Internet Engineering Task Force J. Manner (ed.)
Internet-Draft X. Fu (ed.)
Expires: April, 2003
October 28, 2002
Analysis of Existing Quality of Service Signaling Protocols
<draft-ietf-nsis-signalling-analysis-00.txt>
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Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
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Abstract
This document presents a review of existing protocols for signalling
the Quality of Service requirements of flows to nodes in an IP
network. Protocols are reviewed independently and not compared
against the NSIS requirements document nor to RSVP itself. The
purpose is to learn from existing work and to avoid common
misconceptions about the protocols. A further goal is to avoid to
redesign ideas already implemented in another protocol.
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TODO items
- Evaluate the rest of the protocols
- Add more protocols? Remove protocols?
Table of Contents
1 Introduction ................................................. 3
2 The Resource Reservation Protocol ............................ 4
2.1 Extensions to RSVP ......................................... 5
2.2 Reservation functionality .................................. 6
2.3 Processing Overhead ........................................ 7
2.4 Bandwidth Consumption ...................................... 8
2.5 Mobility Support ........................................... 8
2.6 Security ................................................... 9
2.7 Deployment Issues .......................................... 9
2.8 Conclusions ................................................ 10
3 YESSIR ....................................................... 11
3.1 Reservation Functionality .................................. 11
3.2 Processing Overhead ........................................ 12
3.3 Bandwidth Consumption ...................................... 12
3.4 Mobility Support ........................................... 12
3.5 Security ................................................... 12
3.6 Deployment Issues .......................................... 12
3.7 Conclusions ................................................ 12
4 Boomerang .................................................... 12
4.1 Reservation Functionality .................................. 13
4.2 Processing Overhead ........................................ 13
4.3 Bandwidth Consumption ...................................... 13
4.4 Mobility Support ........................................... 13
4.5 Security ................................................... 13
4.6 Deployment Issues .......................................... 13
4.7 Conclusions ................................................ 14
5 Other Protocols .............................................. 14
5.1 INSIGNIA ................................................... 14
5.2 Mobile RSVP ................................................ 15
5.3 BGRP ....................................................... 15
5.4 ST-II ...................................................... 15
5.5 The ITSUMO Framework ....................................... 16
6 Summary ...................................................... 17
7 Security Considerations ...................................... 17
8 Contributors ................................................. 17
9 Acknowledgement .............................................. 17
10 References .................................................. 17
11 Author's Addresses .......................................... 20
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1. Introduction
The aim of this document is to present existing mature protocols and
architectures for signalling the Quality of Service (QoS)
requirements of flows to nodes in an IP network. The various
protocols are reviewed independently and without comparing against
the NSIS requirements document, because the protocols have already
been designed before the work on present requirements was
initialized. Neither do we want to make any comparison of protocols
against RSVP because this would of little value - all protocols have
their own research backgrounds and targets and therefore do things
differently. We also hope that the NSIS Working Group can learn from
existing work and we can avoid common misconceptions about the
protocols. A further goal is to avoid to redesign ideas already
implemented in an existing protocol.
There have been a number of historic attempts in delivering QoS or
generic signaling into the Internet. In the early years, multicast
was believed to be going to be popular to majority of communications,
hence RSVP and earlier ST-II were designed in a way which is
multicast-oriented. ST-II was developed as a reservation protocol for
point-to-multipoint communication. However, since it is sender-
initiated, it does not scale with the number of receivers in a
multicast group. It is complex and since every sender needs to set up
its own reservation, the total amount of reservation state is large.
RSVP was then designed to provide support for multipoint-to-
multipoint reservation setup in a more efficient way, however its
complexity, scalability and ability to meet new requirements have
been criticized.
YESSIR [PaSc98] and Boomerang [FNM+99] are examples of protocols
designed after RSVP. Both protocols were meant to be simpler than
RSVP. YESSIR is an extension to RTCP, while Boomerang is used with
ICMP.
Previously, there has been a lot of work targeted at creating a new
signalling protocol for resource control. Istvan Cselenyi suggested
to request for QoSSIG BOF in IETF#47 (http://www-nrg.ee.lbl.gov/diff-
serv-arch/msg05055.html), for identifying problems in QoS signaling,
but failed. Some people argued, "in many ways, RSVP improved upon
ST-2, and it did start out simpler, but resulting a design with
complexity and scalability", while some others thought it is "new
knowledge and requirements" that made RSVP insufficient (http://www-
nrg.ee.lbl.gov/diff-serv-arch/msg05066.html), and there is no simpler
way to handle the same problem as RSVP.
Michael Welzl organized a special session "ABR to the Internet" in
SCI 2001, and gathered some inputs for requesting an "ABR to the
Internet" BOF in IETF#51, which was intended to introduce explicit
rate feedback related mechanisms for the Internet (e2e, edge2edge)
but failed because of "missing community interest"
(http://www.tk.uni-linz.ac.at/~michael/abr-internet/).
OPENSIG (http://comet.columbia.edu/opensig/) has been involved in the
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Internet signaling for years. Ping Pan initiated a SIGLITE
(http://www.cs.columbia.edu/~pingpan/projects/siglite.html) BOF
mailing list to investigate light-weight Internet signaling. Finally,
NSIS BOF was successful and the NSIS WG was formed.
The most mature and original protocols are presented in their own
sections and other QoS signalling protocols are presented in later
subsections.
2. The Resource Reservation Protocol
RSVP (the Resource ReServation Protocol) [RSVP] [RFC2205] [BEBH96]
has evolved from ST-II to provide end-to-end QoS signaling services
for application data streams. Hosts use RSVP to request a specific
quality of service (QoS) from the network for particular application
flows. Routers use RSVP to deliver QoS requests to all routers along
the data path. RSVP also can maintain and refresh states for a
requested QoS application flow. This section shortly reviews the RSVP
basic model and its extensions.
RSVP tries to be well-fit in the Integrated Services (IntServ)
[RFC2210], [BEBH96] architecture with certain modularity and
scalability. The design of the RSVP protocol distinguished itself by
a number of fundamental ways, particularly, soft state management,
two-pass signaling message exchanges, receiver-based resource
reservation and separation of QoS signaling from routing.
RSVP Signaling Model: The RSVP signaling model is based on a special
handling of multicast. The sender of a multicast flow advertises the
traffic characteristics periodically to the receivers via "Path"
messages. On receipt of an advertisement, a receiver may generate a
"Resv" message to reserve resources along the flow path from the
sender. Receiver reservations may be heterogeneous. To accommodate
the multipoint-to-multipoint multicast applications, RSVP was
designed to support a vector of reservation attributes called the
"style". A style describes whether all senders of a multicast group
share a single reservation and which receiver is applied. The "Scope"
object additionally provides the explicit list of senders.
Soft State: Because the number of receivers in a multicast flow is
likely to change, and the flow of delivery paths might change during
the life of an application flow, RSVP takes a soft-state approach in
its design, creating and removing the protocol states in routers and
hosts incrementally over time. RSVP sends periodic refresh messages
to maintain its state and to recover from occasional lost messages.
In the absence of refresh messages, the RSVP states automatically
time out and are deleted.
Two-pass Signaling Message Exchanges: The receiver in an application
flow is responsible for requesting the desired QoS from the sender.
To do this, the receiver issues an RSVP QoS request on behalf of the
local application. The request propagates to all routers in reverse
direction of the data paths toward the sender. In this process, RSVP
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requests might be merged, resulting in a protocol that scales well
when there are a large number of receivers.
Receiver-based Resource Reservation: Receiver-initiation is critical
for RSVP to setup multicast sessions with a large number of
heterogeneous receivers. A receiver initiates a reservation request
at a leaf of the multicast distribution tree, traveling towards the
sender. Whenever a reservation is found to already exist in a node in
the distribution tree, the new request will be merged with the
existing reservation. This could result in fewer signalling
operations for the RSVP nodes in the multicast tree close to the
sender, but introduce a restriction to receiver-initiation.
Separation of QoS Signaling from Routing: RSVP messages follow normal
IP routing. RSVP is not a routing protocol, but rather is designed to
operate with current and future unicast and multicast routing
protocols. The routing protocols are responsible for choosing the
routes to use to forward packets, and RSVP consults local routing
tables to obtain routes. RSVP is responsible only for reservation
setup along a data path.
2.1. Extensions to RSVP
There have been various extensions to enhance the basic RSVP
protocol: policy, cryptographic authentication, operation over 802.x
and ATM, aggregation, tunneling, refresh overhead reduction,
diagnostics, RSVP-TE, DCLASS, null service, proxy, mobility schemes,
etc., there have been a large amount of efforts towards a globe-wide
Internet QoS deployment based on RSVP since its development.
Note: only Standards Track RFCs are discussed below; informational
and BCP RFCs (e.g., RFC2998) and I-Ds (e.g., proxy) are not covered
here.
[RFC2749] specifies the usage of COPS policy services in RSVP
environments.
[RSVP2750] specifies the standard format of POLICY_DATA objects and
RSVP handling of policy events.
[RSVP2751] specifies a preemption priority policy element
(PREEMPTION_PRI) for use by RSVP POLICY_DATA Object.
L-N. Hamer, et al, draft-ietf-rap-rsvp-authsession-04 (being approved
by IESG) describes how an RSVP session is authorized by a host and
provides the host with encoded session authorization information as a
POLICY_DATA object.
[RFC2380] presents the implementation requirements for running RSVP
over ATM switched virtual circuits (SVCs).
[RFC2814] introduces an RSVP LAN_NHOP address object that keeps track
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of the next L3 hop as the PATH message traverses an L2 domain between
two L3 entities (RSVP PHOP and NHOP nodes). Both layer-2 and layer-3
addresses are included in the LAN_NHOP; the RSVP_HOP_L2 object is
used to include the Layer 2 address (L2ADDR) of the previous hop,
complementing the L3 address information included in the RSVP_HOP
object (RSVP_HOP_L3 address).
To provide sufficient information for debugging or resource
management, RSVP diagnostic messages (DREQ and DREP) are defined in
[RFC2745] to collect and report RSVP state information along the path
from a receiver to a specific sender.
[RFC2746] describes an IP tunneling enhancement mechanism that allows
RSVP to make reservations across all IP-in-IP tunnels, basically, by
way of recursively applying RSVP over the tunnel portion of the path.
To reduce the refresh volume and maintain reliability, [RFC2961]
defines a Bundle message to reduce overall message handling load, a
MESSAGE_ID object to reduce refresh message processing by allowing
the receiver to more readily identify an unchanged message, and a
MESSAGE_ACK object to detect message loss and support reliable RSVP
message delivery on a per hop basis.
[RFC3175] allows to install one or more aggregated reservations in an
aggregation region, thus the number of individual RSVP sessions can
be reduced.
[RFC3209] specifies the extension to RSVP for establishing explicitly
routed LSPs in MPLS networks using RSVP as a signaling protocol. An
EXPLICIT_ROUTE object is incorporated into RSVP Path messages,
encapsulating a concatenation of hops which constitutes the
explicitly routed path. Using this object, the paths taken by label-
switched RSVP-MPLS flows can be pre-determined, independent of
conventional IP routing.
Section 5 of RFC3270 further specifies the extensions to RSVP to
establish LSPs supporting DiffServ in MPLS networks, introducing a
new DIFFSERV Object (applicable in the Path messages) and using pre-
configured or (e.g. RFC3270) signaled "EXP<-->PHB mapping".
2.2. Reservation functionality
RSVP carries the QoS data of the request through the network,
visiting each node along the data path. To make a resource
reservation at a node, the RSVP module communicates with two local
decision modules, admission control and policy control. Admission
control determines whether the node has sufficient available
resources to supply the requested QoS. Policy control determines
whether the user has administrative permission to make the
reservation. If either check fails, the RSVP module returns an error
notification to the application process that originated the request.
If both checks succeed, the RSVP module sets parameters in a packet
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classifier and packet scheduler to obtain the desired QoS.
The definition of the required resources is not part of the RSVP
standard, but commonly the IntServ specifications for Controlled Load
and Guaranteed Services are used. RSVP allows for unicast and
multicast reservations. Various filtering rules may be used to
identify flows belonging to a reservation - commonly the 5-tuple is
used. RFC 2207 [RFC2207] specifies an RSVP extension to use the IPSEC
SPI (Security Parameter Index), in place of the UDP/TCP-like ports,
so that data flows containing IPSEC protocols can be controlled at a
granularity similar to what is already specified for UDP and TCP.
The IPv6 Flow Label can also be used as a key in the filters.
Furthermore, reservations may be distinct or shared by several
senders.
RFC2996 [RFC2996] introduces a DCLASS Object to carry Differentiated
Services Code Points (DSCPs) in RSVP message objects. If the network
element determines that the RSVP request is admissible to the diff-
serv network, one or more DSCPs corresponding to the behavior
aggregate are determined, and will be carried by the DCLASS Object
added to the RESV message upstream towards the RSVP sender.
For some applications, service parameters are specified by the
network, not by the application (e.g. ERP applications). The Null
Service [RFC2997] allows applications to identify themselves to
network QoS policy agents using RSVP signaling, but does not require
them to specify resource requirements. QoS policy agents in the
network respond by applying QoS policies appropriate for the
application (as determined by the network administrator). The RSVP
sender offers the new service type, 'Null Service Type' in the ADSPEC
that is included with the PATH message. A new TSpec corresponding to
the new service type is added to the SENDER_TSPEC. In addition, the
RSVP sender will typically include with the PATH message policy
objects identifying the user, application and sub-flow, which will be
used for network nodes to manage the correspondent traffic flow.
2.3. Processing Overhead
RSVP scales in that it supports large multicast groups, at the cost
of high complexity in dealing with multicast in its basic protocol.
While the RSVP protocol is also able to make unicast reservations, it
was designed specifically and optimally for multicast. This important
RSVP design consideration leads to the fact that, even for unicast
applications, a full-fledged set of features for supporting multicast
is still needed, mainly: reservation styles and scope object,
receiver-initiated reservation, state management in routers, killer
problems and blockade state handling. A detailed analysis of RSVP
regarding multicast can be found in [Fu02]. [RaNa98] also identified
the issue of inefficient resource reservation resulting from
decentralized multicast routing.
By way of aggregated RSVP [RFC3175] the complexity (in terms of
number of states and needed processing overhead) decreases, but still
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depends on the number of (de-)aggregators and topology, which may be
more than marginal, e.g., in case of many edge nodes or meshed way of
communications through the aggregate region, and remains complexity
in dealing with multicast. In fact, many signaling scenarios do not
need multicast in reality, e.g., typical DiffServ edge router
resource reservation setup. Some multicast protocols (e.g., PIM-SM
[RFC2362]) even consider multicast as a function built on top of
unicast routing rather than as an integral part of it. Since a
signaling protocol would typically traverse along a number of nodes
in the Internet, there is a need to keep the mandatory components of
the signaling protocol as simple as possible, in order to provide a
simpler but adequate signaling service to various non-multicast
signaling scenarios.
Still, for example, the implementation of the daemon can have a huge
effect on the scalability. In [KaSh01], the authors show that their
RSVP daemon is able to handle much more flows than the de-facto ISI
RSVP daemon implementation. Furthermore, the scalability concern
commonly associated with RSVP are more or less subject to
individual's views on what "scalability" is.
2.4. Bandwidth Consumption
(The frequency and size of the RSVP signaling messages.) During the
RSVP setup and refresh process, typically there is a two-pass message
exchange between the sender and the receiver group. Since the
refreshment is hop by hop, bandwidth consumption for RSVP could be
reduced, but may result in more error/failure event handling.
<TBD>
2.5. Mobility Support
Two issues raise concern when RSVP is used by a mobile node (MN): the
reservation identifier and reservation refresh. When an MN changes
locations, it may need to change one of its assigned IP address. An
MN may have an IP address by which it is reachable by nodes outside
the access network and an IP address used to support local mobility
management. Depending on the mobility management mechanism, a
handover may force a change in any of these addresses. As a
consequence the filters associated with a reservation may not
identify the flow anymore and the resource reservation is lost, until
a refresh with a new set of filters is initialized.
The second issue is about following the movement of a mobile node.
RFC2205 defines that Path messages can perform a local repair of
reservation paths. When the route between the communicating end hosts
changes, a Path message will set the state of the reservation on the
new route and a subsequent Resv message will make the resource
reservation. Therefore, by sending a Resv message a host cannot alone
update the reservation, and thus perform a local repair, before a
Path message has passed. Also, in order to provide fast adaptation to
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routing changes without the overhead of short refresh periods, the
local routing protocol module can notify the RSVP process of route
changes for particular destinations. The RSVP process should use this
information to trigger a quick refresh of state for these
destinations, using the new route (Chapter 3.6, RFC2205). However,
not all local mobility protocols, or even Mobile IP, affect routing
directly in routers, and thus mobility may not be noticed at RSVP
routers. Thus, it may take a relatively long time before a
reservation is refreshed following a handover.
The interactions of RSVP and Mobile IP have been well documented in
[Thom01].
2.6. Security
To allow a process on a system to securely identify the owner and the
application of the communicating process (e.g. user id) and convey
this information in RSVP messages (PATH or RESV) in a secure manner,
[RFC2752] specifies the encoding of identities as RSVP POLICY_DATA
Object.
To provide hop-by-hop integrity and authentication of RSVP messages,
RSVP message may contain an INTEGRITY object ([RFC2747]) using a
keyed cryptographic digest technique which assumes that RSVP
neighbors share a secret. (BTW - [RFC3097] updates [RFC2747] to
resolve a duplication of RSVP message types.)
The security issues have been well analyzed in [Tsch02].
2.7. Deployment Issues
As a well-acknowledged protocol in the Internet, RSVP is being more
and more expected to provide a more generic service for various
signaling applications. However, RSVP messages were designed in a way
to optimally support end-to-end QoS signaling. To meet with the
increasing demand for a signaling protocol to also operate in host-
to-edge and edge-to-edge ways, and serve for some other signaling
purposes in addition to end-to-end QoS signaling, RSVP needs to be
developed more flexible and applicable for more generic signaling.
RSVP proxies [BEGD02] extends RSVP by being able to originates or
receive the RSVP message on behalf of the end node(s), so that
applications may still benefit from reservations that are not truly
end-to-end. However, there are certainly scenarios where an
application would want to explicitly convey its non-QoS purposed (as
well as QoS) data from a host into the network, or from an ingress
node to an egress node of an administrative domain, but it must do so
without burdening the network with excess messaging overhead. Typical
examples are an end host desiring a firewall service from its
provider's network and MPLS label setup within an MPLS domain.
RSVP requires support from network routers and user space
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applications. Domains not supporting RSVP are traversed
transparently. Unfortunately, like other IP options, RSVP messages
implemented by way of IP alert option may result in themselfs being
dropped by some routers [FrJo02]. Although applications need to be
built with RSVP libraries, one article presents a mechanism that
would allow any host to benefit from RSVP mechanisms without
applications awareness [MHS02].
A somewhat similar deployment benefit can be gained from the
Localized RSVP [MSK+02]. The draft presents the concept of local
RSVP-based reservation that can be used to trigger reservation within
an access network alone. In those cases, an end-host may request QoS
from its own access network without the co-operation of a
correspondent node outside the access network. A proxy node responds
to the messages sent by the end host and enables both upstream and
downstream reservations. Furthermore, the scheme allows for faster
reservation repairs following a handover by triggering the proxy to
initiate an RSVP local repair.
Still, in end-hosts which are low in processing power and
functionality, having an rsvp daemon running and taking care of the
signalling may introduce unnecessary overhead. One article [Kars01]
proposes to create a remote API so that the daemon would in fact be
running on the end-host's default router and the end-host application
would send its requests to that daemon.
Another potential problem lies in the limited sized of signaled data
due to the limitation of message size. RSVP message must fit entirely
into a single non-fragmented IP datagram. Bundle messages ([RFC2961])
may be as large as an IP datagram, since they may be fragmented. This
means a maximum size of 64K.
2.8. Conclusions
The design of RSVP was originally targeted at multicast applications.
The result has been that the message processing within nodes is
somewhat heavy, mainly due to flow merging. Still, merging rules
could not appear in the specification as they are QoS-specific.
RSVP has a comprehensive set of filtering rules (WF,FF, shared) and
is not tied to certain QoS objects (RSVP is not tied to IntServ GS/CL
specifications). Objects were designed to be modular, but Xspecs
(TSpec, etc) are more or less QoS-specific and should be more
generalized; there is no clear layering/separation between the
signaled data and signaling protocol.
RSVP uses a soft state mechanism to maintain states and allows each
node to define its own refresh timer. The protocol is also
independent of underlying routing protocols. Still, in mobile
networks the movement of the mobile nodes may not properly trigger a
reservation refresh for the new path and therefore a mobile node may
be left without a reservation up to the length of the refresh timer.
Furthermore, RSVP does not work properly with changing end-point
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identifiers, that is, if one of the IP addresses of a mobile node
changes, the filters may not be able to identify the flow that had a
reservation.
From the security point of view, RSVP does provide the necessary
building blocks for deploying the protocol in various environments.
Still, one major problem of RSVP security is that no key distribution
mechanism is provided.
Finally, since the publication of the RSVP standard, tens of
extensions have emerged that allow for much wider deployment than
RSVP was originally designed for, as for instance, the Subnet
Bandwidth Manager, the NULL service type, aggregation, operation over
tunneling and MPLS as well as diagnostic messages.
Domains not supporting RSVP are traversed transparently by default.
Unfortunately, like other IP options, RSVP messages implemented by
way of IP alert option may result in themselves being dropped by some
routers. Also, the maximal size of RSVP-signaled data is limited.
3. YESSIR
YESSIR (YEt another Sender Session Internet Reservations) [PaSc98] is
a resource reservation protocol that seeks to simplify the process of
establishing reserved flows while preserving many unique features
introduced in RSVP. Simplicity is measured in terms of control
message processing, data packet processing, and user-level
flexibility. Features such as robustness, advertising network service
availability and resource sharing among multiple senders are also
supported in the proposal.
The proposed mechanism generates reservation requests by senders to
reduce the processing overhead. It is built as an extension to the
Real-Time Transport Control Protocol (RTCP), taking advantages of
Real-Time Protocol (RTP). YESSIR also introduces a concept called
partial reservation.
3.1. Reservation Functionality
YESSIR was designed for one-way, sender-initiated end-to-end resource
reservation. It also uses soft state to maintain states. It supports
resource query (similar to RSVP diagnosis message), advertising
(similar to RSVP Adspec), shared reservation, partial reservations
and flow merging.
To support multicast, YESSIR simplies the reservation styles to
individual and shared reservation styles. Individual reservations are
made separately for each sender, whereas shared reservations allocate
resources that can be used by all senders in an RTP session. Unlike
RSVP supports shared reservation (SE and WF styles) from the
receiver's direction, YESSIR handles the shared reservation style
from the sender's direction, thus new receivers can re-use the
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existing reservation of the previous sender.
3.2. Processing Overhead
In [PaSc00], it was proved that YESSIR one-pass reservation model has
better performance and lower processing cost, comparing with a
regular two-way signaling protocol.
3.3. Bandwidth Consumption
The bandwidth consumption of YESSIR is somewhat lower than that of,
for example, RSVP, because it does not require additional IP and
transport headers. Bandwidth consumption is limited to the extension
header size.
3.4. Mobility Support
YESSIR does not have any particular support for mobility. The same
issues that were identified with RSVP apply.
3.5. Security
The security of YESSIR relies on RTP/RTCP security measures.
3.6. Deployment Issues
YESSIR requires support in applications since it is an integral part
of RTCP. Similarly, it requires network routers to inspect RTCP
packets to identify reservation requests and refreshes. Routers
unaware of YESSIR forward the RTCP packets transparently.
3.7. Conclusions
<TBD>
4. Boomerang
Boomerang [FNM+99] is a light-weight resource reservation protocol
for IP networks. The protocol has only one message type and a single
signaling loop for reservation set-up and tear-down, has no
requirements on the far end node, but, instead, concentrates the
intelligence in the Initiating Node (IN).
In addition, the Boomerang protocol allows for sender- or receiver-
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oriented reservations and resource query. Flows are identified with
the common 5-tuple and the QoS can be specified with various means,
eg. service class and bit rate. Boomerang messages are in the initial
implementation transported in ICMP ECHO / REPLY messages.
4.1. Reservation Functionality
Boomerang can only be used for unicast sessions, no support for
multicast exists. The requested QoS can be specified with various
methods and both ends of a communication session can make a
reservation for their transmitted flow.
4.2. Processing Overhead
The authors of Boomerang show in [FNS02] that the processing of the
protocol is considerably lower than with the ISI RSVP daemon
implementation.
4.3. Bandwidth Consumption
Boomerang messages are quite short and consume a relatively low
amount of link bandwidth.
<TBD>
4.4. Mobility Support
The same issues that were identified with RSVP apply with Boomerang.
4.5. Security
No mechanisms for providing message integrity or user identification
have been presented.
4.6. Deployment Issues
The Boomerang protocol has similar deployment issues as any host-
network-host protocol. It requires an implementation at both
communicating nodes and in routers. Boomerang-unaware routers should
be able to forward Boomerang messages transparently.
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4.7. Conclusions
Boomerang seems to be a very lightweight protocol and efficient in
its own scenarios. Still, the apparent low processing overhead and
bandwidth consumption results from the limited functionality. No
support for multicast or any security features are present which
allows for a different functionality than RSVP, which the authors
like to compare Boomerang to.
5. Other Protocols
This section presents shortly other signalling protocols designed to
carry resource information for flows.
5.1. INSIGNIA
INSIGNIA [PaSc00] has been developed at the Columbia University and
is proposed as a very simple signaling mechanism for supporting QoS
in mobile ad-hoc networks. It avoids the need for separate signaling
by carrying the signaling along with the data in IP packets using IP
packet header options. This approach, known as "in-band signaling" is
proposed as more suitable in the rapidly changing environment of
mobile networks since the signalled QoS information is not tied to a
particular path. It also allows the flows to be rapidly established
and, thus, is suitable for short lived and dynamic flows.
INSIGNIA aims to minimize signaling by reducing the number of
parameters that are provided to the network. It assumes that real-
time flows may tolerate some loss, but are very delay sensitive so
that the only QoS information needed is the required minimum and
maximum bandwidth.
The INSIGNIA protocol operates at the network layer and assumes that
link status sensing and access schemes are provided by lower layer
entities. The usefulness of the scheme depends upon the MAC layers
but this is undefined so that INSIGNIA can run over any MAC layer.
The protocol requires that each router maintains per-flow state.
The INSIGNIA system implicitly supports mobility. A near-minimal
amount of information is exchanged with the network. To achieve this,
INSIGNIA makes many assumptions about the nature of traffic that a
source will send. This may also simplify admission control and buffer
allocation. The system basically assumes that "real-time" will be
defined as a maximum delay and the user can simply request real-time
service for a particular quantity of traffic.
After handover, data that was transmitted to the old base station can
be forwarded to the new base station so that no data loss should
occur. However, there is no way to differentiate between re-routed
and new traffic so priority cannot be given to handover traffic, for
example.
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5.2. Mobile RSVP
Mobile RSVP (MRSVP) [MRSVP] is an extension to standard RSVP. It is
based on advance reservations, where neighboring access points keep
resources reserved for mobile nodes moving to their coverage area.
When a mobile node requests resources, the neighboring access points
are checked too and a passive reservation is done around the mobile
nodes current location.
<TBD>
5.3. BGRP
Border Gateway Reservation Protocol (BGRP) [BGRP] is a signaling
protocol for interdomain aggregated resource reservation for unicast
traffic. BGRP builds a sink tree for each of the stub domains. Each
sink tree aggregates bandwidth reservations from all data sources in
the network. BGRP maintains these aggregated reservations using soft
state and relies on Differentiated Services for data forwarding.
BGRP scales in terms of message processing load, state storage and
bandwidth. Since backbone routers only maintain the sink tree
information, the total number of reservations at each router scales
linearly with the number of Internet domains.
<TBD>
5.4. ST-II
ST-II [RFC1819] is an experimental resource reservation protocol
intended to provide end-to-end real-time guarantees over an internet.
It allows applications to build multi-destination simplex data
streams with a desired quality of service. ST-II consists of two
protocols: ST for the data transport and SCMP, the Stream Control
Message Protocol, for all control functions. ST is simple and
contains only a single PDU format that is designed for fast and
efficient data forwarding in order to achieve low communication
delays. SCMP packets are transferred within ST packets.
ST-II has no built-in soft states, thus requires that the network be
responsible for correctness. It is sender-initiated, and the overhead
for ST-II to handle group membership dynamics is higher than RSVP
[MESZ94].
<TBD>
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5.5. The ITSUMO Framework
The ITSUMO Framework [CCM+00] is an example of an architecture with a
hierarchy of bandwidth brokers. The architecture is based on
Differentiated Services: the traffic is aggregated and forwarded in
backbone networks based on per-hop behaviors. In the architecture
there is at least one global server and several local nodes in each
Radio Access Network (RAN). The server is referred to as the QoS
Global Server (QGS) and local nodes are referred to as QoS Local
Nodes (QLN). The QLNs are ingress nodes of the DiffServ domain. They
usually reside at the edge of a wired backbone network and a Layer 2
Radio Access Network. The QGS retains the global information of the
domain and informs QLNs what to do when traffic comes in.
The mobile node communicates its QoS requirements directly to the QGS
through the use of SIP messages, for example. Once the mobile node
has had such a request accepted, it is guaranteed within the Service
Level Agreement, that the node can move in the domain and receive the
required QoS. The QGS server has a near-to-complete picture of the
state of the network at any time. This is achieved by regular polling
of all QLNs. The QGS uses the received information to determine if a
particular request can be supported. Once it has concluded that the
request cab be fulfilled, it broadcasts the decision to all nodes
likely to be affected by the mobile node. Mobility guarantees are
made by notifying QLNs of mobile nodes likely to arrive into their
cells.
The Service Level Specification (SLS) is usually agreed by both the
user and the service provider when the user signs up a service
subscription. To change the SLS in wired network, the mobile has to
contact the service provider. Once the negotiation is done, the
mobile can utilize the new SLS. Once the negotiation between the
mobile and the QGS is done, the QGS multicasts the decision to all
QLNs in the same administration domain. Therefore, the mobile node
can utilize the new SLS anywhere within the same administrative
domain. Thus, dynamic SLS for mobile environment is achieved with a
single negotiation in one administration domain.
The ITSUMO approach offers classes of services mainly based on the
combination of two parameters: latency and loss. For each parameter
possible values are high, moderate, and low for latency and high,
moderate, low, and none for the packet loss. The combination of the
two parameters forms a spectrum with 12 classes of services.
Furthermore, the ITSUMO architecture includes a set of mobility
protocols. The Dynamic Registration and Configuration Protocol (DRCP)
is similar than the Dynamic Host Configuration Protocol (DHCP) and
supports host configuration and registration. The Host Mobility and
Management Protocol (HMMP) provides dynamic address binding and
personal mobility.
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6. Summary
- Gather the good ideas from the protocols as a basis for the future
designs
- Perhaps note that extensive features and simplicity do not go hand-
in-hand: "if you want features, be prepared to pay for the cost".
7. Security Considerations
There are no security issues in this document. Individual protocols
include different levels of security issues and those are highlighted
in the relevant sections.
8. Contributors
This document is part of the work done in the NSIS Working Group. The
draft was initially written by Jukka Manner and Xiaoming Fu.
9. Acknowledgement
<TBD as needed>
10. References
[RFC1819] L. Delgrossi and L. Berger, Editors, Internet Stream
Protocol Version 2 (ST2) Protocol Specification - Version ST2+,
RFC 1819, August 1995.
[MESZ94] D. Mitzel, D. Estrin, S. Shenker, and L. Zhang, An
Architectural Comparison of ST-II and RSVP, INFOCOM'94.
[BEBH96] Braden, R., Estrin, D., Berson, S., Herzog, S. and D.
Zappala, "The Design of the RSVP Protocol", ISI Final Technical
Report, Jul 1996.
[RSVP] Zhang, L., Deering, S., Estrin, D. and D. Zappala, "RSVP: A
New Resource Reservation Protocol", IEEE Network, Volume 7, Pages
8-18, Sep 1993.
[RFC2205] Braden, R., Zhang, L., Berson, S., Herzog, S. and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, Sep 1997.
[RFC2207] L. Berger and T. O'Malley, RSVP Extensions for IPSEC Data
Flows, RFC 2207, September 1997.
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated
Services", RFC 2210, September 1997.
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[RFC2998] Bernet, Y., Yavatkar, R., Ford, P., Baker, F., Zhang, L.,
Speer, M., Braden, R. and B. Davie, "Integrated Services Operation
over Diffserv Networks", RFC 2998, November 2000.
[RFC2749] Boyle, J., Cohen, R., Durham, D., Herzog, S., Raja, R.
and A. Sastry, COPS usage for RSVP, RFC 2749, January 2000.
[RFC2750] Herzog, S., RSVP Extensions for Policy Control, RFC
2750, January 2000.
[RFC2751] Herzog, S., Signaled Preemption Priority Policy Element,
RFC 2751, January 2000.
[RFC2752] Yadav, S., et al., "Identity Representation for RSVP",
RFC 2752, January 2000.
[RFC2747] Baker, F., Lindell, B. and M. Talwar, RSVP Cryptographic
Authentication, RFC 2747, January 2000.
[RFC2380] Berger, L., RSVP over ATM Implementation Requirements,
RFC 2380, August 1998.
[RFC2814] Yavatkar, R., Hoffman, D., Bernet, Y., Baker, F. and M.
Speer, SBM (Subnet Bandwidth Manager): A Protocol for Admission
Control over IEEE 802-style Networks, RFC 2814, May 2000.
[RFC2745] Terzis, A., Braden B., S. Vincent, and L. Zhang, RSVP
Diagnostic Messages, RFC 2745, January 2000.
[RFC2746] Terzis, A., Krawczyk, J., Wroclawski, J. and L. Zhang,
RSVP Operation Over IP Tunnels, RFC 2746, January 2000.
[RFC2961] Berger, L., Gan, D., Swallow, G., Pan, P. and F. Tommasi,
RSVP Refresh Reduction Extensions, RFC 2961, April 2001.
[RFC2996] Bernet, Y., Format of the RSVP DCLASS Object, RFC 2996,
November 2000.
[RFC2997] Bernet, Y., Smiht, A. and B. Davie, Specification of the
Null Service Type, RFC 2997, November 2000.
[RFC3175] F. Baker, C. Iturralde, F. Le Faucheur, B. Davie,
Aggregation of RSVP for IPv4 and IPv6 Reservations, RFC 3175,
September 2001
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.
and G. Swallow, Extensions to RSVP for LSP Tunnels, RFC 3209,
December 2001.
[RFC3270] F. Le Faucheur (ed), L. Wu, and et al, Multi-Protocol
Label Switching (MPLS) Support of Differentiated Services, RFC
3270, May 2002.
[RFC2362] Estrin, D., Farinacci, D., Helmy, A., Thaler, D.,
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Deering, S., Handley, M. and V. Jacobson, "Protocol Independent
Multicast-Sparse Mode (PIM-SM): Protocol Specification", RFC 2362,
June, 1998.
[Hame02] L-N. Hamer, et al, Session Authorization Policy Element,
Internet Draft, October 2002.
(draft-ietf-rap-rsvp-authsession-04.txt)
[BEGD02] Bernet, Y., Elfassy, N., Gai, S. and D. Dutt, "RSVP
Proxy", draft-ietf-rsvp-proxy-03 (work in progress), Mar 2002.
[Meer02] H. de Meer, et al. "Analysis of Existing QoS Solutions".
Internet Draft. (draft-demeer-nsis-analysis-02.txt)
[Tsch02] Hannes Tschofenig, "RSVP Security Properties". Internet
Draft, June 2002. (draft-tschofenig-rsvp-sec-properties-00.txt)
[Fu02] Xiaoming Fu, et al, "Analysis on RSVP Regarding Multicast".
Internet Draft, October 2002.
(draft-fu-rsvp-multicast-analysis-01.txt)
[Thom01] Michael Thomas, "Analysis of Mobile IP and RSVP
Interactions". draft-thomas-seamoby-rsvp-analysis-00.txt
(expired). Available from eg.
(www.mtcc.com/standards/draft-thomas-seamoby-rsvp-analysis-00.txt)
[RaNa98] B. Rajagopalan and R. Nair. "Multicast Routing with
Resource Reservation". Journal of High Speed Networks, 7(2), pp.
113-139, July 1998.
[FrJo02] Pierre Fransson and Andreas Jonsson, "The need for an
alternative to IPv4-options", in RVK (RadioVetenskap och
Kommunikation),
Stockholm, Sweden, pp. 162-166, June 200.
[MHS02] Yu-Ben Miao, Wen-Shyang Hwang, Ce-Kuen Shieh, "A
transparent deployment method of RSVP-aware applications on UNIX".
Computer Networks, 40 (2002), pp. 45-56.
[FNS02] Gabor Feher, Krisztian Nemeth, Istvan Cselenyi,
"Performance evaluation framework for IP resource reservation
signalling". Performance Evaluation 48 (2002), pp. 131-156.
[PaSc98] Ping Pan, Henning Schulzrinne, "YESSIR: A Simple
Reservation Mechanism for the Internet". In the Proceedings of
NOSSDAV, Cambridge, UK, July 1998.
[PaSc00] P. Pan, and H. Schulzrinne, "Lightweight Resource
Reservation Signaling: Design, Performance and Implementation",
Bell Labs Technical Memorandum 10009669-03, July 2000.
[KaSh01] Martin Karsten, Jens Schmitt, Ralf Steinmetz,
"Implementation and Evaluation of the KOM RSVP Engine". IEEE
Infocom 2001.
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[Kars01] Martin Karsten, "Experimental Extensions to RSVP -- Remote
Client and One-Pass Signalling". IWQoS 2001, Karlsruhe, Germany,
June 2001.
[LGZC00] S. Lee, A. Gahng-Seop, X. Zhang, A. Campbell,"INSIGNIA: An
IP-Based Quality of Service Framework for Mobile Ad Hoc
Networks". Journal of Parallel and Distributed Computing (Academic
Press), Special issue on Wireless and Mobile Computing and
Communications}, Vol. 60, Number 4, April, 2000, pp. 374-406.
[CCM+00] Jyh-Cheng Chen, Armando Caro, Anthony McAuley, Shinichi
Baba, Yoshihiro Ohba, Parameswaran Ramanathan,"A QoS Architecture
for Future Wireless IP Networks". Proceedings of the Twelfth IASTED
International Conference on Parallel and Distributed Computing and
Systems (PDCS 2000), Las Vegas, NV, November, 2000.
[FNM+99] G. Feher, K. Nemeth, M. Maliosz, I. Cselenyi, J.
Bergkvist, D. Ahlard, T. Engborg, "Boomerang A Simple Protocol for
Resource Reservation in IP Networks", IEEE RTAS, 1999.
[MSK+02] J. Manner, T. Suihko, M. Kojo, M. Liljeberg, K.
Raatikainen, "Localized RSVP". Internet Draft, May 2002.
(draft-manner-lrsvp-00.txt)
[BGRP] P. Pan, E, Hahne, and H. Schulzrinne, "BGRP: A Tree-Based
Aggregation Protocol for Inter-domain Reservations", Journal of
Communications and Networks, Vol. 2, No. 2, June 2000, pp. 157-167.
[MRSVP] A. Talukdar, B. Badrinath, and A. Acharya, MRSVP: A
Resource Reservation Protocol for an Integrated Services Network
with Mobile Hosts, Wireless Networks, vol. 7, no. 1,
pp. 5-19. 2001.
11. Author's Addresses
Questions about this document may be directed to:
Jukka Manner
Department of Computer Science
University of Helsinki
P.O. Box 26 (Teollisuuskatu 23)
FIN-00014 HELSINKI
Finland
Voice: +358-9-191-44210
Fax: +358-9-191-44441
E-Mail: jmanner@cs.helsinki.fi
Xiaoming Fu
Institute of Informatics
Georg-August-University of Goettingen
Lotzestrasse 16-18
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37083 Goettingen
Germany
Voice: +49-551-39-14411
Fax: +49-551-39-14403
E-Mail: fu@cs.uni-goettingen.de
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Full Copyright Statement
Copyright (C) The Internet Society (2001). All Rights Reserved.
This document and translations of it may be copied and furnished to
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or assist in its implementation may be prepared, copied, published
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included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
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Manner et al Expires April 2003 [Page 22]
