Benchmarking Working Group Gabor Feher, BUTE
INTERNET-DRAFT Krisztian Nemeth, BUTE
Expiration Date: July 2005 Andras Korn, BUTE
Istvan Cselenyi, TeliaSonera
January 2005
Benchmarking Terminology for Routers Supporting Resource Reservation
<draft-ietf-bmwg-benchres-term-05.txt>
Status of this Memo
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed,
or will be disclosed, and any of which I become aware will be
disclosed, in accordance with RFC 3668.
Table of contents
Abstract...........................................................2
1. Introduction....................................................3
2. Existing definitions............................................3
3. Definition of Terms.............................................4
3.1 Traffic Flow Types..........................................4
3.1.1 Data Flow..............................................4
3.1.2 Distinguished Data Flow................................4
3.1.3 Best-Effort Data Flow..................................5
3.2 Resource Reservation Protocol Basics........................5
3.2.1 QoS Session............................................5
3.2.2 Resource Reservation Protocol..........................6
3.2.3 Resource Reservation Capable Router....................7
3.2.4 Reservation State......................................7
3.2.5 Resource Reservation Protocol Orientation..............8
3.3 Router Load Factors.........................................9
3.3.1 Best-Effort Traffic Load Factor........................9
3.3.2 Distinguished Traffic Load Factor......................9
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 1]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
3.3.3 Session Load Factor...................................10
3.3.4 Signaling Intensity Load Factor.......................10
3.3.5 Signaling Burst Load Factor...........................11
3.4 Performance Metrics........................................11
3.4.1 Signaling Message Handling Time.......................11
3.4.2 Distinguished Traffic Delay...........................12
3.4.3 Best-effort Traffic Delay.............................13
3.4.4 Signaling Message Loss................................13
3.4.5 Session Maintenance Capacity..........................14
3.5 Scalability Limit..........................................15
4. Security Considerations........................................16
5. IANA Considerations............................................16
6. Acknowledgements...............................................16
7. References.....................................................16
7.1 Normative References.......................................16
7.2 Informative References.....................................16
Authors' Addresses................................................17
Disclaimer of Validity............................................17
Copyright Notice..................................................18
Disclaimer........................................................18
Abstract
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 2]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
The purpose of this document is to define terminology specific to
the benchmarking of resource reservation signaling of Integrated
Services IP routers. These terms can be used in additional documents
that define benchmarking methodologies for routers that support
resource reservation or reporting formats for the benchmarking
measurements.
1. Introduction
Signaling based resource reservation (e.g. via RSVP [3]) is an
important part of the different QoS provisioning approaches.
Therefore network operators who are planning to deploy signaling
based resource reservation may want to scrutinize the scalability
limitations of reservation capable routers and the impact of
signaling on their data forwarding performance.
An objective way of quantifying the scalability constraints of QoS
signaling is to perform measurements on routers that are capable of
resource reservation. This document defines terminology for a
specific set of tests that vendors or network operators can carry
out to measure and report the signaling performance characteristics
of router devices that support resource reservation protocols. The
results of these tests provide comparable data for different
products, and thus support the decision process before purchase.
Moreover, these measurements provide input characteristics for the
dimensioning of a network in which resources are provisioned
dynamically by signaling. Finally, the tests are applicable for
characterizing the impact of the resource reservation signaling on
the forwarding performance of the routers.
This benchmarking terminology document is based on the knowledge
gained by examination of (and experimentation with) different
resource reservation protocols: the IETF standard RSVP [3] and
several experimental ones, such as YESSIR [5], ST2+ [6], SDP [7],
Boomerang [8] and Ticket [9]. Some of these protocols are also
analyzed in an IETF NSIS working group draft [10]. Although at the
moment the authors are only aware of resource reservation capable
router products that interpret RSVP, this document defines terms
that are valid in general and not restricted to any of the above
listed protocols.
In order to avoid any confusion we would like to emphasize that this
terminology considers only signaling protocols that provide IntServ
resource reservation; the DiffServ world, for example, is out of our
scope.
2. Existing definitions
RFC 1242 "Benchmarking Terminology for Network Interconnect
Devices" [1] and RFC 2285 "Benchmarking Terminology for LAN
Switching Devices" [2] contain discussions and definitions for a
number of terms relevant to the benchmarking of signaling
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 3]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
performance of reservation capable routers and should be consulted
before attempting to make use of this document.
Additionally, this document defines terminology in a way that is
consistent with the terms used by Next Steps in Signaling working
group laid out in [4].
For the sake of clarity and continuity this document adopts the
template for definitions set out in Section 2 of RFC 1242.
Definitions are indexed and grouped together into different sections
for ease of reference.
3. Definition of Terms
3.1 Traffic Flow Types
This group of definitions describes traffic flow types forwarded by
resource reservation capable routers.
3.1.1 Data Flow
Definition:
A data flow is a stream of data packets from one sender to one or
more receivers, where each packet has a flow identifier unique to
the flow.
Discussion:
The flow identifier can be an arbitrary subset of the packet
header fields that uniquely distinguishes the flow from others.
For example, the 5-tuple "source address; source port; destination
address; destination port; protocol number" is commonly used for
this purpose (where port number are applicable). It is also
possible to take advantage of the Flow Label field of IPv6
packets. For more comment on flow identification refer to [4].
The flow identification can be time- and/or resource-consuming,
but this can sometimes be avoided as routers do not necessarily
have to classify each packet. Instead, packets that should be
classified by routers can be marked with special flags that
routers understand. One existing marking approach is to use the
Type of Service (IPv4)/Traffic Class (IPv6) field of the IP
header. Naturally, unmarked packets are not classified by routers
and this way valuable resources can be saved.
3.1.2 Distinguished Data Flow
Definition:
Distinguished data flows are flows that resource reservation
capable routers intentionally treat better or worse than
"ordinary" data flows, according to a QoS agreement defined for
the distinguished flow.
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 4]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
Discussion:
Packets of distinguished data flows are marked so that the routers
that forward them know they require differentiated treatment.
Routers classify these incoming packets and identify the data flow
they belong to.
The most common usage of the distinguished data flow is to get
higher priority treatment than that of best-effort data flows (see
the next definition). In these cases, a distinguished data flow is
sometimes referred to as a "premium data flow". Nevertheless
theoretically it is possible to require worse treatment than that
of best-effort flows.
3.1.3 Best-Effort Data Flow
Definition:
Best-effort data flows are flows that are not treated in any
special manner by resource reservation capable routers; thus,
their packets are served (forwarded) in some default way.
Discussion:
"Best-effort" means that the router makes its best effort to
forward the data packet quickly and safely, but does not guarantee
anything (e.g. delay or loss probability). This type of traffic is
the most common in today's Internet.
The packets belonging to the best-effort data flows are not
specially marked and thus they are not classified by the routers.
3.2 Resource Reservation Protocol Basics
This group of definitions applies to signaling based resource
reservation protocols implemented by IP router devices.
3.2.1 QoS Session
Definition:
A QoS session is an application layer concept, shared between a
set of network nodes, that pertains to a specific set of data
flows. The information associated with the session includes the
data required to identify the set of data flows in addition to a
specification of the QoS treatment they require.
Discussion:
A QoS session is an end-to-end relationship. Whenever end-nodes
decide to obtain special QoS treatment for their data
communication, they set up a QoS session; as part of the process,
they or their proxies make a QoS agreement with the network,
specifying their data flows and the QoS treatment that the flows
require.
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 5]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
It is possible for the same QoS session to span multiple network
domains that have different resource provisioning architectures.
In this document, however, we only deal with the case where the
QoS session is realized over an IntServ architecture. It is
assumed that sessions will be established using signaling messages
of a resource reservation protocol.
QoS sessions must have unique identifiers; it must be possible to
determine which QoS session a given signaling message pertains to.
Therefore, each signaling message should include the identifier of
its corresponding session. As an example, in the case of RSVP, the
"session specification" identifies the QoS session plus refers to
the data flow; the "flowspec" specifies the desired QoS treatment
and the "filter spec" defines the subset of data packets in the
data flow that receive the QoS defined by the flowspec.
QoS sessions can be unicast or multicast depending on the number
of participants. In a multicast group there can be several data
traffic sources and destinations. Here the QoS agreement does not
have to be the same for each branch of the multicast tree
forwarding the data flow of the group. Instead, a dedicated
network resource in a router can be shared among many traffic
sources from the same multicast group (c.f. multicast reservation
styles in the case of RSVP).
Issues:
Even though QoS sessions are considered to be unique, resource
reservation capable routers might aggregate them and allocate
network resources to these aggregated sessions at once. The
aggregation can be based on similar data flow attributes (e.g.
similar destination addresses) or it can combine arbitrary
sessions as well. While reservation aggregation significantly
lightens the signaling processing task of a resource reservation
capable router, it also requires the administration of the
aggregated QoS sessions and might also lead to the violation of
the quality guaranties referring to individual data flows within
an aggregation [11].
3.2.2 Resource Reservation Protocol
Definition:
Resource reservation protocols define signaling messages and
message processing rules used to control resource allocation in
IntServ architectures.
Discussion:
It is the signaling messages of a resource reservation protocol
that carry the information related to QoS sessions. This
information includes a session identifier, the actual QoS
parameters, and possibly flow descriptors.
The message processing rules of the signaling protocols ensure
that signaling messages reach all network nodes concerned. Some
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 6]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
resource reservation protocols (e.g. RSVP) are only concerned with
this, i.e. carrying the QoS-related information to all the
appropriate network nodes, without being aware of its content.
This latter approach allows changing the way the QoS parameters
are described, and different kind of provisioning can be realized
without the need to change the protocol itself.
3.2.3 Resource Reservation Capable Router
Definition:
A router is resource reservation capable (it supports resource
reservation) if it is able to interpret signaling messages of a
resource reservation protocol, and based on these messages is able
to adjust the management of its flow classifiers and network
resources so as to conform with the content of the messages.
Discussion:
Routers capture signaling messages and manipulate reservation
states and/or reserved network resources according to the content
of the messages. This ensures that the flows are treated as their
specified QoS requirements indicate.
3.2.4 Reservation State
Definition:
A reservation state is the set of entries in the router's memory
that contain all relevant information about a given QoS session
registered with the router.
Discussion:
States are needed because IntServ related resource reservation
protocols require the routers to keep track of QoS session and
data-flow-related metadata. The reservation state includes the
parameters of the QoS treatment; the description of how and where
to forward the incoming signaling messages; refresh timing
information; etc.
Based on how reservation states are stored in a reservation
capable router, the routers can be categorized into two classes:
Hard-state resource reservation protocols (e.g. ST2 [6]) require
routers to store the reservation states permanently, established
by a set-up signaling primitive, until the router is explicitly
informed that the QoS session is canceled.
There are also soft-state resource reservation capable routers,
where there are no permanent reservation states, and each state
has to be regularly refreshed by appropriate refresh signaling
messages. If no refresh signaling message arrives during a certain
period then the router stops the maintenance of the QoS session
assuming that the end-points do not intend to keep the session up
any longer or the communication lines are broken somewhere along
the data path. This feature makes soft-state resource reservation
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 7]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
capable routers more robust than hard-state routers, since no
failures can cause resources to stay permanently stuck in the
routers. (Note, it is still possible to have an explicit teardown
message in soft-state protocols for quicker resource release.)
Issues:
Based on the initiating point of the refresh messages, soft-state
resource reservation protocols can be divided into two groups.
First, there are protocols where it is the responsibility of the
end-points or their proxies to initiate refresh messages. These
messages are forwarded along the path of the data flow refreshing
the corresponding reservation states in each router affected by
the flow. Secondly, there are other protocols, where routers and
end-points have their own schedule for the reservation state
refreshes and they signal these refreshes to the neighboring
routers.
3.2.5 Resource Reservation Protocol Orientation
Definition:
The orientation of a resource reservation protocol tells which end
of the protocol communication initiates the allocation of the
network resources. Thus, the protocol can be sender or receiver
initiated, depending on the location of the data flow source
(sender) and destination (receiver) compared to the reservation
initiator.
Discussion:
In the case of sender-initiated protocols the resource reservation
propagates the same directions as of the data flow. Consequently,
in the case of receiver-initiated protocols the signaling messages
reserving resources are forwarded backward on the path of the data
flow. Due to the asymmetric routing nature of the Internet, in
this latter case, the path of the desired data flow should be
known before the reservation initiator would be able to send the
resource allocation messages. For example in the case of RSVP, the
RSVP PATH message, traveling from the data flow sources towards
the destinations, first marks the path of the data flow on which
the resource allocation messages will travel backward.
This definition considers only protocols that reserve resources
for just one data flow between the end-nodes. The reservation
orientation of protocols reserving more than one data flow is not
defined here.
Issues:
The location of the reservation initiator affects the basics of
the resource reservation protocols and therefore it is an
important design decision. In the case of multicast QoS sessions,
the sender-oriented protocols require the traffic sources to
maintain a list of receivers and send their allocation messages
considering the different requirements of the receivers. Using
multicast QoS sessions, the receiver-oriented protocols give the
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 8]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
chance to the receivers to manage their own resource allocation
requests and thus ease the task of the sources.
3.3 Router Load Factors
The router load expressing the utilization of the device naturally
affects the performance of the router. During the benchmarking
process several load conditions have to be examined.
This group of definitions describes different load components that
impact only a specific part of the resource reservation capable
router.
3.3.1 Best-Effort Traffic Load Factor
Definition:
The best-effort traffic load factor is defined as the volume of
the best-effort data traffic that traverses the router in a
second.
Discussion:
Forwarding the best-effort data packets, which requires obtaining
the routing information and transferring the data packet between
network interfaces, requires processing power, which is related to
this load factor.
Issues:
The same amount of data segmented into differently sized packets
causes different amounts of load on the router, which has to be
considered during the benchmarking measurements.
Measurement unit:
bits per second (bps)
3.3.2 Distinguished Traffic Load Factor
Definition:
The distinguished traffic load factor is defined as the volume of
the distinguished data traffic that traverses the router in a
second.
Discussion:
Similarly to the best-effort data, forwarding the distinguished
data packets requires obtaining the routing information and
transferring the data packet between network interfaces. However,
in this case packets have to be classified as well, which requires
additional processing capacity.
Issues:
Just as in the best-effort case, the same amount of data segmented
into differently sized packets causes different amounts of load on
the router, which has to be considered during the benchmarking
measurements.
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 9]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
Measurement unit:
bits per second (bps)
3.3.3 Session Load Factor
Definition:
The session load factor is the number of QoS sessions the router
is keeping track of.
Discussion:
Resource reservation capable routers maintain reservation states
keeping track of the QoS sessions. Obviously, the more reservation
states are registered with the router, the more complex the
traffic classification becomes, and the longer time it takes to
look up the corresponding resource reservation sate. Moreover, not
only the traffic flows, but also the signaling messages that
control the reservation states have to be identified first, before
taking any other action, and this kind of classification also
means extra work for the router.
In the case of soft-state resource reservation protocols, the
session load also affects reservation state maintenance. For
example, the supervision of timers that watchdog the reservation
state refreshes may cause further load on the router.
Measurement unit:
This factor is measured by the number of QoS sessions impacting
the router, thus it has no unit.
3.3.4 Signaling Intensity Load Factor
Definition:
The signaling intensity load factor is defined as the number of
signaling messages that hit the router during one second.
Discussion:
The processing of signaling messages requires processor power that
raises the load on the control plane of the router.
In routers where the control plane and the data plane are not
totally independent (e.g. certain parts of the tasks are served by
the same processor; or the architecture has common memory buffers,
transfer buses or any other resources) the signaling load can have
an impact on the router's packet forwarding performance as well.
Naturally, just as everywhere else in this document, the term
"signaling messages" refer only to the resource reservation
protocol related primitives.
Issues:
Most of the resource reservation protocols have several protocol
primitives realized by different signaling message types. Each of
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 10]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
these message types may require a different amount of processing
power from the router. This fact has to be considered during the
benchmarking measurements.
Measurement unit:
The unit of this factor is 1/second.
3.3.5 Signaling Burst Load Factor
Definition:
The signaling burst load factor is defined as the number of
signaling messages that arrive to one input port of the router
back-to-back ([1]), causing persistent load on the signaling
message handler.
Discussion:
The definition focuses on one input port only and does not
consider the traffic arriving at the other input ports.
As a consequence, a set of messages arriving at different ports,
but with such a timing that would be a burst if the messages
arrived at the same port, is not considered to be a burst. The
reason for this is that it is not guaranteed at a black-box test
that this would have the same effect on the router as a burst
(incoming at the same interface) has.
This definition conforms to the burst definition given in [2].
Issues:
Most of the resource reservation protocols have several protocol
primitives realized by different signaling message types. Bursts
built up of different messages may have a different effect on the
router. Consequently, during measurements the content of the burst
has to be considered as well.
Measurement unit:
This load factor is measured by the number of messages in the
burst, thus it has no unit.
3.4 Performance Metrics
This group of definitions is a collection of measurable quantities
that describe the impact the different load components have on the
router.
3.4.1 Signaling Message Handling Time
Definition:
The signaling message handling time (or, in short, signal handling
time) is the latency ([1]) of a signaling message passing through
the router.
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 11]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
Discussion:
The router interprets the signaling messages, acts based on their
content and usually forwards them in an unmodified or modified
form. Thus the message handling time is usually longer than the
forwarding time of data packets of the same size.
There might be signaling message primitives, however, that are
drained or generated by the router, like certain refresh messages.
In this case the signal handling time is immeasurable, therefore
it is not defined for such messages.
In the case of signaling messages that carry information
pertaining to multicast flows, the router might issue multiple
signaling messages after processing them. In this case, by
definition, the signal handling time is the latency between the
incoming signaling message and the last outgoing signaling message
related to the received one.
The signal handling time is an important characteristic as it
directly affects the setup time of a QoS session.
Issues:
The signal handling time may be dependent on the type of the
signaling message. For example, it usually takes a shorter time
for the router to remove a reservation state than to set it up.
This fact has to be considered during the benchmarking process.
Measurement unit:
The unit of the signaling message handling time is the second.
3.4.2 Distinguished Traffic Delay
Definition:
Distinguished traffic delay is the latency ([1]) of a
distinguished data packet passing through the tested router
device.
Discussion:
Distinguished traffic packets must be classified first in order to
assign the network resources dedicated to the flow. The time of
the classification is added to the usual forwarding time
(including the queuing) that a router would spend on the packet
without any resource reservation capability. This classification
procedure might be quite time consuming in routers with vast
amounts of reservation states.
There are routers where the processing power is shared between the
control plane and the data plane. This means that the processing
of signaling messages may have an impact on the data forwarding
performance of the router. In this case the distinguished traffic
delay metric also indicates the influence the two planes have on
each other.
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 12]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
Issues:
Queuing of the incoming data packets in routers can bias this
metric, so the measurement procedures have to consider this
effect.
Measurement unit:
The unit of the distinguished traffic delay is the second.
3.4.3 Best-effort Traffic Delay
Definition:
Best-effort traffic delay is the latency of a best-effort data
packet traversing the tested router device.
Discussion:
If the processing power of the router is shared between the
control and data plane, then the processing of signaling messages
may have an impact on the data forwarding performance of the
router. In this case the best-effort traffic delay metric is an
indicator of the influence the two planes have on each other.
Issues:
Queuing of the incoming data packets in routers can bias this
metric as well, so measurement procedures have to consider this
effect.
Measurement unit:
The unit of the best-effort traffic delay is the second.
3.4.4 Signaling Message Loss
Definition:
Signaling message loss is the ratio of the actual and the expected
number of signaling messages leaving a resource reservation
capable router, subtracted from one.
Discussion:
This definition gives the same value as the ratio of the lost and
the expected messages. The reason for choosing the given
definition is that the number of lost messages cannot be measured
directly.
There are certain types of signaling messages that are required to
be forwarded by reservation capable routers as soon as their
processing is finished. However, due to the high router load or
for other reasons, the forwarding or even the processing of these
signaling messages might be canceled. There are other kinds of
signaling messages, that should have been generated by the router,
without any corresponding incoming message. In case of high router
load, it is possible that such a message never leaves the router.
To characterize these situations we introduce the signaling
message loss metric expressing the ratio of the signaling messages
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 13]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
that actually have left the router and those ones that were
expected to leave the router.
Since the most frequent reason for signaling message loss is high
router load, this metric is suitable for sounding out the
scalability limits of resource reservation capable routers.
During the measurements one must be able to determine whether a
signaling message is still in the queues of the router or if it
has already been dropped. For this reason we define a signaling
message as lost if no forwarded signaling message is emitted
within a reasonably long time period. This period is defined along
with the benchmarking methodology.
Measurement unit:
This measure has no unit; it is expressed as a real number, which
is between zero and one, including the limits.
3.4.5 Session Maintenance Capacity
Definition:
The session maintenance capacity metric is used in the case of
soft-state resource reservation protocols only. It is defined as
the ratio of the number of QoS sessions actually maintained and
the number of QoS sessions that should have been maintained during
one refresh period.
Discussion:
For soft-state protocols maintaining a QoS session means
refreshing the reservation states associated with it.
When a soft-state resource reservation capable router is
overloaded, it may happen that the router is not able to refresh
all the registered reservation states, because it does not have
the time to run the state refresh task. In this case sooner or
later some QoS sessions will be lost even if the endpoints still
require their maintenance.
The session maintenance capacity sounds out the maximal number of
QoS sessions that the router is capable of maintaining.
Issues:
The actual process of session maintenance is protocol and
implementation dependent, so is the method to examine that a
session is maintained or not.
In the case of soft-state resource reservation protocols a router
that fails to maintain a QoS session may not emit refresh
signaling messages either. This has direct consequences on the
signaling message loss metric.
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 14]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
Measurement unit:
This measure has no unit; it is expressed as a real number, which
is between zero and one (including the limits).
3.5 Scalability Limit
Definition:
The scalability limit of the router is the critical load
condition, when the router is still in the steady state but the
smallest amount of additional load would drive it to the
overloaded state.
Discussion:
All existing routers have finite buffer memory and finite
processing power. In the steady state of the router, the buffer
memories are not fully utilized and the processing power is enough
to cope with all tasks running on the router. As the router load
increases the buffers are starting to fill up and/or the router
has to postpone more and more tasks. However, there is a certain
point where no more buffer memory is available, or a task cannot
be postponed any longer; thus the router is forced to drop a
packet or an activity. This is the overloaded state of the
resource reservation capable router, which can be recognized by
the fact that some kind of data (signaling or packet) or task
(e.g. QoS session maintenance) loss occurs.
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 15]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
4. Security Considerations
As this document only provides terminology and describes neither a
protocol nor an implementation or a procedure, there are no security
considerations associated with it.
5. IANA Considerations
This document has no actions for IANA.
6. Acknowledgements
We would like to thank the following individuals for their help in
the research and development work, which contributed to form this
document: Joakim Bergkvist and Norbert Vegh from Telia Research AB,
Sweden; Balazs Szabo, Gabor Kovacs and Peter Vary from the High
Speed Networks Laboratory, Budapest University of Technology and
Economics, Hungary.
7. References
7.1 Normative References
[1] S. Bradner, "Benchmarking Terminology for Network
Interconnection Devices", RFC 1242, July 1991
[2] R. Mandeville, "Benchmarking Terminology for LAN Switching
Devices", RFC 2285, February 1998
7.2 Informative References
[3] B. Braden, Ed., et. al., "Resource Reservation Protocol (RSVP)
- Version 1 Functional Specification", RFC 2205, September
1997.
[4] R. Hancock, et al., "Next Steps in Signaling: Framework"
(draft-ietf-nsis-fw-07.txt) (Internet draft: work in progress),
November 2004
[5] P. Pan, H. Schulzrinne, "YESSIR: A Simple Reservation Mechanism
for the Internet", Computer Communication Review, on-line
version, volume 29, number 2, April 1999
[6] L. Delgrossi, L. Berger, "Internet Stream Protocol Version 2
(ST2) Protocol Specification - Version ST2+", RFC 1819, August
1995
[7] P. White, J. Crowcroft, "A Case for Dynamic Sender-Initiated
Reservation in the Internet", Journal on High Speed Networks,
Special Issue on QoS Routing and Signaling, Vol. 7 No. 2, 1998
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 16]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
[8] J. Bergkvist, D. Ahlard, T. Engborg, K. Nemeth, G. Feher, I.
Cselenyi, M. Maliosz, "Boomerang : A Simple Protocol for
Resource Reservation in IP Networks", Vancouver, IEEE Real-Time
Technology and Applications Symposium, June 1999
[9] A. Eriksson, C. Gehrmann, "Robust and Secure Light-weight
Resource Reservation for Unicast IP Traffic", International WS
on QoS'98, IWQoS'98, May 18-20, 1998
[10] J. Manner, X. Fu, "Analysis of Existing Quality of Service
Signaling Protocols" (draft-ietf-nsis-signalling-analysis-
05.txt) (Internet draft: work in progress), December 2004
[11] F. Baker, C. Iturralde, F. Le Faucheur, B. Davie, "Aggregation
of RSVP for IPv4 and IPv6 Reservations", RFC 3175, September
2001
Authors' Addresses
Gabor Feher
Budapest University of Technology and Economics
Department of Telecommunications and Mediainformatics
Magyar Tudosok krt. 2, H-1117, Budapest, Hungary
Phone: +36 1 463-1538
Email: Gabor.Feher@tmit.bme.hu
Krisztian Nemeth
Budapest University of Technology and Economics
Department of Telecommunications and Mediainformatics
Magyar Tudosok krt. 2, H-1117, Budapest, Hungary
Phone: +36 1 463-1565
Email: Krisztian.Nemeth@tmit.bme.hu
Andras Korn
Budapest University of Technology and Economics
Institute of Mathematics, Department of Analysis
Egry Jozsef u. 2, H-1111 Budapest, Hungary
Phone: +36 1 463-2475
Email: Korn@math.bme.hu
Istvan Cselenyi
TeliaSonera International Carrier
Vaci ut 22-24, H-1132 Budapest, Hungary
Phone: +36 1 412-2705
Email: Istvan.Cselenyi@teliasonera.com
Disclaimer of Validity
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed
to pertain to the implementation or use of the technology
described in this document or the extent to which any license
under such rights might or might not be available; nor does it
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 17]
INTERNET-DRAFT <draft-ietf-bmwg-benchres-term-05.txt> January 2005
represent that it has made any independent effort to identify any
such rights. Information on the IETF's procedures with respect to
rights in IETF Documents can be found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use
of such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository
at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention
any copyrights, patents or patent applications, or other
proprietary rights that may cover technology that may be required
to implement this standard. Please address the information to the
IETF at ietf-ipr@ietf.org.
Copyright Notice
Copyright (C) The Internet Society (2005). This document is
subject to the rights, licenses and restrictions contained in BCP
78, and except as set forth therein, the authors retain all their
rights.
Disclaimer
This document and the information contained herein are provided
on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT
THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR
ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.
Feher, Nemeth, Korn, Cselenyi Expires July 2005 [Page 18]
