Generic Aggregate RSVP Reservations July 2006
Internet Draft Francois Le Faucheur
Bruce Davie
Cisco Systems, Inc.
Pratik Bose
Lockheed Martin
Chris Christou
Michael Davenport
Booz Allen Hamilton
draft-ietf-tsvwg-rsvp-ipsec-02.txt
Expires: January 2007 July 2006
Generic Aggregate RSVP Reservations
draft-ietf-tsvwg-rsvp-ipsec-02.txt
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Abstract
[RSVP-AGG] defines aggregate RSVP reservations allowing resources to
be reserved in a Diffserv network for a given DSCP from a given
source to a given destination. [RSVP-AGG] also defines how end-to-end
RSVP reservations can be aggregated onto such aggregate reservations
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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 DSCP. However, this is not
supported by the aggregate reservations defined in [RSVP-AGG]. 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 DSCP 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.
Copyright Notice
Copyright (C) The Internet Society (2006).
Table Of Content
1. Introduction...................................................3
1.1. Related RFCs and Internet-Drafts..........................5
1.2. Organization Of This Document.............................6
2. Object Definition..............................................6
2.1. SESSION Class.............................................7
2.2. SESSION-OF-INTEREST (SOI) Class..........................10
3. Processing Rules For Handling Generic Aggregate RSVP Reservations
.................................................................11
3.1. Required Changes to Path and Resv Processing.............12
4. Procedures for Aggregation over Generic Aggregate RSVP
Reservations.....................................................13
5. Example Usage Of Multiple Generic Aggregate Reservations Per DSCP
From a Given Aggregator to a Given Deaggregator..................17
6. Security Considerations.......................................19
7. IANA Considerations...........................................20
8. Acknowledgments...............................................20
9. Normative References..........................................20
10. Informative References.......................................21
11. Authors' Addresses...........................................21
Appendix A: Example Signaling Flow...............................23
Specification of Requirements
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 [RFC2119].
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1. Introduction
[RSVP-AGG] defines RSVP aggregate reservations allowing resources to
be reserved in a Diffserv network for a flow characterized by its 3-
tuple <source IP address, destination IP address, DSCP>.
[RSVP-AGG] also defines the procedures for aggregation of end-to-end
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
DSCP of the PHB from which Diffserv resources are to be reserved. For
example, in the case of IPv4, the SESSION object is specified as:
o Class = SESSION,
C-Type = RSVP-AGGREGATE-IP4
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+-------------+-------------+-------------+-------------+
| IPv4 Session Address (4 bytes) |
+-------------+-------------+-------------+-------------+
| /////////// | Flags | ///////// | DSCP |
+-------------+-------------+-------------+-------------+
These aggregate reservations use a SENDER_TEMPLATE and FILTER_SPEC
types specified in [RSVP-AGG] and which contains 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 DSCPs. 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 DSCP.
Situations have since been identified where multiple such aggregate
reservations are needed for the same source IP address, destination
IP address and DSCP. 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 DSCP. Using
multiple aggregate reservations for the same DSCP allows enforcement
of the different preemption priorities within the aggregation region.
In turn this allows much more efficient management of the Diffserv
resources and in period of resource shortage allows to sustain a
larger number of E2E reservations with higher preemption priorities.
For example, [SIG-NESTED] discusses in details 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 DSCP), each
with different preemption priorities, can be used to efficiently
support the preemption priorities of end-to-end reservations.
This document addresses this requirement for multiple aggregate
reservations for the same DSCP, 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
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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 DSCP. This allows
multiple generic aggregate reservations to be established for a given
DSCP, 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 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 with those.
The generic aggregate reservations may also be used end-to-end
directly by end-systems attached to a Diffserv network.
1.1. Related RFCs and Internet-Drafts
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
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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 Section 6 and 7, respectively.
Finally, Appendix 1 provides an example signaling flow is
illustrating aggregation of E2E RSVP reservations onto generic
aggregate RSVP reservations.
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.
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The GENERIC-AGGREGATE-IP4 SESSION and GENERIC-AGGREGATE-IP6 SESSION
objects are applicable to all types of RSVP messages.
This specification only defines the use of the GENERIC-AGG-IP4-SOI
and GENERIC-AGG-IP6-SOI objects in two circumstances:
- inside an E2E PathErr message which contains an error code of
NEW-AGGREGATE-NEEDED in order to convey the session of a new
generic aggregate reservation which 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.
All the new objects defined in this document are optional with
respect to RSVP so that general RSVP implementations not concerned
with generic aggregate reservations do not have to support these
objects. RSVP routers supporting generic aggregate IPv4 (respectively
IPv6) reservations MUST support the GENERIC-AGGREGATE-IP4 SESSION
object (respectively GENERIC-AGGREGATE-IP6 SESSION). RSVP routers
supporting RSVP aggregation over generic aggregate IPv4 (respectively
IPv6) reservations MUST support the GENERIC-AGG-IP4-SOI object
(respectively GENERIC-AGG-IP6-SOI).
2.1. SESSION Class
o GENERIC-AGGREGATE-IP4 SESSION object:
Class = 1 (SESSION)
C-Type = To be allocated by IANA
0 7 8 15 16 23 24 31
+-------------+-------------+-------------+-------------+
| IPv4 DestAddress (4 bytes) |
+-------------+-------------+-------------+--+----------+
| Reserved | Flags | vDstPort |Rd| DSCP |
+-------------+-------------+-------------+--+----------+
| Extended vDstPort |
+-------------+-------------+-------------+-------------+
0 7 8 15 16 23 24 31
IPv4 DestAddress (IPv4 Destination Address)
IPv4 address of the receiver (or Deaggregator)
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Reserved
A 8-bit field. All bits MUST be set to 0 on transmit. This field
MUST be ignored on receipt.
VDstPort (Virtual Destination Port)
An 8-bit identifier used in the SESSION that remains constant
over the life of the generic aggregate reservation.
Rd (Reserved)
A 2-bit field. All bits MUST be set to 0 on transmit. This field
MUST be ignored on receipt.
DSCP (Diffserv Code Point)
A 6-bit field containing the DSCP of the PHB from which Diffserv
resources are to be reserved.
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 globally 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 = To be allocated by IANA
0 7 8 15 16 23 24 31
+-------------+-------------+-------------+-------------+
| |
+ +
| |
+ IPv6 DestAddress (16 bytes) +
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| |
+ +
| |
+-------------+-------------+-------------+--+----------+
| Reserved | Flags | vDstPort |Rd| DSCP |
+-------------+-------------+-------------+--+----------+
| |
+ +
| 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
A 8-bit field. All bits MUST be set to 0 on transmit. This field
MUST be ignored on receipt.
VDstPort (Virtual Destination Port)
A 8-bit identifier used in the SESSION that remains constant
over the life of the generic aggregate reservation.
Rd (Reserved)
A 2-bit field. All bits MUST be set to 0 on transmit. This field
MUST be ignored on receipt.
DSCP (Diffserv Code Point)
A 6-bit field containing the DSCP of the PHB from which Diffserv
resources are to be reserved
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.
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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 globally 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 = To be allocated by IANA
C-Type = To be allocated by IANA
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
which 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.
o GENERIC-AGG-IP6-SOI object:
Class = To be allocated by IANA
(same as for GENERIC-AGG-IP4-SOI)
C-Type = To be allocated by IANA
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 //
| |
+-------------+-------------+-------------+-------------+
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Content of a GENERIC-AGGREGATE-IP6 SESSION Object:
This field contains a copy of the Session object of the session
which 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 | vDstPort |Rd| DSCP |
+-------------+-------------+-------------+--+----------+
| 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
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 additions to the Processing Rules presented in
[RSVP-PROCESS]. These additions are required in order to properly
process the GENERIC-AGGREGATE-IP4 (resp. GENERIC-AGGREGATE-IP6)
SESSION object and the RSVP-AGGREGATE-IP4 (resp. 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.
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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. Required Changes to Path and Resv Processing
Both RESV and PATH processing will need to be changed to support the
new objects.
The following PATH message processing changes are required:
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 DSCP 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 DSCP 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.
The changes to RESV message processing are:
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 MAY have a data
classifier installed for the flow:
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* If the node needs to perform fine-grain classification (for
example to perform fine-grain policing on ingress at a trust
boundary) then the node MUST create a data classifier
described by the 3-tuple <DestAddress, SrcAddress, DSCP>.
Note that if multiple reservations are established with
different Virtual Destination Ports (and/or different
Extended Virtual Destination Ports) but with the same
<DestAddress, SrcAddress, DSCP>, 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.
* If the node only needs to perform Diffserv classification
(for example inside the aggregation domain downstream of the
trust boundary) then the node MUST rely on the Diffserv data
classifier based on the DSCP only.
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 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
which contains the GENERIC-AGGREGATE Session to be used for
establishment of the requested generic aggregate reservation. Since
this GENERIC-AGGREGATE SESSION contains the DSCP, 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-
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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 new 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
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 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, in this document, the Deaggregator MUST use the
generic aggregate reservations and hence use the GENERIC-AGGREGATE
SESSION specified earlier in this document.
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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 DSCP, 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 identity to each other. For example the
Aggregator includes one of its IP addresses in the RSVP HOP object in
the E2E Path which is transmitted downstream and received by the
Deaggregator once it traversed the aggregation region. Similarly, the
Deaggregator identifies itself to the Aggregator by 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 identity 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 turns 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, nor
will it result in a change of mapping of E2E reservations on generic
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Generic Aggregate RSVP Reservations July 2006
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 which 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 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 (ie 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.
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) which 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 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, DSCP
and possibly VDstPort. Configuration on the Deaggregator would
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Generic Aggregate RSVP Reservations July 2006
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/DSCP/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 usual for a device at the edge of a
Diffserv cloud.
5. Example Usage Of Multiple Generic Aggregate Reservations Per DSCP
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
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Generic Aggregate RSVP Reservations July 2006
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 PHB)
o traffic from the E2E reservations is encapsulated in Aggregate
IP reservations from Aggregator to Deaggregator using GRE
tunneling ([GRE]).
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:
A first generic aggregate reservation for aggregation of Voice
reservations from Cloud-1 to Cloud-3 requiring use of P1:
* GENERIC-AGGREGATE-IP4 SESSION:
IPv4 DestAddress= Agg-Deag-3
vDstPort=V1
DSCP=EF
Extended VDstPort= Agg-Deag-1
* STYLE=FF or SE
* IPv4/GPI FILTER_SPEC:
IPv4 SrcAddress= Agg-Deag-1
* POLICY_DATA (PREEMPTION_PRI)=P1
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
DSCP=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.
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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:
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
DSCP=EF
Extended VDstPort= Agg-Deag-2
* STYLE=FF or SE
* IPv4/GPI FILTER_SPEC:
IPv4 SrcAddress= Agg-Deag-2
* POLICY_DATA (PREEMPTION_PRI)=P1
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
DSCP=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 V1 and V4 are arbitrary VDstPort values picked by Agg-Deag-3.
Note that V3 and V4 could be equal to (respectively) V1 and V2 since,
in this example, the Extended VDstPort of the GENERIC-AGGREGATE
Session contains the address of the Deaggregator and, thus, ensures
that different sessions are used for each Deaggregator.
6. Security Considerations
The security considerations associated with the RSVP protocol [RSVP]
apply to this document as it relies on RSVP.
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Generic Aggregate RSVP Reservations July 2006
When generic aggregate reservations are used for aggregation of E2E
reservations, the security considerations discussed in [RSVP-AGG]
apply.
The security considerations discussed in [SIG-NESTED] apply when the
generic aggregate reservations are used in the presence of IPsec
gateways.
7. IANA Considerations
This document requests that IANA allocates two new C-Types under the
existing SESSION Class (Class 1)for the two new RSVP objects defined
in section 2.1: GENERIC-AGGREGATE-IP4 SESSION and GENERIC-AGGREGATE-
IP6 SESSION.
This document also requests that IANA allocates one new Class-Num for
the SESSION-OF-INTEREST class, and two new C-Types for the two new
RSVP objects under that class defined in section 2.2: GENERIC-AGG-
IP4-SOI and GENERIC-AGG-IP4-SOI.
8. Acknowledgments
This document borrows heavily from [RSVP-AGG]. It also borrows the
concepts of Virtual Destination Port and Extended Virtual Destination
Port respectively from [RSVP-IPSEC] and [RSVP-TE].
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.
9. Normative References
[RFC2119] "Key words for use in RFCs to Indicate Requirement Levels",
Bradner, RFC2119
[RSVP] "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional
Specification", Braden et al, RFC2205
[RSVP-IPSEC] "RSVP Extensions for IPsec Data Flows", Berger et al,
RFC2207
[RSVP-AGG] "Aggregation of RSVP for IPv4 and IPv6 Reservations",
Baker et al, RFC3175
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Generic Aggregate RSVP Reservations July 2006
[RSVP-PROCESS] "Resource ReSerVation Protocol (RSVP) -- Version 1
Message Processing Rules", Braden et al, RFC2209
[GRE] "Generic Routing Encapsulation (GRE) ", Farinacci et al, RFC
2784
10. Informative References
[SIG-NESTED] "QoS Signaling in a Nested Virtual Private Network",
Baker et al, draft-ietf-tsvwg-vpn-signaled-preemption, work in
progress
[BW-REDUC] "A Resource Reservation Extension for the Reduction of
andwidth of a Reservation Flow", Polk et al, RFC 4495
[RSVP-TUNNEL] "RSVP Operation Over IP Tunnels", Terzis et al., RFC
2746, January 2000.
[RSVP-PREEMP] Herzog, S., "Signaled Preemption Priority Policy
Element", RFC 3181, October 2001.
[RSVP-TE] Awduche et al, RSVP-TE: Extensions to RSVP for LSP Tunnels,
RFC 3209, December 2001.
11. 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.
300 Beaver Brook Road
Boxborough, MA 01719
USA
Email: bdavie@cisco.com
Pratik Bose
Lockheed Martin
22300 Comsat Drive Clarksburg, MD 20814
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Generic Aggregate RSVP Reservations July 2006
USA
Email: pratik.bose@lmco.com
Christou Christou
Booz Allen Hamilton
8283 Greensboro Drive
McLean, VA 22102
USA
Email: christou_chris@bah.com
Michael Davenport
Booz Allen Hamilton
8283 Greensboro Drive
McLean, VA 22102
USA
Email: davenport_michael@bah.com
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Le Faucheur, et al. [Page 22]
Generic Aggregate RSVP Reservations July 2006
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
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Copyright Notice
Copyright (C) The Internet Society (2006). This document is subject
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except as set forth therein, the authors retain all their rights.
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 which is the first between a given pair of
Aggregator/Deaggregator.
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)
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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 DSCPs. To do that, the Deaggregator 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
DSCP is set to x. In the second E2E PathErr, the SOI contains a
GENERIC-AGGREGATE SESSION (GAy) whose DSCP 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 Path 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
Le Faucheur, et al. [Page 24]
Generic Aggregate RSVP Reservations July 2006
with establishment of generic aggregate reservations for both DSCPs.
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
Resv 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 DSCP=x. The Deaggregator knows that a
generic aggregate reservation (GAx) is in place for the corresponding
DSCP since (7). The Deaggregator performs admission control of the
E2E Resv onto the generic aggregate Reservation for DSCP=x (GAx).
Assuming that the generic aggregate reservation for DSCP=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 and forwards the E2E Resv to the
Aggregator including a SESSION-OF-INTEREST object conveying the
selected mapping onto GAx (and hence onto DSCP=x).
(9) The Aggregator records the mapping of the E2E Resv onto GAx (and
onto DSCP=x). The Aggregator removes the SOI object and forwards the
E2E Resv towards the sender.
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