Extensions to the Path Computation Element Communication Protocol (PCEP) to compute service aware Label Switched Path (LSP).
draft-ietf-pce-pcep-service-aware-05
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8233.
|
|
|---|---|---|---|
| Authors | Dhruv Dhody , Vishwas Manral , Zafar Ali , George Swallow , Kenji Kumaki | ||
| Last updated | 2014-08-10 | ||
| Replaces | draft-dhody-pce-pcep-service-aware | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | Became RFC 8233 (Proposed Standard) | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-pce-pcep-service-aware-05
PCE Working Group D. Dhody
Internet-Draft Huawei Technologies
Intended status: Standards Track V. Manral
Expires: February 11, 2015 Ionos Network
Z. Ali
G. Swallow
Cisco Systems
K. Kumaki
KDDI Corporation
August 10, 2014
Extensions to the Path Computation Element Communication Protocol (PCEP)
to compute service aware Label Switched Path (LSP).
draft-ietf-pce-pcep-service-aware-05
Abstract
In certain networks like financial information network (stock/
commodity trading) and enterprises using cloud based applications,
Latency (delay), Latency-Variation (jitter) and Packet Loss is
becoming a key requirement for path computation along with other
constraints and metrics. Latency, Latency-Variation and Packet Loss
is associated with the Service Level Agreement (SLA) between
customers and service providers.
IGP Traffic Engineering (TE) Metric extensions describes mechanisms
with which network performance information is distributed via OSPF
and IS-IS respectively. The Path Computation Element Communication
Protocol (PCEP) provides mechanisms for Path Computation Elements
(PCEs) to perform path computations in response to Path Computation
Clients (PCCs) requests. This document describes the extension to
PCEP to carry Latency, Latency-Variation and Packet Loss as
constraints for end to end path computation.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 11, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . . 4
4. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Latency (Delay) Metric . . . . . . . . . . . . . . . . . 5
4.1.1. Latency (Delay) Metric Value . . . . . . . . . . . . 6
4.2. Latency Variation (Jitter) Metric . . . . . . . . . . . . 6
4.2.1. Latency Variation (Jitter) Metric Value . . . . . . . 7
4.3. Packet Loss Metric . . . . . . . . . . . . . . . . . . . 8
4.3.1. Packet Loss Metric Value . . . . . . . . . . . . . . 8
4.4. Non-Understanding / Non-Support of Service Aware Path
Computation . . . . . . . . . . . . . . . . . . . . . . . 9
4.5. Mode of Operation . . . . . . . . . . . . . . . . . . . . 9
4.5.1. Examples . . . . . . . . . . . . . . . . . . . . . . 10
5. Objective Functions . . . . . . . . . . . . . . . . . . . . . 11
6. Protocol Consideration . . . . . . . . . . . . . . . . . . . 11
6.1. Inter-domain Consideration . . . . . . . . . . . . . . . 11
6.1.1. Inter-AS Link . . . . . . . . . . . . . . . . . . . . 12
6.1.2. Inter-Layer Consideration . . . . . . . . . . . . . . 12
6.2. Reoptimization Consideration . . . . . . . . . . . . . . 12
6.3. Point-to-Multipoint (P2MP) . . . . . . . . . . . . . . . 12
6.3.1. P2MP Latency Metric . . . . . . . . . . . . . . . . . 12
6.3.2. P2MP Latency Variation Metric . . . . . . . . . . . . 13
6.3.3. P2MP Packet Loss Metric . . . . . . . . . . . . . . . 13
6.4. Stateful PCE . . . . . . . . . . . . . . . . . . . . . . 13
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7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
7.1. METRIC types . . . . . . . . . . . . . . . . . . . . . . 14
7.2. OF Codes . . . . . . . . . . . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
9. Manageability Considerations . . . . . . . . . . . . . . . . 15
9.1. Control of Function and Policy . . . . . . . . . . . . . 15
9.2. Information and Data Models . . . . . . . . . . . . . . . 15
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 15
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 15
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 15
9.6. Impact On Network Operations . . . . . . . . . . . . . . 15
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
11.1. Normative References . . . . . . . . . . . . . . . . . . 16
11.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 18
1. Introduction
Real time network performance is becoming a critical in the path
computation in some networks. Mechanisms to measure Latency,
Latency-Variation, and Packet Loss in an MPLS network are described
in [RFC6374]. Further, there exist mechanisms to measure these
network performance metrics after the LSP has been established, which
is inefficient. It is important that Latency, Latency-Variation, and
Packet Loss are considered during path selection process, even before
the LSP is set up.
Traffic Engineering Database (TED) is populated with network
performance information like link latency, latency variation and
packet loss through [OSPF-TE-METRIC-EXT] or [ISIS-TE-METRIC-EXT].
Path Computation Client (PCC) can request Path Computation Element
(PCE) to provide a path meeting end to end network performance
criteria. This document extends Path Computation Element
Communication Protocol (PCEP) [RFC5440] to handle network performance
constraint.
PCE MAY use mechanism described in [MPLS-TE-METRIC-EXT] on how to use
the link latency, latency variation and packet loss information for
end to end path selection.
[OSPF-TE-METRIC-EXT] and [ISIS-TE-METRIC-EXT] include parameters
related to bandwidth (Residual bandwidth, Available bandwidth and
Utilized bandwidth); [PCEP-BW-UTIL] describes extensions to PCEP to
consider them.
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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 following terminology is used in this document.
IGP: Interior Gateway Protocol. Either of the two routing
protocols, Open Shortest Path First (OSPF) or Intermediate System
to Intermediate System (IS-IS).
IS-IS: Intermediate System to Intermediate System.
OSPF: Open Shortest Path First.
PCC: Path Computation Client: any client application requesting a
path computation to be performed by a Path Computation Element.
PCE: Path Computation Element. An entity (component, application,
or network node) that is capable of computing a network path or
route based on a network graph and applying computational
constraints.
TE: Traffic Engineering.
3. PCEP Requirements
End-to-end service optimization based on latency, latency-variation
and packet loss is a key requirement for service provider. Following
key requirements associated with latency, latency-variation and loss
are identified for PCEP:
1. PCE supporting this draft MUST have the capability to compute
end-to-end path with latency, latency-variation and packet loss
constraints. It MUST also support the combination of network
performance constraint (latency, latency-variation, loss...) with
existing constraints (cost, hop-limit...).
2. PCC MUST be able to request for network performance constraint(s)
in PCReq message as the key constraint to be optimized or to
suggest boundary condition that should not be crossed.
3. PCEs are not required to support service aware path computation.
Therefore, it MUST be possible for a PCE to reject a PCReq
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message with a reason code that indicates no support for service-
aware path computation.
4. PCEP SHOULD provide a means to return end to end network
performance information of the computed path in a PCRep message.
5. PCEP SHOULD provide mechanism to compute multi-domain (e.g.,
Inter-AS, Inter-Area or Multi-Layer) service aware paths.
It is assumed that such constraints are only meaningful if used
consistently: for instance, if the delay of a computed path segment
is exchanged between two PCEs residing in different domains,
consistent ways of defining the delay must be used.
4. PCEP Extensions
This section defines PCEP extensions (see [RFC5440]) for requirements
outlined in Section 3. The proposed solution is used to support
network performance and service aware path computation.
The METRIC object is defined in section 7.8 of [RFC5440], comprising
of metric-value, metric-type (T field) and flags. This document
defines the following optional types for the METRIC object.
For explanation of these metrics, the following terminology is used
and expanded along the way.
- A network comprises of a set of N links {Li, (i=1...N)}.
- A path P of a P2P LSP is a list of K links {Lpi,(i=1...K)}.
4.1. Latency (Delay) Metric
Link delay metric is defined in [OSPF-TE-METRIC-EXT] and
[ISIS-TE-METRIC-EXT]. P2P latency metric type of METRIC object in
PCEP encodes the sum of the link delay metric of all links along a
P2P Path. Specifically, extending on the above mentioned
terminology:
- A Link delay metric of link L is denoted D(L).
- A P2P latency metric for the Path P = Sum {D(Lpi), (i=1...K)}.
This is as per sum of means composition function (section 4.2.5 of
[RFC6049]).
* Metric Type T=xx(TBA - IANA): Latency metric
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PCC MAY use this latency metric in PCReq message to request a path
meeting the end to end latency requirement. In this case B bit MUST
be set to suggest a bound (a maximum) for the path latency metric
that must not be exceeded for the PCC to consider the computed path
as acceptable. The path metric must be less than or equal to the
value specified in the metric-value field.
PCC MAY also use this metric to ask PCE to optimize latency during
path computation, in this case B flag will be cleared.
PCE MAY use this latency metric in PCRep message along with NO-PATH
object in case PCE cannot compute a path meeting this constraint.
PCE MAY also use this metric to reply the computed end to end latency
metric to PCC.
4.1.1. Latency (Delay) Metric Value
[OSPF-TE-METRIC-EXT] and [ISIS-TE-METRIC-EXT] defines "Unidirectional
Link Delay Sub-TLV" in a 24-bit field. [RFC5440] defines the METRIC
object with 32-bit metric value. Consequently, encoding for Latency
(Delay) Metric Value is defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Latency (Delay) Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved (8 bits): Reserved field. This field MUST be set to zero
on transmission and MUST be ignored on receipt.
Latency (Delay) Metric (24 bits): Represents the end to end Latency
(delay) quantified in units of microseconds and MUST be encoded as
integer value. With the maximum value 16,777,215 representing
16.777215 sec.
4.2. Latency Variation (Jitter) Metric
Link delay variation metric is defined in [OSPF-TE-METRIC-EXT] and
[ISIS-TE-METRIC-EXT]. P2P latency variation metric type of METRIC
object in PCEP encodes the sum of the link delay variation metric of
all links along a P2P Path. Specifically, extending on the above
mentioned terminology:
- A Latency variation of link L is denoted DV(L) (average delay
variation for link L).
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- A P2P latency variation metric for the Path P = Sum {DV(Lpi),
(i=1...K)}.
Note that the IGP advertisement for link attributes includes average
latency variation over a period of time. An implementation,
therefore, MAY use sum of the average latency variation of links
along a path to derive the average latency variation of the Path. An
implementation MAY also use some enhanced composition function for
computing average latency variation of a Path.
* Metric Type T=yy(TBA - IANA): Latency Variation metric
PCC MAY use this latency variation metric in PCReq message to request
a path meeting the end to end latency variation requirement. In this
case B bit MUST be set to suggest a bound (a maximum) for the path
latency variation metric that must not be exceeded for the PCC to
consider the computed path as acceptable. The path metric must be
less than or equal to the value specified in the metric-value field.
PCC MAY also use this metric to ask PCE to optimize latency variation
during path computation, in this case B flag will be cleared.
PCE MAY use this latency variation metric in PCRep message along with
NO-PATH object in case PCE cannot compute a path meeting this
constraint. PCE MAY also use this metric to reply the computed end
to end latency variation metric to PCC.
4.2.1. Latency Variation (Jitter) Metric Value
[OSPF-TE-METRIC-EXT] and [ISIS-TE-METRIC-EXT] defines "Unidirectional
Delay Variation Sub-TLV" in a 24-bit field. [RFC5440] defines the
METRIC object with 32-bit metric value. Consequently, encoding for
Latency Variation (Jitter) Metric Value is defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Latency variation (jitter) Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved (8 bits): Reserved field. This field MUST be set to zero
on transmission and MUST be ignored on receipt.
Latency variation (jitter) Metric (24 bits): Represents the end to
end Latency variation (jitter) quantified in units of microseconds
and MUST be encoded as integer value. With the maximum value
16,777,215 representing 16.777215 sec.
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4.3. Packet Loss Metric
[OSPF-TE-METRIC-EXT] and [ISIS-TE-METRIC-EXT] defines "Unidirectional
Link Loss". Packet Loss metric type of METRIC object in PCEP encodes
a function of the link's unidirectional loss metric of all links
along a P2P Path. Specifically, extending on the above mentioned
terminology:
The end to end Packet Loss for the path is represented by this
metric.
- A Packet loss of link L is denoted PL(L) in percentage.
- A Packet loss in fraction of link L is denoted FPL(L) = PL(L)/100.
- A P2P packet loss metric in percentage for the Path P = (1 -
((1-FPL(Lp1)) * (1-FPL(Lp2)) * .. * (1-FPL(LpK))) * 100 for a path P
with link 1 to K.
This is as per the composition function (section 5.1.5 of [RFC6049]).
* Metric Type T=zz(TBA - IANA): Packet Loss metric
PCC MAY use this packet loss metric in PCReq message to request a
path meeting the end to end packet loss requirement. In this case B
bit MUST be set to suggest a bound (a maximum) for the path packet
loss metric that must not be exceeded for the PCC to consider the
computed path as acceptable. The path metric must be less than or
equal to the value specified in the metric-value field.
PCC MAY also use this metric to ask PCE to optimize packet loss
during path computation, in this case B flag will be cleared.
PCE MAY use this packet loss metric in PCRep message along with NO-
PATH object in case PCE cannot compute a path meeting this
constraint. PCE MAY also use this metric to reply the computed end
to end packet loss metric to PCC.
4.3.1. Packet Loss Metric Value
[OSPF-TE-METRIC-EXT] and [ISIS-TE-METRIC-EXT] defines "Unidirectional
Link Loss Sub-TLV" in a 24-bit field. [RFC5440] defines the METRIC
object with 32-bit metric value. Consequently, encoding for Packet
Loss Metric Value is defined as follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Packet loss Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved (8 bits): Reserved field. This field MUST be set to zero
on transmission and MUST be ignored on receipt.
Packet loss Metric (24 bits): Represents the end to end packet loss
quantified as a percentage of packets lost and MUST be encoded as
integer. The basic unit is 0.000003%, with the maximum value
16,777,215 representing 50.331645% (16,777,215 * 0.000003%). This
value is the highest packet loss percentage that can be expressed.
4.4. Non-Understanding / Non-Support of Service Aware Path Computation
If the P bit is clear in the object header and PCE does not
understand or does not support service aware path computation it
SHOULD simply ignore this METRIC object.
If the P Bit is set in the object header and PCE receives new METRIC
type in path request and it understands the METRIC type, but the PCE
is not capable of service aware path computation, the PCE MUST send a
PCErr message with a PCEP-ERROR Object Error-Type = 4 (Not supported
object) [RFC5440]. The path computation request MUST then be
cancelled.
If the PCE does not understand the new METRIC type, then the PCE MUST
send a PCErr message with a PCEP-ERROR Object Error-Type = 3 (Unknown
object) [RFC5440].
4.5. Mode of Operation
As explained in [RFC5440], the METRIC object is optional and can be
used for several purposes. In a PCReq message, a PCC MAY insert one
or more METRIC objects:
o To indicate the metric that MUST be optimized by the path
computation algorithm (Latency, Latency-Variation or Loss)
o To indicate a bound on the path METRIC (Latency, Latency-Variation
or Loss) that MUST NOT be exceeded for the path to be considered
as acceptable by the PCC.
In a PCRep message, the METRIC object MAY be inserted so as to
provide the METRIC (Latency, Latency-Variation or Loss) for the
computed path. It MAY also be inserted within a PCRep with the NO-
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PATH object to indicate that the metric constraint could not be
satisfied.
The path computation algorithmic aspects used by the PCE to optimize
a path with respect to a specific metric are outside the scope of
this document.
All the rules of processing METRIC object as explained in [RFC5440]
are applicable to the new metric types as well.
In a PCReq message, a PCC MAY insert more than one METRIC object to
be optimized, in such a case PCE should find the path that is optimal
when both the metrics are considered together.
4.5.1. Examples
Example 1: If a PCC sends a path computation request to a PCE where
two metric to optimize are the latency and the packet loss, two
METRIC objects are inserted in the PCReq message:
o First METRIC object with B=0, T=xx (TBA - IANA), C=1, metric-
value=0x0000
o Second METRIC object with B=0, T=zz (TBA - IANA), C=1, metric-
value=0x0000
PCE in such a case should try to optimize both the metrics and find a
path with the minimum latency and packet loss, if a path can be found
by the PCE and there is no policy that prevents the return of the
computed metric, the PCE inserts first METRIC object with B=0, T=xx
(TBA - IANA), metric-value= computed end to end latency and second
METRIC object with B=1, T=zz (TBA - IANA), metric-value= computed end
to end packet loss.
Example 2: If a PCC sends a path computation request to a PCE where
the metric to optimize is the latency and the packet loss must not
exceed the value of M, two METRIC objects are inserted in the PCReq
message:
o First METRIC object with B=0, T=xx (TBA - IANA), C=1, metric-
value=0x0000
o Second METRIC object with B=1, T=zz (TBA - IANA), metric-value=M
If a path satisfying the set of constraints can be found by the PCE
and there is no policy that prevents the return of the computed
metric, the PCE inserts one METRIC object with B=0, T=xx (TBA -
IANA), metric-value= computed end to end latency. Additionally, the
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PCE may insert a second METRIC object with B=1, T=zz (TBA - IANA),
metric-value= computed end to end packet loss.
5. Objective Functions
[RFC5541] defines mechanism to specify an optimization criteria,
referred to as objective functions. The new metric types specified
in this document MAY continue to use the existing objective functions
like Minimum Cost Path (MCP). Latency (Delay) and Latency Variation
(Jitter) are well suited to use MCP as an optimization criteria. For
Packet Loss following new OF is defined -
o A network comprises a set of N links {Li, (i=1...N)}.
o A path P is a list of K links {Lpi,(i=1...K)}.
o Packet loss of link L is denoted PL(L) in percentage.
o Packet loss in fraction of link L is denoted FPL(L) = PL(L) / 100.
o The Packet loss of a path P (in percentage) is denoted PL(P),
where PL(P) = (1 - ((1-FPL(Lp1)) * (1-FPL(Lp2)) * .. *
(1-FPL(LpK))) * 100.
Objective Function Code: (TBA - IANA)
Name: Minimum Packet Loss Path (MPLP)
Description: Find a path P such that PL(P) is minimized.
6. Protocol Consideration
There is no change in the message format of PCReq and PCRep Messages.
6.1. Inter-domain Consideration
[RFC5441] describes the Backward-Recursive PCE-Based Computation
(BRPC) procedure to compute end to end optimized inter-domain path by
cooperating PCEs. The new metric defined in this document can be
applied to end to end path computation, in similar manner as existing
IGP or TE metric.
All domains should have the same understanding of the METRIC
(Latency-Variation etc) for end-to-end inter-domain path computation
to make sense. Otherwise some form of Metric Normalization as
described in [RFC5441] MAY need to be applied.
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6.1.1. Inter-AS Link
The IGP in each neighbor domain can advertise its inter-domain TE
link capabilities, this has been described in [RFC5316] (ISIS) and
[RFC5392] (OSPF). The network performance link properties are
described in [OSPF-TE-METRIC-EXT] and [ISIS-TE-METRIC-EXT], the same
properties must be advertised using the mechanism described in
[RFC5392] (OSPF) and [RFC5316] (ISIS).
6.1.2. Inter-Layer Consideration
[RFC5623] provides a framework for PCE-Based inter-layer MPLS and
GMPLS Traffic Engineering. Lower-layer LSPs that are advertised as
TE links into the higher-layer network form a Virtual Network
Topology (VNT). The advertisement in higher-layer should include the
network performance link properties based on the end to end metric of
lower-layer LSP. Note that the new metric defined in this document
are applied to end to end path computation, even though the path may
cross multiple layers.
6.2. Reoptimization Consideration
PCC can monitor the setup LSPs and in case of degradation of network
performance constraints, it MAY ask PCE for reoptimization as per
[RFC5440]. Based on the changes in performance parameters in TED, a
PCC MAY also issue a reoptimization request.
6.3. Point-to-Multipoint (P2MP)
This document defines the following optional types for the METRIC
object defined in [RFC5440] for P2MP TE LSPs.
6.3.1. P2MP Latency Metric
P2MP latency metric type of METRIC object in PCEP encodes the path
latency metric for destination that observes the worst latency metric
among all destinations of the P2MP tree. Specifically, extending on
the above mentioned terminology:
- A P2MP Tree T comprises of a set of M destinations {Dest_j,
(j=1...M)}
- P2P latency metric of the Path to destination Dest_j is denoted by
LM(Dest_j).
- P2MP latency metric for the P2MP tree T = Maximum {LM(Dest_j),
(j=1...M)}.
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Value for P2MP latency metric type (T) is to be assigned by IANA.
6.3.2. P2MP Latency Variation Metric
P2MP latency variation metric type of METRIC object in PCEP encodes
the path latency variation metric for destination that observes the
worst latency variation metric among all destinations of the P2MP
tree. Specifically, extending on the above mentioned terminology:
- A P2MP Tree T comprises of a set of M destinations {Dest_j,
(j=1...M)}
- P2P latency variation metric of the Path to destination Dest_j is
denoted by LVM(Dest_j).
- P2MP latency variation metric for the P2MP tree T = Maximum
{LVM(Dest_j), (j=1...M)}.
Value for P2MP latency variation metric type (T) is to be assigned by
IANA.
6.3.3. P2MP Packet Loss Metric
P2MP packet loss metric type of METRIC object in PCEP encodes the
path packet loss metric for destination that observes the worst
packet loss metric among all destinations of the P2MP tree.
Specifically, extending on the above mentioned terminology:
- A P2MP Tree T comprises of a set of M destinations {Dest_j,
(j=1...M)}
- P2P packet loss metric of the Path to destination Dest_j is denoted
by PLM(Dest_j).
- P2MP packet loss metric for the P2MP tree T = Maximum {PLM(Dest_j),
(j=1...M)}.
Value for P2MP packet loss metric type (T) is to be assigned by IANA.
6.4. Stateful PCE
[STATEFUL-PCE] specifies a set of extensions to PCEP to enable
stateful control of MPLS-TE and GMPLS LSPs via PCEP and maintaining
of these LSPs at the stateful PCE. A Path Computation LSP State
Report message (also referred to as PCRpt message) is a PCEP message
sent by a PCC to a PCE to report the current state of an LSP. This
message contains the metric-list as part of attributes, the new
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metric types defined in this document for network performance
parameter MAY be carried to report them to stateful PCEs.
7. IANA Considerations
7.1. METRIC types
Six new metric types are defined in this document for the METRIC
object (specified in [RFC5440]). IANA maintains a registry of metric
types in the "METRIC Object T Field" sub-registry of the "Path
Computation Element Protocol (PCEP) Numbers" registry.
IANA is requested to make the following allocations:
Value Description Reference
xx(TBD) Latency (delay) metric [This I.D.]
yy(TBD) Latency Variation (jitter) metric [This I.D.]
zz(TBD) Packet Loss metric [This I.D.]
(TBD) P2MP latency metric [This I.D.]
(TBD) P2MP latency variation metric [This I.D.]
(TBD) P2MP packet loss metric [This I.D.]
7.2. OF Codes
One new Objective Functions have been defined in this document for
the OF code (described in [RFC5541]). IANA maintains this registry
at "Objective Function" sub-registry of the "Path Computation Element
Protocol (PCEP) Numbers" registry.
IANA is requested to make the following allocations:
Code Name Reference
(TBD) MPLP [This I.D.]
8. Security Considerations
This document defines new METRIC types and OF code which does not add
any new security concerns beyond those discussed in [RFC5440] and
[RFC5541] in itself. Some deployments may find the service aware
information like delay and packet loss as extra sensitive and thus
should employ suitable PCEP security mechanisms like TCP-AO.
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9. Manageability Considerations
9.1. Control of Function and Policy
The only configurable item is the support of the new service-aware
METRICS on a PCE which MAY be controlled by a policy module. If the
new METRIC is not supported/allowed on a PCE, it MUST send a PCErr
message as specified in Section 4.4.
9.2. Information and Data Models
[PCEP-MIB] describes the PCEP MIB, there are no new MIB Objects for
this document.
9.3. 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].
9.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440].
9.5. Requirements On Other Protocols
PCE requires the TED to be populated with network performance
information like link latency, latency variation and packet loss.
This mechanism is described in [OSPF-TE-METRIC-EXT] and
[ISIS-TE-METRIC-EXT].
9.6. 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].
10. Acknowledgments
We would like to thank Young Lee, Venugopal Reddy, Reeja Paul,
Sandeep Kumar Boina, Suresh Babu, Quintin Zhao, Chen Huaimo and
Avantika for their useful comments and suggestions.
Also the authors gratefully acknowledge reviews and feedback provided
by Qin Wu, Alfred Morton and Paul Aitken during performance
directorate review.
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11. References
11.1. 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.
11.2. Informative References
[RFC5441] Vasseur, JP., Zhang, R., Bitar, N., and JL. Le Roux, "A
Backward-Recursive PCE-Based Computation (BRPC) Procedure
to Compute Shortest Constrained Inter-Domain Traffic
Engineering Label Switched Paths", RFC 5441, April 2009.
[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.
[RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
Objective Functions in the Path Computation Element
Communication Protocol (PCEP)", RFC 5541, June 2009.
[RFC5623] Oki, E., Takeda, T., Le Roux, JL., and A. Farrel,
"Framework for PCE-Based Inter-Layer MPLS and GMPLS
Traffic Engineering", RFC 5623, September 2009.
[RFC6049] Morton, A. and E. Stephan, "Spatial Composition of
Metrics", RFC 6049, January 2011.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374, September 2011.
[OSPF-TE-METRIC-EXT]
Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
Previdi, "OSPF Traffic Engineering (TE) Metric
Extensions", draft-ietf-ospf-te-metric-extensions-05 (work
in progress), December 2013.
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[ISIS-TE-METRIC-EXT]
Previdi, S., Giacalone, S., Ward, D., Drake, J., Atlas,
A., Filsfils, C., and W. Wu, "IS-IS Traffic Engineering
(TE) Metric Extensions", draft-ietf-isis-te-metric-
extensions-03 (work in progress), April 2014.
[MPLS-TE-METRIC-EXT]
Atlas, A., Drake, J., Giacalone, S., Ward, D., Previdi,
S., and C. Filsfils, "Performance-based Path Selection for
Explicitly Routed LSPs using TE Metric Extensions", draft-
ietf-mpls-te-express-path-00 (work in progress), October
2013.
[PCEP-MIB]
Koushik, K., Emile, S., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Protocol (PCEP)
Management Information Base", draft-ietf-pce-pcep-mib-09
(work in progress), July 2014.
[STATEFUL-PCE]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-09 (work in progress), June 2014.
[PCEP-BW-UTIL]
Wu, W., Dhody, D., and S. Previdi, "Extensions to Path
Computation Element Communication Protocol (PCEP) for
handling the Link Bandwidth Utilization", draft-wu-pce-
pcep-link-bw-utilization-03 (work in progress), June 2014.
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Appendix A. Contributor Addresses
Clarence Filsfils
Cisco Systems
EMail: cfilsfil@cisco.com
Siva Sivabalan
Cisco Systems
EMail: msiva@cisco.com
Stefano Previdi
Cisco Systems
EMail: sprevidi@cisco.com
Udayasree Palle
Huawei Technologies
Leela Palace
Bangalore, Karnataka 560008
INDIA
EMail: udayasree.palle@huawei.com
Xian Zhang
Huawei Technologies
F3-1-B R&D Center, Huawei Base Bantian, Longgang District
Shenzhen, Guangdong 518129
P.R.China
Email: zhang.xian@huawei.com
Authors' Addresses
Dhruv Dhody
Huawei Technologies
Leela Palace
Bangalore, Karnataka 560008
INDIA
EMail: dhruv.ietf@gmail.com
Vishwas Manral
Ionos Network
4100 Moorpark Av
San Jose, CA
USA
EMail: vishwas.ietf@gmail.com
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Zafar Ali
Cisco Systems
EMail: zali@cisco.com
George Swallow
Cisco Systems
EMail: swallow@cisco.com
Kenji Kumaki
KDDI Corporation
EMail: ke-kumaki@kddi.com
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