draft-ietf-pce-pcep-domain-sequence-00.txt   draft-ietf-pce-pcep-domain-sequence-01.txt 
PCE Working Group D. Dhody PCE Working Group D. Dhody
Internet-Draft U. Palle Internet-Draft U. Palle
Intended status: Experimental Huawei Technologies India Pvt Intended status: Experimental Huawei Technologies India Pvt
Expires: November 23, 2012 Ltd Expires: January 6, 2013 Ltd
R. Casellas R. Casellas
CTTC - Centre Tecnologic de CTTC - Centre Tecnologic de
Telecomunicacions de Catalunya Telecomunicacions de Catalunya
May 22, 2012 July 5, 2012
Standard Representation Of Domain Sequence Standard Representation Of Domain Sequence
draft-ietf-pce-pcep-domain-sequence-00 draft-ietf-pce-pcep-domain-sequence-01
Abstract Abstract
The ability to compute shortest constrained Traffic Engineering Label The ability to compute shortest constrained Traffic Engineering Label
Switched Paths (TE LSPs) in Multiprotocol Label Switching (MPLS) and Switched Paths (TE LSPs) in Multiprotocol Label Switching (MPLS) and
Generalized MPLS (GMPLS) networks across multiple domains has been Generalized MPLS (GMPLS) networks across multiple domains has been
identified as a key requirement for P2P and P2MP scenarios. In this identified as a key requirement for P2P and P2MP scenarios. In this
context, a domain is a collection of network elements within a common context, a domain is a collection of network elements within a common
sphere of address management or path computational responsibility sphere of address management or path computational responsibility
such as an IGP area or an Autonomous Systems. This document such as an IGP area or an Autonomous Systems. This document
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 23, 2012. This Internet-Draft will expire on January 6, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Detail Description . . . . . . . . . . . . . . . . . . . . . . 5 3. Detail Description . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Domains . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Domains . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Domain-Sequence . . . . . . . . . . . . . . . . . . . . . 5 3.2. Domain-Sequence . . . . . . . . . . . . . . . . . . . . . 6
3.3. Standard Representation . . . . . . . . . . . . . . . . . 6 3.3. Standard Representation . . . . . . . . . . . . . . . . . 7
3.4. Mode of Operation . . . . . . . . . . . . . . . . . . . . 8 3.3.1. New Sub-Objects . . . . . . . . . . . . . . . . . . . 7
3.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.3.1.1. Autonomous system . . . . . . . . . . . . . . . . 7
3.5.1. Inter-Area Path Computation . . . . . . . . . . . . . 9 3.3.1.2. IGP Area . . . . . . . . . . . . . . . . . . . . . 8
3.5.2. Inter-AS Path Computation . . . . . . . . . . . . . . 11 3.3.2. Use in PCEP Objects . . . . . . . . . . . . . . . . . 9
3.5.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . 11 3.3.2.1. Include Route Object . . . . . . . . . . . . . . . 9
3.5.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . 13 3.3.2.2. Exclude Route Object . . . . . . . . . . . . . . . 13
3.5.3. Boundary Node and Inter-AS-Link . . . . . . . . . . . 15 3.3.2.3. Explicit Route Object . . . . . . . . . . . . . . 15
3.5.4. PCE serving multiple domains . . . . . . . . . . . . . 16 3.3.2.4. Explicit Exclusion Route Sub-Object . . . . . . . 16
3.5.5. P2MP . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.4. Other Considerations . . . . . . . . . . . . . . . . . . . 16
3.5.6. HPCE . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.4.1. Inter-Area Path Computation . . . . . . . . . . . . . 16
3.5.7. Relationship to PCE Sequence . . . . . . . . . . . . . 18 3.4.2. Inter-AS Path Computation . . . . . . . . . . . . . . 18
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 3.4.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . 18
4.1. New IRO Object Type . . . . . . . . . . . . . . . . . . . 19 3.4.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . 20
4.2. Sub-Objects . . . . . . . . . . . . . . . . . . . . . . . 19 3.4.3. Boundary Node and Inter-AS-Link . . . . . . . . . . . 22
5. Security Considerations . . . . . . . . . . . . . . . . . . . 19 3.4.4. PCE serving multiple domains . . . . . . . . . . . . . 23
6. Manageability Considerations . . . . . . . . . . . . . . . . . 19 3.4.5. P2MP . . . . . . . . . . . . . . . . . . . . . . . . . 23
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19 3.4.6. HPCE . . . . . . . . . . . . . . . . . . . . . . . . . 23
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 3.4.7. Relationship to PCE Sequence . . . . . . . . . . . . . 25
8.1. Normative References . . . . . . . . . . . . . . . . . . . 19 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
8.2. Informative References . . . . . . . . . . . . . . . . . . 20 4.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . 25
4.2. New Sub-Objects . . . . . . . . . . . . . . . . . . . . . 26
4.3. Error Object Field Values . . . . . . . . . . . . . . . . 26
5. Security Considerations . . . . . . . . . . . . . . . . . . . 26
6. Manageability Considerations . . . . . . . . . . . . . . . . . 27
6.1. Control of Function and Policy . . . . . . . . . . . . . . 27
6.2. Information and Data Models . . . . . . . . . . . . . . . 27
6.3. Liveness Detection and Monitoring . . . . . . . . . . . . 27
6.4. Verify Correct Operations . . . . . . . . . . . . . . . . 27
6.5. Requirements On Other Protocols . . . . . . . . . . . . . 27
6.6. Impact On Network Operations . . . . . . . . . . . . . . . 28
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.1. Normative References . . . . . . . . . . . . . . . . . . . 28
8.2. Informative References . . . . . . . . . . . . . . . . . . 28
1. Introduction 1. Introduction
A PCE may be used to compute end-to-end paths across multi-domain A PCE may be used to compute end-to-end paths across multi-domain
environments using a per-domain path computation technique [RFC5152]. environments using a per-domain path computation technique [RFC5152].
The so called backward recursive path computation (BRPC) mechanism The so called backward recursive path computation (BRPC) mechanism
[RFC5441] defines a PCE-based path computation procedure to compute [RFC5441] defines a PCE-based path computation procedure to compute
inter-domain constrained (G)MPLS TE LSPs. However, both per-domain inter-domain constrained (G)MPLS TE LSPs. However, both per-domain
and BRPC techniques assume that the sequence of domains to be crossed and BRPC techniques assume that the sequence of domains to be crossed
from source to destination is known, either fixed by the network from source to destination is known, either fixed by the network
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PCE: Path Computation Element. An entity (component, application, PCE: Path Computation Element. An entity (component, application,
or network node) that is capable of computing a network path or or network node) that is capable of computing a network path or
route based on a network graph and applying computational route based on a network graph and applying computational
constraints. constraints.
P2MP: Point-to-Multipoint P2MP: Point-to-Multipoint
P2P: Point-to-Point P2P: Point-to-Point
RSVP: Resource Reservation Protocol
TE LSP: Traffic Engineering Label Switched Path. TE LSP: Traffic Engineering Label Switched Path.
3. Detail Description 3. Detail Description
3.1. Domains 3.1. Domains
A domain can be defined as a separate administrative or geographic A domain can be defined as a separate administrative or geographic
environment within the network. A domain may be further defined as a environment within the network. A domain may be further defined as a
zone of routing or computational ability. Under these definitions a zone of routing or computational ability. Under these definitions a
domain might be categorized as an Antonymous System (AS) or an domain might be categorized as an Autonomous System (AS) or an
Interior Gateway Protocol (IGP) area ( as per [RFC4726] and Interior Gateway Protocol (IGP) area ( as per [RFC4726] and
[RFC4655]). To uniquely identify a domain in the domain sequence [RFC4655]). To uniquely identify a domain in the domain sequence
both AS and Area-id is important. both AS and Area-id MAYBE important.
3.2. Domain-Sequence 3.2. Domain-Sequence
A domain-sequence is an ordered sequence of domains traversed to A domain-sequence is an ordered sequence of domains traversed to
reach the destination domain. In this context a Domain could be an reach the destination domain. In this context a Domain could be an
Autonomous System (AS) or an IGP Area. Note that an AS can be Autonomous System (AS) or an IGP Area. Note that an AS can be
further made of multiple Area. further made of multiple Areas.
Domain Sequence can be applied as a constraint and carried in path Domain Sequence can be applied as a constraint and carried in path
computation request to PCE(s). In case of HPCE [PCE-HIERARCHY-FWK] computation request to PCE(s). In case of HPCE [PCE-HIERARCHY-FWK]
Parent PCE MAY send the domain sequence as a result in path Parent PCE MAY send the domain sequence as a result in path
computation reply. computation reply.
In this context, ordered sequence is important, in a P2P path, the In this context, ordered sequence is important, in a P2P path, the
domains listed appear in the order that they are crossed. In a P2MP domains listed appear in the order that they are crossed. In a P2MP
path, the domain tree is represented as list of domain sequences. path, the domain tree is represented as list of domain sequences.
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Thus a Domain-Sequence MAY be made up of one or more of - Thus a Domain-Sequence MAY be made up of one or more of -
o AS Number o AS Number
o Area ID o Area ID
o Boundary Node ID o Boundary Node ID
o Inter-AS-Link Address o Inter-AS-Link Address
Consequently, a Domain-Sequence can be used:
1. by a PCE in order to discover or select the next PCE in a
collaborative path computation, such as in BRPC [RFC5441];
2. by the Parent PCE to return the domain sequence when unknown,
this can further be an input to BRPC procedure;
3. By a PCC (or PCE) to constraint the domains used in a H-PCE path
computation, explicitly specifying which domains to be expanded;
3.3. Standard Representation 3.3. Standard Representation
3.3.1. New Sub-Objects
Some sub-objects are defined in [RFC3209], [RFC3473], [RFC3477] and
[RFC4874], but new sub-objects related to Domain-Sequence are needed.
3.3.1.1. Autonomous system
[RFC3209] already defines 2 octet AS number.
To support 4 octet AS number as per [RFC4893] following subobject is
defined:
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 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L: The L bit is an attribute of the subobject as define in [RFC3209].
Type: (TBA by IANA) indicating 4 octet AS Number.
Length: 8 (Total length of the subobject in bytes).
Reserved: Zero at transmission, Ignored at receipt.
AS-ID: The 4 octet AS Number. Note that if 16-bit AS numbers are in
use, the low order bits (16 through 31) should be used and the high
order bits (0 through 15) should be set to zero.
3.3.1.2. IGP Area
Since the length and format of Area-id is different for OSPF and
ISIS, following two subobjects are defined:
For OSPF, the area-id is a 32 bit number. The Subobject looks
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 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Area Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L: The L bit is an attribute of the subobject as define in [RFC3209].
Type: (TBA by IANA) indicating 4 octet OSPF Area ID.
Length: 8 (Total length of the subobject in bytes).
Reserved: Zero at transmission, Ignored at receipt.
OSPF Area Id: The 4 octet OSPF Area ID.
For IS-IS, the area-id is of variable length and thus the length of
the Subobject is variable. The Area-id is as described in IS-IS by
ISO standard [ISO 10589].
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 | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// IS-IS Area ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L: The L bit is an attribute of the subobject as define in [RFC3209].
Type: (TBA by IANA) indicating IS-IS Area ID.
Length: Variable (Total length of the subobject in bytes including
padding). The Length MUST be at least 4, and MUST be a multiple of
4.
Area-Len: Variable (Length of the actual (non-padded) IS-IS Area
Identifier in octets; Valid values are from 2 to 11 inclusive).
Reserved: Zero at transmission, Ignored at receipt.
IS-IS Area Id: The variable-length IS-IS area identifier. Padded
with trailing zeroes to a four-octet boundary.
3.3.2. Use in PCEP Objects
These sub-objects MAYBE used in -
o Include Route Object (IRO): As per [RFC5440], used to specify set
of network elements that MUST be traversed. These subobjects are
used to specify the domain-sequence that MUST be traversed to
reach the destination.
o Exclude Route Object (XRO): As per [RFC5521], used to specify
certain abstract nodes that MUST be excluded from whole path.
These subobjects are used to specify certain domains that MUST be
avoided to reach the destination.
o Explicit Route Object (ERO): As per [RFC5440],used to specify a
computed path in the network. These subobjects are used to
specify the domain-sequence when computed by a Parent PCE
([PCE-HIERARCHY-FWK]).
o Explicit Exclusion Route Sub-Object (EXRS): As per [RFC5521], used
to specify exclusion of certain abstract nodes between a specific
pair of nodes. EXRS are a sub-object inside the IRO. These
subobjects are used to specify the domains that must be excluded
between two abstract nodes.
3.3.2.1. Include Route Object
3.3.2.1.1. Option 1: New IRO Object Type
The IRO (Include Route Object) [RFC5440] is an optional object used The IRO (Include Route Object) [RFC5440] is an optional object used
to specify a set of specified network elements that the computed path to specify a set of specified network elements that the computed path
MUST traverse. [RFC5440] in its description of IRO does not MUST traverse. [RFC5440] in its description of IRO does not
constrain the sub-objects to be in a given particular order. When constrain the sub-objects to be in a given particular order. When
considering a domain sequence, the domain relative ordering is a considering a domain sequence, the domain relative ordering is a
basic criterion and, as such, this document specifies a new IRO basic criterion and, as such, this document specifies a new IRO
object type. object type.
We define a new type of IRO Object to define Domain Sequence. We define a new type of IRO Object to define Domain Sequence.
skipping to change at page 6, line 40 skipping to change at page 10, line 28
object type is identical to the sub-object type defined in the object type is identical to the sub-object type defined in the
related documents. Some new sub-objects related to Domain-Sequence related documents. Some new sub-objects related to Domain-Sequence
are also added in this document. are also added in this document.
The following sub-object types are used. The following sub-object types are used.
Type Sub-object Type Sub-object
1 IPv4 prefix 1 IPv4 prefix
2 IPv6 prefix 2 IPv6 prefix
4 Unnumbered Interface ID 4 Unnumbered Interface ID
32 Autonomous system number (2 Byte) 32 Autonomous system number (2 Byte)
33 Explicit Exclusion (EXRS)
TBD Autonomous system number (4 Byte) TBD Autonomous system number (4 Byte)
TBD OSPF Area id TBD OSPF Area id
TBD ISIS Area id TBD ISIS Area id
[RFC3209] defines sub-objects for IPv4, IPv6 and unnumbered Interface [RFC3209] defines sub-objects for IPv4, IPv6 and unnumbered Interface
ID, which in the context of domain-sequence is used to specify ID, which in the context of domain-sequence is used to specify
Boundary Node (ABR/ASBR) and Inter-AS-Links. Boundary Node (ABR/ASBR) and Inter-AS-Links. The sub-objects for AS
Number (2 or 4 Byte) and IGP Area is used to specify the domains in
the domain-sequence.
[RFC3209] also defines 2 octet AS number. The new IRO Object-Type used to define the domain-sequence would
handle the L bit (Loose / Strict) in the sub-objects.
To support 4 octet AS number [RFC4893] following subobject is Note that PCReq message is free to carry both type of IRO with IRO
defined: Type 1 ([RFC5440]) used to specify the intra-domain abstract nodes
and resources and the new IRO Type as described in this document to
specify the domain-sequence.
All other rules of PCEP objects and message processing (ex. P bit
handling of Common Object Header) is as per [RFC5440].
3.3.2.1.1.1. Mode of Operation
A domain sequence IRO object constraints or defines the domains
involved in a multi-domain path computation, typically involving two
or more collaborative PCEs.
A domain sequence can have varying degrees on granularity; it is
possible to have a domain sequence composed of, uniquely, AS
identifiers. It is also possible to list the involved areas for a
given AS.
In any case, the mapping between domains and responsible PCEs is not
defined in this document. It is assumed that a PCE that needs to
obtain a "next PCE" from a domain sequence is able to do so (e.g. via
administrative configuration, or discovery).
A PCC builds a domain sequence IRO (new type) to encode the domain
sequence, that is all domains that it wishes the cooperating PCEs to
traverse in order to compute the end to end path.
For each inclusion, the PCC clears the L-bit to indicate that the PCE
is required to include the domain, or sets the L-bit to indicate that
the PCC simply desires that the domain be included in the domain-
sequence.
When a PCE receives a PCReq message it looks for a domain sequence
IRO (new type) to see if domain-sequence are required. If the PCE
finds more than one domain sequence IRO (new type), it MUST use the
first one in the message and MUST ignore subsequent instances.
If the PCE does not recognize the domain sequence IRO (new type), it
MUST return a PCErr message with Error-Type "Unknown Object" and
Error-value "Unrecognized object Type" as described in [RFC5440].
If the PCE is unwilling or unable to process the domain sequence IRO
(new type), it MUST return a PCErr message with the Error-Type "Not
supported object" and follow the relevant procedures described in
[RFC5440].
If a PCE that supports the domain sequence IRO (new type) and
encounters a subobject that it does not support or recognize, it MUST
act according to the setting of the L-bit in the subobject. If the
L-bit is clear, the PCE MUST respond with a PCErr with Error-Type
"Unrecognized subobject" and set the Error-Value to the subobject
type code. If the L-bit is set, the PCE MAY respond with a PCErr as
already stated or MAY ignore the subobject: this choice is a local
policy decision.
If a PCE parses a domain sequence IRO (new type) and encounters these
subobject that it recognizes, it MUST act according to the
requirements expressed in the subobject. That is, if the L-bit is
clear, the PCE(s) MUST produce a path that follows domain-sequence
nodes in order identified by the sub-objects in the path. If the
L-bit is set, the PCE(s) SHOULD produce a path along the domain
sequence unless it is not possible to construct a path complying with
the other constraints expressed in the PCReq message.
A successful path computation reported in a PCRep message MUST
include an ERO to specify the path that has been computed as
specified in [RFC5440] following the domain-sequence.
When a PCE returns a path in a PCRep, it MAY also supply a domain
sequence IRO (new type) in a PCRep message with the NO-PATH object
indicates that the set of elements of the original domain sequence
IRO prevented the PCE from finding a path.
Sub-Object types for AS and IGP Area guide the next domain selection
and finding the PCE serving that domain.
Note that a particular domain in the domain-sequence can be
identified by -
o Just Area: Only the IGP (OSPF or ISIS) Area subobject is used to
identify the next domain. (Refer Figure 1)
o Just AS: Only the AS subobject is used to identify the next
domain. (Refer Figure 2)
o AS and IGP Area: Combination of both AS and Area are used to
identify the next domain. In this case the order is AS Subobject
followed by Area. (Refer Figure 3)
Sub-Object of other types representing Boundary Node or Inter-As-Link
do not pay any role in selection of next domain and subsequently PCE
selection in the domain-sequence. But they MUST be applied during
the final path computation procedure as before.
3.3.2.1.2. Option 2: Same IRO Object Type
The IRO (Include Route Object) [RFC5440] is an optional object used
to specify a set of specified network elements that the computed path
MUST traverse.
The new sub-objects denoting the domain-sequence is carried in the
same IRO Type 1, and all the rules of processing as specified in
[RFC5440] are applied.
Note the following differences -
o Order: Since there is no inherent order specified in the encoding
of the subobjects in IRO Type 1 [RFC5440]. It is the job of PCE
to figure out the order of the domains to be crossed to reach the
destination domain. Note that in case of doubt, or when
applicable, PCE can still apply the ordering as specified in the
PCReq message.
o Loose / Strict: [RFC5440] state that the L bit of the sub-objects
within an IRO Type 1 [RFC5440] has no meaning. This is applicable
for sub-objects denoting domain-sequence as well.
o Scope: Sub-objects referring to domains and boundary nodes will
mix with subobjects for internal network nodes of multiple
domains. It is the job of PCE to figure out the scope and apply
the processing rules accordingly. The PCE should distinguish
between - the subobject is unknown (not in TED) or known but the
computation fails. The PCE processing the IRO MAY include as many
of the elements of the IRO as possible. If the PCE is passing the
request onwards, it is OK for it to have unknown nodes, and it can
assume that the next PCE might be able to satisfy the remaining
elements of the IRO. On the other hand, if the PCE is making an
end-to-end (or edge-to-edge, or end-to-edge) path and will return
the response to a PCC (rather than pass it on) then the PCE must
fail if it cannot satisfy the IRO. Ultimately, when the path
segments are aggregated by a head-end PCE or by a parent PCE, that
PCE can check to see whether any elements of the IRO are still
missing and handle accordiangly.
3.3.2.2. Exclude Route Object
The Exclude Route Object (XRO) [RFC5521] is an optional object used
to specify exclusion of certain abstract nodes or resources from the
whole path.
The following subobject types are defined to be used in XRO as
defined in [RFC3209], [RFC3477], [RFC4874], and [RFC5521].
Type Sub-object
1 IPv4 prefix
2 IPv6 prefix
4 Unnumbered Interface ID
32 Autonomous system number (2 Byte)
34 SRLG
64 IPv4 Path Key
65 IPv6 Path Key
TBD Autonomous system number (4 Byte)
TBD OSPF Area id
TBD ISIS Area id
The new subobjects to support 4 octet AS and IGP (OSPF / ISIS) Area
MAY also be used in the XRO to specify exclusion of certain domains
in the path computation procedure.
The X-bit indicates whether the exclusion is mandatory or desired. 0
indicates that the domain specified MUST be excluded from the path
computed by the PCE(s). 1 indicates that the domain specified SHOULD
be excluded from the inter-domain path computed by the PCE(s), but
MAY be included subject to PCE policy and the absence of a viable
path that meets the other constraints and excludes the domain. All
other fields are consistent with the definition in Section 3.3.1.
4 Octet Autonomous system:
0 1 2 3 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 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 | Length | Reserved | |X| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Id (4 bytes) | | AS Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Since the length of Area-id is different for OSPF and ISIS, we OSPF Area:
propose different sub-objects.
For OSPF, the area-id is a 32 bit number. The Subobject looks 0 1 2 3
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 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 | Length | Reserved | |X| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Area Id (4 bytes) | | OSPF Area Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The length if fixed.
For ISIS, the area-id is of variable length and thus the length of IS-IS Area:
the Subobject is variable. The Area-id is as described in ISIS by
ISO standard [ISO 10589]. The Length MUST be at least 4, and MUST be
a multiple of 4.
0 1 2 3 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 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 | Length | Reserved | |X| Type | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// ISIS Area ID // // IS-IS Area ID //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The above sub-objects in various combinations can be used to encode If a PCE that supports XRO and encounters a subobject that it does
the domain-sequence. When the domain-sequence is used as a not support or recognize, it MUST act according to the setting of the
constraint in path computation request it is carried in IRO Domain X-bit in the subobject. If the X-bit is clear, the PCE MUST respond
Sequence Object Type. The same sub-objects and their encoding can be with a PCErr with Error-Type "Unrecognized subobject" and set the
used in ERO and path reply message when the domain sequence is Error-Value to the subobject type code. If the X-bit is set, the PCE
computed from Parent PCE. MAY respond with a PCErr as already stated or MAY ignore the
subobject: this choice is a local policy decision.
All other rules of PCEP objects and message processing is as per
[RFC5440].
3.4. Mode of Operation
A domain sequence IRO object constraints or defines the domains All the other processing rules are as per [RFC5521].
involved in a muti-domain path computation, typically involving two
or more collaborative PCEs.
Consequently, a Domain-Sequence can be used: 3.3.2.3. Explicit Route Object
1. by a PCE in order to discover or select the next PCE in a The Explicit Route Object (ERO) [RFC5440] is used to specify a
collaborative path computation, such as in BRPC [RFC5441]; computed path in the network. PCEP ERO sub-object types correspond
to RSVP-TE ERO sub-object types as defined in [RFC3209], [RFC3473],
[RFC3477], [RFC4873], [RFC4874], and [RFC5520].
2. by the Parent PCE to return the domain sequence when unknown, Type Sub-object
this can further be an input to BRPC procedure; 1 IPv4 prefix
2 IPv6 prefix
3 Label
4 Unnumbered Interface ID
32 Autonomous system number (2 Byte)
33 Explicit Exclusion (EXRS)
37 Protection
64 IPv4 Path Key
65 IPv6 Path Key
TBD Autonomous system number (4 Byte)
TBD OSPF Area id
TBD ISIS Area id
3. By a PCC (or PCE) to constraint the domains used in a H-PCE path The new subobjects to support 4 octet AS and IGP (OSPF / ISIS) Area
computation, explicitly specifying which domains to be expanded; MAY also be used in the ERO to specify an abstract node (a group of
nodes whose internal topology is opaque to the ingress node of the
LSP). Using this concept of abstraction, an explicitly routed LSP
can be specified as a sequence of domains.
A domain sequence can have varying degrees on granularity; it is In case of Hierarchical PCE, a Parent PCE ([PCE-HIERARCHY-FWK]) MAY
possible to have a domain sequence composed of, uniquely, AS be requested to find the domain-sequence. The Parent PCE MUST use
identifiers. It is also possible to list the involved areas for a ERO with AS and IGP Area subobjects to encode the computed domain-
given AS. sequence. Refer example in Section 3.4.6.
In any case, the mapping between domains and responsible PCEs is not 3.3.2.4. Explicit Exclusion Route Sub-Object
defined in this document. It is assumed that a PCE that needs to
obtain a "next PCE" from a domain sequence is able to do so (e.g. via
administrative configuration, or discovery).
The following algorithm can be applied to select the next domain and, Explicit Exclusion Route Sub-Object (EXRS) [RFC5521] is used to
if need be, the PCE responsible for that domain. Note the PCC select specify exclusion of certain abstract nodes between a specific pair
the PCE(1) based on its own domain information. of nodes.
START The EXRS subobject may carry any of the subobjects defined for
Get the first Sub-Object S1 from the Domain-Sequence inclusion in the XRO, thus the new subobjects to support 4 octet AS
IF S1's Type is Area (OSPF or ISIS) and IGP (OSPF / ISIS) Area MAY also be used in the EXRS. The
IF S1's Domain is same as current PCE's Area meanings of the fields of the new XRO subobjects are unchanged when
Remove S1 from Domain-Sequence and Goto START the subobjects are included in an EXRS, except that scope of the
ELSE exclusion is limited to the single hop between the previous and
Find the next PCE based on S1's Area within the AS subsequent elements in the IRO.
ENDIF
ELSEIF S1's Type is AS (2 or 4 Byte)
IF S1's Domain is same as current PCE's AS
Remove S1 from Domain-Sequence and Goto START
ELSE
Get the next Sub-Object S2 from the Domain-Sequence
IF the S2 is NULL or S2's type is AS
Find the next PCE based on S1's Domain (AS) only
ELSEIF S1's Type is Area
Find the next PCE based on S1's Domain (AS)
and S2's Domain (Area)
ELSE
ENDIF
ENDIF
ENDIF
IF Domain-Sequence is empty or next PCE is not found
Send PCRep with NO-Path
ENDIF
If the Sub-Object is of other type representing Boundary Node or All the processing rules are as per [RFC5521].
Inter-As-Link, it is not used to select the next PCE, but used only
while applying BRPC or any other inter-domain procedure.
3.5. Examples 3.4. Other Considerations
3.5.1. Inter-Area Path Computation 3.4.1. Inter-Area Path Computation
In an inter-area path computation where ingress and egress belong to In an inter-area path computation where ingress and egress belong to
different IGP area, the domain sequence MAYBE represented using a different IGP area, the domain sequence MAYBE represented using a
ordered list of AREA sub-objects. AS number MAYBE skipped, as area ordered list of AREA sub-objects. AS number MAYBE skipped, as area
information is enough to select the next PCE. information is enough to select the next PCE.
+-------------------+ +-------------------+ +-------------------+ +-------------------+
| | | | | | | |
| +--+ | | +--+ | | +--+ | | +--+ |
| +--+ | | | | | | | | +--+ | | | | | | |
skipping to change at page 11, line 28 skipping to change at page 18, line 28
|IRO | |Sub | |Sub | |Sub | |Sub | |IRO | |Sub | |Sub | |Sub | |Sub |
|Object | |Object As| |Object | |Object | |Object | |Object | |Object As| |Object | |Object | |Object |
|Header | |100 | |Area 2 | |Area 0 | |Area 4 | |Header | |100 | |Area 2 | |Area 0 | |Area 4 |
| | | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | |
+---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+
AS is optional and it MAY be skipped. PCE should be able to AS is optional and it MAY be skipped. PCE should be able to
understand both notations. understand both notations.
3.5.2. Inter-AS Path Computation 3.4.2. Inter-AS Path Computation
In inter-AS path computation, where ingress and egress belong to In inter-AS path computation, where ingress and egress belong to
different AS, the domain sequence is represented using an ordered different AS, the domain sequence is represented using an ordered
list of AS sub-objects. The domain sequence MAY further include list of AS sub-objects. The domain sequence MAY further include
decomposed area information in AREA sub-objects. decomposed area information in AREA sub-objects.
3.5.2.1. Example 1 3.4.2.1. Example 1
As shown in Figure 2, where AS to be made of a single area, the area As shown in Figure 2, where AS to be made of a single area, the area
subobject MAY be skipped in the domain sequence as AS is enough to subobject MAY be skipped in the domain sequence as AS is enough to
uniquely identify the next domain and PCE. uniquely identify the next domain and PCE.
+---------------------------------+ +---------------------------------+
|AS 200 | |AS 200 |
| +------+ | | +------+ |
| | | | | | | |
+------------------------+ | | | +------+ | +------------------------+ | | | +------+ |
skipping to change at page 13, line 25 skipping to change at page 20, line 25
+---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+
|IRO | |Sub | |Sub | |Sub | |Sub | |IRO | |Sub | |Sub | |Sub | |Sub |
|Object | |Object As| |Object | |Object As| |Object | |Object | |Object As| |Object | |Object As| |Object |
|Header | |100 | |Area 0 | |200 | |Area 0 | |Header | |100 | |Area 0 | |200 | |Area 0 |
| | | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | |
+---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+
Area is optional and it MAY be skipped. PCE should be able to Area is optional and it MAY be skipped. PCE should be able to
understand both notations. understand both notations.
3.5.2.2. Example 2 3.4.2.2. Example 2
As shown in Figure 3, where AS 200 is made up of multiple areas and As shown in Figure 3, where AS 200 is made up of multiple areas and
multiple domain-sequence exist, PCE MAY include both AS and AREA multiple domain-sequence exist, PCE MAY include both AS and AREA
subobject to uniquely identify the next domain and PCE. subobject to uniquely identify the next domain and PCE.
| |
| +-------------+ +----------------+ | +-------------+ +----------------+
| |Area 2 | |Area 4 | | |Area 2 | |Area 4 |
| | +--+| | +--+ | | | +--+| | +--+ |
| | | || | | | | | | | || | | | |
skipping to change at page 15, line 28 skipping to change at page 22, line 28
that appear before it or, if no AS sub-objects are present, it is that appear before it or, if no AS sub-objects are present, it is
assumed to be the current AS. assumed to be the current AS.
If the area information cannot be provided, PCE MAY forward the path If the area information cannot be provided, PCE MAY forward the path
computation request to the next PCE based on AS only. If multiple computation request to the next PCE based on AS only. If multiple
PCEs of different area domain exist, PCE MAY apply local policy to PCEs of different area domain exist, PCE MAY apply local policy to
select the next PCE. Furthermore the domain sequence (list of areas select the next PCE. Furthermore the domain sequence (list of areas
within AS) in the next PCE MAYBE pre-administered or MAYBE discovered within AS) in the next PCE MAYBE pre-administered or MAYBE discovered
via some mechanism (ex. HPCE). via some mechanism (ex. HPCE).
3.5.3. Boundary Node and Inter-AS-Link 3.4.3. Boundary Node and Inter-AS-Link
A PCC or PCE MAY add additional constraints covering which Boundary A PCC or PCE MAY add additional constraints covering which Boundary
Nodes (ABR or ASBR) or Border links (Inter-AS-link) MUST be traversed Nodes (ABR or ASBR) or Border links (Inter-AS-link) MUST be traversed
while defining a domain sequence. In which case the Boundary Node or while defining a domain sequence. In which case the Boundary Node or
Link MAY be encoded as a part of the domain-sequence using the Link MAY be encoded as a part of the domain-sequence using the
existing sub-objects. existing sub-objects.
Boundary Node (ABR / ASBR) can be encoded using the IPv4 or IPv6 Boundary Node (ABR / ASBR) can be encoded using the IPv4 or IPv6
prefix sub-objects. The Inter-AS link can be encoded using the IPv4 prefix sub-objects. The Inter-AS link can be encoded using the IPv4
or IPv6 prefix or unnumbered interface sub-objects. or IPv6 prefix or unnumbered interface sub-objects.
skipping to change at page 16, line 15 skipping to change at page 23, line 15
For Figure 2, an inter-AS-link to be traversed can be specified as: For Figure 2, an inter-AS-link to be traversed can be specified as:
+---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+
|IRO | |Sub | |Sub | |Sub | |Sub | |IRO | |Sub | |Sub | |Sub | |Sub |
|Object | |Object As| |Object | |Object | |Object As| |Object | |Object As| |Object | |Object | |Object As|
|Header | |100 | |IPv4 | |IPv4 | |200 | |Header | |100 | |IPv4 | |IPv4 | |200 |
| | | | |x.x.x.x | |x.x.x.x | | | | | | | |x.x.x.x | |x.x.x.x | | |
| | | | | | | | | | | | | | | | | | | |
+---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+
3.5.4. PCE serving multiple domains 3.4.4. PCE serving multiple domains
A single PCE MAYBE responsible for multiple domains; for example PCE A single PCE MAYBE responsible for multiple domains; for example PCE
function deployed on an ABR. Domain sequence should have no impact function deployed on an ABR. Domain sequence should have no impact
on this. PCE which can support 2 adjacent domains can internally on this. PCE which can support 2 adjacent domains can internally
handle this situation without any impact on the neighboring domains. handle this situation without any impact on the neighboring domains.
3.5.5. P2MP 3.4.5. P2MP
In case of P2MP the path domain tree is nothing but a series of In case of inter-domain P2MP path computation, (Refer
Domain Sequences, as shown in the below figure: [PCE-P2MP-PROCEDURES]) the path domain tree is nothing but a series
of Domain Sequences, as shown in the below figure:
D1-D3-D6, D1-D3-D5 and D1-D2-D4. D1-D3-D6, D1-D3-D5 and D1-D2-D4.
D1 D1
/ \ / \
D2 D3 D2 D3
/ / \ / / \
D4 D5 D6 D4 D5 D6
3.5.6. HPCE All rules of processing as applied to P2P can be applied to P2MP as
well.
In case of P2MP, different destinations MAY have different domain
sequence within the domain tree, it requires domain-sequence to be
attached per destination. (Refer [PCE-P2MP-PER-DEST])
3.4.6. HPCE
As per [PCE-HIERARCHY-FWK], consider a case as shown in Figure 4 As per [PCE-HIERARCHY-FWK], consider a case as shown in Figure 4
consisting of multiple child PCEs and a parent PCE. consisting of multiple child PCEs and a parent PCE.
+--------+ +--------+
| Parent | | Parent |
| PCE | | PCE |
+--------+ +--------+
+-------------------+ +-------------------+ +-------------------+ +-------------------+
skipping to change at page 18, line 29 skipping to change at page 25, line 29
|ERO | |Sub | |Sub | |Sub | |Sub | |ERO | |Sub | |Sub | |Sub | |Sub |
|Object | |Object As| |Object | |Object | |Object | |Object | |Object As| |Object | |Object | |Object |
|Header | |100 | |Area 2 | |Area 0 | |Area 4 | |Header | |100 | |Area 2 | |Area 0 | |Area 4 |
| | | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | |
+---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+
Note that, in the case of ERO objects, no new PCEP object type is Note that, in the case of ERO objects, no new PCEP object type is
required since the ordering constraint is assumed. required since the ordering constraint is assumed.
3.5.7. Relationship to PCE Sequence 3.4.7. Relationship to PCE Sequence
[RFC5886] and [PCE-P2MP-PROCEDURES] along with Domain Sequence [RFC5886] and [PCE-P2MP-PROCEDURES] along with Domain Sequence
introduces the concept of PCE-Sequence, where a sequence of PCEs, introduces the concept of PCE-Sequence, where a sequence of PCEs,
based on the domain sequence, should be decided and attached in the based on the domain sequence, should be decided and attached in the
PCReq at the very beginning of path computation. An alternative PCReq at the very beginning of path computation.
would be to use domain sequences, which simplifies as explained
below:
Advantages
o All PCE must be aware of all other PCEs in all domain for PCE- An alternative would be to use domain sequences, note that PCE-
Sequence. There is no clear method for this. In domain-sequence Sequence can be used along with domain-sequence in which case PCE-
PCE should be aware of the domains and not all the PCEs serving Sequence SHOULD have higher precedence in selecting the next PCE in
the domain. PCE needs to be aware of the neighboring PCEs as done the inter-domain path computation procedures. Note that Domain-
by discovery protocols. Sequence IRO constraints should still be checked as per the rules of
processing IRO.
o There maybe multiple PCE in a domain, the selection of PCE should 4. IANA Considerations
not be made at the PCC/PCE(1). This decision is made only at the
neighboring PCE which is aware of state of PCEs via notification
messages.
o Domain sequence would be compatible to P2P inter-domain BRPC 4.1. PCEP Objects
method as described in [RFC5441].
4. IANA Considerations The "PCEP Parameters" registry contains a subregistry "PCEP Objects".
IANA is requested to make the following allocations from this
registry.
4.1. New IRO Object Type Object Name Reference
Class
10 IRO [RFC5440]
Object-Type
(TBA): Domain Sequence [This I.D.]
IANA has defined a registry for Domain-Sequence. 4.2. New Sub-Objects
IRO Object-Class 10 The "PCEP Parameters" registry contains a subregistry "PCEP Objects"
with an entry for the Include Route Object (IRO) and Exclude Route
Object (XRO). IANA is requested to add further subobjects as
follows:
IRO Object-Type 2 Subobject Type Reference
TBA 4 octet AS number [This I.D.]
TBA OSPF Area ID [This I.D.]
TBA IS-IS Area ID [This I.D.]
4.2. Sub-Objects 4.3. Error Object Field Values
IANA has defined a registry for following sub-objects. The "PCEP Parameters" registry contains a subregistry "Error Types
and Values". IANA is requested to make the following allocations
from this subregistry
Type Sub-object ERROR Meaning Reference
TBD AS Number (4 Byte) Type
TBD OSPF Area id TBA "Unrecognized subobject" [This I.D.]
TBD ISIS Area id Error-Value: type code
5. Security Considerations 5. Security Considerations
This document specifies a standard representation of domain sequence, This document specifies a standard representation of domain sequence,
which is used in all inter-domain PCE scenarios as explained in other which MAYBE used in inter-domain PCE scenarios as explained in other
RFC and drafts. It does not introduce any new security RFC and drafts. The new sub-objects and domain sequence mechanisms
considerations. defined in this document allow finer and more specific control of the
path computed by a cooperating PCE(s). Such control increases the
risk if a PCEP message is intercepted, modified, or spoofed because
it allows the attacker to exert control over the path that the PCE
will compute or to make the path computation impossible. Therefore,
the security techniques described in [RFC5440] are considered more
important.
Note, however, that the domain sequence mechanisms also provide the
operator with the ability to route around vulnerable parts of the
network and may be used to increase overall network security.
6. Manageability Considerations 6. Manageability Considerations
TBD 6.1. Control of Function and Policy
Several local policy decisions should be made at the PCE. Firstly,
the exact behavior with regard to desired inclusion and exclusion of
domains must be available for examination by an operator and may be
configurable. Second, the behavior on receipt of an unrecognized
sub-objects with the L or X-bit set should be configurable and must
be available for inspection. The inspection and control of these
local policy choices may be part of the PCEP MIB module.
6.2. Information and Data Models
A MIB module for management of the PCEP is being specified in a
separate document [PCEP-MIB]. That MIB module allows examination of
individual PCEP messages, in particular requests, responses and
errors. The MIB module MUST be extended to include the ability to
view the domain-sequence extensions defined in this document.
6.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already
listed in [RFC5440].
6.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440].
6.5. Requirements On Other Protocols
The Sub-objects defined in this document SHOULD be supported by RSVP
especially for per-domain path computation [RFC5152] where the
domains need to encoded in the RSVP messages.
Apart from this, mechanisms defined in this document do not imply any
requirements on other protocols in addition to those already listed
in [RFC5440].
6.6. Impact On Network Operations
Mechanisms defined in this document do not have any impact on network
operations in addition to those already listed in [RFC5440].
7. Acknowledgments 7. Acknowledgments
We would like to thank Pradeep Shastry, Suresh babu, Quintin Zhao, We would like to thank Adrian Farrel, Pradeep Shastry, Suresh Babu,
Fatai Zhang, Daniel King, Oscar Gonzalez and Chen Huaimo for their Quintin Zhao, Fatai Zhang, Daniel King, Oscar Gonzalez, Chen Huaimo,
useful comments and suggestions. Venugopal Reddy, Reeja Paul and Sandeep Boina for their useful
comments and suggestions.
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to [RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14, Indicate Requirement Levels", BCP 14,
RFC 2119, March 1997. RFC 2119, March 1997.
[ISO 10589] ISO, "Intermediate system to Intermediate [ISO 10589] ISO, "Intermediate system to Intermediate
skipping to change at page 20, line 37 skipping to change at page 29, line 8
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", Computation Element (PCE)-Based Architecture",
RFC 4655, August 2006. RFC 4655, August 2006.
[RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A [RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A
Framework for Inter-Domain Multiprotocol Label Framework for Inter-Domain Multiprotocol Label
Switching Traffic Engineering", RFC 4726, Switching Traffic Engineering", RFC 4726,
November 2006. November 2006.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D.,
and A. Farrel, "GMPLS Segment Recovery",
RFC 4873, May 2007.
[RFC4874] Lee, CY., Farrel, A., and S. De Cnodder,
"Exclude Routes - Extension to Resource
ReserVation Protocol-Traffic Engineering
(RSVP-TE)", RFC 4874, April 2007.
[RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four- [RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-
octet AS Number Space", RFC 4893, May 2007. octet AS Number Space", RFC 4893, May 2007.
[RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A [RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A
Per-Domain Path Computation Method for Per-Domain Path Computation Method for
Establishing Inter-Domain Traffic Engineering Establishing Inter-Domain Traffic Engineering
(TE) Label Switched Paths (LSPs)", RFC 5152, (TE) Label Switched Paths (LSPs)", RFC 5152,
February 2008. February 2008.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path [RFC5440] Vasseur, JP. and JL. Le Roux, "Path
Computation Element (PCE) Communication Computation Element (PCE) Communication
Protocol (PCEP)", RFC 5440, March 2009. Protocol (PCEP)", RFC 5440, March 2009.
[RFC5441] Vasseur, JP., Zhang, R., Bitar, N., and JL. Le [RFC5441] Vasseur, JP., Zhang, R., Bitar, N., and JL. Le
Roux, "A Backward-Recursive PCE-Based Roux, "A Backward-Recursive PCE-Based
Computation (BRPC) Procedure to Compute Computation (BRPC) Procedure to Compute
Shortest Constrained Inter-Domain Traffic Shortest Constrained Inter-Domain Traffic
Engineering Label Switched Paths", RFC 5441, Engineering Label Switched Paths", RFC 5441,
April 2009. April 2009.
[RFC5520] Bradford, R., Vasseur, JP., and A. Farrel,
"Preserving Topology Confidentiality in Inter-
Domain Path Computation Using a Path-Key-Based
Mechanism", RFC 5520, April 2009.
[RFC5521] Oki, E., Takeda, T., and A. Farrel,
"Extensions to the Path Computation Element
Communication Protocol (PCEP) for Route
Exclusions", RFC 5521, April 2009.
[RFC5886] Vasseur, JP., Le Roux, JL., and Y. Ikejiri, "A [RFC5886] Vasseur, JP., Le Roux, JL., and Y. Ikejiri, "A
Set of Monitoring Tools for Path Computation Set of Monitoring Tools for Path Computation
Element (PCE)-Based Architecture", RFC 5886, Element (PCE)-Based Architecture", RFC 5886,
June 2010. June 2010.
[PCE-P2MP-PROCEDURES] Zhao, Q., Dhody, D., Ali, Z., Saad,, T., [PCE-P2MP-PROCEDURES] Zhao, Q., Dhody, D., Ali, Z., Saad,, T.,
Sivabalan,, S., and R. Casellas, "PCE-based Sivabalan,, S., and R. Casellas, "PCE-based
Computation Procedure To Compute Shortest Computation Procedure To Compute Shortest
Constrained P2MP Inter-domain Traffic Constrained P2MP Inter-domain Traffic
Engineering Label Switched Paths (draft-ietf- Engineering Label Switched Paths (draft-ietf-
pce-pcep-inter-domain-p2mp-procedures-02)", pce-pcep-inter-domain-p2mp-procedures-02)",
February 2012. February 2012.
[PCE-HIERARCHY-FWK] King, D. and A. Farrel, "The Application of [PCE-HIERARCHY-FWK] King, D. and A. Farrel, "The Application of
the Path Computation Element Architecture to the Path Computation Element Architecture to
the Determination of a Sequence of Domains in the Determination of a Sequence of Domains in
MPLS and GMPLS. MPLS and GMPLS.
(draft-ietf-pce-hierarchy-fwk-00)", (draft-ietf-pce-hierarchy-fwk-04)", June 2012.
October 2011.
[PCEP-MIB] Kiran Koushik, A S., Stephan, E., Zhao, Q.,
and D. King, "PCE communication protocol(PCEP)
Management Information Base", July 2010.
[PCE-P2MP-PER-DEST] Dhody, D. and U. Palle, "Supporting explicit-
path per destination in Path Computation
Element Communication Protocol (PCEP) P2MP
Path Request Message. (draft-dhody-pce-pcep-
p2mp-per-destination-01)", Feb 2012.
Authors' Addresses Authors' Addresses
Dhruv Dhody Dhruv Dhody
Huawei Technologies India Pvt Ltd Huawei Technologies India Pvt Ltd
Leela Palace Leela Palace
Bangalore, Karnataka 560008 Bangalore, Karnataka 560008
INDIA INDIA
EMail: dhruv.dhody@huawei.com EMail: dhruv.dhody@huawei.com
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