously been established. A RES/RT packet service
may be degraded to RES/BE service if the flow is rerouted along a
new path when insufficient resources were available on the new path.
A best effort packet sets the reservation mode to REQ as default and
the service type to BE requiring no resource reservation to be made
in the network. Reception of a RES/BE by a destination node
indicates an active adaptive real-time flow was degraded to BE due
to insufficient resource availability after rerouting to a new path.
3.4 PAYLOAD INDICATOR
The payload field indicates the type of packet being transported.
INSIGNIA supports two types of payload, i.e., base (BL) and
enhancement layers (EL). The semantics of the adaptive real-time
services are related to the payload type and resource availability.
Base and enhancement layers can be assured via distributed end-to-
end admission control and resource reservation. Maximum bandwidth
reservation is required to support both base and enhancement layers
of a flow whereas only minimum bandwidth reservation is required to
support the base layer. When a flow with minimum reservation
receives a EL packet in reserved mode (RES/RT) set, it indicates
either the reservations for EL has been restored at the bottleneck
node or an adaptation (scale-up) has been occurred.
3.5 BANDWIDTH INDICATOR
The bandwidth indicator represents the potential resource
availability for a flow/session along its current path between a
source and destination pair. In this respect the bandwidth indicator
represents the prospective resource availability to an application
Lee and Campbell Expires May 1999 [Page 10]
INTERNET DRAFT INSIGNIA November, 1998
which will change over time. This does not, however, represent an
actual resource reservation but the potential for one to succeed
give the current indication. The bandwidth indicator is carried in
each packet and can be therefore viewed as a dynamic state variable
that can be updated by any mobile host on the current path. Based on
its value it represents a good bandwidth hint that resources are
available along the current path to meet the flows minimum or
maximum needs. In this capacity the bandwidth indicator plays an
important role during the flow setup phase and, more importantly,
during the adaptation phase.
During flow setup the bandwidth indicator represents the resource
availability along the chosen setup route. Reception of setup
request packets with the bandwidth indicator bit set to MAX
indicates that all nodes en-route have sufficient resources to
support the maximum bandwidth requested. In contrast, a packet with
the bandwidth indicator set to MIN implies that at least one of the
intermediate nodes (known as the bottlenecked mobile host) between
the source and destination has insufficient bandwidth resources to
meet the maximum needs (if specified); however, reception of a
packet with the bandwidth indicator set to MIN does indicate that
all nodes can support the minimum bandwidth requirement. In this
case, only the base layer reservation is acknowledged as having
been successful established via QOS reporting (see Section 4.2). QOS
reporting between the destination and source can be used to force
the source to 'drop' enhancement layers. In this case the source
would only forward the BL packets toward the destination in reserved
mode. Any enhancement layer packets would be forwarded as best-
effort packets. This action has the benefit of releasing an 'partial
reservations' for the enhancement layer that may exist between a
bottlenecked mobile host and the destination. We will discuss the
issue of 'partial reservations' (which may occur in all phases of
INSIGNIA operation)in the sections of flow setup, restoration and
adaptation.
The bandwidth indicator is also utilized for restoring the
reservation for EL if previously degraded to best effort service.
In order to accomplish scaling up adaptation, the adaptation
handler resident at destination should monitors a flow's resource
availability (by monitoring the bandwidth indicator)
and, based on the adaptation policy, initiate a 'scale up' operation
using a QOS report.
3.6 BANDWIDTH REQUEST
The bandwidth request allows a source to specify its maximum (MAX)
and minimum (MIN) bandwidth requirements for adaptive real-time
service support. This assumes that the source has selected the RT
service type. A source may also simply specify a minimum or a
maximum bandwidth requirement. For adaptive real-time services the
base layer is supported by the MIN bandwidth whereas the MAX
Lee and Campbell Expires May 1999 [Page 11]
INTERNET DRAFT INSIGNIA November, 1998
bandwidth supports the delivery of the base and enhancement layers
between a source and destination pair.
4. INSIGNIA OPERATIONS
The IP option and operations support the delivery of adaptive real-
time services to mobile hosts. These operations collectively define
the foundation of the INSIGNIA system and include flow setup, flow
restoration, soft-state management, adaptation and QOS reporting.
Once a flow has been established between a source-destination pair,
QOS reports are used to inform the source of the progress of the
delivered packet quality at the destination. Node mobility may
trigger topology changes. In this case the MANET routing protocol
may provide alternative or new path information to destination,
in which case, INSIGNIA would attempt to restore reservations at all
nodes on the new path through the restoration operation. Moreover,
adaptation may be triggered to adjust a flow to match resources
availability found on the new path. Managing the network state,
while responding to these network dynamics, is handled by a soft-
state management mechanism in INSIGNIA. In the following sections,
each of the INSIGNIA operations are outlined.
4.1 FLOW SETUP
To establish adaptive real-time flows, source nodes set the
appropriate fields in the IP option before forwarding 'reservation
request' packets toward destination mobile hosts. A reservation
request packet is characterized as having its reservation mode set
to REQ, service type set to RT, a valid payload (viz. BL or EL) and
a MAX/MIN bandwidth requirement.
Reservation packets traverse intermediate nodes executing admission
control modules, allocating resources and establishing flow-state at
all nodes between source-destination pairs. If any intermediate
mobile node lacks resources to support the requested flow setup, the
appropriate IP option field is changed to indicate this condition
(or state).
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
+---+----+-----+-------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|REQ| RT |BL/EL|max/min| max_bandwidth | min_bandwidth |
+---+----+-----+-------+---------------+---------------+
Figure 3. INSIGNIA Packet Requesting MAX/MIN reservation
If an intermediate mobile receives a request packet and can only
support the minimum requirement then the flow request is degraded to
the minimum request at the bottleneck mobile node by resetting the
Lee and Campbell Expires May 1999 [Page 12]
INTERNET DRAFT INSIGNIA November, 1998
bandwidth indicator to MIN. Meanwhile the source continues to send
reservation requests packets until the destination informs it of the
status of flow establishment phase via QOS report (discussed in
Section 4.2). Subsequent reservation request packets do not execute
admission control but simply refresh existing soft-state
reservation.
The establishment of an adaptive real-time flow is illustrated in
Figure 4. A source mobile host (M1) issues a flow setup by
requesting resource reservation. M2 performs admission control upon
reception of the request packet. Resources are allocated if
available and the request packet is forwarded to the next mobile
(M3). This process is repeated hop by hop until the request packet
reaches the destination mobile host (M6). The destination mobile
node determines the resource allocation status by checking the
service type and current level of service.
When a reservation request is received at the destination node, the
INSIGNIA module checks the reservation status. The status of the
flow setup is determined by inspecting the bandwidth indication
field. If the bandwidth indicator is set to MAX then this implies
that all mobile hosts between the source destination have
successfully allocated resources to meet the base and enhancement
layers bandwidth requirements. On the other hand, a bandwidth
indication set to MIN indicates that only the base layer can be
currently supported. In this case, all reserved packets with a
payload of EL received at the destination have their service level
flipped from RT to BE by the bottleneck node. In such case, a
partial reservation may exist between the source and bottleneck
mobile node. This partial reservation can be viewed as a waste of
resources between the source and bottlenecked node (since they go
unused) or, as a 'near reservation' where all but the remaining
nodes (between the bottlenecked node and the destination) hold
reservations. Holding on to these reservations - in effect locking
them in - is a 'hedge' against completing the setup phase in the
near future. The treatment of 'partial reservations' is still under
consideration. Currently, the adaptation process allows the mobile
host to clear partial reservations using the adaptation process or
leave them in place.
+----+ +----+
QOS_REPORT(2)| M9 |---| M8 |\QOS_REPORT(2)
+----+ /+----+ +----+ \ +----+
| M2 |/ / \| M7 |\QOS_REPORT(2)
REQ(1)/+----+\ / +----+ \+----+
+----+/ \ +----+/ +----+ | M6 |
| M1 | REQ(1)\| M3 |---| M4 |REQ(1) /+----+
+----+ +----+ +----+\ +----+/
REQ(1) \| M5 | REQ(1)
+----+
Figure 4. INSIGNIA Request Packet and QOS report
Lee and Campbell Expires May 1999 [Page 13]
INTERNET DRAFT INSIGNIA November, 1998
4.2 QOS REPORTING
QOS reports are used to inform the source of the status of received
adaptive real-time flows. Destination nodes actively monitor on-
going flows inspecting status information (e.g., bandwidth
indication) and calculating QOS statistics (viz. packet loss, delay,
out-of-sequence delivery and throughput). QOS reports are
periodically sent to source host for the purpose of completing flow
establishment and managing adaptations. QOS reporting is application
dependent where the periodicity of reports is determined by the
application's sensitivity to the delivered QOS. Note that QOS
reports do not have to travel on the reverse path toward the source.
Typically they will take an alternate route through the ad hoc
network as illustrated in Figure 4.
In the case of flow establishment, reception of a reservation
request packet with the bandwidth indicator set to MAX (or MIN)
indicates that the source's maximum (minimum) reservation has been
successfully made en-route. The destination informs the source of
this reservation status by setting the bandwidth indicator field
with MAX (MIN) in the QOS report, accordingly. The QOS report is a
best effort data packet with a payload that comprises of a 'mirror
copy' of the INSIGNIA IP option received by the destination,
adaptation commands and measured QOS information.
QOS reports are also used as part of on-going adaptation process
that responds to mobility and resources changes in the mobile ad hoc
network. Periodic QOS reports can be used to inform the source to
'drop' (e.g., drop all EL packets) or 'scale-up' (i.e., transmit EL
packets) based on available resources and the adaptation policy of
the application. These are the 'adaptation commands'.
4.2.1 QOS REPORT INTERVAL
Since each flow has different sensitivity to QOS, the periodicity of
QOS report for each flow should reflect this sensitivity. A flow
that is sensitive to service quality requires more frequent QOS
report than one that is less sensitive (i.e., more QOS control). A
source relates the sensitivity of a flow via setting the TTL value
with relatively small value. The destination utilizes the TTL value,
requested bandwidth and the adaptation policy to determine the
flow's sensitivity to service quality. We are currently
investigating the migration of this function to the INSIGNIA IP
options field.
4.2.2 QOS PACKET FORMAT
The role of the QOS report is to serve as a simple notification of
the satisfaction level perceived by the destination. The QOS report
includes a 'mirror copy' of the INSIGNIA IP option, adaptation
commands and measured QOS. In fact, the QOS report of INSIGNIA has
Lee and Campbell Expires May 1999 [Page 14]
INTERNET DRAFT INSIGNIA November, 1998
the same format as a best effort INSIGNIA data packet. A QOS report
has the reservation mode set to RES and service type set to BE. The
minimum bandwidth field is set to zeros and maximum bandwidth is set
to ones. By doing so, the QOS report can be distinguished from the
degraded RES packet. The various packet formats are illustrated in
Figure 8.
4.2.3 QOS REPORT DELIVERY
QOS reports should be delivered in a timely fashion. We propose to
schedule QOS reports before the transmission of best effort packets
but without affecting the performance of reserved flows. The IP
option codepoint for QOS reports, even though best effort in
service type, set it a side from all other best effort traffic for a
'better than best effort treatment' at intermediate nodes.
4.3 SOFT-STATE MANAGEMENT
Maintaining the quality of service of real time flows in mobile ad
hoc network is one of the most challenging aspects that INSIGNIA
addresses. Typically, wireline networks requires little QOS or
state management where the routes and the reservations remain fixed
for the duration of the session/flows. This style of 'hard-state'
connection oriented communications guarantees quality of service for
the duration of the holding time. However, these techniques are not
applicable/valid in mobile ad hoc networks where paths and
reservations need to dynamically respond to topology changes in a
timely manner over multiple time scales and network dynamics.
Based on the work by Clark [3], 'mobile soft-state' relies on the
fact that sources periodically send data messages along the existing
path. If a data packet arrives at a mobile router and no reservation
exists then admission control and resource reservations are needed
to establish soft-state reservations. Subsequent reception of a data
packet at a router is used to refresh the soft-state reservation.
Thus a mobile host receiving a data packet for an existing
reservation reconfirms the reservation over the next time interval.
The holding-time for a reservation is based on a soft-state timer
interval and not, as in the case of call setup, based on the session
duration holding time. If a new packet is not received within a
soft-state timer interval, resources are released and flow-states
removed automatically without any explicit tear-down messaging.
The soft-state approach is well suited for management of resources
in dynamic environment where the path and reservation associated
with a flow may change rapidly. The transmission of data packets is
strongly coupled to maintenance of flow-states, i.e., reservations.
As the route changes in the network, new reservations will be
automatically restored by the restoration mechanism provided that
resources are available along the new path.
Lee and Campbell Expires May 1999 [Page 15]
INTERNET DRAFT INSIGNIA November, 1998
Another benefit of mobile soft-state is that resources allocated
during flow establishment are automatically removed when the path
changes without any explicit signaling interactions. In-band
approaches are flexible and scalable in dealing with a number of
difficult mobile ad hoc network issues whereas out-of-band signaling
systems need to maintain source route information and respond to
topology changes by directly signaling 'affected mobiles' to
allocate or free radio resources. In some case, this is impossible
to do when using out-of-band signaling techniques if the 'affected
router' is out of radio contact from the signaling entity that is
attempting to de-allocate resources over the old path.
4.4 FLOW RESTORATION
Flows are often rerouted during the lifetime of sessions due to
mobility in mobile ad hoc networks. The goal of flow restoration is
to re-establish reservation as fast and efficiently as possible.
Rerouting of an active flow involves new admission control and
resource reservations for nodes on the new path. Restoration
procedures also call for the removal of flow-state at nodes along
the old path. In an ideal case, the restoration of flows can be
accomplished within the duration of a few consecutive packets
because of the in-band nature of INSIGNIA's control.
When a mobile moves out of radio contact and loses connectivity,
the forwarding router mobile interacts with the routing module and
forwards subsequent packets via the new route. (Note that if the
routing table does not have an alternative route toward the
destination then the performance of the restoration process is
tightly coupled to the performance of the proactive/reactive MANET
routing protocol that is operational. This issue is for further
study. In [25], however, we implemented INSIGNIA in a mid size ad
hoc network using TORA [1] as the routing protocol and discuss
performance issues there).
The mobile hosts on a new path receive rerouted packets and inspect
their flow state tables. If a reservation does not exist for the
rerouted flow then the INSIGNIA module invokes admission control and
tries to allocate resources. Note that, if the reserved packets are
routed back on to the existing path then the old states are likely
to be still valid; hence, the states and reservations are simply
refreshed, minimizing any service disruption due to re-rerouting.
Network dynamics may also trigger rerouting with service
degradation. When a reserved flow is rerouted to a node where
resources are unavailable, the flow is degraded to best effort
service. Subsequent downstream nodes receiving these degraded
packets make no attempt to attempt to allocate resources or refresh
existing soft-state associated with the flow. This results in the
automatic removal of any reservation state. In time the reservation
may be restored if resources free up at the bottleneck mobile node
Lee and Campbell Expires May 1999 [Page 16]
INTERNET DRAFT INSIGNIA November, 1998
or because of the subsequent rerouting allowing the complete
restoration of the flow quality. The worst case scenario is that the
flow will remain degraded for the duration of the session holding
time.
The enhancement layer of a reserved flow with maximum reservation
may get degraded during flow restoration if the nodes along the new
path can only support the minimum bandwidth requirement. If the
degradation of enhancement layer packets persist, it may cause
service disruptions and may trigger the destination mobile to invoke
an adaptation procedure that force the source node to drop the EL
packets. Adaptation details are provided in the following section.
4.5 ADAPTATION
Reception quality of a flow is monitored and based on an
application-specific adaptation policy, actions may be taken to
adapt the flow to observed network conditions. Actions taken are
conditional on the adaptation-policy resident at the destination
node, e.g., adaptation policy may chose to maintain the service
level under degraded conditions or scale-down flows to their base
layers in respond to degraded conditions. Other policy could scale-
up flows whenever resources become available. The application is
free to program its own adaptation policy that is executed by
INSIGNIA through interaction between the destination and
source nodes. Details about the adaptation policy API are described
in [19].
The adaptation process includes the following adaptation actions:
(1) 'EL degradation' is a network driven action that forwards the
EL packets as best effort packets due to lack of resources;
(2) 'Drop enhancement layer' is a destination mobile driven action
which requests a source to drop its enhancement layers. This
happens when the EL degradation persists beyond an acceptable
period; and
(3) 'Scale-up', which requests a source to send its base and/or
enhancement layers in reserved mode. This event occurs when
a flow has only minimum reservation and the destination
learns (through the bandwidth indicator) that the route
can accommodate the maximum resource requirement.
The EL degradation is a network driven action whereas the others two
actions are driven by an adaptation handler resident at the
destination mobile host. Typically, the EL degradation can be
observed after rerouting of an adaptive real-time flow. In such an
event the EL packets are degraded and forwarded as best effort
packets whereas BL packets are forwarded in reserved mode. Note that
preference is given to base layers over enhancement layers in the
event that reserved packets have to be degraded to best effort.
Lee and Campbell Expires May 1999 [Page 17]
INTERNET DRAFT INSIGNIA November, 1998
If the EL degradation persists, a `drop` command may be issued by
the adaptation handler at the destination mobile host according to
the adaptation policy. The decision to drop the EL packets is
facilitated by monitoring the incoming packets. The destination
mobile can readily detect the degraded RES packets by reading the IP
option fields (where the degraded packets have the format of Figure
5d). Figure 5 illustrates the different modes of INSIGNIA packets.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
+---+----+-----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|REQ| BE |BL/EL| max | max_bandwidth | min_bandwidth |
+---+----+-----+-----+---------------+---------------+
Figure 5a. A Best Effort Packet
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
+---+----+-----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|REQ| RT |BL/EL| max | max_bandwidth | min_bandwidth |
+---+----+-----+-----+---------------+---------------+
Figure 5b. A Request Packet (EL or BL)
+---+----+-----+-------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| RT |BL/EL|max/min| max_bandwidth | min_bandwidth |
+---+----+-----+-------+---------------+---------------+
Figure 5c. Typical Reserved (RES) Packet (EL or BL)
+---+----+-----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| BE |BL/EL| max | max_bandwidth | min_bandwidth |
+---+----+-----+-----+---------------+---------------+
Figure 5d. A Degraded RES Packet (EL or BL)
+---+----+----+-------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| BE | BL |max/min|1 1 1 1 1 1 1 1|0 0 0 0 0 0 0 0|
+---+----+----+-------+---------------+---------------+
|<----------->| |<----- unique format --------->|
a QOS report
* max/min indicates the accepted service level
Figure 5e. Format of a QOS report
'Dropping' the EL packet at the source removes partial reservations
that may exist between a source and bottleneck mobile freeing up
resources for other adaptive real-time flows to utilize. It also
removes degraded enhancement layer packets from the network which in
turn benefits the normal best effort service flows.
INSIGNIA is also equipped with capability to restore the reservation
needed for enhancement layers. This process takes advantage of
network and session dynamics allowing existing sessions to take
advantages of resources released due to re-routing (e.g., resources
released along an old path) or session termination. These events may
Lee and Campbell Expires May 1999 [Page 18]
INTERNET DRAFT INSIGNIA November, 1998
allow other mobile nodes to take advantage of released resources by
scaling up. The bandwidth indicator plays a key role in 'reading'
the channels resource availability state in relation to the
bandwidth needs of the particular session/flow.
Typically, the scale-up process is invoked when the destination
observes sufficient resource have become available along the
existing path restore the reservation of an enhancement layer. The
decision to scale up is determined by the adaptation policy.
The following example scenario shows an example of a set of
states (marked [1] through [7]) observed at the destination
illustrating a flow adaptation scenario:
Adaptation Procedures :
[1] Incoming Packets at time t1 with maximum resource allocation
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| RT | BL | max | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| RT | EL | max | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
.
.
.
[2] EL packets are degraded due to lack of resources at an
intermediate mobile node at time t2 and now packet formats become
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| RT | BL | min | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| BE | EL | min | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
* Note that EL packet is degraded to a best effort packet
.
.
.
[3] If the degraded EL packets are determined to be not useful for
destination mobile host, an EL drop command is issued via QOS
report. Upon reception of the QOS report the source transmits only
BL packets in reserved mode and do not transmit any EL packets.
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| RT | BL | min | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
* EL packets are not transmitted/received
.
.
.
Lee and Campbell Expires May 1999 [Page 19]
INTERNET DRAFT INSIGNIA November, 1998
[4] Constant resource availability is detected through the bandwidth
indicator at t4 where the received packets indicating the resource
availability have the following format.
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| RT | BL | max | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
* Currently no EL packets are received.
* Destination learns from the bandwidth indicator bit (set to max)
that the current route has the resources available to restore the
EL packet flow.
.
.
.
[5] Through the next QOS report destination informs the source to
reinitiate the transmission on EL in RES mode. If the recovery
(scale up) is successful, destination receives the following
packets.
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| RT | BL | max | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| BE | EL | max | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
.
.
.
[6] If scale up attempt fails at any mobile node on the route,
destination receives degraded EL packets.
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| RT | BL | min | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
+---+----+----+-----+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RES| BE | EL | min | max_bandwidth | min_bandwidth |
+---+----+----+-----+---------------+---------------+
[7] If the EL degradation persist after step [6], another drop EL
command is issued via following QOS report.
The decision to drop/scale up is entirely up to the application-
specific adaptation policy residing at destination mobile. For
example a video flow may be sensitive to delays and delivery of
constantly changing bandwidth so once enhancement layer packets are
dropped, it requires stable resource availability of resources
before a scale up decision is made. In the case of real-time data,
there may not be any drop command and the application may want to
closely follow the dynamics of resource availability. In such case
the adaptation policy is quite different from that of a video flow
example.
Lee and Campbell Expires May 1999 [Page 20]
INTERNET DRAFT INSIGNIA November, 1998
5. NETWORK LAYER FUNCTIONALITY - INTEROPERABILITY WITH IMEP
Since Internet MANET Encapsulation Protocol is a network layer
protocol designed to support the operation of many routing
algorithms and any other higher layer protocols intended for use in
mobile ad hoc networks, INSIGNIA can be fully incorporated with IMEP
mechanisms. IMEP will provide mechanisms for supporting link status
and neighbor connectivity sensing, lower layer control packet
aggregation and encapsulation, one-hop neighbor broadcast (or
multicast) reliability, multi-point relaying, network-layer address
resolution and provides hooks for inter-router authentication
procedures.
IMEP [18] improves overall network performance by reducing the
number of network control message broadcasts through encapsulation
and aggregation of multiple MANET control messages (e.g. routing
protocol packets, acknowledgements, link status sensing messages,
network-level address resolution, etc.) into larger IMEP messages.
Usage of the IMEP is desirable because per-message, multiple access
delay in contention-based schemes such as CSMA/CA, IEEE 802.11, FAMA
etc. is significant, and thus favors the use of fewer, larger
messages. It would also be useful in reservation-based, time-slotted
access schemes where smaller packets must be aggregated into
appropriately-sized IP packets for transmission in a given time
slot. Upper layer protocols other than routing may make use of this
encapsulation functionality for the same purpose.
Moreover, IMEP will provide the commonality among many network-level
routing algorithms. Many algorithms intended for use in a MANET will
require common functionality such as link status sensing, security
authentication with adjacent mobiles, broadcast reliability of
network control messages, etc. This common functionality can be
extracted from various protocols and can become generic protocol
useful to all. The routing algorithms would also benefit from the
common approach to mobile and interface identification and
addressing. The IMEP will run at the network layer and will be an
adjunct to whichever network routing protocol is using it. Routing
control packets will be encapsulated in IMEP messages, which will be
further encapsulated into IP packets.
6. SECURITY ISSUES
The MANET computing environment is very different from the ordinary
computing environment. In many cases, mobile computers will be
connected to the network via wireless links. Such links are
particularly vulnerable to passive eavesdropping, active replay
attacks, and other active attacks. A stringent authentication and
registration processes are required to avoid any malicious users.
Lee and Campbell Expires May 1999 [Page 21]
INTERNET DRAFT INSIGNIA November, 1998
Authentication :
The IMEP Authentication object [18] is used to authenticate all
IMEP objects. The types of authentication to be supported and
specified in a proposed MANET Authentication Architecture under
development.
Registration :
Upper layer protocols, i.e., INSIGNIA must register with IMEP
prior to use.
7. APPLICATIONS
INSIGNIA can be used as signaling support for small (pico-cell) and
large scale mobile networks. Flows and microflows can be supported.
Voice, video and real-time data applications can be supported using
the INSIGNIA adaptive real-time service. In addition, INSIGNIA
networks support traditional best effort services.
8. ACKNOWLEDGMENT
We would like to thank Mischa Schwartz and Javier Gomez Castellanos
for comments on this work.
9. REFERENCE
[1] V. Park, and S. Corson, "Temporally Ordered Routing Algorithm
(TORA) Version 1 Functional Specification", draft-ietf-manet-
tora-spec-00.txt, November 1997.
[2] J. Macker, and M. S. Corson, "Mobile Ad hoc Networking (MANET):
Routing Protocol Performance Issues and Evaluation
Considerations", draft-ietf-manet-issues-01.txt, April 1998.
[3] D. D. Clark and D.L. Tennenhouse, "Architectural Consideration
for a New Generation of Protocols", Proc. ACM SIGCOMM'90, August
1990.
[4] M. Gerla and J.T-C Tsai, "Multicluster, mobile. Multimedia Radio
Network", Wireless Networks 1(3), 1995
[5] Z. Haas and M. Pearlman, "The Zone Routing Protocol (ZRP) for Ad
Hoc Networks", draft-ietf-manet-zone-zrp-00.txt
[6] C. Perkins, "Ad hoc On demand Distance Vector Routing",
draft-ieft-manet-aodv-01.txt
[7] D. B. Johnson and D. A. Maltz, "Dynamic Source Routing in Ad Hoc
Wireless Network", In Mobile Computing, Chapter 5, pp. 153-181.
[8] M. S. Corson, "Issues in Supporting Quality of Service in Mobile
Ad Hoc Networks", Proc. IFIP Fifth International Workshop on
Quality of Service (IWQOS '97), Columbia University.
[9] C. R. Lin and M. Gerla, "A Distributed Architecture for
Multimedia in a Multihop Dynamic Packet Radio Network,"
Proceedings of IEEE Globecom'95, Nov., pp. 1468-1472.
Lee and Campbell Expires May 1999 [Page 22]
INTERNET DRAFT INSIGNIA November, 1998
[10] V. Park and M. S. Corson, "A Highly Adaptive Distributed Routing
Algorithm for Mobile Wireless Networks", Proceedings of IEEE
INFOCOM'97, April 1997
[11] V. Park and M.S. Corson, "A Performance Comparison of the
Temporally-Ordered-Routing Algorithm and Ideal Link-State
Routing", Proceedings of IEEE Symposium on Computers and
Communication '98, June 1998, Athens, Greece.
[12] W. Almesberger, T. Ferrari and J. Le Boudec, "SRP: a Scalable
Resource Reservation Protocol for the Internet",
http://lrcwww.epfl.ch/srp/
[13] R. Ramanathan and M. Streenstrup, "Hierarchically-organized,
multihop mobile wireless networks for quality-of-service
support", ftp://ftp.bbn.com /pub/ramanath/mmwn-paper.ps
[14] C. R. Lin and M. Gerla, "Asynchronous Multimedia Multihop
Wireless Networks," Proceedings of IEEE INFOCOM'97, April 1997.
[15] R. Braden, L. Zhang, S. Berson, S. Herzog, S. Jamin, "Resource
ReSerVation Protocol (RSVP)", RFC 2205, September 1997.
[16] P. Sharma, D. Estrin, S. Floyd, and V. Jacobson, "Scalable Timers
for Soft-State Protocols", IEEE INFOCOM 1997, April 1997.
[17] P. Ferguson, "Simple Differential Services: IP TOS and
Precedence, Delay Indication and Drop Preferences",
draft-ferguson-delay-drop-00.txt
[18] M. S. Corson and V. Park, "An Internet MANET Encapsulation
Protocol (IMEP) Specification. Internet Draft,
draft-ietf-manet-imep-spec-01.txt, November 1997.
[19] R. R-F. Liao and A.T. Campbell, "On Programmable Universal Mobile
Channels in a Cellular Internet", 4th ACM/IEEE International
Conference on Mobile Computing and Networking
(MOBICOM'98) , Dallas, October, 1998.
[20] M.S. Corson and A.T Campbell, "Toward Supporting Quality of
Service in Mobile Ad Hoc Networks", First Conference on Open
Architecture and Network Programming, San Franscisco, April 3-4,
1998.
[21] J. Broch, D. A. Maltz, D. B. Johnson, Y-C Hu, and J. Jetcheva, "A
Performance Comparison of Multi-Hop Wireless Ad Hoc Network
Routing Protocols", to appear in Proc. of the 4th Annual ACM/IEEE
International Conference on Mobile Computing and Networking, ACM,
Dallas, TX, October 1998.
[22] S. Lu, V. Bharghavan, and R. Srikant. "Fair scheduling in
wireless packet networks". In Proceedings of ACM SIGCOMM, San
Francisco, California, 1997
[23] OPNET, http://www.mil3.com
[24] A. S. Acampora and M. Naghshineh, "QOS provisioning in micro-
cellular networks supporting multiple classes of traffic",
Wireless Networks, 2(3), 1996.
[25] Lee, S-B. and A.T. Campbell, "INSIGNIA: In-band Signaling
Support for QOS in Mobile Ad Hoc Networks" Proc of 5th
International Workshop on Mobile Multimedia Communications
(MoMuC,98), Berlin, Germany, October 1998.
Lee and Campbell Expires May 1999 [Page 23]
INTERNET DRAFT INSIGNIA November, 1998
10. AUTHORS' ADDRESSES
Seoung-Bum Lee, Andrew T. Campbell
COMET Group
Columbia University
530 w 120th street
Schapiro Research Building
New York, NY 10027
phone (212) 854 - 0871
[sbl,campbell]@comet.columbia.edu
See comet.columbia.edu/insignia for more information
Lee and Campbell Expires May 1999 [Page 24]
