Network Working Group D. Dhody, Ed.
Internet-Draft Huawei Technologies
Intended status: Standards Track A. Farrel, Ed.
Expires: December 30, 2017 Juniper Networks
Z. Li
Huawei Technologies
June 28, 2017
PCEP Extension for Flow Specification
draft-li-pce-pcep-flowspec-02
Abstract
The Path Computation Element (PCE) is a functional component capable
of selecting the paths through a traffic engineered networks. These
paths may be supplied in response to requests for computation, or may
be unsolicited directions issued by the PCE to network elements.
Both approaches use the PCE Communication Protocol (PCEP) to convey
the details of the computed path.
Traffic flows may be categorized and described using "Flow
Specifications". RFC 5575 defines the Flow Specification and
describes how it may be distributed in BGP to allow specific traffic
flows to be associated with routes.
This document specifies a set of extensions to PCEP to support
dissemination of Flow Specifications. This allows a PCE to indicate
what traffic should be placed on each flow that it is aware of. It
also allows a PCE to play a role in a BGP network by installing Flow
Specification information at BGP speakers.
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 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 30, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Procedures for PCE Use of Flow Specifications . . . . . . . . 5
3.1. Capability Advertisement . . . . . . . . . . . . . . . . 5
3.1.1. PCEP OPEN Message . . . . . . . . . . . . . . . . . . 5
3.1.2. IGP PCE Capabilities Advertisement . . . . . . . . . 6
3.2. Dissemination Procedures . . . . . . . . . . . . . . . . 6
3.3. Flow Specification Synchronization . . . . . . . . . . . 7
4. PCE FlowSpec Capability TLV . . . . . . . . . . . . . . . . . 8
5. PCE Flow Spec Object . . . . . . . . . . . . . . . . . . . . 8
6. Flow Filter TLV . . . . . . . . . . . . . . . . . . . . . . . 9
7. Flow Specification TLVs . . . . . . . . . . . . . . . . . . . 10
8. Detailed Procedures . . . . . . . . . . . . . . . . . . . . . 13
8.1. Default Behavior . . . . . . . . . . . . . . . . . . . . 14
8.2. Composite Flow Specifications . . . . . . . . . . . . . . 14
8.2.1. Modifying Flow Specifications . . . . . . . . . . . . 14
8.3. Multiple Flow Specifications . . . . . . . . . . . . . . 14
8.3.1. Adding and Removing Flow Specifications . . . . . . . 15
8.4. Priorities and Overlapping Flow Specifications . . . . . 15
8.5. Error Processing . . . . . . . . . . . . . . . . . . . . 15
9. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 15
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
10.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 18
10.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 18
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10.3. Flow Specification TLV Type Indicators . . . . . . . . . 19
10.4. PCEP Error Codes . . . . . . . . . . . . . . . . . . . . 19
10.5. PCE Capability Flag . . . . . . . . . . . . . . . . . . 20
11. Security Considerations . . . . . . . . . . . . . . . . . . . 20
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
13.1. Normative References . . . . . . . . . . . . . . . . . . 20
13.2. Informative References . . . . . . . . . . . . . . . . . 21
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction
Dissemination of traffic flow specifications (Flow Specifications)
was introduced for BGP in [RFC5575]. A Flow Specification is
comprised of traffic filtering rules and actions. The routers that
receive a Flow Specification can classify received packets according
to the traffic filtering rules and shape, rate limit, filter, or
redirect packets based on the actions. The Flow Specification
carried by BGP can be used to automate inter-domain coordination of
traffic filtering to mitigate (distributed) denial-of-service attacks
and can also be used to provide traffic filtering in the context of a
BGP/MPLS Virtual Private Network (VPN) service.
[RFC5575] also defines that a Flow Specification received from an
external autonomous system will need to be validated against unicast
routing before being accepted. [I-D.ietf-idr-bgp-flowspec-oid]
describes a modification to the validation procedure to enable Flow
Specifications to be originated from a centralized BGP route
controller.
[I-D.ietf-ospf-flowspec-extensions] defines extensions to OSPF to
distribute Flow Specifications in the networks that only deploy an
IGP (Interior Gateway Protocol) (i.e., OSPF). It also defines the
validation procedures for imposing filtering information at routers.
[RFC4655] defines the Path Computation Element (PCE), a functional
component capable of computing paths for use in networks. PCE was
originally conceived for use in Multiprotocol Label Switching (MPLS)
for Traffic Engineering networks to derive the routes of Label
Switched Paths (LSPs). However, the scope of PCE was quickly
extended to make it applicable to Generalized MPLS (GMPLS) networks,
and more recent work has brought other traffic engineering
technologies and planning applications into scope (for example,
Segment Routing [I-D.ietf-pce-segment-routing]).
[RFC5440] describes the Path Computation Element Protocol (PCEP).
PCEP defines the communication between a Path Computation Client
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(PCC) and a PCE, or between PCE and PCE, enabling computation of MPLS
for Traffic Engineering LSP (TE-LSP) characteristics.
Stateful PCE [I-D.ietf-pce-stateful-pce] specifies a set of
extensions to PCEP to enable stateful control of TE-LSPs between and
across PCEP sessions in compliance with [RFC4657]. It includes
mechanisms to effect LSP state synchronization between PCCs and PCEs,
delegation of control of LSPs to PCEs, and PCE control of timing and
sequence of path computations within and across PCEP sessions and
focuses on a model where LSPs are configured on the PCC and control
over them is delegated to the PCE. [I-D.ietf-pce-pce-initiated-lsp]
describes the setup, maintenance, and teardown of PCE-initiated LSPs
under the stateful PCE model, without the need for local
configuration on the PCC, thus allowing for a dynamic network that is
centrally controlled and deployed.
[I-D.ietf-teas-pce-central-control] introduces the architecture for
PCE as a central controller and describes how PCE can be viewed as a
component that performs computation to place 'flows' within the
network and decide how these flows are routed.
When a PCE is used to initiate tunnels (such as TE-LSPs) using PCEP,
it is important that the head end of the tunnels understands what
traffic to place on each tunnel. The data flows intended for a
tunnel can be described using Flow Specifications, and when PCEP is
in use for tunnel initiation it makes sense for that same protocol to
be used to distribute the Flow Specifications that describe what data
flows on those tunnels.
This document specifies a set of extensions to PCEP to support
dissemination of Flow Specifications. The extensions include the
creation, update, and withdrawal of Flow Specifications via PCEP and
can be applied to tunnels initiated by the PCE or to tunnels where
control is delegated to the PCE by the PCC. Furthermore, a PCC
requesting a new path can include Flow Specifications in the request
to indicate the purpose of the tunnel allowing the PCE to factor this
in during the path computation.
Flow Specifications are carried in TLVs within a new Flow Spec Object
defined in this document. The flow filtering rules indicated by the
Flow Specifications are mainly defined by BGP Flow Specifications.
2. Terminology
This document uses the following terms defined in [RFC5440]: PCC,
PCE, PCEP Peer.
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The following term from [RFC5575] is used frequently throughout this
document:
Flow Specification (FlowSpec): A Flow Specification is an n-tuple
consisting of several matching criteria that can be applied to IP
traffic, including filters and actions. Each FlowSpec consists of
a set of filters and a set of actions.
This document uses the terms "stateful PCE" and "active PCE" as
advocated in [RFC7399].
3. Procedures for PCE Use of Flow Specifications
There are three elements of procedure:
o A PCE and a PCC must be able to indicate whether or not they
support the use of Flow Specifications.
o A PCE or PCC must be able to include Flow Specifications in PCEP
messages with clear understanding of the applicability of those
Flow Specifications in each case including whether the use of such
information is mandatory, constrained, or optional.
o Synchronization of Flow Specification information/state between
PCEP peers.
The following subsections describe these points.
3.1. Capability Advertisement
3.1.1. PCEP OPEN Message
During PCEP session establishment, a PCC or PCE that supports the
procedures described in this document announces this fact by
including the "PCE FlowSpec Capability" TLV, described in Section 4,
in the OPEN Object carried in the to advertise its support for PCEP
extensions for PCE FlowSpec Capability.
The presence of the PCE FlowSpec Capability TLV in the OPEN Object in
a PCE's OPEN message indicates that the PCE can support distribute
the FlowSpec to PCCs and can receive FlowSpecs in messages from the
PCCs.
The presence of the PCE FlowSpec Capability TLV in the OPEN Object in
a PCC's OPEN message indicates that the PCC supports the FlowSpec
functionality described in this document.
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If either one of a pair of PCEP peers does not indicate support of
the FlowSpec functionality described in this document by including
the PCE FlowSpec Capability TLV in the OPEN Object in its OPEN
message, then the other peer MUST NOT include a FlowSpec object in
any PCEP message send to the peer that does not support the
procedures. If a FlowSpec object is received even though support has
not been indicated, the receiver will respond with a PCErr message
reporting the objects containing the FlowSpec as described in
[RFC5440]: that is, it will use 'Unknown Object' if it does not
support this specification, and 'Not supported object' if it supports
this specification but has not chosen to support FlowSpec objects on
this PCEP session.
3.1.2. IGP PCE Capabilities Advertisement
The ability to advertise support for PCEP and PCE features in IGP
advertisements is provided for OSPF in [RFC5088] and for IS-IS in
[RFC5089]. The mechanism uses the PCE Discovery TLV which has a PCE-
CAP-FLAGS sub-TLV containing bit-flags each of which indicates
support for a different feature.
This document defines a new PCE-CAP-FLAGS sub-TLV bit, the FlowSpec
Capable flag (bit number TBD1). Setting the bit indicates that an
advertising PCE supports the procedures defined in this document.
Note that while PCE FlowSpec Capability may be advertised during
discovery, PCEP speakers that wish to use Flow Specification in PCEP
MUST negotiate PCE FlowSpec Capability during PCEP session setup, as
specified in Section 3.1.1. A PCC MAY initiate PCE FlowSpec
Capability negotiation at PCEP session setup even if it did not
receive any IGP PCE capability advertisement.
3.2. Dissemination Procedures
This section introduces the procedures to support Flow Specifications
in PCEP messages.
The primary purpose of distributing Flow Specifications information
is to allow a PCE to indicate to a PCC what traffic it should place
on a path (such as an LSP or a Segment Routing path). This means
that the Flow Specification may be included in:
o PCInitiate messages so that an active PCE can indicate the traffic
to place on a path at the time that the PCE instantiates the path.
o PCUpd messages so that an active PCE can indicate or change the
traffic to place on a path that has already been set up.
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o PCRpt messages so that a PCC could report the traffic that the PCC
plans to place on the path.
o PCReq messages so that a PCC can indicate what traffic it plans to
place on a path at the time it requests the PCE to perform a
computation in case that information aids the PCE in its work.
o PCRep messages so that a PCE that has been asked to compute a path
can suggest which traffic could be placed on a path that a PCC may
be about to set up.
o PCErr messages so that issues related to paths and the traffic
they carry can be reported to the PCE by the PCC, and so that
problems with other PCEP messages that carry Flow Specifications
can be reported.
To carry Flow Specifications in PCEP messages, this document defines
a new PCEP object called the PCE Flow Spec Object. The object
optional can appear more than once in any of the messages described
above.
The PCE Flow Spec Object carries one or more Flow Filter TLVs, each
of which describes a traffic flow.
The inclusion of multiple PCE Flow Spec Objects allow multiple
traffic flows to be placed on a single path.
Once a PCE and PCC have established that they can both support the
use of Flow Specifications in PCEP messages such information may be
exchanged at any time for new or existing paths.
3.3. Flow Specification Synchronization
The Flow Specifications are carried along with the LSP State
information as per [I-D.ietf-pce-stateful-pce], making the Flow
Specifications as part of the LSP database (LSP-DB). Thus, the
synchronization of the Flow Specification information is done as part
of the LSP-DB synchronization. This may be achieved using normal
state synchronization procedures as described in
[I-D.ietf-pce-stateful-pce] or enhanced state synchronization
procedures as defined in [I-D.ietf-pce-stateful-sync-optimizations].
The approach selected will be implementation and deployment specific
and will depend on issues such as how the databases are constructed
and what level of synchronization support is needed.
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4. PCE FlowSpec Capability TLV
The PCE-FLOWSPEC-CAPABILITY TLV is an optional TLV associated with
the OPEN Object [RFC5440] to exchange PCE FlowSpec capabilities of
PCEP speakers.
The format of the PCE-FLOWSPEC-CAPABILITY TLV follows the format of
all PCEP TLVs as defined in [RFC5440] and is shown in Figure 1.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD2] | Length=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value=0 | Padding |
+---------------------------------------------------------------+
Figure 1: PCE-FLOWSPEC-CAPABILITY TLV format
The type of the PCE-FLOWSPEC-CAPABILITY TLV is TBD2 and it has a
fixed length of 2 octets. The Value field is set to default value 0.
The inclusion of this TLV in an OPEN object indicate that the sender
can perform FlowSpec handling as defined in this document.
5. PCE Flow Spec Object
The PCEP Flow Spec object defined in this document are compliant with
the PCEP object format defined in [RFC5440].
The PCEP Flow Spec object carries a FlowSpec filter rule encoded in a
TLV (as defined in Section 6 and is OPTIONAL in the PCReq, PCRep,
PCErr, PCInitiate, PCRpt, and PCUpd messages. It MAY be present
zero, one, or more times. Each instance of the object specifies a
traffic flow.
The FLOW SPEC Object-Class is TBD3 (to be assigned by IANA).
The FLOW SPEC Object-Type is 1.
The format of the body of the PCE Flow Spec object is shown in
Figure 2
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FS-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Flow Filter TLV (variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: PCE Flow Spec Object Body Format
FS-ID(32-bit): A PCEP-specific identifier for the FlowSpec
information. A PCE creates an unique FS-ID for each FlowSpec that is
constant for the lifetime of a PCEP session. All subsequent PCEP
messages then address the FlowSpec by the FS-ID. The values 0 and
0xFFFFFFFF are reserved.
Reserved bits: MUST be set to zero on transmission and ignored on
receipt.
R bit: The Remove bit is set when a PCE Flow Spec Object is included
in a PCEP message to indicate removal of the Flow Specification from
the associated tunnel. If the bit is clear, the Flow Specification
is being added or modified.
Flow Filter TLV (variable): One TLV MAY be included.
The Flow Filter TLV is OPTIONAL when the R bit is set. The TLV MUST
be present when the R bit is clear. If the TLV is missing when the R
bit is clear, the PCEP peer MUST respond with a PCErr message with
error-type TBD8 (FlowSpec Error), error-value 1 (Malformed FlowSpec).
6. Flow Filter TLV
A new PCEP TLV is defined to convey Flow Specification filtering
rules that specify what traffic is carried on a path. The TLV
follows the format of all PCEP TLVs as defined in [RFC5440]. The
Type field values come from the codepoint space for PCEP TLVs an has
the value TBD4.
The Value field contains one or more sub-TLVs (the Flow Specification
TLVs) as defined in Section 7. Only one Flow Filter TLV can be
present which represents the complete definition of a Flow
Specification for traffic to be placed on the tunnel indicated by the
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PCEP message in which the PCE Flow Spec Object is carried. The set
of Flow Specification TLVs in a single instance of a Flow Filter TLV
are combined to indicate the specific Flow Specification.
7. Flow Specification TLVs
The Flow Specification TLVs carried as sub-TLVs of the Flow Filter
TLV also follow the format of all PCEP TLVs as defined in [RFC5440],
however, the Type values are selected from a separate IANA registry
(see Section 10) rather than from the common PCEP TLV registry.
Type values are chosen so that there can be commonality with Flow
Specifications defined for use with BGP. This is possible because
the BGP Flow Spec encoding uses a single octet to encode the type
where PCEP uses two octets. Thus the space of values for the Type
field is partitioned as shown in Figure 3.
Range |
---------------+---------------------------------------------------
0 | Reserved - must not be allocated.
|
1 .. 255 | Per BGP registry defined by [RFC5575].
| Not to be allocated in this registry.
|
256 .. 65535 | New PCEP Flow Specs allocated according to the
| registry defined in this document.
Figure 3: Flow Specification TLV Type Ranges
The content of Value field each TLV is specific to the type and
describes the parameters of the Flow Specification. The definition
of the format of many of these Value fields is inherited from BGP
specifications as shown in Figure 4. Specifically, the inheritance
is from [RFC5575] and [I-D.ietf-idr-flow-spec-v6], but may also be
inherited from future BGP specifications.
When multiple Flow Specification TLVs are present in a single Flow
Filter TLVs they are combined to produce a more detailed description
of a flow. For examples and rules about how this is achieved, see
[RFC5575].
When used in other protocols (such as BGP) these Flow Specifications
are also associated with actions to indicate how traffic matching the
Flow Specification should be treated. However, in PCEP the only
action is to associated the traffic with a tunnel and to forward
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matching traffic on to that path, so no encoding of an action is
needed.
Section 8.4 describes how overlapping Flow Specifications are
prioritized and handled.
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+-------+-------------------------+-----------------------------+
| Type | Description | Value defined in |
| | | |
+-------+-------------------------+-----------------------------+
| * | Destination IPv4 Prefix | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | Source IPv4 Prefix | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | IP Protocol | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | Port | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | Destination port | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | Source port | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | ICMP type | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | ICMP code | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | TCP flags | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | Packet length | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | DSCP | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | Fragment | [RFC5575] |
+-------+-------------------------+-----------------------------+
| * | Flow Label | [I-D.ietf-idr-flow-spec-v6] |
+-------+-------------------------+-----------------------------+
| * | Destination IPv6 Prefix | [I-D.ietf-idr-flow-spec-v6] |
+-------+-------------------------+-----------------------------+
| * | Source IPv6 Prefix | [I-D.ietf-idr-flow-spec-v6] |
+-------+-------------------------+-----------------------------+
| * | Next Header | [I-D.ietf-idr-flow-spec-v6] |
+-------+-------------------------+-----------------------------+
| TBD5 | Route Distinguisher | [I-D.dhodylee-pce-pcep-ls] |
+-------+-------------------------+-----------------------------+
| TBD6 | IPv4 Multicast Flow | [This.I-D] |
+-------+-------------------------+-----------------------------+
| TBD7 | IPv6 Multicast Flow | [This.I-D] |
+-------+-------------------------+-----------------------------+
* Indicates that the TLV Type value comes from the value used in
Figure 4: Table of Flow Specification TLV Types
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All Flow Specification TLVs with Types in the range 1 to 255 have
Values defined for use in BGP (for example in [RFC5575] and
[I-D.ietf-idr-flow-spec-v6]) and are set using the BGP encoding, but
without the type or length octets (the relevant information is in the
Type and Length fields of the TLV). The Value field is padded with
trailing zeros to achieve 4-byte alignment if necessary.
[I-D.dhodylee-pce-pcep-ls] defines a way to convey identification of
a VPN in PCEP via a Route Distinguisher (RD) [RFC4364] and encoded in
ROUTE-DISTINGUISHER TLV. A Flow Specification TLV with Type TBD5
carries a Value field matching that in the ROUTE-DISTINGUISHER TLV
and is used to identify that other flow filter information (for
example, an IPv4 destination prefix) is associated with a specific
VPN identified by the RD.
Although it may be possible to describe a multicast Flow
Specification from the combination of other Flow Specification TLVs
with specific values, it is more convenient to use a dedicated Flow
Specification TLV. Flow Specification TLVs with Type values TBD6 and
TBD7 are used to identify a multicast flow for IPv4 and IPv6
respectively. The Value field is encoded as shown in Figure 5.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsvd |S|W|R| Rsvd |B|Z| Src Mask Len | Grp Mask Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Source Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Group multicast Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Multicast Flow Specification TLV Encoding
The fields of the two Multicast Flow Specification TLVs are as
described in Section 4.9.1 of [RFC7761] noting that the two address
fields are 32 bits for the IPv4 Multicast Flow and 128 bits for the
IPv6 Multicast Flow.
8. Detailed Procedures
This section outlines some specific detailed procedures for using the
protocol extensions defined in this document.
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8.1. Default Behavior
The default behavior is that no Flow Specification is applied to a
tunnel. That is, the default is that the Flow Spec object is not
used as in all systems before the implementation of this
specification.
In this case it is a local matter (such as through configuration) how
tunnel head ends are instructed what traffic to place on a tunnel.
8.2. Composite Flow Specifications
Flow Specifications may be represented by a single Flow Specification
TLV or may require a more complex description using multiple Flow
Specification TLVs. For example, a flow indicated by a source-
destination pair of IPv6 addresses would be described by the
combination of Destination IPv6 Prefix and Source IPv6 Prefix Flow
Specification TLVs.
8.2.1. Modifying Flow Specifications
A PCE may want to modify a Flow Specification associate with a
tunnel, or a PCC may want to report a change to the Flow
Specification it is using with a tunnel.
It is important that the specific Flow Specification is identified so
that it is clear that this is a modification of an existing flow and
not the addition of a new flow as described in Section 8.3. The FS-
ID field of the PCE Flow Spec Object is used to identify an specific
Flow Specification.
When modifying a Flow Specification, all Flow Specification TLVs for
the intended specification of the flow MUST be included in the PCE
Flow Spec Object and the FS-ID MUST be retained from the previous
description of the flow.
8.3. Multiple Flow Specifications
It is possible that multiple flows will be place on a single tunnel.
In some cases it is possible to to define these within a single PCE
Flow Spec Object: for example, two Destination IPv4 Prefix TLVs could
be included to indicate that packets matching either prefix are
acceptable. Note that from PCEP point of view it would be considered
as a single Flow Specification identified by an FS-ID.
However, in other scenarios using multiple Flow Specification TLVs
would be confusing. For example, if flows from A to B and from C to
D are to be included then using two Source IPv4 Prefix TLVs and two
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Destination IPv4 Prefix TLVs would be confusing. In these cases,
each Flow Specification is carried in its own PCE Flow Spec Object
with multiple objects present on a single PCEP message. Use of
separate object allow easier removal and modification of Flow
Specification.
8.3.1. Adding and Removing Flow Specifications
The Remove bit in the the PCE Flow Spec Object is left clear when a
Flow Specification is being added or modified.
To remove a Flow Specification, a PCE Flow Spec Object is included
with the FS-ID matching the one being removed, and the R bit set to
indicate removal. In this case it is not necessary to include any
Flow Specification TLVs.
8.4. Priorities and Overlapping Flow Specifications
TBD
8.5. Error Processing
TBD
9. PCEP Messages
The FLOW SPEC Object is OPTIONAL and MAY be carried in the PCEP
messages.
The PCInitiate message is defined in [I-D.ietf-pce-pce-initiated-lsp]
and updated as below:
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<PCInitiate Message> ::= <Common Header>
<PCE-initiated-lsp-list>
Where:
<PCE-initiated-lsp-list> ::= <PCE-initiated-lsp-request>
[<PCE-initiated-lsp-list>]
<PCE-initiated-lsp-request> ::=
( <PCE-initiated-lsp-instantiation>|
<PCE-initiated-lsp-deletion> )
<PCE-initiated-lsp-instantiation> ::= <SRP>
<LSP>
[<END-POINTS>]
<ERO>
[<attribute-list>]
[<flowspec-list>]
Where:
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
The PCUpd message is defined in [I-D.ietf-pce-stateful-pce] and
updated as below:
<PCUpd Message> ::= <Common Header>
<update-request-list>
Where:
<update-request-list> ::= <update-request>
[<update-request-list>]
<update-request> ::= <SRP>
<LSP>
<path>
[<flowspec-list>]
Where:
<path>::= <intended-path><intended-attribute-list>
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
The PCRpt message is defined in [I-D.ietf-pce-stateful-pce] and
updated as below:
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<PCRpt Message> ::= <Common Header>
<state-report-list>
Where:
<state-report-list> ::= <state-report>[<state-report-list>]
<state-report> ::= [<SRP>]
<LSP>
<path>
[<flowspec-list>]
Where:
<path>::= <intended-path>
[<actual-attribute-list><actual-path>]
<intended-attribute-list>
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
The PCReq message is defined in [RFC5440] and updated in
[I-D.ietf-pce-stateful-pce], it is further updated below for flow
specification:
<PCReq Message>::= <Common Header>
[<svec-list>]
<request-list>
Where:
<svec-list>::= <SVEC>[<svec-list>]
<request-list>::= <request>[<request-list>]
<request>::= <RP>
<END-POINTS>
[<LSP>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<RRO>[<BANDWIDTH>]]
[<IRO>]
[<LOAD-BALANCING>]
[<flowspec-list>]
Where:
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
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The PCRep message is defined in [RFC5440] and updated in
[I-D.ietf-pce-stateful-pce], it is further updated below for flow
specification:
<PCRep Message> ::= <Common Header>
<response-list>
Where:
<response-list>::=<response>[<response-list>]
<response>::=<RP>
[<LSP>]
[<NO-PATH>]
[<attribute-list>]
[<path-list>]
[<flowspec-list>]
Where:
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
10. IANA Considerations
IANA maintains the "Path Computation Element Protocol (PCEP) Numbers"
registry. This document requests IANA actions to allocate code
points for the protocol elements defined in this document.
10.1. PCEP Objects
Each PCEP object has an Object-Class and an Object-Type. IANA
maintains a subregistry called "PCEP Objects". IANA is requested to
make an assingment from this subregistry as follows:
Object-Class | Value Name | Object-Type | Reference
-------------+---------------+----------------------+----------------
TBD3 | FLOW SPEC | 0 (Reserved) | [This.I-D]
| 1 | [This.I-D]
10.2. PCEP TLV Type Indicators
IANA maintains a subregistry called "PCEP TLV Type Indicators". IANA
is requested to make an assingment from this subregistry as follows:
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Value | Meaning | Reference
--------+------------------------------+-------------
TBD2 | PCE-FLOWSPEC-CAPABILITY TLV | [This.I-D]
TBD4 | FLOW FILTER TLV | [This.I-D]
10.3. Flow Specification TLV Type Indicators
IANA is requested to create a new subregistry call the PCEP Flow
Specification TLV Type Indicators registry.
Allocations from this registry are to be made according to the
following assignment policies [RFC8126]:
Range | Assignment policy
---------------+---------------------------------------------------
0 | Reserved - must not be allocated.
|
1 .. 255 | Reserved - must not be allocated.
| Usage mirrors the BGP FlowSpec registry [RFC5575].
|
258 .. 64506 | Specification Required
|
64507 .. 65531 | First Come First Served
|
65532 .. 65535 | Experimental
IANA is requested to pre-populate this registry with values defined
in this document as follows:
Value | Meaning
-------+------------------------
TBD5 | Route Distinguisher
TBD6 | IPv4 Multicast
TBD7 | IPv6 Multicast
10.4. PCEP Error Codes
IANA maintains a subregistry called "PCEP-ERROR Object Error Types
and Values". Entries in this subregistry are described by Error-Type
and Error-value. IANA is requested to make the following assignment
from this subregistry:
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Error-| Meaning | Error-value | Reference
Type | | |
-------+--------------------+----------------------------+-----------
TBD8 | FlowSpec error | 0: Unassigned | [This.I-D]
| | 1: Unsupported FlowSpec | [This.I-D]
| | 2: Malformed FlowSpec | [This.I-D]
| | 3: Unresolvable conflict | [This.I-D]
| | 4-255: Unassigned | [This.I-D]
10.5. PCE Capability Flag
IANA maintains a subregistry called "Open Shortest Path First v2
(OSPFv2) Parameters" with a sub-registry called "Path Computation
Element (PCE) Capability Flags". IANA is requested to assign a new
capability bit from this registry as follows:
Bit | Capability Description | Reference
-------+-------------------------------+------------
TBD1 | FlowSpec | [This.I-D]
11. Security Considerations
TBD.
12. Acknowledgements
Thanks to Julian Lucek and Sudhir Cheruathur for useful discussions.
13. References
13.1. Normative References
[I-D.dhodylee-pce-pcep-ls]
Dhody, D., Lee, Y., and D. Ceccarelli, "PCEP Extension for
Distribution of Link-State and TE Information.", draft-
dhodylee-pce-pcep-ls-08 (work in progress), June 2017.
[I-D.ietf-idr-flow-spec-v6]
McPherson, D., Raszuk, R., Pithawala, B.,
akarch@cisco.com, a., and S. Hares, "Dissemination of Flow
Specification Rules for IPv6", draft-ietf-idr-flow-spec-
v6-08 (work in progress), March 2017.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.
[RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
and D. McPherson, "Dissemination of Flow Specification
Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
<http://www.rfc-editor.org/info/rfc5575>.
13.2. Informative References
[I-D.ietf-idr-bgp-flowspec-oid]
Uttaro, J., Alcaide, J., Filsfils, C., Smith, D., and P.
Mohapatra, "Revised Validation Procedure for BGP Flow
Specifications", draft-ietf-idr-bgp-flowspec-oid-04 (work
in progress), March 2017.
[I-D.ietf-ospf-flowspec-extensions]
liangqiandeng, l., You, J., Wu, N., Fan, P., Patel, K.,
and A. Lindem, "OSPF Extensions for Flow Specification",
draft-ietf-ospf-flowspec-extensions-01 (work in progress),
April 2016.
[I-D.ietf-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-ietf-pce-pce-initiated-lsp-10 (work in
progress), June 2017.
[I-D.ietf-pce-segment-routing]
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "PCEP Extensions for Segment Routing",
draft-ietf-pce-segment-routing-09 (work in progress),
April 2017.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-21 (work in progress), June 2017.
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[I-D.ietf-pce-stateful-sync-optimizations]
Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X.,
and D. Dhody, "Optimizations of Label Switched Path State
Synchronization Procedures for a Stateful PCE", draft-
ietf-pce-stateful-sync-optimizations-10 (work in
progress), March 2017.
[I-D.ietf-teas-pce-central-control]
Farrel, A., Zhao, Q., Li, Z., and C. Zhou, "An
Architecture for Use of PCE and PCEP in a Network with
Central Control", draft-ietf-teas-pce-central-control-03
(work in progress), June 2017.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <http://www.rfc-editor.org/info/rfc4364>.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<http://www.rfc-editor.org/info/rfc4655>.
[RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol Generic
Requirements", RFC 4657, DOI 10.17487/RFC4657, September
2006, <http://www.rfc-editor.org/info/rfc4657>.
[RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "OSPF Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088,
January 2008, <http://www.rfc-editor.org/info/rfc5088>.
[RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5089, DOI 10.17487/RFC5089,
January 2008, <http://www.rfc-editor.org/info/rfc5089>.
[RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path
Computation Element Architecture", RFC 7399,
DOI 10.17487/RFC7399, October 2014,
<http://www.rfc-editor.org/info/rfc7399>.
[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
Multicast - Sparse Mode (PIM-SM): Protocol Specification
(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
2016, <http://www.rfc-editor.org/info/rfc7761>.
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[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<http://www.rfc-editor.org/info/rfc8126>.
Appendix A. Contributor Addresses
Shankara
Huawei Technologies
Divyashree Techno Park,
Whitefield Bangalore,
Karnataka
560066
India
Email: shankara@huawei.com
Qiandeng Liang
Huawei Technologies
101 Software Avenue,
Yuhuatai District
Nanjing
210012
China
Email: liangqiandeng@huawei.com
Cyril Margaria
Juniper Networks
200 Somerset Corporate Boulevard, Suite 4001
Bridgewater, NJ
08807
USA
Email: cmargaria@juniper.net
Colby Barth
Juniper Networks
200 Somerset Corporate Boulevard, Suite 4001
Bridgewater, NJ
08807
USA
Email: cbarth@juniper.net
Xia Chen
Huawei Technologies
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Huawei Bld., No.156 Beiqing Rd.
Beijing
100095
China
Email: jescia.chenxia@huawei.com
Shunwan Zhuang
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing
100095
China
Eemail: zhuangshunwan@huawei.com
Authors' Addresses
Dhruv Dhody (editor)
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Adrian Farrel (editor)
Juniper Networks
Email: afarrel@juniper.net
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
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