PCEP Extensions for BIER
draft-chen-pce-bier-02
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| Last updated | 2017-07-31 | ||
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draft-chen-pce-bier-02
Networking Working Group Ran. Chen
Internet-Draft Zheng. Zhang
Intended status: Standards Track ZTE Corporation
Expires: January 31, 2018 July 30, 2017
PCEP Extensions for BIER
draft-chen-pce-bier-02
Abstract
Bit Index Explicit Replication (BIER)-TE shares architecture and
packet formats with BIER as described in
[I-D.ietf-bier-architecture]. BIER-TE forwards and replicates
packets based on a BitString in the packet header, but every
BitPosition of the BitString of a BIER-TE packet indicates one or
more adjacencies.BIER-TE Path can be derived from a Path Computation
Element (PCE).
This document specifies extensions to the Path Computation Element
Protocol (PCEP) to handle requests and responses for the computation
of paths for BIER-TE.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 31, 2018.
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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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Overview of PCEP Operation in BIER Networks . . . . . . . . . 3
4. BIER PCEP Message Extensions . . . . . . . . . . . . . . . . 3
4.1. BIER Capability Advertisement . . . . . . . . . . . . . . 3
4.1.1. The OPEN Object . . . . . . . . . . . . . . . . . . . 3
4.1.1.1. The BIER PCE Capability TLV . . . . . . . . . . . 3
4.2. Path Computation Request/Reply Message Extensions . . . . 4
4.2.1. The RP/SPR Object . . . . . . . . . . . . . . . . . . 4
4.2.2. The New BIER END-POINT Object . . . . . . . . . . . . 5
4.2.3. ERO Object . . . . . . . . . . . . . . . . . . . . . 5
4.2.3.1. BIER-ERO Subobject . . . . . . . . . . . . . . . 6
4.2.4. RRO Object . . . . . . . . . . . . . . . . . . . . . 7
4.2.4.1. RRO Processing . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 7
6.2. PCEP-Error Objects and Types . . . . . . . . . . . . . . 8
6.3. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 8
6.4. New Path Setup Type . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative references . . . . . . . . . . . . . . . . . . 9
7.2. Informative references . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Bit Index Explicit Replication (BIER)-TE shares architecture and
packet formats with BIER as described in
[I-D.ietf-bier-architecture]. BIER-TE forwards and replicates
packets based on a BitString in the packet header, but every
BitPosition of the BitString of a BIER-TE packet indicates one or
more adjacencies.BIER-TE Path can be derived from a Path Computation
Element (PCE).
This document specifies extensions to the Path Computation Element
Protocol (PCEP) to handle requests and responses for the computation
of paths for BIER-TE.
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2. Conventions used in this document
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.
3. Overview of PCEP Operation in BIER Networks
BIER-TE forwards and replicates packets based on a BitString in the
packet header. In a PCEP session, An ERO object specified in
[RFC5440] can be extended to carry a BIER-TE path consists of one or
more BIER-ERO subobject(s). BIER-TE computed by a PCE can be
represented in the following forms:
o An ordered set of adjacencies BitString(s) in which each bit
represents that the adjacencies to which the BFR should replicate
packets to in the domain.
In this document, we define a set of PCEP protocol extensions,
including a new PCEP capability,a new Path Setup Type (PST) ,a new
BIER END-POINT Object, new ERO subobjects, new RRO subobjects, new
PCEP error codes and procedures.
4. BIER PCEP Message Extensions
The following section describes the protocol extensions required to
support BIER-TE path.
4.1. BIER Capability Advertisement
4.1.1. The OPEN Object
This document defines a new optional TLV for use in the OPEN Object.
4.1.1.1. The BIER PCE Capability TLV
The BIER-PCE-CAPABILITY TLV is an optional TLV associated with the
OPEN Object to exchange BIER capability of PCEP speakers. The format
of the BIER-PCE-CAPABILITY TLV is shown in the following figure:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
The code point for the TLV type is to be defined by IANA.
Length: 4 bytes.
The "Reserved" (2 octet) and "Flags" (2 octet) fields are currently
unused, and MUST be set to zero on transmission and ignored on
reception.
4.1.1.1.1. Exchanging BIER Capability
This document defines a new optional BIER-PCE-CAPABILITY TLV for use
in the OPEN object to negotiate the BIER capability. The inclusion
of this TLV in the OPEN message destined to a PCC indicates the PCE's
capability to perform BIER-TE path computations, and the inclusion of
this TLV in the OPEN message destined to a PCE indicates the PCC's
capability to support BIER-TE Path.
A PCE that is able to support the BIER extensions defined in this
document SHOULD include the BIER-PCE-CAPABILITY TLV on the OPEN
message. If the PCE does not include the BIER-PCE-CAPABILITY TLV in
the OPEN message and PCC does include the TLV, it is RECOMMENDED that
the PCC indicates a mismatch of capabilities.
4.2. Path Computation Request/Reply Message Extensions
4.2.1. The RP/SPR Object
In order to setup an BIER-TE, a new PATH-SETUP-TYPE
TLV[I-D.ietf-pce-lsp-setup-type] MUST be contained in RP or SRP
object. This document defines a new Path Setup Type (PST) for BIER
as follows:
o PST = 2: Path is setup using BIER Traffic Engineering technique.
If a PCEP speaker does not recognize the PATH-SETUP-TYPE TLV, it MUST
ignore the TLV in accordance with [RFC5440]. If a PCEP speaker
recognizes the TLV but does not support the TLV, it MUST send PCErr
with Error-Type = 2 (Capability not supported).
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4.2.2. The New BIER END-POINT Object
The END-POINTS object is used in a PCReq message to specify the BIER
information of the path for which a path computation is requested.
To represent the end points for a BIER path efficiently, we define a
new END-POINT Object for the BIER path:
The format of the new END-POINTS Object is as follows:
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Subdomain-ID | BS Length | Source BFR-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination BFR-id ~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~ Destination BFR-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
Subdomain-id: Unique value identifying the BIER sub-domain. 1 octet
BS Length: A 1 octet field encoding the supported BitString length.
Source BFR-id:A 2 octet field encoding the source BFR-id.
Destniation BFR-id:A 2 octet field encoding the destniation BFR-id.
4.2.3. ERO Object
BIER-TE consists of one or more adjacencies BitStrings where every
BitPosition of the BitString indicates one or more adjacencies, as
described in([I-D.eckert-bier-te-arch]).
The ERO object specified in [RFC5440] is used to encode the path of a
TE LSP through the network.The ERO is carried within a PCRep message
to provide the computed TE LSP if the path computation was
successful.In order to carry BIER-TE explicit paths, this document
defines a new ERO subobjects referred to as "BIER-ERO subobjects"
whose formats are specified in the following section. An BIER-ERO
subobjects carrying a adjacencies BitStrings consists of one or more
BIER-ERO subobject(s).
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4.2.3.1. BIER-ERO Subobject
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BS Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adjacency BitString |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3
Type: TBD
Length: 4 bytes
BS Length: A 1 octet field encoding the supported BitString length.
The "Reserved" (1 octets) fields are currently unused, and MUST be
set to zero on transmission and ignored on reception.
Adjacency BitString: A 4 octet field encoding the Adjacency BitString
where every BitPosition of the BitString indicates one or more
adjacencies.
4.2.3.1.1. BIER-ERO Processing
If a PCC finds a non-recognize the BIER-ERO subobject, the PCC MUST
respond with a PCErr message with Error-Type=3 ("Unknown Object") and
Error-Value=2 ("Unrecognized object Type") or Error-Type=4 ("Not
supported object") and Error-Value=2 ("Not supported object Type") as
described in [RFC5440] .
If a PCC receives an BIER-ERO subobject in which either
BitStringLength or Adjacency BitString is absent, it MUST consider
the entire BIER-ERO subobject invalid and send a PCErr message with
Error-Type = 10 ("Reception of an invalid object") and Error-Value =
TBD ("BitStringLength is absent ") and Error-Value = TBD ("Adjacency
BitString is absent ")
If a PCC detects that all subobjects of BIER-ERO are not identical,
it MUST send a PCErr message with Error-Type = 10 ("Reception of an
invalid object") and Error-Value = TBD ("Non-identical BIER-ERO
subobjects").
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If a PCC receives an BIER-ERO subobject in which BitStringLength
values are not chosen from: 64, 128, 256, 512, 1024, 2048, and 4096,
as it described in ([I-D.ietf-bier-architecture]). The PCC MUST send
a PCErr message with Error-Type = 10 ("Reception of an invalid
object") and Error-Value = TBD ("Invalid BitStringLength").
4.2.4. RRO Object
A PCC can record BIER-ERO explicit paths and report the paths to a
PCE via RRO. An RRO object contains one or more subobjects called
"BIER-RRO subobjects" whose formats are the same as that of BIER-ERO
subobject.
4.2.4.1. RRO Processing
Processing rules of BIER-RRO subobject are identical to those of
BIER-ERO subobject defined in section 4.2.3.1 in this document.
5. Security Considerations
TBD.
6. IANA Considerations
6.1. PCEP Objects
As discussed in Section 4.2.2, a new END-POINTS Object-Type is
defined. IANA has made the following Object-Type allocations from
the "PCEP Objects" sub-registry:
Object Object-Class Value
--------------------- --------------------------
BIER END-POINT Object TBD
As discussed in Section 4.2.3 and 4.2.4, a new sub-object type for
the PCEP explicit route object (ERO), and a new sub-object type for
the PCEP record route object (RRO) are defined.
IANA has made the following sub-objects allocation from the RSVP
Parameters registry:
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Object Sub-Object Sub-Object Type
--------------------- -------------------------- --------------------------
EXPLICIT_ROUTE BIER-ERO (PCEP-specific) TBD
ROUTE_RECORD BIER-RRO (PCEP-specific) TBD
6.2. PCEP-Error Objects and Types
As described in Section 4.2.3.1.1, a number of new PCEP-ERROR Object
Error Values have been defined.
Error-Type Meaning Reference
---------- ----------------------------------- ---------------------------------
10 Reception of an invalid object. RFC5540
Error-value = TBD: BitStringLength is absent This document
Error-value = TBD: BitString is absent This document
Error-value = TBD: Invalid BitStringLength This document
6.3. PCEP TLV Type Indicators
IANA is requested to allocate a new code point in the PCEP TLV Type
Indicators registry, as follows:
Value Meaning Reference
-------------------- ---------------------------- -----------------------------------
TBD BIER-PCE-CAPABILITY TLV This document
6.4. New Path Setup Type
IANA is requested to allocate a new code point in the PCEP
PATH_SETUP_TYPE TLV PST field registry, as follows:
Value Description Reference
---------------- ------------------------------------ ----------------------------
2 Path is setup using BIER Traffic This document
Engineering technique
7. References
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7.1. Normative references
[I-D.ietf-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-ietf-bier-architecture-07 (work in
progress), June 2017.
[I-D.ietf-pce-lsp-setup-type]
Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J.
Hardwick, "Conveying path setup type in PCEP messages",
draft-ietf-pce-lsp-setup-type-04 (work in progress), April
2017.
[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>.
7.2. Informative references
[I-D.eckert-bier-te-arch]
Eckert, T., Cauchie, G., Braun, W., and M. Menth, "Traffic
Engineering for Bit Index Explicit Replication BIER-TE",
draft-eckert-bier-te-arch-05 (work in progress), June
2017.
Authors' Addresses
Ran Chen
ZTE Corporation
No.50 Software Avenue,Yuhuatai District
Nanjing, Jiangsu Province 210012
China
Phone: +86 025 88014636
Email: chen.ran@zte.com.cn
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Zheng Zhang
ZTE Corporation
No.50 Software Avenue,Yuhuatai District
Nanjing, Jiangsu Province 210012
China
Email: zhang.zheng@zte.com.cn
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