Internet DRAFT - draft-zhang-pce-pcep-stateful-pce-gmpls
draft-zhang-pce-pcep-stateful-pce-gmpls
Network Working Group Xian Zhang
Internet-Draft Young Lee
Intended status: Standards Track Fatai Zhang
Huawei
Ramon Casellas
CTTC
Oscar Gonzalez de Dios
Telefonica I+D
Zafar Ali
Cisco Systems
Expires: April 21, 2014 October 21, 2013
Path Computation Element (PCE) Protocol Extensions for Stateful PCE
Usage in GMPLS-controlled Networks
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with
the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 21, 2014.
Zhang et al Expires April 2014 [Page 1]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
Abstract
The Path Computation Element (PCE) facilitates Traffic Engineering
(TE) based path calculation in large, multi-domain, multi-region, or
multi-layer networks. [Stateful-PCE] provides the fundamental PCE
communication Protocol (PCEP) extensions needed to support stateful
PCE functions, without specifying the technology-specific extensions.
This memo provides extensions required for PCEP so as to enable the
usage of a stateful PCE capability in GMPLS-controlled networks.
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 RFC-2119 [RFC2119].
Table of Contents
Table of Contents .............................................. 2
1. Introduction ................................................ 3
2. PCEP Extensions ............................................. 3
2.1. Overview of Requirements................................ 3
2.2. Stateful PCE Capability Advertisement ................... 4
2.2.1. PCE Capability Advertisement in Multi-layer Networks 4
2.3. LSP Delegation in GMPLS-controlled Networks ............. 5
2.4. LSP Synchronization in GMPLS-controlled networks......... 6
2.5. Modification of Existing PCEP Messages and Procedures.... 7
2.5.1. Use cases ......................................... 8
2.5.2. Modification for LSP Re-optimization ............... 8
2.5.3. Modification for Route Exclusion ................... 9
2.6. Additional Error Type and Error Values Defined.......... 10
3. IANA Considerations ........................................ 10
4. Manageability Considerations ................................ 10
4.1. Requirements on Other Protocols and Functional Components10
5. Security Considerations..................................... 11
6. Acknowledgement ............................................ 11
7. References ................................................. 11
7.1. Normative References................................... 11
7.2. Informative References................................. 11
8. Contributors' Address....................................... 12
Authors' Addresses ............................................ 13
Zhang et al Expires April 2014 [Page 2]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
1. Introduction
[RFC 4655] presents the architecture of a Path Computation Element
(PCE)-based model for computing Multiprotocol Label Switching (MPLS)
and Generalized MPLS (GMPLS) Traffic Engineering Label Switched
Paths (TE LSPs). To perform such a constrained computation, a PCE
stores the network topology (i.e., TE links and nodes) and resource
information (i.e., TE attributes) in its TE Database (TED). To
request path computation services to a PCE, [RFC 5440] defines the
PCE communication Protocol (PCEP) for interaction between a Path
Computation Client (PCC) and a PCE, or between two PCEs. PCEP as
specified in [RFC 5440] mainly focuses on MPLS networks and the PCEP
extensions needed for GMPLS-controlled networks are provided in
[PCEP-GMPLS].
Stateful PCEs are shown to be helpful in many application scenarios,
in both MPLS and GMPLS networks, as illustrated in [Stateful-APP].
In order for these applications to able to exploit the capability of
stateful PCEs, extensions to the PCE communication protocol (i.e.,
PCEP) are required.
[Stateful-PCE] provides the fundamental extensions needed for
stateful PCE to support general functionality, but leaves out the
specification for technology-specific objects/TLVs. Complementarily,
this document focuses on the extensions that are necessary in order
for the deployment of stateful PCEs in GMPLS-controlled networks.
2. PCEP Extensions
2.1. Overview of Requirements
This section notes the main functional requirements for PCEP
extensions to support stateful PCE for use in GMPLS-controlled
networks, based on the description in [Stateful-APP]. Many
requirements are common across a variety of network types (e.g.,
MPLS-TE networks and GMPLS networks) and the protocol extensions to
meet the requirements are already described in [Stateful-PCE]. This
document does not repeat the description of those protocol
extensions. Other requirements that are also common across a variety
of network types do not currently have protocol extensions defined
in [Stateful-PCE]. In these cases, this document presents protocol
extensions for discussion by the PCE working group and potential
inclusion in [Stateful-PCE]. In addition, this document presents
protocol extensions for a set of requirements which are specific to
the use of a stateful PCE in a GMPLS-controlled network.
The basic requirements are as follows:
Zhang et al Expires April 2014 [Page 3]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
o Advertisement of the stateful PCE capability. This generic
requirement is covered in Section 7.1.1 of [Stateful-PCE].
Section 2.2 of this document discusses other potential extensions
for this functionality.
o LSP delegation is already covered in Section 5.5 of [Stateful-PCE].
Section 2.3 of this document provides extension for its
application in GMPLS-controlled networks. Moreover, further
discussion of some generic details that may need additional
consideration is provided.
o LSP state synchronization. This is a generic requirement already
covered in Section 5.4 of [Stateful-PCE]. However, there are
further extensions required specifically for GMPLS-controlled
networks and discussed in Section 2.4. Reference to LSPs by
identifiers is discussed in Section 7.2 of [Stateful-PCE]. This
feature can be applied to reduce the data carried in PCEP messages.
Use cases and additional Error Codes are necessary, as described
in Section 2.5 and 2.6.
2.2. Stateful PCE Capability Advertisement
Whether a PCE has stateful capability or not can be advertised
during the PCEP session establishment process. It can also be
advertised through routing protocols as described in [RFC5088]. In
either case, the following additional aspects should also be
considered.
2.2.1. PCE Capability Advertisement in Multi-layer Networks
In multi-layer network scenarios, such as an IP-over-optical network,
if there are dedicated PCEs responsible for each layer, then the
PCCs should be informed of which PCEs they should synchronize their
LSP states with, as well as send path computation requests to. The
Layer-Cap TLV defined in [INTER-LAYER] can be used to indicate which
layer a PCE is in charge of. (Editor's note: this change is
currently not included in the current version of the [INTER-LAYER]
draft. It is expected that it will be included in its next version.)
This TLV is optional and MAY be carried in the OPEN object. It is
RECOMMMENDED that a PCC synchronizes its LSP states with the same
PCEs that it can use for path computation in a multi-layer network.
In a single layer, this TLV MAY not be used. However, if the PCE
capability discovery depends on IGP and if an IGP instance spans
across multiple layers, this TLV is still needed.
Alternatively, the extension to current OSPF PCED TLV is needed. A
new domain-type denoting the layer information can be defined:
Zhang et al Expires April 2014 [Page 4]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
domain-type: T.B.D.
When it is carried in PCE-DOMAIN sub-TLV, it denotes the layer for
which a PCE is responsible for path computation as well as LSP state
synchronization. When carried in the PCE-NEIG-DOMAIN sub-TLV, it
denotes its adjacent layers for which a PCE can compute paths and
synchronize the LSP states. The DOMAIN-ID information can be
represented using the following format, to denote the layer
information:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP Enc. Type | Switching Type| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2.3. LSP Delegation in GMPLS-controlled Networks
To enable the PCE to control an LSP, the PCUpd message is defined in
[Stateful-PCE]. However, However, the specification of technology
specific extensions is not covered. The following defines the
<path> descriptor, present in the PCUpd message, that should be
used in GMPLS-controlled networks:
<path>::=<ERO><attribute-list>
Where:
<attribute-list> ::= [<LSPA>]
[<BANDWIDTH>]
[<GENERALIZED-BANDWIDTH>...]
[<metric-list>]
<metric-list>::= <METRIC>[<metric-list>]
As explained in [stateful-APP], LSP parameter update controlled by a
stateful PCE in a multi-domain network is complex and requires well-
defined operational procedures as well as protocol design.
[TBD: protocol extensions]
Zhang et al Expires April 2014 [Page 5]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
2.4. LSP Synchronization in GMPLS-controlled networks
For LSP state synchronization of stateful PCEs in GMPLS networks,
the LSP attributes, such as its bandwidth, associated route as well
as protection information etc, should be updated by PCCs to PCE LSP
database (LSP-DB). Note the LSP state synchronization described in
this document denotes both the bulk LSP report at the initialization
phase as well as the LSP state report afterwards described in
[Stateful-PCE].
As per [Stateful-PCE], it does not cover technology-specific
specification for state synchronization. Therefore, extensions of
PCEP for stateful PCE usage in GMPLS networks are required. For LSP
state synchronization, the objects/TLVs that should be used for
stateful PCE in GMPLS networks are defined in [PCEP-GMPLS] and are
briefly summarized as below:
o GENERALIZED BANDWIDTH
o GENERALIZED ENDPOINTS
o PROTECTION ATTRIBUTE
o Use of IF_ID_ERROR_SPEC. [Stateful-PCE] section 7.2.2 only
considers RSVP ERROR_SPEC TLVs. GMPLS extends this to also support
IF_ID_ERROR_SPEC, for example, to report about failed unnumbered
interfaces.
o Extended objects to support the inclusion of the label and
unnumbered links.
Per [Stateful-PCE], the PCRpt message is defined for LSP state
synchronization purposes. PCRpt is used by a PCC to report one or
more of its LSPs to a stateful PCE. However, the <path> descriptor
is technology-specific and left undefined.
For LSP state synchronization in GMPLS-controlled networks, the
encoding of the <path> descriptor is defined as follows:
<path>::=<ERO><attribute-list>
Where:
<attribute-list> ::= [<LSPA>]
[<BANDWIDTH>]
[<GENERALIZED-BANDWIDTH>...]
Zhang et al Expires April 2014 [Page 6]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
[<IRO>]
[<XRO>]
[<metric-list>]
<metric-list>::= <METRIC>[<metric-list>]
The objects included in the <path> descriptor can be found in
[RFC5440], [PCE-GMPLS] and [RFC5521].
For all the objects presented in this section, the P and I bit MUST
be set to 0 since they are only used by a PCC to report its LSP
information.
In GMPLS-controlled networks, the <ERO> object may include a list of
the label sub-object for SDH/SONET, OTN and DWDM networks. It may
also include a list of unnumbered interface IDs to denote the
allocated resource. The <RRO>, <IRO> and <XRO> objects MAY include
unnumbered interface IDs and labels for networks such as OTN and WDM
networks.
If the LSP being reported is a protecting LSP, the <PROTECTION-
ATTRIBUTE> TLV MUST be included in the <LSPA> object to denote its
attributes and restrictions. Moreover, if the status of the
protecting LSP changes from non-operational to operational, this
should be synchronized to the stateful PCE. For example, in 1:1
protection, the combination of S=0, P=1 and O=0 denotes the
protecting path is set up already but not used for carrying traffic.
Upon the working path failure, the operational status of the
aforementioned protecting LSP changes to in-use (i.e., O=1). This
information should be synchronized with a stateful PCE through a
PCRpt message.
The O bit in the <GENERALIZED-BANDWIDTH> object has no meaning for
LSP state synchronization and MUST be set to 0. Furthermore, this
object MAY appear twice, one with R set to 1 and the other with R
set to 0. This is to denote the asymmetric bandwidth property of the
updated bi-directional LSP.
2.5. Modification of Existing PCEP Messages and Procedures
One of the advantages mentioned in [Stateful-APP] is that the
stateful nature of a PCE simplifies the information conveyed in PCEP
messages, notably between PCC and PCE, since it is possible to refer
to PCE managed state for active LSPs. To be more specific, with a
Zhang et al Expires April 2014 [Page 7]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
stateful PCE, it is possible to refer to a LSP with a unique
identifier in the scope of the PCC-PCEP session and thus use such
identifier to refer to that LSP.
2.5.1. Use cases
Use Case 1: Assuming a stateful PCE's LSP-DB is up-to-date, a PCC
(e.g. NMS) requesting for a re-optimization of one or several LSPs
can send the request with "R" bit set and only provides the relevant
LSP unique identifiers.
Upon receiving the PCReq message, PCE should be able to correlate
with one or multiple LSPs with their detailed state information and
carry out optimization accordingly.
The handling of RP object specified in [RFC5440] is stated as
following:
"The absence of an RRO in the PCReq message for a non-zero-bandwidth
TE LSP (when the R bit of the RP object is set) MUST trigger the
sending of a PCErr message with Error-Type="Required Object Missing"
and Error-value="RRO Object missing for re-optimization."
If a PCE has stateful capabilities, and such capabilities have been
negotiated and advertised, specific rules given in [RFC5440] may
need to be relaxed. In particular, the re-optimization case: if the
re-optimization request refers to a given LSP state, and the RRO
information is available, the PCE can proceed.
Use Case 2: in order to set up a LSP which has a constraint that its
route should not use resources used by one or more existing LSPs, a
PCC can send a PCReq with the identifiers of these LSPs. A stateful
PCE should be able to find the corresponding route and resource
information so as to meet the constraints set by the requesting PCC.
Hence, the LSP identifier TLV defined in [Stateful-PCE] can be used
in XRO object for this purpose. Note that if the PCC is a node in
the network, the constraint LSP ID information will be confined to
the LSPs initiated by itself.
2.5.2. Modification for LSP Re-optimization
For re-optimization, upon receiving a path computation request and
the "R" bit is set, the stateful PCE SHOULD still perform the re-
optimization in the following two cases:
Case 1: the existing bandwidth and route information of the to-be-
optimized LSP is provided in the path computation request. This
Zhang et al Expires April 2014 [Page 8]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
information should be provided via <BANDWIDTH>, <GENERARLIZED-
BANDWIDTH>, <ERO> objects.
Case 2: the existing bandwidth and route information can be found
locally in its LSP-DB. In this case, the PCRep and PCReq messages
need to be modified to carry LSP identifiers. The stateful PCE can
find this information using the per-node LSP ID together with the
PCC's address.
If no LSP state information is available to carry out re-
optimization, the stateful PCE should report the error "LSP state
information unavailable for the LSP re-optimization" (Error Type =
T.B.D., Error value= T.B.D.).
2.5.3. Modification for Route Exclusion
A LSP identifier sub-object is defined and its format as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type (T.B.D.) | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PLSP-ID | Flag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L bit:
The L bit SHOULD NOT be set, so that the subobject represents
a strict hop in the explicit route.
Type:
Subobject Type for a per-node LSP identifier.
Length:
The Length contains the total length of the subobject in bytes,
including the Type and Length fields.
PLSP-ID:
This is the identifier given to a LSP and it is unique on a
node basis. It is defined in [Stateful-PCE].
Flags:
This field is defined in [Stateful-PCE]. It is not used in
this sub-object and should be ignored upon receipt.
Zhang et al Expires April 2014 [Page 9]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
Optional TLVs:
Additional TLVs can be defined in the future to provide
further information to identify a LSP. In this document, no TLVs are
defined.
One or multiple of these sub-objects can be present in the XRO
object. When a stateful PCE receives a path computation request
carrying this sub-object, it should find relevant information of
these LSPs and preclude the resource during the path computation
process. If a stateful PCE cannot recognize one or more of the
received LSP identifiers, it should reply PCErr saying "the LSP
state information for route exclusion purpose cannot be found"
(Error-type = T.B.D., Error-value= T.B.D.). Optionally, it may
provide with the unrecognized identifier information to the
requesting PCC.
2.6. Additional Error Type and Error Values Defined
Error Type Meaning
21(TBD) LSP state information missing
Error-value 1: LSP state information unavailable for the
LSP re-optimization
Error-value 2: the LSP state information for route
exclusion purpose cannot be found
3. IANA Considerations
IANA is requested to allocate new Types for the TLV/Object defined
in this document.T.B.D.
4. Manageability Considerations
The description and functionality specifications presented related
to stateful PCEs should also comply with the manageability
specifications covered in Section 8 of [RFC4655]. Furthermore, a
further list of manageability issues presented in [Stateful-PCE]
should also be considered.
Additional considerations are presented in the next sections.
4.1. Requirements on Other Protocols and Functional Components
When the detailed route information is included for LSP state
synchronization (either at the initial stage or during LSP state
Zhang et al Expires April 2014 [Page 10]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
report process), this require the ingress node of an LSP carry the
RRO object in order to enable the collection of such information.
5. Security Considerations
The security issues presented in [RFC5440] and [Stateful-PCE] apply
to this document.
6. Acknowledgement
We would like to thank Adrian Farrel and Cyril Margaria for the
useful comments and discussions.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to indicate
requirements levels", RFC 2119, March 1997.
[RFC4655] Farrel, A., Vasseur, J.-P., and Ash, J., "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
August 2006.
[RFC5440] Vasseur, J.-P., and Le Roux, JL., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
March 2009.
[RFC5088] Le Roux, JL., Vasseur, J.-P., Ikejiri, Y., Zhang, R.,
"OSPF Protocol Extensions for Path Computation Element
(PCE) Discovery", RFC 5088, January 2008.
[INTER-LAYER] Oki, E., Takeda, Tomonori, Le Roux, JL., Farrel, A.,
Zhang, F., "Extensions to the Path Computation Element
communication Protocol (PCEP) for Inter-Layer MPLS and
GMPLS Traffic Engineering", draft-ietf-pce-inter-layer-ext,
work in progress.
7.2. Informative References
[Stateful-APP] Zhang, X., Minei, I., et al "Applicability of
Stateful Path Computation Element (PCE) ", draft-ietf-pce-
stateful-pce-app, , work in progress.
[Stateful-PCE]Crabbe, E., Medved, J., Varga, R., Minei, I., "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-pce,
work in progress.
Zhang et al Expires April 2014 [Page 11]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
[PCE-IA-WSON] Lee, Y., Bernstein G., Takeda, T., Tsuritani, T.,
"PCEP Extensions for WSON Impairments", draft-lee-pce-
wson-impairments, work in progress.
[PCEP-GMPLS] Margaria, C., Gonzalez de Dios, O., Zhang, F., "PCEP
extensions for GMPLS", draft-ietf-pce-gmpls-pcep-
extensions, work in progress.
8. Contributors' Address
Dhruv Dhody
Huawei Technology
Leela Palace
Bangalore, Karnataka 560008
INDIA
EMail: dhruvd@huawei.com
Yi Lin
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28972914
Email: yi.lin@huawei.com
Zhang et al Expires April 2014 [Page 12]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
Authors' Addresses
Xian Zhang
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28972645
Email: zhang.xian@huawei.com
Young Lee
Huawei
1700 Alma Drive, Suite 100
Plano, TX 75075
US
Phone: +1 972 509 5599 x2240
Fax: +1 469 229 5397
EMail: ylee@huawei.com
Fatai Zhang
Huawei
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
P.R. China
Phone: +86-755-28972912
Email: zhangfatai@huawei.com
Ramon Casellas
CTTC
Av. Carl Friedrich Gauss n7
Castelldefels, Barcelona 08860
Spain
Phone:
Email: ramon.casellas@cttc.es
Oscar Gonzalez de Dios
Telefonica Investigacion y Desarrollo
Emilio Vargas 6
Madrid, 28045
Spain
Zhang et al Expires April 2014 [Page 13]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
Phone: +34 913374013
Email: ogondio@tid.es
Zafar Ali
Cisco Systems
Email: zali@cisco.com
Intellectual Property
The IETF Trust takes no position regarding the validity or scope of
any Intellectual Property Rights or other rights that might be
claimed to pertain to the implementation or use of the technology
described in any IETF Document or the extent to which any license
under such rights might or might not be available; nor does it
represent that it has made any independent effort to identify any
such rights.
Copies of Intellectual Property disclosures made to the IETF
Secretariat and any assurances of licenses to be made available, or
the result of an attempt made to obtain a general license or
permission for the use of such proprietary rights by implementers or
users of this specification can be obtained from the IETF on-line
IPR repository at http://www.ietf.org/ipr
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
any standard or specification contained in an IETF Document. Please
address the information to the IETF at ietf-ipr@ietf.org.
The definitive version of an IETF Document is that published by, or
under the auspices of, the IETF. Versions of IETF Documents that are
published by third parties, including those that are translated into
other languages, should not be considered to be definitive versions
of IETF Documents. The definitive version of these Legal Provisions
is that published by, or under the auspices of, the IETF. Versions
of these Legal Provisions that are published by third parties,
including those that are translated into other languages, should
not be considered to be definitive versions of these Legal
Provisions.
For the avoidance of doubt, each Contributor to the IETF Standards
Process licenses each Contribution that he or she makes as part of
the IETF Standards Process to the IETF Trust pursuant to the
provisions of RFC 5378. No language to the contrary, or terms,
Zhang et al Expires April 2014 [Page 14]
draft-zhang-pce-pcep-stateful-pce-gmpls-03.txt October 2013
conditions or rights that differ from or are inconsistent with the
rights and licenses granted under RFC 5378, shall have any effect
and shall be null and void, whether published or posted by such
Contributor, or included with or in such Contribution.
Disclaimer of Validity
All IETF Documents and the information contained therein are
provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION
HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET
SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE
DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION THEREIN
WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Full Copyright Statement
Copyright (c) 2013 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with
respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Simplified BSD License.
Zhang et al Expires April 2014 [Page 15]
