Internet DRAFT - draft-dhodylee-pce-pcep-te-data-extn
draft-dhodylee-pce-pcep-te-data-extn
PCE Working Group D. Dhody
Internet-Draft Y. Lee
Intended status: Experimental Huawei Technologies
Expires: September 5, 2015 D. Ceccarelli
Ericsson
March 4, 2015
PCEP Extension for Transporting TE Data
draft-dhodylee-pce-pcep-te-data-extn-02
Abstract
In order to compute and provide optimal paths, Path Computation
Elements (PCEs) require an accurate and timely Traffic Engineering
Database (TED). Traditionally this TED has been obtained from a link
state routing protocol supporting traffic engineering extensions.
This document extends the Path Computation Element Communication
Protocol (PCEP) with TED population capability.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on September 5, 2015.
Copyright Notice
Copyright (c) 2015 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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carefully, as they describe your rights and restrictions with respect
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Requirements for PCEP extension . . . . . . . . . . . . . . . 4
5. New Functions to Support TED via PCEP . . . . . . . . . . . . 5
6. Overview of Extension to PCEP . . . . . . . . . . . . . . . . 5
6.1. New Messages . . . . . . . . . . . . . . . . . . . . . . 5
6.2. Capability Advertisement . . . . . . . . . . . . . . . . 6
6.3. Initial TED Synchronization . . . . . . . . . . . . . . . 6
6.3.1. Optimizations for TED Synchronization . . . . . . . . 9
6.4. TE Report . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. TE Report Message . . . . . . . . . . . . . . . . . . . . 10
8.2. The PCErr Message . . . . . . . . . . . . . . . . . . . . 10
9. Objects and TLV . . . . . . . . . . . . . . . . . . . . . . . 11
9.1. Open Object . . . . . . . . . . . . . . . . . . . . . . . 11
9.1.1. TED Capability TLV . . . . . . . . . . . . . . . . . 11
9.2. TE Object . . . . . . . . . . . . . . . . . . . . . . . . 12
9.2.1. Routing Universe TLV . . . . . . . . . . . . . . . . 13
9.2.2. Local TE Node Descriptors TLV . . . . . . . . . . . . 14
9.2.3. Remote TE Node Descriptors TLV . . . . . . . . . . . 15
9.2.4. TE Node Descriptors Sub-TLVs . . . . . . . . . . . . 15
9.2.5. TE Link Descriptors TLV . . . . . . . . . . . . . . . 16
9.2.6. TE Node Attributes TLV . . . . . . . . . . . . . . . 17
9.2.7. TE Link Attributes TLV . . . . . . . . . . . . . . . 18
10. Other Considerations . . . . . . . . . . . . . . . . . . . . 20
10.1. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . 20
11. Security Considerations . . . . . . . . . . . . . . . . . . . 20
12. Manageability Considerations . . . . . . . . . . . . . . . . 20
12.1. Control of Function and Policy . . . . . . . . . . . . . 20
12.2. Information and Data Models . . . . . . . . . . . . . . 20
12.3. Liveness Detection and Monitoring . . . . . . . . . . . 21
12.4. Verify Correct Operations . . . . . . . . . . . . . . . 21
12.5. Requirements On Other Protocols . . . . . . . . . . . . 21
12.6. Impact On Network Operations . . . . . . . . . . . . . . 21
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
15.1. Normative References . . . . . . . . . . . . . . . . . . 22
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15.2. Informative References . . . . . . . . . . . . . . . . . 22
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction
In Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS),
a Traffic Engineering Database (TED) is used in computing paths for
connection oriented packet services and for circuits. The TED
contains all relevant information that a Path Computation Element
(PCE) needs to perform its computations. It is important that the
TED be complete and accurate each time, the PCE performs a path
computation.
In MPLS and GMPLS, interior gateway routing protocols (IGPs) have
been used to create and maintain a copy of the TED at each node
running the IGP. One of the benefits of the PCE architecture
[RFC4655] is the use of computationally more sophisticated path
computation algorithms and the realization that these may need
enhanced processing power not necessarily available at each node
participating in an IGP.
Section 4.3 of [RFC4655] describes the potential load of the TED on a
network node and proposes an architecture where the TED is maintained
by the PCE rather than the network nodes. However, it does not
describe how a PCE would obtain the information needed to populate
its TED. PCE may construct its TED by participating in the IGP
([RFC3630] and [RFC5305] for MPLS-TE; [RFC4203] and [RFC5307] for
GMPLS). An alternative is offered by BGP-LS
[I-D.ietf-idr-ls-distribution] .
[I-D.lee-pce-transporting-te-data] proposes some other approaches for
creating and maintaining the TED directly on a PCE as an alternative
to IGPs and BGP flooding and investigate the impact from the PCE,
routing protocol, and node perspectives.
[RFC5440] describes the specifications for the Path Computation
Element Communication Protocol (PCEP). PCEP specifies the
communication between a Path Computation Client (PCC) and a Path
Computation Element (PCE), or between two PCEs based on the PCE
architecture [RFC4655].
This document specifies a PCEP extension for TED population
capability to support functionalities described in
[I-D.lee-pce-transporting-te-data].
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1.1. 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].
2. Terminology
The terminology is as per [RFC4655] and [RFC5440].
3. Applicability
As per [I-D.lee-pce-transporting-te-data], the mechanism specified in
this draft is applicable to:
o Where there is no IGP-TE or BGP-LS running at the PCE to learn
TED.
o Where there is IGP-TE or BGP-LS running but with a need for a
faster TED population and convergence at the PCE.
* A PCE may receive partial information (say basic TE) from IGP-
TE and other information (optical and impairment) from PCEP.
* A PCE may receive full information from both IGP-TE and PCEP.
A PCC may further choose to send only local TE information or both
local and remote learned TED information.
How a PCE manages the TED information is implementation specific and
thus out of scope of this document.
4. Requirements for PCEP extension
Following key requirements associated with TED population are
identified for PCEP:
1. The PCEP speaker supporting this draft MUST be a mechanism to
advertise the TED capability.
2. PCC supporting this draft MUST have the capability to report the
TED to the PCE. This includes self originated TE information and
remote TE information learned via routing protocols. PCC MUST be
capable to do the initial bulk sync at the time of session
initialization as well as changes to TED after.
3. A PCE MAY learn TED from PCEP as well as from existing mechanism
like IGP-TE/BGP-LS. PCEP extension MUST have a mechanism to link
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the TED information learned via other means. There MUST NOT be
any changes to the existing TED population mechanism via IGP-TE/
BGP-LS. PCEP extension SHOULD keep the TE properties in a
routing protocol (IGP-TE or BGP-LS) neutral way, such that an
implementation which do want to learn about a Link-state topology
do not need to know about any OSPF or IS-IS or BGP protocol
specifics.
4. It SHOULD be possible to encode only the changes in TED
properties (after the initial sync) in PCEP messages.
5. The same mechanism should be used for both MPLS TE as well as
GMPLS, optical and impairment aware properties.
6. The extension in this draft SHOULD be extensible to support
various architecture options listed in
[I-D.lee-pce-transporting-te-data].
5. New Functions to Support TED via PCEP
Several new functions are required in PCEP to support TED population.
A function can be initiated either from a PCC towards a PCE (C-E) or
from a PCE towards a PCC (E-C). The new functions are:
o Capability advertisement (E-C,C-E): both the PCC and the PCE must
announce during PCEP session establishment that they support PCEP
extensions for TED population defined in this document.
o TE synchronization (C-E): after the session between the PCC and a
PCE is initialized, the PCE must learn PCC's TED before it can
perform path computations. In case of stateful PCE it is
RECOMENDED that this operation be done before LSP state
synchronization.
o TE Report (C-E): a PCC sends a TE report to a PCE whenever the TED
changes.
6. Overview of Extension to PCEP
6.1. New Messages
In this document, we define a new PCEP messages called TE Report
(TERpt), a PCEP message sent by a PCC to a PCE to report TED. Each
TE Report in a TERpt message can contain the TE node or TE Link
properties. An unique PCEP specific TE identifier (TE-ID) is also
carried in the message to identify the TE node or link and that
remains constant for the lifetime of a PCEP session. This identifier
on its own is sufficient when no IGP-TE or BGP-LS running in the
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network for PCE to learn TED. Incase PCE learns some information
from PCEP and some from the existing mechanism, the PCC SHOULD
include the mapping of IGP-TE or BGP-LS identifier to map the TED
information populated via PCEP with IGP-TE/BGP-LS. See Section 8.1
for details.
6.2. Capability Advertisement
During PCEP Initialization Phase, PCEP Speakers (PCE or PCC)
advertise their support of TED population PCEP extensions. A PCEP
Speaker includes the "TED Capability" TLV, described in Section 9, in
the OPEN Object to advertise its support for PCEP TED extensions.
The presence of the TED Capability TLV in PCC's OPEN Object indicates
that the PCC is willing to send TE Reports whenever local TE
information changes. The presence of the TED Capability TLV in PCE's
OPEN message indicates that the PCE is interested in receiving TE
Reports whenever local TE changes.
The PCEP protocol extensions for TED population MUST NOT be used if
one or both PCEP Speakers have not included the TED Capability TLV in
their respective OPEN message. If the PCE that supports the
extensions of this draft but did not advertise this capability, then
upon receipt of a PCRpt message from the PCC, it SHOULD generate a
PCErr with error-type 19 (Invalid Operation), error-value TBD1
(Attempted TE Report if TED capability was not advertised) and it
will terminate the PCEP session.
The TE reports sent by PCC MAY carry the remote TE information
learned via existing means like IGP-TE and BGP-LS only if both PCEP
Speakers set the R (remote) Flag in the "TED Capability" TLV to
'Remote Allowed (R Flag = 1)'. If this is not the case and TE
reports carry remote TE information, then a PCErr with error-type 19
(Invalid Operation) and error-value TBD1 (Attempted TE Report if TED
capability was not advertised) and it will terminate the PCEP
session.
6.3. Initial TED Synchronization
The purpose of TED Synchronization is to provide a checkpoint-in-
time state replica of a PCC's TED in a PCE. State Synchronization is
performed immediately after the Initialization phase (see
[RFC5440]]). In case of stateful PCE ([I-D.ietf-pce-stateful-pce])
it is RECOMENDED that the TED synchronization should be done before
LSP state synchronization.
During TED Synchronization, a PCC first takes a snapshot of the state
of its TED, then sends the snapshot to a PCE in a sequence of TE
Reports. Each TE Report sent during TE Synchronization has the SYNC
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Flag in the TE Object set to 1. The end of synchronization marker is
a TERpt message with the SYNC Flag set to 0 for an TE Object with
TED-ID equal to the reserved value 0. If the PCC has no TED state to
synchronize, it will only send the end of synchronization marker.
Either the PCE or the PCC MAY terminate the session using the PCEP
session termination procedures during the synchronization phase. If
the session is terminated, the PCE MUST clean up state it received
from this PCC. The session re-establishment MUST be re-attempted per
the procedures defined in [RFC5440], including use of a back-off
timer.
If the PCC encounters a problem which prevents it from completing the
TED population, it MUST send a PCErr message with error-type TBD2 (TE
Synchronization Error) and error-value 5 (indicating an internal PCC
error) to the PCE and terminate the session.
The PCE does not send positive acknowledgements for properly received
TED synchronization messages. It MUST respond with a PCErr message
with error-type TBD2 (TE Synchronization Error) and error-value 1
(indicating an error in processing the TERpt) if it encounters a
problem with the TE Report it received from the PCC and it MUST
terminate the session.
The TE reports may carry local as well as remote TED information
depending on the R flag in TED capability TLV.
The successful TED Synchronization sequences is shown in Figure 1.
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+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
|-----TERpt, SYNC=1----->| (Sync start)
| |
|-----TERpt, SYNC=1----->|
| . |
| . |
| . |
|-----TERpt, SYNC=1----->|
| . |
| . |
| . |
| |
|-----TERpt, SYNC=0----->| (End of sync marker
| | TE Report
| | for TED-ID=0)
| | (Sync done)
Figure 1: Successful state synchronization
The sequence where the PCE fails during the TED Synchronization phase
is shown in Figure 2.
+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
|-----TERpt, SYNC=1----->|
| |
|-----TERpt, SYNC=1----->|
| . |
| . |
| . |
|-----TERpt, SYNC=1----->|
| |
|-TERpt, SYNC=1 |
| \ ,-PCErr---|
| \ / |
| \/ |
| /\ |
| / `-------->| (Ignored)
|<--------` |
Figure 2: Failed TED synchronization (PCE failure)
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The sequence where the PCC fails during the TED Synchronization phase
is shown in Figure 3.
+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
|-----TERpt, SYNC=1----->|
| |
|-----TERpt, SYNC=1----->|
| . |
| . |
| . |
|-------- PCErr--------->|
| |
Figure 3: Failed TED synchronization (PCC failure)
6.3.1. Optimizations for TED Synchronization
TBD
6.4. TE Report
The PCC MUST report any changes in the TEDB to the PCE by sending a
TE Report carried on a TERpt message to the PCE, indicating that the
TE state. Each TE node and TE Link would be uniquely identified by a
PCEP TE identifier (TE-ID). The TE reports may carry local as well
as remote TED information depending on the R flag in TED capability
TLV. In case R flag is set, It MAY also include the mapping of IGP-
TE or BGP-LS identifier to map the TED information populated via PCEP
with IGP-TE/BGP-LS.
More details about TERpt message are in Section 8.1.
7. Transport
A permanent PCEP session MUST be established between a PCE and PCC
supporting TED population via PCEP. In the case of session failure,
session re-establishment MUST be re-attempted per the procedures
defined in [RFC5440].
8. PCEP Messages
As defined in [RFC5440], a PCEP message consists of a common header
followed by a variable-length body made of a set of objects that can
be either mandatory or optional. An object is said to be mandatory
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in a PCEP message when the object must be included for the message to
be considered valid. For each PCEP message type, a set of rules is
defined that specify the set of objects that the message can carry.
An implementation MUST form the PCEP messages using the object
ordering specified in this document.
8.1. TE Report Message
A PCEP TE Report message (also referred to as TERpt message) is a
PCEP message sent by a PCC to a PCE to report the TED state. A TERpt
message can carry more than one TE Reports. The Message-Type field
of the PCEP common header for the PCRpt message is set to [TBD3].
The format of the PCRpt message is as follows:
<TERpt Message> ::= <Common Header>
<te-report-list>
Where:
<te-report-list> ::= <TE>[<te-report-list>]
The TE object is a mandatory object which carries TE information of a
TE node or a TE link. Each TE object has an unique TE-ID as
described in Section 9.2. If the TE object is missing, the receiving
PCE MUST send a PCErr message with Error-type=6 (Mandatory Object
missing) and Error-value=[TBD4] (TE object missing).
A PCE may choose to implement a limit on the TE information a single
PCC can populate. If a TERpt is received that causes the PCE to
exceed this limit, it MUST send a PCErr message with error-type 19
(invalid operation) and error-value 4 (indicating resource limit
exceeded) in response to the TERpt message triggering this condition
and MAY terminate the session.
8.2. The PCErr Message
If a PCEP speaker has advertised the TED capability on the PCEP
session, the PCErr message MAY include the TE object. If the error
reported is the result of an TE report, then the TE-ID number MUST be
the one from the TERpt that triggered the error.
The format of a PCErr message from [RFC5440] is extended as follows:
The format of the PCRpt message is as follows:
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<PCErr Message> ::= <Common Header>
( <error-obj-list> [<Open>] ) | <error>
[<error-list>]
<error-obj-list>::=<PCEP-ERROR>[<error-obj-list>]
<error>::=[<request-id-list> | <te-id-list>]
<error-obj-list>
<request-id-list>::=<RP>[<request-id-list>]
<te-id-list>::=<TE>[<te-id-list>]
<error-list>::=<error>[<error-list>]
9. Objects and TLV
The PCEP objects defined in this document are compliant with the PCEP
object format defined in [RFC5440]. The P flag and the I flag of the
PCEP objects defined in this document MUST always be set to 0 on
transmission and MUST be ignored on receipt since these flags are
exclusively related to path computation requests.
9.1. Open Object
This document defines a new optional TLV for use in the OPEN Object.
9.1.1. TED Capability TLV
The TED-CAPABILITY TLV is an optional TLV for use in the OPEN Object
for TED population via PCEP capability advertisement. Its format is
shown in the following figure:
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=[TBD5] | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The type of the TLV is [TBD5] and it has a fixed length of 4 octets.
The value comprises a single field - Flags (32 bits):
o R (remote - 1 bit): if set to 1 by a PCC, the R Flag indicates
that the PCC allows reporting of remote TED information learned
via other means like IGP-TE and BGP-LS; if set to 1 by a PCE, the
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R Flag indicates that the PCE is capable of receiving remote TED
information (from the PCC point of view). The R Flag must be
advertised by both a PCC and a PCE for TERpt messages to report
remote as well as local TE information on a PCEP session. The
TLVs related to IGP-TE/BGP-LS identifier MUST be encoded when both
PCEP speakers have the R Flag set.
Unassigned bits are considered reserved. They MUST be set to 0 on
transmission and MUST be ignored on receipt.
Advertisement of the TED capability implies support of local TE
population, as well as the objects, TLVs and procedures defined in
this document.
9.2. TE Object
The TE (traffic engineering) object MUST be carried within TERpt
messages and MAY be carried within PCErr messages. The TE object
contains a set of fields used to specify the target TE node or link.
It also contains a flag indicating to a PCE that the TED
synchronization is in progress. The TLVs used with the TE object
correlate with the IGP-TE/BGP-LS TE encodings.
TE Object-Class is [TBD6].
Two Object-Type values are defined for the TE object:
o TE Node: TE Object-Type is 1.
o TE Link: TE Object-Type is 2.
The format of the TE object body is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Flag |R|S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Protocol-ID (8-bit): The field provide the source information.
Incase PCC only provides local information (R flag is not set), it
MUST use Protocol-ID as Direct. The following values are defined
(same as [I-D.ietf-idr-ls-distribution]):
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+-------------+----------------------------------+
| Protocol-ID | Source protocol |
+-------------+----------------------------------+
| 1 | IS-IS Level 1 |
| 2 | IS-IS Level 2 |
| 3 | OSPFv2 |
| 4 | Direct |
| 5 | Static configuration |
| 6 | OSPFv3 |
+-------------+----------------------------------+
Flags (32-bit):
o S (SYNC - 1 bit): the S Flag MUST be set to 1 on each TERpt sent
from a PCC during TED Synchronization. The S Flag MUST be set to
0 in other TERpt messages sent from the PCC.
o R (Remove - 1 bit): On TERpt messages the R Flag indicates that
the TE node/link has been removed from the PCC and the PCE SHOULD
remove from its database. Upon receiving an TE Report with the R
Flag set to 1, the PCE SHOULD remove all state for the TE node/
link identified by the TE Identifiers from its database.
TE-ID(32-bit): A PCEP-specific identifier for the TE node or link. A
PCC creates a unique TE-ID for each TE node/link that is constant for
the lifetime of a PCEP session. The PCC will advertise the same TE-
ID on all PCEP sessions it maintains at a given times. All
subsequent PCEP messages then address the TE node/link by the TE-ID.
The values of 0 and 0xFFFFFFFF are reserved.
Unassigned bits are considered reserved. They MUST be set to 0 on
transmission and MUST be ignored on receipt.
TLVs that may be included in the TE Object are described in the
following sections.
9.2.1. Routing Universe TLV
In case of remote TED population when existing IGP-TE/BGP-LS are also
used, OSPF and IS-IS may run multiple routing protocol instances over
the same link as described in [I-D.ietf-idr-ls-distribution]. See
[RFC6822] and [RFC6549]. These instances define independent "routing
universes". The 64-Bit 'Identifier' field is used to identify the
"routing universe" where the TE object belongs. The TE objects
representing IGP objects (nodes or links) from the same routing
universe MUST have the same 'Identifier' value; TE objects with
different 'Identifier' values MUST be considered to be from different
routing universes.
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The format of the ROUTING-UNIVERSE TLV is shown in the following
figure:
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=[TBD7] | Length=8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Below table lists the 'Identifier' values that are defined as well-
known in this draft (same as [I-D.ietf-idr-ls-distribution]).
+------------+---------------------+
| Identifier | Routing Universe |
+------------+---------------------+
| 0 | L3 packet topology |
| 1 | L1 optical topology |
+------------+---------------------+
If this TLV is not present the default value 0 is assumed.
9.2.2. Local TE Node Descriptors TLV
As described in [I-D.ietf-idr-ls-distribution], each link is anchored
by a pair of Router-IDs that are used by the underlying IGP, namely,
48 Bit ISO System-ID for IS-IS and 32 bit Router-ID for OSPFv2 and
OSPFv3. Incase of additional auxiliary Router-IDs used for TE, these
MUST also be included in the TE link attribute TLV (see
Section 9.2.6).
It is desirable that the Router-ID assignments inside the TE Node
Descriptor are globally unique. Autonomous System (AS) Number and
PCEP-TED Identifier in order to disambiguate the Router-IDs, as
described in [I-D.ietf-idr-ls-distribution].
The Local TE Node Descriptors TLV contains Node Descriptors for the
node anchoring the local end of the link. This TLV MUST be included
in the TE Report when during a given PCEP session a TE node/link is
first reported to a PCE. A PCC sends to a PCE the first TE Report
either during State Synchronization, or when a new TE node/link is
learned at the PCC. The value contains one or more Node Descriptor
Sub-TLVs, which allows specification of a flexible key for any given
Node/Link information such that global uniqueness of the TE node/link
is ensured.
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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=[TBD8] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Node Descriptor Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The value contains one or more Node Descriptor Sub-TLVs defined in
Section 9.2.4.
9.2.3. Remote TE Node Descriptors TLV
The Remote TE Node Descriptors contains Node Descriptors for the node
anchoring the remote end of the link. This TLV MUST be included in
the TE Report when during a given PCEP session a TE link is first
reported to a PCE. A PCC sends to a PCE the first TE Report either
during State Synchronization, or when a new TE link is learned at the
PCC. The length of this TLV is variable. The value contains one or
more Node Descriptor Sub-TLVs defined in Section 9.2.4.
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=[TBD9] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Node Descriptor Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
9.2.4. TE Node Descriptors Sub-TLVs
The Node Descriptor Sub-TLV type Type and lengths are listed in the
following table:
+--------------------+-------------------+----------+
| Sub-TLV | Description | Length |
+--------------------+-------------------+----------+
| TBD10 | Autonomous System | 4 |
| TBD11 | BGP-LS Identifier | 4 |
| TBD12 | OSPF Area-ID | 4 |
| TBD13 | Router-ID | Variable |
+--------------------+-------------------+----------+
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The sub-TLV values in Node Descriptor TLVs are defined as follows
(similar to [I-D.ietf-idr-ls-distribution]):
o Autonomous System: opaque value (32 Bit AS Number)
o BGP-LS Identifier: opaque value (32 Bit ID). In conjunction with
ASN, uniquely identifies the BGP-LS domain as described in
[I-D.ietf-idr-ls-distribution]. This sub-TLV is present only if
the node implements BGP-LS and the ID is set by the operator.
o Area ID: It is used to identify the 32 Bit area to which the TE
object belongs. Area Identifier allows the different TE objects
of the same router to be discriminated.
o Router ID: opaque value. Usage is described in
[I-D.ietf-idr-ls-distribution] for IGP Router ID. In case only
local TE information is transported and PCE learns TED only from
PCEP, it contain the unique local TE IPv4 or IPv6 router ID.
o There can be at most one instance of each sub-TLV type present in
any Node Descriptor.
9.2.5. TE Link Descriptors TLV
The TE Link Descriptors TLV contains Link Descriptors for each TE
link. This TLV MUST be included in the TE Report when during a given
PCEP session a TE link is first reported to a PCE. A PCC sends to a
PCE the first TE Report either during State Synchronization, or when
a new TE link is learned at the PCC. The length of this TLV is
variable. The value contains one or more TE Link Descriptor Sub-TLVs
The 'TE Link descriptor' TLVs uniquely identify a link among multiple
parallel links between a pair of anchor routers similar to
[I-D.ietf-idr-ls-distribution].
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=[TBD14] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Link Descriptor Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Link Descriptor Sub-TLV type and lengths are listed in the
following table:
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+-----------+---------------------+---------------+-----------------+
| Sub-TLV | Description | IS-IS TLV | Value defined |
| | | /Sub-TLV | in: |
+-----------+---------------------+---------------+-----------------+
| TBD15 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| | Identifiers | | |
| TBD16 | IPv4 interface | 22/6 | [RFC5305]/3.2 |
| | address | | |
| TBD17 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 |
| | address | | |
| TBD18 | IPv6 interface | 22/12 | [RFC6119]/4.2 |
| | address | | |
| TBD19 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 |
| | address | | |
+-----------+---------------------+---------------+-----------------+
The format and semantics of the 'value' fields in most 'Link
Descriptor' sub-TLVs correspond to the format and semantics of value
fields in IS-IS Extended IS Reachability sub-TLVs, defined in
[RFC5305], [RFC5307] and [RFC6119]. Although the encodings for 'Link
Descriptor' TLVs were originally defined for IS-IS, the TLVs can
carry data sourced either by IS-IS or OSPF or direct.
The information about a link present in the LSA/LSP originated by the
local node of the link determines the set of sub-TLVs in the Link
Descriptor of the link as described in
[I-D.ietf-idr-ls-distribution].
9.2.6. TE Node Attributes TLV
This is an optional, non-transitive attribute that is used to carry
TE node attributes. The TE node attribute TLV may be encoded in the
TE node Object.
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=[TBD20] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Node Attributes Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Node Attributes Sub-TLV type and lengths are listed in the
following table:
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+--------------+-----------------------+----------+-----------------+
| Sub TLV | Description | Length | Value defined |
| | | | in: |
+--------------+-----------------------+----------+-----------------+
| TBD21 | Node Flag Bits | 1 | [I-D.ietf-idr- |
| | | | ls-distribution]|
| | | | /3.3.1.1 |
| TBD22 | Opaque Node | variable | [I-D.ietf-idr- |
| | Properties | | ls-distribution]|
| | | | /3.3.1.5 |
| TBD23 | Node Name | variable | [I-D.ietf-idr- |
| | | | ls-distribution]|
| | | | /3.3.1.3 |
| TBD24 | IS-IS Area Identifier | variable | [I-D.ietf-idr- |
| | | | ls-distribution]|
| | | | /3.3.1.2 |
| TBD25 | IPv4 Router-ID of | 4 | [RFC5305]/4.3 |
| | Local Node | | |
| TBD26 | IPv6 Router-ID of | 16 | [RFC6119]/4.1 |
| | Local Node | | |
+--------------+-----------------------+----------+-----------------+
9.2.7. TE Link Attributes TLV
TE Link attribute TLV may be encoded in the TE Link Object. The
format and semantics of the 'value' fields in some 'Link Attribute'
sub-TLVs correspond to the format and semantics of value fields in
IS-IS Extended IS Reachability sub-TLVs, defined in [RFC5305],
[RFC5307] and [I-D.ietf-idr-ls-distribution]. Although the encodings
for 'Link Attribute' TLVs were originally defined for IS-IS, the TLVs
can carry data sourced either by IS-IS or OSPF or direct.
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=[TBD27] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Link Attributes Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following 'Link Attribute' sub-TLVs are are valid :
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+-----------+---------------------+--------------+------------------+
| Sub-TLV | Description | IS-IS TLV | Defined in: |
| | | /Sub-TLV | |
| | | BGP-LS TLV | |
+-----------+---------------------+--------------+------------------+
| TBD28 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| | Local Node | | |
| TBD29 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Local Node | | |
| TBD30 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| | Remote Node | | |
| TBD31 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Remote Node | | |
| TBD32 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| | Identifiers | | |
| TBD33 | Administrative | 22/3 | [RFC5305]/3.1 |
| | group (color) | | |
| TBD34 | Maximum link | 22/9 | [RFC5305]/3.3 |
| | bandwidth | | |
| TBD35 | Max. reservable | 22/10 | [RFC5305]/3.5 |
| | link bandwidth | | |
| TBD36 | Unreserved | 22/11 | [RFC5305]/3.6 |
| | bandwidth | | |
| TBD37 | TE Default Metric | 22/18 | [I-D.ietf-idr- |
| | | | ls-distribution] |
| | | | /3.3.2.3 |
| TBD38 | Link Protection | 22/20 | [RFC5307]/1.2 |
| | Type | | |
| TBD39 | MPLS Protocol Mask | 1094 | [I-D.ietf-idr- |
| | | | ls-distribution] |
| | | | /3.3.2.2 |
| TBD40 | IGP Metric | 1095 | [I-D.ietf-idr- |
| | | | ls-distribution] |
| | | | /3.3.2.4 |
| TBD41 | Shared Risk Link | 1096 | [I-D.ietf-idr- |
| | Group | | ls-distribution] |
| | | | /3.3.2.5 |
| TBD42 | Opaque link | 1097 | [I-D.ietf-idr- |
| | attributes | | ls-distribution] |
| | | | /3.3.2.6 |
| TBD43 | Link Name attribute | 1098 | [I-D.ietf-idr- |
| | | | ls-distribution] |
| | | | /3.3.2.7 |
+-----------+---------------------+--------------+------------------+
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10. Other Considerations
10.1. Inter-AS Links
The main source of TE information is the IGP, which is not active on
inter-AS links. In some cases, the IGP may have information of
inter-AS links ([RFC5392], [RFC5316]). In other cases, an
implementation SHOULD provide a means to inject inter-AS links into
PCEP. The exact mechanism used to provision the inter-AS links is
outside the scope of this document.
11. Security Considerations
This document extends PCEP to support TED population including a new
TERpt message with new object and TLVs. Procedures and protocol
extensions defined in this document do not effect the overall PCEP
security model. See [RFC5440], [I-D.ietf-pce-pceps]. Tampering with
the TERpt message may have an effect on path computations at PCE. It
also provides adversaries an opportunity to eavesdrop and learn
sensitive information and plan sophisticated attacks on the network
infrastructure. The PCE implementation SHOULD provide mechanisms to
prevent strains created by network flaps and amount of TED
information. Thus it is suggested that any mechanism used for
securing the transmission of other PCEP message be applied here as
well. As a general precaution, it is RECOMMENDED that these PCEP
extensions only be activated on authenticated and encrypted sessions
belonging to the same administrative authority.
12. Manageability Considerations
All manageability requirements and considerations listed in [RFC5440]
apply to PCEP protocol extensions defined in this document. In
addition, requirements and considerations listed in this section
apply.
12.1. Control of Function and Policy
In addition to configuring specific PCEP session parameters, as
specified in section 8.1 of [RFC5440], a PCE or PCC implementation
MUST allow configuring the TED PCEP capability. A PCC SHOULD allow
the operator to specify an TED population policy where TERpt are sent
to which PCE.
12.2. Information and Data Models
PCEP session configuration and information in the PCEP MIB module
SHOULD be extended to include advertised TED capabilities, TED
synchronization status and TED etc.
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12.3. Liveness Detection and Monitoring
PCEP protocol extensions defined in this document do not require any
new mechanisms beyond those already defined in section 8.3 of
[RFC5440].
12.4. Verify Correct Operations
Mechanisms defined in section 8.4 of [RFC5440] also apply to PCEP
protocol extensions defined in this document. In addition to
monitoring parameters defined in [RFC5440], a PCEP implementation
with TED SHOULD provide the following parameters:
o Total number of TE Reports
o Number of TE nodes and links
o Number of dropped TERpt messages
12.5. Requirements On Other Protocols
PCEP protocol extensions defined in this document do not put new
requirements on other protocols.
12.6. Impact On Network Operations
Mechanisms defined in section 8.6 of [RFC5440] also apply to PCEP
protocol extensions defined in this document.
Additionally, a PCEP implementation SHOULD allow a limit to be placed
on the amount and rate of TERpt messages sent by a PCEP speaker and
processed by the peer. It SHOULD also allow sending a notification
when a rate threshold is reached.
13. IANA Considerations
14. Acknowledgments
This document borrows some of the structure and text from the
[I-D.ietf-pce-stateful-pce].
15. References
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15.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", RFC 5440, March
2009.
15.2. Informative References
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, September
2003.
[RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 4203, October 2005.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
[RFC5307] Kompella, K. and Y. Rekhter, "IS-IS Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 5307, October 2008.
[RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5316, December 2008.
[RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5392, January 2009.
[RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
Engineering in IS-IS", RFC 6119, February 2011.
[RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi-
Instance Extensions", RFC 6549, March 2012.
[RFC6822] Previdi, S., Ginsberg, L., Shand, M., Roy, A., and D.
Ward, "IS-IS Multi-Instance", RFC 6822, December 2012.
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[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-10 (work in progress), October 2014.
[I-D.ietf-pce-pceps]
Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure
Transport for PCEP", draft-ietf-pce-pceps-02 (work in
progress), October 2014.
[I-D.ietf-idr-ls-distribution]
Gredler, H., Medved, J., Previdi, S., Farrel, A., and S.
Ray, "North-Bound Distribution of Link-State and TE
Information using BGP", draft-ietf-idr-ls-distribution-10
(work in progress), January 2015.
[I-D.lee-pce-transporting-te-data]
Lee, Y. and z. zhenghaomian@huawei.com, "PCE in Support of
Transporting Traffic Engineering Data", draft-lee-pce-
transporting-te-data-01 (work in progress), October 2014.
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Appendix A. Contributor Addresses
Udayasree Palle
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037
India
EMail: udayasree.palle@huawei.com
Sergio Belotti
Alcatel-Lucent
Italy
EMail: sergio.belotti@alcatel-lucent.com
Authors' Addresses
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037
India
EMail: dhruv.ietf@gmail.com
Young Lee
Huawei Technologies
5340 Legacy Drive, Building 3
Plano, TX 75023
USA
EMail: leeyoung@huawei.com
Daniele Ceccarelli
Ericsson
Torshamnsgatan,48
Stockholm
Sweden
EMail: daniele.ceccarelli@ericsson.com
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