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Keywords: [--------|p], session object, session of interest, phb, per hop behavior
Network Working Group F. Le Faucheur
Request for Comments: 4860 B. Davie
Category: Standards Track Cisco Systems, Inc.
P. Bose
Lockheed Martin
C. Christou
M. Davenport
Booz Allen Hamilton
May 2007
Generic Aggregate Resource ReSerVation Protocol (RSVP) Reservations
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
RFC 3175 defines aggregate Resource ReSerVation Protocol (RSVP)
reservations allowing resources to be reserved in a Diffserv network
for a given Per Hop Behavior (PHB), or given set of PHBs, from a
given source to a given destination. RFC 3175 also defines how end-
to-end RSVP reservations can be aggregated onto such aggregate
reservations when transiting through a Diffserv cloud. There are
situations where multiple such aggregate reservations are needed for
the same source IP address, destination IP address, and PHB (or set
of PHBs). However, this is not supported by the aggregate
reservations defined in RFC 3175. In order to support this, the
present document defines a more flexible type of aggregate RSVP
reservations, referred to as generic aggregate reservation. Multiple
such generic aggregate reservations can be established for a given
PHB (or set of PHBs) from a given source IP address to a given
destination IP address. The generic aggregate reservations may be
used to aggregate end-to-end RSVP reservations. This document also
defines the procedures for such aggregation. The generic aggregate
reservations may also be used end-to-end directly by end-systems
attached to a Diffserv network.
Le Faucheur, et al. Standards Track [Page 1]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
Table of Contents
1. Introduction ....................................................3
1.1. Related IETF Documents .....................................6
1.2. Organization of This Document ..............................6
1.3. Requirements Language ......................................7
2. Object Definition ...............................................7
2.1. SESSION Class ..............................................8
2.2. SESSION-OF-INTEREST (SOI) Class ...........................11
3. Processing Rules for Handling Generic Aggregate RSVP
Reservations ...................................................13
3.1. Extensions to Path and Resv Processing ....................13
4. Procedures for Aggregation over Generic Aggregate RSVP
Reservations ...................................................14
5. Example Usage Of Multiple Generic Aggregate Reservations
per PHB from a Given Aggregator to a Given Deaggregator ........19
6. Security Considerations ........................................21
7. IANA Considerations ............................................24
8. Acknowledgments ................................................25
9. Normative References ...........................................26
10. Informative References ........................................26
Appendix A. Example Signaling Flow ................................28
Le Faucheur, et al. Standards Track [Page 2]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
1. Introduction
[RSVP-AGG] defines RSVP aggregate reservations that allow resources
to be reserved in a Diffserv network for a flow characterized by its
3-tuple <source IP address, destination IP address, Diffserv Code
Point>.
[RSVP-AGG] also defines the procedures for aggregation of end-to-end
(E2E) RSVP reservations onto such aggregate reservations when
transiting through a Diffserv cloud. Such aggregation is illustrated
in Figure 1. This document reuses the terminology defined in
[RSVP-AGG].
--------------------------
/ Aggregation \
|----| | Region | |----|
H--| R |\ |-----| |------| /| R |-->H
H--| |\\| | |---| |---| | |//| |-->H
|----| \| | | I | | I | | |/ |----|
| Agg |======================>| Deag |
/| | | | | | | |\
H--------//| | |---| |---| | |\\-------->H
H--------/ |-----| |------| \-------->H
| |
\ /
--------------------------
H = Host requesting end-to-end RSVP reservations
R = RSVP router
Agg = Aggregator
Deag = Deaggregator
I = Interior Router
--> = E2E RSVP reservation
==> = Aggregate RSVP reservation
Figure 1 : Aggregation of E2E Reservations
over Aggregate RSVP Reservations
These aggregate reservations use a SESSION type specified in
[RSVP-AGG] that contains the receiver (or Deaggregator) IP address
and the Diffserv Code Point (DSCP) of the Per Hop Behavior (PHB) from
which Diffserv resources are to be reserved. For example, in the
case of IPv4, the SESSION object is specified as:
Le Faucheur, et al. Standards Track [Page 3]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
o Class = SESSION,
C-Type = RSVP-AGGREGATE-IP4
+-------------+-------------+-------------+-------------+
| IPv4 Session Address (4 bytes) |
+-------------+-------------+-------------+-------------+
| /////////// | Flags | ///////// | DSCP |
+-------------+-------------+-------------+-------------+
These aggregate reservations use SENDER_TEMPLATE and FILTER_SPEC
types, specified in [RSVP-AGG], that contain only the sender (or
Aggregator) IP address. For example, in the case of IPv4, the
SENDER_TEMPLATE object is specified as:
o Class = SENDER_TEMPLATE,
C-Type = RSVP-AGGREGATE-IP4
+-------------+-------------+-------------+-------------+
| IPv4 Aggregator Address (4 bytes) |
+-------------+-------------+-------------+-------------+
Thus, it is possible to establish, from a given source IP address to
a given destination IP address, separate such aggregate reservations
for different PHBs (or different sets of PHBs). However, from a
given source IP address to a given IP destination address, only a
single [RSVP-AGG] aggregate reservation can be established for a
given PHB (or given set of PHBs).
Situations have since been identified where multiple such aggregate
reservations are needed for the same source IP address, destination
IP address, and PHB (or set of PHBs). One example is where E2E
reservations using different preemption priorities (as per
[RSVP-PREEMP]) need to be aggregated through a Diffserv cloud using
the same PHB. Using multiple aggregate reservations for the same PHB
allows enforcement of the different preemption priorities within the
aggregation region. In turn, this allows more efficient management
of the Diffserv resources, and in periods of resource shortage, this
allows sustainment of a larger number of E2E reservations with higher
preemption priorities.
For example, [SIG-NESTED] discusses in detail how end-to-end RSVP
reservations can be established in a nested VPN environment through
RSVP aggregation. In particular, [SIG-NESTED] describes how multiple
parallel generic aggregate reservations (for the same PHB), each with
different preemption priorities, can be used to efficiently support
the preemption priorities of end-to-end reservations.
Le Faucheur, et al. Standards Track [Page 4]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
This document addresses this requirement for multiple aggregate
reservations for the same PHB (or same set of PHBs), by defining a
more flexible type of aggregate RSVP reservations, referred to as
generic aggregate reservations. This is achieved primarily by adding
the notions of a Virtual Destination Port and of an Extended Virtual
Destination Port in the RSVP SESSION object.
The notion of Virtual Destination Port was introduced in [RSVP-IPSEC]
to address a similar requirement (albeit in a different context) for
identification and demultiplexing of sessions beyond the IP
destination address. This document reuses this notion from
[RSVP-IPSEC] for identification and demultiplexing of generic
aggregate sessions beyond the IP destination address and PHB. This
allows multiple generic aggregate reservations to be established for
a given PHB (or set of PHBs), from a given source IP address to a
given destination IP address.
[RSVP-TE] introduced the concept of an Extended Tunnel ID (in
addition to the tunnel egress address and the Tunnel ID) in the
SESSION object used to establish MPLS Traffic Engineering tunnels
with RSVP. The Extended Tunnel ID provides a very convenient
mechanism for the tunnel ingress node to narrow the scope of the
session to the ingress-egress pair. The ingress node can achieve
this by using one of its own IP addresses as a globally unique
identifier and including it in the Extended Tunnel ID and therefore
within the SESSION object. This document reuses this notion of
Extended Tunnel ID from [RSVP-TE], simply renaming it Extended
Virtual Destination Port. This provides a convenient mechanism to
narrow the scope of a generic aggregate session to an Aggregator-
Deaggregator pair.
The RSVP SESSION object for generic aggregate reservations uses the
PHB Identification Code (PHB-ID) defined in [PHB-ID] to identify the
PHB, or set of PHBs, from which the Diffserv resources are to be
reserved. This is instead of using the Diffserv Code Point (DSCP) as
per [RSVP-AGG]. Using the PHB-ID instead of the DSCP allows explicit
indication of whether the Diffserv resources belong to a single PHB
or to a set of PHBs. It also facilitates handling of situations
where a generic aggregate reservation spans two (or more) Diffserv
domains that use different DSCP values for the same Diffserv PHB (or
set of PHBs) from which resources are reserved. This is because the
PHB-ID allows conveying of the PHB (or set of PHBs) independently of
what DSCP value(s) are used locally for that PHB (or set of PHBs).
The generic aggregate reservations may be used to aggregate end-to-
end RSVP reservations. This document also defines the procedures for
such aggregation. These procedures are based on those of [RSVP-AGG],
and this document only specifies the differences from those.
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
The generic aggregate reservations may also be used end-to-end
directly by end-systems attached to a Diffserv network.
1.1. Related IETF Documents
This document is heavily based on [RSVP-AGG]. It reuses [RSVP-AGG]
wherever applicable and only specifies the necessary extensions
beyond [RSVP-AGG].
The mechanisms defined in [BW-REDUC] allow an existing reservation to
be reduced in allocated bandwidth by RSVP routers in lieu of tearing
that reservation down. These mechanisms are applicable to the
generic aggregate reservations defined in the present document.
[RSVP-TUNNEL] describes a general approach to running RSVP over
various types of tunnels. One of these types of tunnel, referred to
as a "type 2 tunnel", has some similarity with the generic aggregate
reservations described in this document. The similarity stems from
the fact that a single, aggregate reservation is made for the tunnel
while many individual flows are carried over that tunnel. However,
[RSVP-TUNNEL] does not address the use of Diffserv-based
classification and scheduling in the core of a network (between
tunnel endpoints), but rather relies on a UDP/IP tunnel header for
classification. This is why [RSVP-AGG] required additional objects
and procedures beyond those of [RSVP-TUNNEL]. Like [RSVP-AGG], this
document also assumes the use of Diffserv-based classification and
scheduling in the aggregation region and, thus, requires additional
objects and procedures beyond those of [RSVP-TUNNEL].
As explained earlier, this document reuses the notion of Virtual
Destination Port from [RSVP-IPSEC] and the notion of Extended Tunnel
ID from [RSVP-TE].
1.2. Organization Of This Document
Section 2 defines the new RSVP objects related to generic aggregate
reservations and to aggregation of E2E reservations onto those.
Section 3 describes the processing rules for handling of generic
aggregate reservations. Section 4 specifies the procedures for
aggregation of end-to-end RSVP reservations over generic aggregate
RSVP reservations. Section 5 provides example usage of how the
generic aggregate reservations may be used.
The Security Considerations and the IANA Considerations are discussed
in Sections 6 and 7, respectively.
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
Finally, Appendix A provides an example signaling flow that
illustrates aggregation of E2E RSVP reservations onto generic
aggregate RSVP reservations.
1.3. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [KEYWORDS].
2. Object Definition
This document reuses the RSVP-AGGREGATE-IP4 FILTER_SPEC, RSVP-
AGGREGATE-IP6 FILTER_SPEC, RSVP-AGGREGATE-IP4 SENDER_TEMPLATE, and
RSVP-AGGREGATE-IP6 SENDER_TEMPLATE objects defined in [RSVP-AGG].
This document defines:
- two new objects (GENERIC-AGGREGATE-IP4 SESSION and GENERIC-
AGGREGATE-IP6 SESSION) under the existing SESSION Class, and
- two new objects (GENERIC-AGG-IP4-SOI and GENERIC-AGG-IP6-SOI)
under a new SESSION-OF-INTEREST Class.
Detailed description of these objects is provided below in this
section.
The GENERIC-AGGREGATE-IP4 SESSION and GENERIC-AGGREGATE-IP6 SESSION
objects are applicable to all types of RSVP messages.
This specification defines the use of the GENERIC-AGG-IP4-SOI and
GENERIC-AGG-IP6-SOI objects in two circumstances:
- inside an E2E PathErr message that contains an error code of
NEW-AGGREGATE-NEEDED in order to convey the session of a new
generic aggregate reservation that needs to be established.
- inside an E2E Resv message in order to convey the session of the
generic aggregate reservation onto which this E2E reservation
needs to be mapped.
Details of the corresponding procedures can be found in Section 4.
However, it is envisioned that the ability to signal, inside RSVP
messages, the Session of another reservation (which has some
relationship with the current RSVP reservation) might have some other
applicability in the future. Thus, those objects have been specified
in a more generic manner under a flexible SESSION-OF-INTEREST class.
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
All the new objects defined in this document are optional with
respect to RSVP so that general RSVP implementations that are not
concerned with generic aggregate reservations do not have to support
these objects. RSVP routers supporting generic aggregate IPv4 or
IPv6 reservations MUST support the GENERIC-AGGREGATE-IP4 SESSION
object or the GENERIC-AGGREGATE-IP6 SESSION object, respectively.
RSVP routers supporting RSVP aggregation over generic aggregate IPv4
or IPv6 reservations MUST support the GENERIC-AGG-IP4-SOI object or
GENERIC-AGG-IP6-SOI object, respectively.
2.1. SESSION Class
o GENERIC-AGGREGATE-IP4 SESSION object:
Class = 1 (SESSION)
C-Type = 17
0 7 8 15 16 23 24 31
+-------------+-------------+-------------+-------------+
| IPv4 DestAddress (4 bytes) |
+-------------+-------------+-------------+-------------+
| Reserved | Flags | PHB-ID |
+-------------+-------------+-------------+-------------+
| Reserved | vDstPort |
+-------------+-------------+-------------+-------------+
| Extended vDstPort |
+-------------+-------------+-------------+-------------+
0 7 8 15 16 23 24 31
IPv4 DestAddress (IPv4 Destination Address)
IPv4 address of the receiver (or Deaggregator).
Reserved
An 8-bit field. All bits MUST be set to 0 on transmit. This
field MUST be ignored on receipt.
Flags
An 8-bit field. The content and processing of this field are the
same as for the Flags field of the IPv4/UDP SESSION object (see
[RSVP]).
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
PHB-ID (Per Hop Behavior Identification Code)
A 16-bit field containing the Per Hop Behavior Identification Code
of the PHB, or of the set of PHBs, from which Diffserv resources
are to be reserved. This field MUST be encoded as specified in
Section 2 of [PHB-ID].
Reserved
A 16-bit field. All bits MUST be set to 0 on transmit. This
field MUST be ignored on receipt.
VDstPort (Virtual Destination Port)
A 16-bit identifier used in the SESSION that remains constant over
the life of the generic aggregate reservation.
Extended vDstPort (Extended Virtual Destination Port)
A 32-bit identifier used in the SESSION that remains constant over
the life of the generic aggregate reservation. A sender (or
Aggregator) that wishes to narrow the scope of a SESSION to the
sender-receiver pair (or Aggregator-Deaggregator pair) SHOULD
place its IPv4 address here as a network unique identifier. A
sender (or Aggregator) that wishes to use a common session with
other senders (or Aggregators) in order to use a shared
reservation across senders (or Aggregators) MUST set this field to
all zeros.
o GENERIC-AGGREGATE-IP6 SESSION object:
Class = 1 (SESSION)
C-Type = 18
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
0 7 8 15 16 23 24 31
+-------------+-------------+-------------+-------------+
| |
+ +
| |
+ IPv6 DestAddress (16 bytes) +
| |
+ +
| |
+-------------+-------------+-------------+-------------+
| Reserved | Flags | PHB-ID |
+-------------+-------------+-------------+-------------+
| Reserved | vDstPort |
+-------------+-------------+-------------+-------------+
| |
+ +
| Extended vDstPort |
+ +
| (16 bytes) |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 7 8 15 16 25 26 31
IPv6 DestAddress (IPv6 Destination Address)
IPv6 address of the receiver (or Deaggregator).
Reserved
An 8-bit field. All bits MUST be set to 0 on transmit. This
field MUST be ignored on receipt.
Flags
An 8-bit field. The content and processing of this field are the
same as for the Flags field of the IPv6/UDP SESSION object (see
[RSVP]).
PHB-ID (Per Hop Behavior Identification Code)
A 16-bit field containing the Per Hop Behavior Identification Code
of the PHB, or of the set of PHBs, from which Diffserv resources
are to be reserved. This field MUST be encoded as specified in
Section 2 of [PHB-ID].
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
Reserved
A 16-bit field. All bits MUST be set to 0 on transmit. This
field MUST be ignored on receipt.
VDstPort (Virtual Destination Port)
A 16-bit identifier used in the SESSION that remains constant over
the life of the generic aggregate reservation.
Extended vDstPort (Extended Virtual Destination Port)
A 128-bit identifier used in the SESSION that remains constant
over the life of the generic aggregate reservation. A sender (or
Aggregator) that wishes to narrow the scope of a SESSION to the
sender-receiver pair (or Aggregator-Deaggregator pair) SHOULD
place its IPv6 address here as a network unique identifier. A
sender (or Aggregator) that wishes to use a common session with
other senders (or Aggregators) in order to use a shared
reservation across senders (or Aggregators) MUST set this field to
all zeros.
2.2. SESSION-OF-INTEREST (SOI) Class
o GENERIC-AGG-IP4-SOI object:
Class = 132
C-Type = 1
0 7 8 15 16 23 24 31
+-------------+-------------+-------------+-------------+
| | SOI |GEN-AGG-IP4- |
| Length (bytes) | Class-Num |SOI C-Type |
+-------------+-------------+-------------+-------------+
| |
// Content of a GENERIC-AGGREGATE-IP4 SESSION Object //
| |
+-------------+-------------+-------------+-------------+
Content of a GENERIC-AGGREGATE-IP4 SESSION Object:
This field contains a copy of the SESSION object of the session
that is of interest for the reservation. In the case of a
GENERIC-AGG-IP4-SOI, the session of interest conveyed in this
field is a GENERIC-AGGREGATE-IP4 SESSION.
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
o GENERIC-AGG-IP6-SOI object:
Class = 132
C-Type = 2
0 7 8 15 16 23 24 31
+-------------+-------------+-------------+-------------+
| | SOI |GEN-AGG-IP6- |
| Length (bytes) | Class-Num |SOI C-Type |
+-------------+-------------+-------------+-------------+
| |
// Content of a GENERIC-AGGREGATE-IP6 SESSION Object //
| |
+-------------+-------------+-------------+-------------+
Content of a GENERIC-AGGREGATE-IP6 SESSION Object:
This field contains a copy of the SESSION object of the session
that is of interest for the reservation. In the case of a
GENERIC-AGG-IP6-SOI, the session of interest conveyed in this
field is a GENERIC-AGGREGATE-IP6 SESSION.
For example, if a SESSION-OF-INTEREST object is used inside an E2E
Resv message (as per the procedures defined in Section 4) to indicate
which generic aggregate IPv4 session the E2E reservation is to be
mapped onto, then the GENERIC-AGG-IP4-SOI object will be used, and it
will be encoded like this:
0 7 8 15 16 23 24 31
+-------------+-------------+-------------+-------------+
| | SOI |GEN-AGG-IP4- |
| Length (bytes) | Class-Num |SOI C-Type |
+-------------+-------------+-------------+-------------+
| IPv4 DestAddress (4 bytes) |
+-------------+-------------+-------------+--+----------+
| Reserved | Flags | PHB-ID |
+-------------+-------------+-------------+-------------+
| Reserved | vDstPort |
+-------------+-------------+-------------+-------------+
| Extended vDstPort |
+-------------+-------------+-------------+-------------+
0 7 8 15 16 23 24 31
Note that a SESSION-OF-INTEREST object is not a SESSION object in
itself. It does not replace the SESSION object in RSVP messages. It
does not modify the usage of the SESSION object in RSVP messages. It
simply allows conveying the Session of another RSVP reservation
inside RSVP signaling messages, for some particular purposes. In the
context of this document, it is used to convey, inside an E2E RSVP
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
message pertaining to an end-to-end reservation, the Session of a
generic aggregate reservation associated with the E2E reservation.
Details for the corresponding procedures are specified in Section 4.
3. Processing Rules for Handling Generic Aggregate RSVP Reservations
This section presents extensions to the processing of RSVP messages
required by [RSVP] and presented in [RSVP-PROCESS]. These extensions
are required in order to properly process the GENERIC-AGGREGATE-IP4
or GENERIC-AGGREGATE-IP6 SESSION object and the RSVP-AGGREGATE-IP4 or
RSVP-AGGREGATE-IP6 FILTER_SPEC object. Values for referenced error
codes can be found in [RSVP]. As with the other RSVP documents,
values for internally reported (API) errors are not defined.
When referring to the new GENERIC-AGGREGATE-IP4 and GENERIC-
AGGREGATE-IP6 SESSION objects, IP version will not be included, and
they will be referred to simply as GENERIC-AGGREGATE SESSION, unless
a specific distinction between IPv4 and IPv6 is being made.
When referring to the [RSVP-AGG] RSVP-AGGREGATE-IP4 and RSVP-
AGGREGATE-IP6 SESSION, FILTER_SPEC, and SENDER_TEMPLATE objects, IP
version will not be included, and they will be referred to simply as
RSVP-AGGREGATE, unless a specific distinction between IPv4 and IPv6
is being made.
3.1. Extensions to Path and Resv Processing
The following PATH message processing changes are defined:
o When a session is defined using the GENERIC-AGGREGATE SESSION
object, only the [RSVP-AGG] RSVP-AGGREGATE SENDER_TEMPLATE may
be used. When this condition is violated in a PATH message
received by an RSVP end-station, the RSVP end-station SHOULD
report a "Conflicting C-Type" API error to the application.
When this condition is violated in a PATH message received by an
RSVP router, the RSVP router MUST consider this as a message
formatting error.
o For PATH messages that contain the GENERIC-AGGREGATE SESSION
object, the VDstPort value, the Extended VDstPort value, and the
PHB-ID value should be recorded (in addition to the
destination/Deaggregator address and source/Aggregator address).
These values form part of the recorded state of the session.
The PHB-ID may need to be passed to traffic control; however the
vDstPort and Extended VDstPort are not passed to traffic control
since they do not appear inside the data packets of the
corresponding reservation.
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
The following changes to RESV message processing are defined:
o When a RESV message contains a [RSVP-AGG] RSVP-AGGREGATE
FILTER_SPEC, the session MUST be defined using either the RSVP-
AGGREGATE SESSION object (as per [RSVP-AGG]) or the GENERIC-
AGGREGATE SESSION object (as per this document). If this
condition is not met, an RSVP router or end-station MUST
consider that there is a message formatting error.
o When the RSVP-AGGREGATE FILTER_SPEC is used and the SESSION type
is GENERIC-AGGREGATE, each node uses data classifiers as per the
following:
* to perform Diffserv classification the node MUST rely on the
Diffserv data classifier based on the DSCP only. The relevant
DSCP value(s) are those that are associated with the PHB-ID of
the generic aggregate reservation.
* If the node also needs to perform fine-grain classification
(for example, to perform fine-grain input policing at a trust
boundary) then the node MUST create a data classifier
described by the 3-tuple <DestAddress, SrcAddress, DSCP>.
The relevant DSCP value(s) are those that are associated with
the PHB-ID of the generic aggregate reservation.
Note that if multiple generic aggregate reservations are
established with different Virtual Destination Ports (and/or
different Extended Virtual Destination Ports) but with the
same <DestAddress, SrcAddress, PHB-ID>, then those cannot be
distinguished by the classifier. If the router is using the
classifier for policing purposes, the router will therefore
police those together and MUST program the policing rate to
the sum of the reserved rate across all the corresponding
reservations.
4. Procedures for Aggregation over Generic Aggregate RSVP Reservations
The procedures for aggregation of E2E reservations over generic
aggregate RSVP reservations are the same as the procedures specified
in [RSVP-AGG] with the exceptions of the procedure changes listed in
this section.
As specified in [RSVP-AGG], the Deaggregator is responsible for
mapping a given E2E reservation on a given aggregate reservation.
The Deaggregator requests establishment of a new aggregate
reservation by sending to the Aggregator an E2E PathErr message with
an error code of NEW-AGGREGATE-NEEDED. In [RSVP-AGG], the
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
Deaggregator conveys the DSCP of the new requested aggregate
reservation by including a DCLASS Object in the E2E PathErr and
encoding the corresponding DSCP inside. This document modifies and
extends this procedure. The Deaggregator MUST include in the E2E
PathErr message a SESSION-OF-INTEREST object that contains the
GENERIC-AGGREGATE SESSION to be used for establishment of the
requested generic aggregate reservation. Since this GENERIC-
AGGREGATE SESSION contains the PHB-ID, the DCLASS object need not be
included in the PathErr message.
Note that the Deaggregator can easily ensure that different
Aggregators use different sessions for their Aggregate Path towards a
given Deaggregator. This is because the Deaggregator can easily
select VDstPort and/or Extended VDstPort numbers which are different
for each Aggregator (for example, by using the Aggregator address as
the Extended VDstPort) and can communicate those inside the GENERIC-
AGGREGATE SESSION included in the SESSION-OF-INTEREST object. This
provides an easy solution to establish separate reservations from
every Aggregator to a given Deaggregator. Conversely, if reservation
sharing were needed across multiple Aggregators, the Deaggregator
could facilitate this by allocating the same VDstPort and Extended
VDstPort to the multiple Aggregators, and thus including the same
GENERIC-AGGREGATE SESSION inside the SESSION-OF-INTEREST object in
the E2E PathErr messages sent to these Aggregators. The Aggregators
could then all establish an Aggregate Path with the same GENERIC-
AGGREGATE SESSION.
Therefore, various sharing scenarios can easily be supported.
Policies followed by the Deaggregator to determine which Aggregators
need shared or separate reservations are beyond the scope of this
document.
The Deaggregator MAY also include in the E2E PathErr message (with an
error code of NEW-AGGREGATE-NEEDED) additional RSVP objects which are
to be used for establishment of the newly needed generic aggregate
reservation. For example, the Deaggregator MAY include in the E2E
PathErr an RSVP Signaled Preemption Priority Policy Element (as
specified in [RSVP-PREEMP]).
The [RSVP-AGG] procedures for processing of an E2E PathErr message
received with an error code of NEW-AGGREGATE-NEEDED by the Aggregator
are extended correspondingly. On receipt of such a message
containing a SESSION-OF-INTEREST object, the Aggregator MUST trigger
establishment of a generic aggregate reservation. In particular, it
MUST start sending aggregate Path messages with the GENERIC-AGGREGATE
SESSION found in the received SESSION-OF-INTEREST object. When an
RSVP Signaled Preemption Priority Policy Element is contained in the
received E2E PathErr message, the Aggregator MUST include this object
Le Faucheur, et al. Standards Track [Page 15]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
in the Aggregate Path for the corresponding generic aggregate
reservation. When other additional objects are contained in the
received E2E PathErr message and those can be unambiguously
interpreted as related to the new needed generic aggregate
reservation (as opposed to related to the E2E reservation), the
Aggregator SHOULD include those in the Aggregate Path for the
corresponding generic aggregate reservation. The Aggregator MUST use
as the Source Address (i.e., as the Aggregator Address in the Sender-
Template) for the generic aggregate reservation, the address it uses
to identify itself as the PHOP (RSVP previous hop) when forwarding
the E2E Path messages corresponding to the E2E PathErr message.
The Deaggregator follows the same procedures as described in
[RSVP-AGG] for establishing, maintaining and clearing the aggregate
Resv state. However, a Deaggregator behaving according to the
present specification MUST use the generic aggregate reservations and
hence use the GENERIC-AGGREGATE SESSION specified earlier in this
document.
This document also modifies the procedures of [RSVP-AGG] related to
exchange of E2E Resv messages between Deaggregator and Aggregator.
The Deaggregator MUST include the new SESSION-OF-INTEREST object in
the E2E Resv message, in order to indicate to the Aggregator the
generic aggregate session to map a given E2E reservation onto.
Again, since the GENERIC-AGGREGATE SESSION (included in the SESSION-
OF-INTEREST object) contains the PHB-ID, the DCLASS object need not
be included in the E2E Resv message. The Aggregator MUST interpret
the SESSION-OF-INTEREST object in the E2E Resv as indicating which
generic aggregate reservation session the corresponding E2E
reservation is mapped onto. The Aggregator MUST not include the
SESSION-OF-INTEREST object when sending an E2E Resv upstream towards
the sender.
Based on relevant policy, the Deaggregator may decide at some point
that an aggregate reservation is no longer needed and should be torn
down. In that case, the Deaggregator MUST send an aggregate
ResvTear. On receipt of the aggregate ResvTear, the Aggregator
SHOULD send an aggregate PathTear (unless the relevant policy
instructs the Aggregator to do otherwise or to wait for some time
before doing so, for example in order to speed up potential re-
establishment of the aggregate reservation in the future).
[RSVP-AGG] describes how the Aggregator and Deaggregator can
communicate their respective identities to each other. For example,
the Aggregator includes one of its IP addresses in the RSVP HOP
object in the E2E Path that is transmitted downstream and received by
the Deaggregator once it traversed the aggregation region.
Similarly, the Deaggregator identifies itself to the Aggregator by
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
including one of its IP addresses in various fields, including the
ERROR SPECIFICATION of the E2E PathErr message (containing the NEW-
AGGREGATE-NEEDED Error Code) and in the RSVP HOP object of the E2E
Resv message. However, [RSVP-AGG] does not discuss which IP
addresses are to be selected by the Aggregator and Deaggregator for
such purposes. Because these addresses are intended to identify the
Aggregator and Deaggregator and not to identify any specific
interface on these devices, this document RECOMMENDS that the
Aggregator and Deaggregator SHOULD use interface-independent
addresses (for example, a loopback address) whenever they communicate
their respective identities to each other. This ensures that
respective identification of the Aggregator and Deaggregator is not
impacted by any interface state change on these devices. In turn,
this results in more stable operations and considerably reduced RSVP
signaling in the aggregation region. For example, if interface-
independent addresses are used by the Aggregator and the
Deaggregator, then a failure of an interface on these devices may
simply result in the rerouting of a given generic aggregate
reservation, but will not result in the generic aggregate reservation
having to be torn down and another one established. Moreover, it
will not result in a change of mapping of E2E reservations on generic
aggregate reservations (assuming the Aggregator and Deaggregator
still have reachability after the failure, and the Aggregator and
Deaggregator are still on the shortest path to the destination).
However, when identifying themselves to real RSVP neighbors (i.e.,
neighbors that are not on the other side of the aggregation region),
the Aggregator and Deaggregator SHOULD continue using interface-
dependent addresses as per regular [RSVP] procedures. This applies
for example when the Aggregator identifies itself downstream as a
PHOP for the generic aggregate reservation or identifies itself
upstream as a NHOP (RSVP next hop) for an E2E reservation. This also
applies when the Deaggregator identifies itself downstream as a PHOP
for the E2E reservation or identifies itself upstream as a NHOP for
the generic aggregate reservation. As part of the processing of
generic aggregate reservations, interior routers (i.e., routers
within the aggregation region) SHOULD continue using interface-
dependent addresses as per regular [RSVP] procedures.
More generally, within the aggregation region (i.e., between
Aggregator and Deaggregator) the operation of RSVP should be modeled
with the notion that E2E reservations are mapped to aggregate
reservations and are no longer tied to physical interfaces (as was
the case with regular RSVP). However, generic aggregate reservations
(within the aggregation region) as well as E2E reservations (outside
the aggregation region) retain the model of regular RVSP and remain
tied to physical interfaces.
Le Faucheur, et al. Standards Track [Page 17]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
As discussed above, generic aggregate reservations may be established
edge-to-edge as a result of the establishment of E2E reservations
(from outside the aggregation region) that are to be aggregated over
the aggregation region. However, generic aggregate reservations may
also be used end-to-end by end-systems directly attached to a
Diffserv domain, such as Public Switched Telephone Network (PSTN)
gateways. In that case, the generic aggregate reservations may be
established by the end-systems in response to application-level
triggers such as voice call signaling. Alternatively, generic
aggregate reservations may also be used edge-to-edge to manage
bandwidth in a Diffserv cloud even if RSVP is not used end-to-end. A
simple example of such a usage would be the static configuration of a
generic aggregate reservation for a certain bandwidth for traffic
from an ingress (Aggregator) router to an egress (Deaggregator)
router.
In this case, the establishment of the generic aggregate reservations
is controlled by configuration on the Aggregator and on the
Deaggregator. Configuration on the Aggregator triggers generation of
the aggregate Path message and provides sufficient information to the
Aggregator to derive the content of the GENERIC-AGGREGATE SESSION
object. This would typically include Deaggregator IP address, PHB-ID
and possibly VDstPort. Configuration on the Deaggregator would
instruct the Deaggregator to respond to a received generic aggregate
Path message and would provide sufficient information to the
Deaggregator to control the reservation. This may include bandwidth
to be reserved by the Deaggregator (for a given <Deaggregator,
PHB-ID, VDstPort> tuple).
In the absence of E2E microflow reservations, the Aggregator can use
a variety of policies to set the DSCP of packets passing into the
aggregation region and how they are mapped onto generic aggregate
reservations, thus determining whether they gain access to the
resources reserved by the aggregate reservation. These policies are
a matter of local configuration, as is typical for a device at the
edge of a Diffserv cloud.
Le Faucheur, et al. Standards Track [Page 18]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
5. Example Usage Of Multiple Generic Aggregate Reservations per PHB
from a Given Aggregator to a Given Deaggregator
Let us consider the environment depicted in Figure 2 below. RSVP
aggregation is used to support E2E reservations between Cloud-1,
Cloud-2, and Cloud-3.
I----------I I----------I
I Cloud-1 I I Cloud-2 I
I----------I I----------I
| |
Agg-Deag-1------------ Agg-Deag-2
/ \
/ Aggregation |
| Region |
| |
| ---/
\ /
\Agg-Deag-3---------/
|
I----------I
I Cloud-3 I
I----------I
Figure 2 : Example Usage of Generic Aggregate IP Reservations
Let us assume that:
o The E2E reservations from Cloud-1 to Cloud-3 have a preemption
of either P1 or P2.
o The E2E reservations from Cloud-2 to Cloud-3 have a preemption
of either P1 or P2.
o The E2E reservations are only for Voice (which needs to be
treated in the aggregation region using the EF -Expedited
Forwarding- PHB).
o Traffic from the E2E reservations is encapsulated in aggregate
IP reservations from Aggregator to Deaggregator using Generic
Routing Encapsulation [GRE] tunneling.
Then, the following generic aggregate RSVP reservations may be
established from Agg-Deag-1 to Agg-Deag-3 for aggregation of the end-
to-end RSVP reservations:
(1) A first generic aggregate reservation for aggregation of Voice
reservations from Cloud-1 to Cloud-3 requiring use of P1:
Le Faucheur, et al. Standards Track [Page 19]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
* GENERIC-AGGREGATE-IP4 SESSION:
IPv4 DestAddress = Agg-Deag-3
vDstPort = V1
PHB-ID = EF
Extended VDstPort = Agg-Deag-1
* STYLE = FF or SE
* IPv4/GPI FILTER_SPEC:
IPv4 SrcAddress = Agg-Deag-1
* POLICY_DATA (PREEMPTION_PRI) = P1
(2) A second generic aggregate reservation for aggregation of Voice
reservations from Cloud-1 to Cloud-3 requiring use of P2:
* GENERIC-AGGREGATE-IP4 SESSION:
IPv4 DestAddress = Agg-Deag-3
vDstPort = V2
PHB-ID = EF
Extended VDstPort = Agg-Deag-1
* STYLE = FF or SE
* IPv4/GPI FILTER_SPEC:
IPv4 SrcAddress = Agg-Deag-1
* POLICY_DATA (PREEMPTION_PRI) = P2
where V1 and V2 are arbitrary VDstPort values picked by Agg-
Deag-3.
The following generic aggregate RSVP reservations may be established
from Agg-Deag-2 to Agg-Deag-3 for aggregation of the end-to-end RSVP
reservations:
(3) A third generic aggregate reservation for aggregation of Voice
reservations from Cloud-2 to Cloud-3 requiring use of P1:
* GENERIC-AGGREGATE-IP4 SESSION:
IPv4 DestAddress = Agg-Deag-3
vDstPort = V3
PHB-ID = EF
Extended VDstPort = Agg-Deag-2
* STYLE = FF or SE
Le Faucheur, et al. Standards Track [Page 20]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
* IPv4/GPI FILTER_SPEC:
IPv4 SrcAddress = Agg-Deag-2
* POLICY_DATA (PREEMPTION_PRI) = P1
(4) A fourth generic aggregate reservation for aggregation of Voice
reservations from Cloud-2 to Cloud-3 requiring use of P2:
* GENERIC-AGGREGATE-IP4 SESSION:
IPv4 DestAddress = Agg-Deag-3
vDstPort = V4
PHB-ID = EF
Extended VDstPort = Agg-Deag-2
* STYLE = FF or SE
* IPv4/GPI FILTER_SPEC:
IPv4 SrcAddress = Agg-Deag-2
* POLICY_DATA (PREEMPTION_PRI) = P2
where V3 and V4 are arbitrary VDstPort values picked by Agg-
Deag-3.
Note that V3 and V4 could be equal to V1 and V2 (respectively)
since, in this example, the Extended VDstPort of the GENERIC-
AGGREGATE Session contains the address of the Aggregator and,
thus, ensures that different sessions are used from each
Aggregator.
6. Security Considerations
In the environments addressed by this document, RSVP messages are
used to control resource reservations for generic aggregate
reservations and may be used to control resource reservations for E2E
reservations being aggregated over the generic aggregate
reservations. To ensure the integrity of the associated reservation
and admission control mechanisms, the RSVP Authentication mechanisms
defined in [RSVP-CRYPTO1] and [RSVP-CRYPTO2] may be used. These
protect RSVP message integrity hop-by-hop and provide node
authentication as well as replay protection, thereby protecting
against corruption and spoofing of RSVP messages. These hop-by-hop
integrity mechanisms can be naturally used to protect the RSVP
messages used for generic aggregate reservations and to protect RSVP
messages used for E2E reservations outside the aggregation region.
These hop-by-hop RSVP integrity mechanisms can also be used to
protect RSVP messages used for E2E reservations when those transit
through the aggregation region. This is because the Aggregator and
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RFC 4860 Generic Aggregate RSVP Reservations May 2007
Deaggregator behave as RSVP neighbors from the viewpoint of the E2E
flows (even if they are not necessarily IP neighbors).
[RSVP-CRYPTO1] discusses several approaches for key distribution.
First, the RSVP Authentication shared keys can be distributed
manually. This is the base option and its support is mandated for
any implementation. However, in some environments, this approach may
become a burden if keys frequently change over time. Alternatively,
a standard key management protocol for secure key distribution can be
used. However, existing key distribution protocols may not be
appropriate in all environments because of the complexity or
operational burden they involve.
The use of RSVP Authentication in parts of the network where there
may be one or more IP hops in between two RSVP neighbors raises an
additional challenge. This is because, with some RSVP messages such
as a Path message, an RSVP router does not know the RSVP next hop for
that message at the time of forwarding it. In fact, part of the role
of a Path message is precisely to discover the RSVP next hop (and to
dynamically re-discover it when it changes, say because of a routing
change). Hence, the RSVP router may not know which security
association to use when forwarding such a message. This applies in
particular to the case where RSVP Authentication mechanisms are to be
used for protection of RSVP E2E messages (e.g., E2E Path) while they
transit through an aggregation region and where the dynamic
Deaggregator determination procedure defined in [RSVP-AGG] is used.
This is because the Aggregator and the Deaggregator behave as RSVP
neighbors for the E2E reservation, while there may be one or more IP
hops in between them, and the Aggregator does not know ahead of time
which router is going to act as the Deaggregator.
In that situation, one approach is to share the same RSVP
Authentication shared key across all the RSVP routers of a part of
the network where there may be RSVP neighbors with IP hops in
between. For example, all the Aggregators or Deaggregators of an
aggregation region could share the same RSVP Authentication key,
while different per-neighbor keys could be used between any RSVP
router pair straddling the boundary between two administrative
domains that have agreed to use RSVP signaling.
When the same RSVP Authentication shared key is to be shared among
multiple RSVP neighbors, manual key distribution may be used. For
situations where RSVP is being used for multicast flows, it might
also be possible, in the future, to adapt a multicast key management
method (e.g. from IETF Multicast Security Working Group) for key
distribution with such multicast RSVP usage. For situations where
RSVP is being used for unicast flows across domain boundaries, it is
not currently clear how one might provide automated key management.
Le Faucheur, et al. Standards Track [Page 22]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
Specification of a specific automated key management technique is
outside the scope of this document. Operators should consider these
key management issues when contemplating deployment of this
specification.
The RSVP Authentication mechanisms do not provide confidentiality.
If confidentiality is required, IPsec ESP [IPSEC-ESP] may be used,
although it imposes the burden of key distribution. It also faces
the additional issue discussed for key management above in the case
where there can be IP hops in between RSVP hops. In the future,
confidentiality solutions may be developed for the case where there
can be IP hops in between RSVP hops, perhaps by adapting
confidentiality solutions developed by the IETF MSEC Working Group.
Such confidentiality solutions for RSVP are outside the scope of this
document.
Protection against traffic analysis is also not provided by RSVP
Authentication. Since generic aggregate reservations are intended to
reserve resources collectively for a whole set of users or hosts,
malicious snooping of the corresponding RSVP messages could provide
more traffic analysis information than snooping of an E2E
reservation. When RSVP neighbors are directly attached, mechanisms
such as bulk link encryption might be used when protection against
traffic analysis is required. This approach could be used inside the
aggregation region for protection of the generic aggregate
reservations. It may also be used outside the aggregation region for
protection of the E2E reservation. However, it is not applicable to
the protection of E2E reservations while the corresponding E2E RSVP
messages transit through the aggregation region.
When generic aggregate reservations are used for aggregation of E2E
reservations, the security considerations discussed in [RSVP-AGG]
apply and are revisited here.
First, the loss of an aggregate reservation to an aggressor causes
E2E flows to operate unreserved, and the reservation of a great
excess of bandwidth may result in a denial of service. These issues
are not confined to the extensions defined in the present document:
RSVP itself has them. However, they may be exacerbated here by the
fact that each aggregate reservation typically facilitates
communication for many sessions. Hence, compromising one such
aggregate reservation can result in more damage than compromising a
typical E2E reservation. Use of the RSVP Authentication mechanisms
to protect against such attacks has been discussed above.
An additional security consideration specific to RSVP aggregation
involves the modification of the IP protocol number in RSVP Path
messages that traverse an aggregation region. Malicious modification
Le Faucheur, et al. Standards Track [Page 23]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
of the IP protocol number in a Path message would cause the message
to be ignored by all subsequent RSVP devices on its path, preventing
reservations from being made. It could even be possible to correct
the value before it reached the receiver, making it difficult to
detect the attack. Note that, in theory, it might also be possible
for a node to modify the IP protocol number for non-RSVP messages as
well, thus interfering with the operation of other protocols. It is
RECOMMENDED that implementations of this specification only support
modification of the IP protocol number for RSVP Path, PathTear, and
ResvConf messages. That is, a general facility for modification of
the IP protocol number SHOULD NOT be made available.
Network operators deploying routers with RSVP aggregation capability
should be aware of the risks of inappropriate modification of the IP
protocol number and should take appropriate steps (physical security,
password protection, etc.) to reduce the risk that a router could be
configured by an attacker to perform malicious modification of the
protocol number.
7. IANA Considerations
IANA modified the RSVP parameters registry, 'Class Names, Class
Numbers, and Class Types' subregistry, and assigned two new C-Types
under the existing SESSION Class (Class number 1), as described
below:
Class
Number Class Name Reference
------ ----------------------- ---------
1 SESSION [RFC2205]
Class Types or C-Types:
17 GENERIC-AGGREGATE-IP4 [RFC4860]
18 GENERIC-AGGREGATE-IP6 [RFC4860]
Le Faucheur, et al. Standards Track [Page 24]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
IANA also modified the RSVP parameters registry, 'Class Names, Class
Numbers, and Class Types' subregistry, and assigned one new Class
Number for the SESSION-OF-INTEREST class and two new C-Types for that
class, according to the table below:
Class
Number Class Name Reference
------ ----------------------- ---------
132 SESSION-OF-INTEREST [RFC4860]
Class Types or C-Types:
1 GENERIC-AGG-IP4-SOI [RFC4860]
2 GENERIC-AGG-IP6-SOI [RFC4860]
These allocations are in accordance with [RSVP-MOD].
8. Acknowledgments
This document borrows heavily from [RSVP-AGG]. It also borrows the
concepts of Virtual Destination Port and Extended Virtual Destination
Port from [RSVP-IPSEC] and [RSVP-TE], respectively.
Also, we thank Fred Baker, Roger Levesque, Carol Iturralde, Daniel
Voce, Anil Agarwal, Alexander Sayenko, and Anca Zamfir for their
input into the content of this document. Thanks to Steve Kent for
insightful comments on usage of RSVP reservations in IPsec
environments.
Ran Atkinson, Fred Baker, Luc Billot, Pascal Delprat, and Eric Vyncke
provided guidance and suggestions for the security considerations
section.
Le Faucheur, et al. Standards Track [Page 25]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
9. Normative References
[IPSEC-ESP] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, December 2005.
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[PHB-ID] Black, D., Brim, S., Carpenter, B., and F. Le
Faucheur, "Per Hop Behavior Identification Codes", RFC
3140, June 2001.
[RSVP] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S.,
and S. Jamin, "Resource ReSerVation Protocol (RSVP) --
Version 1 Functional Specification", RFC 2205,
September 1997.
[RSVP-AGG] Baker, F., Iturralde, C., Le Faucheur, F., and B.
Davie, "Aggregation of RSVP for IPv4 and IPv6
Reservations", RFC 3175, September 2001.
[RSVP-CRYPTO1] Baker, F., Lindell, B., and M. Talwar, "RSVP
Cryptographic Authentication", RFC 2747, January 2000.
[RSVP-CRYPTO2] Braden, R. and L. Zhang, "RSVP Cryptographic
Authentication -- Updated Message Type Value", RFC
3097, April 2001.
[RSVP-IPSEC] Berger, L. and T. O'Malley, "RSVP Extensions for IPSEC
Data Flows", RFC 2207, September 1997.
[RSVP-MOD] Kompella, K. and J. Lang, "Procedures for Modifying
the Resource reSerVation Protocol (RSVP)", BCP 96, RFC
3936, October 2004.
10. Informative References
[BW-REDUC] Polk, J. and S. Dhesikan, "A Resource Reservation
Protocol (RSVP) Extension for the Reduction of
Bandwidth of a Reservation Flow", RFC 4495, May 2006.
[GRE] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC
2784, March 2000.
[RSVP-PREEMP] Herzog, S., "Signaled Preemption Priority Policy
Element", RFC 3181, October 2001.
Le Faucheur, et al. Standards Track [Page 26]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
[RSVP-PROCESS] Braden, R. and L. Zhang, "Resource ReSerVation
Protocol (RSVP) -- Version 1 Message Processing
Rules", RFC 2209, September 1997.
[RSVP-TE] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
V., and G. Swallow, "RSVP-TE: Extensions to RSVP for
LSP Tunnels", RFC 3209, December 2001.
[RSVP-TUNNEL] Terzis, A., Krawczyk, J., Wroclawski, J., and L.
Zhang, "RSVP Operation Over IP Tunnels", RFC 2746,
January 2000.
[SIG-NESTED] Baker, F. and P. Bose, "QoS Signaling in a Nested
Virtual Private Network", Work in Progress, February
2007.
Le Faucheur, et al. Standards Track [Page 27]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
Appendix A. Example Signaling Flow
This appendix does not provide additional specification. It only
illustrates the specification detailed in Section 4 through a
possible flow of RSVP signaling messages. This flow assumes an
environment where E2E reservations are aggregated over generic
aggregate RSVP reservations. It illustrates a possible RSVP message
flow that could take place in the successful establishment of a
unicast E2E reservation that is the first between a given pair of
Aggregator/Deaggregator.
Le Faucheur, et al. Standards Track [Page 28]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
Aggregator Deaggregator
E2E Path
----------->
(1)
E2E Path
------------------------------->
(2)
E2E PathErr(New-agg-needed,SOI=GAx)
<----------------------------------
E2E PathErr(New-agg-needed,SOI=GAy)
<----------------------------------
(3)
AggPath(Session=GAx)
------------------------------->
AggPath(Session=GAy)
------------------------------->
(4)
E2E Path
----------->
(5)
AggResv (Session=GAx)
<-------------------------------
AggResv (Session=GAy)
<-------------------------------
(6)
AggResvConfirm (Session=GAx)
------------------------------>
AggResvConfirm (Session=GAy)
------------------------------>
(7)
E2E Resv
<---------
(8)
E2E Resv (SOI=GAx)
<-----------------------------
(9)
E2E Resv
<-----------
(1) The Aggregator forwards E2E Path into the aggregation region
after modifying its IP protocol number to RSVP-E2E-IGNORE
(2) Let's assume no Aggregate Path exists. To be able to accurately
update the ADSPEC of the E2E Path, the Deaggregator needs the
ADSPEC of Aggregate Path. In this example, the Deaggregator
elects to instruct the Aggregator to set up Aggregate Path states
for the two supported PHB-IDs. To do that, the Deaggregator
Le Faucheur, et al. Standards Track [Page 29]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
sends two E2E PathErr messages with a New-Agg-Needed PathErr
code. Both PathErr messages also contain a SESSION-OF-INTEREST
(SOI) object. In the first E2E PathErr, the SOI contains a
GENERIC-AGGREGATE SESSION (GAx) whose PHB-ID is set to x. In the
second E2E PathErr, the SOI contains a GENERIC-AGGREGATE SESSION
(GAy) whose PHB-ID is set to y. In both messages the GENERIC-
AGGREGATE SESSION contains an interface-independent Deaggregator
address inside the DestAddress and appropriate values inside the
vDstPort and Extended vDstPort fields.
(3) The Aggregator follows the request from the Deaggregator and
signals an Aggregate Path for both GENERIC-AGGREGATE Sessions
(GAx and GAy).
(4) The Deaggregator takes into account the information contained in
the ADSPEC from both Aggregate Paths and updates the E2E Path
ADSPEC accordingly. The Deaggregator also modifies the E2E Path
IP protocol number to RSVP before forwarding it.
(5) In this example, the Deaggregator elects to immediately proceed
with establishment of generic aggregate reservations for both
PHB-IDs. In effect, the Deaggregator can be seen as anticipating
the actual demand of E2E reservations so that resources are
available on the generic aggregate reservations when the E2E Resv
requests arrive, in order to speed up establishment of E2E
reservations. Assume also that the Deaggregator includes the
optional Resv Confirm Request in these Aggregate Resv.
(6) The Aggregator merely complies with the received ResvConfirm
Request and returns the corresponding Aggregate ResvConfirm.
(7) The Deaggregator has explicit confirmation that both Aggregate
Resvs are established.
(8) On receipt of the E2E Resv, the Deaggregator applies the mapping
policy defined by the network administrator to map the E2E Resv
onto a generic aggregate reservation. Let's assume that this
policy is such that the E2E reservation is to be mapped onto the
generic aggregate reservation with PHB-ID=x. The Deaggregator
knows that a generic aggregate reservation (GAx) is in place for
the corresponding PHB-ID since (7). The Deaggregator performs
admission control of the E2E Resv onto the generic aggregate
reservation for PHB-ID=x (GAx). Assuming that the generic
aggregate reservation for PHB-ID=x (GAx) had been established
with sufficient bandwidth to support the E2E Resv, the
Deaggregator adjusts its counter, tracking the unused bandwidth
on the generic aggregate reservation. Then it forwards the E2E
Resv to the Aggregator including a SESSION-OF-INTEREST object
Le Faucheur, et al. Standards Track [Page 30]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
conveying the selected mapping onto GAx (and hence onto
PHB-ID=x).
(9) The Aggregator records the mapping of the E2E Resv onto GAx (and
onto PHB-ID=x). The Aggregator removes the SOI object and
forwards the E2E Resv towards the sender.
Authors' Addresses
Francois Le Faucheur
Cisco Systems, Inc.
Village d'Entreprise Green Side - Batiment T3
400, Avenue de Roumanille
06410 Biot Sophia-Antipolis
France
EMail: flefauch@cisco.com
Bruce Davie
Cisco Systems, Inc.
1414 Massachusetts Ave.
Boxborough, MA 01719
USA
EMail: bds@cisco.com
Pratik Bose
Lockheed Martin
700 North Frederick Ave.
Gaithersburg, MD 20879
USA
EMail: pratik.bose@lmco.com
Chris Christou
Booz Allen Hamilton
13200 Woodland Park Road
Herndon, VA 20171
USA
EMail: christou_chris@bah.com
Michael Davenport
Booz Allen Hamilton
Suite 390
5220 Pacific Concourse Drive
Los Angeles, CA 90045
USA
EMail: davenport_michael@bah.com
Le Faucheur, et al. Standards Track [Page 31]
RFC 4860 Generic Aggregate RSVP Reservations May 2007
Full Copyright Statement
Copyright (C) The IETF Trust (2007).
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.
This document and the information contained herein are provided on an
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Le Faucheur, et al. Standards Track [Page 32]