Internet DRAFT - draft-wu-idr-te-pm-bgp
draft-wu-idr-te-pm-bgp
IDR Working Group Q. Wu
Internet-Draft D. Wang
Intended status: Standards Track Huawei
Expires: April 24, 2014 S. Previdi
Cisco
H. Gredler
Juniper
S. Ray
Cisco
October 21, 2013
BGP attribute for North-Bound Distribution of Traffic Engineering (TE)
performance Metrics
draft-wu-idr-te-pm-bgp-03
Abstract
In order to populate network performance information like link
latency, latency variation, packet loss and bandwidth into Traffic
Engineering Database(TED) and ALTO server, this document describes
extensions to BGP protocol, that can be used to distribute network
performance information (such as link delay, delay variation, packet
loss, residual bandwidth, available bandwidth and utilized bandwidth
).
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
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 April 24, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 4
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. MPLS-TE with PCE . . . . . . . . . . . . . . . . . . . . . 5
3.2. ALTO Server Network API . . . . . . . . . . . . . . . . . 5
4. Carrying TE Performance information in BGP . . . . . . . . . . 7
5. Attribute TLV Details . . . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. Normative References . . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . . 12
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 13
A.1. draft-wu-idr-te-pm-bgp-03 . . . . . . . . . . . . . . . . 13
A.2. draft-wu-idr-te-pm-bgp-02 . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
As specified in [RFC4655],a Path Computation Element (PCE) is an
entity that is capable of computing a network path or route based on
a network graph, and of applying computational constraints during the
computation. In order to compute an end to end path, the PCE needs
to have a unified view of the overall topology[I-D.ietf-pce-pcep-
service-aware]. [I.D-ietf-idr-ls-distribution] describes a mechanism
by which links state and traffic engineering information can be
collected from networks and shared with external components using the
BGP routing protocol. This mechanism can be used by both PCE and
ALTO server to gather information about the topologies and
capabilities of the network.
With the growth of network virtualization technology, the needs for
inter-connection between various overlay technologies (e.g.
Enterprise BGP/MPLS IP VPNs) in the Wide Area Network (WAN) become
important. The Network performance or QoS requirements such as
latency, limited bandwidth, packet loss, and jitter, are all critical
factors that must be taken into account in the end to end path
computation ([I-D.ietf-pce-pcep-service-aware]) and selection which
enable establishing segment overlay tunnel between overlay nodes and
stitching them together to compute end to end path.
In order to populate network performance information like link
latency, latency variation, packet loss and bandwidth into TED and
ALTO server, this document describes extensions to BGP protocol, that
can be used to distribute network performance information (such as
link delay, delay variation, packet loss, residual bandwidth,
available bandwidth, and utilized bandwidth).
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2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2119].
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3. Use Cases
3.1. MPLS-TE with PCE
In inter-AS path computation, PCE in each AS participant in different
IGP. In Hierarchy of PCE, A child PCE must be configured with the
address of its parent PCE[RFC6805].Configuration system is challenged
by handling changes in parent PCE identities and coping with failure
events, especially when parent PCE and child PCE are not a part of
the same routing domain.
The following figure shows how a PCE can get its TE performance
information beyond that contained in the LINK_STATE attributes [I.D-
ietf-idr-ls-distribution] using the mechanism described in this
document.
+----------+ +---------+
| ----- | | BGP |
| | TED |<-+-------------------------->| Speaker |
| ----- | TED synchronization | |
| | | mechanism: +---------+
| | | BGP with TE performance
| v | NLRI
| ----- |
| | PCE | |
| ----- |
+----------+
^
| Request/
| Response
v
Service +----------+ Signaling +----------+
Request | Head-End | Protocol | Adjacent |
-------->| Node |<------------>| Node |
+----------+ +----------+
Figure 1: External PCE node using a TED synchronization mechanism
3.2. ALTO Server Network API
The ALTO Server can aggregate information from multiple systems to
provide an abstract and unified view that can be more useful to
applications.
The following figure shows how an ALTO Server can get TE performance
information from the underlying network beyond that contained in the
LINK_STATE attributes [I.D-ietf-idr-ls-distribution] using the
mechanism described in this document.
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+--------+
| Client |<--+
+--------+ |
| ALTO +--------+ BGP with +---------+
+--------+ | Protocol | ALTO | TE Performance | BGP |
| Client |<--+------------| Server |<----------------| Speaker |
+--------+ | | | NLR | |
| +--------+ +---------+
+--------+ |
| Client |<--+
+--------+
Figure 2: ALTO Server using network performance information
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4. Carrying TE Performance information in BGP
This document proposes new BGP TE performance TLVs that can be
announced as attribute in the BGP-LS attribute (defined in [I.D-ietf-
idr- ls-distribution]) to distribute network performance information.
The extensions in this document build on the ones provided in BGP-LS
[I.D -ietf-idr-ls-distribution] and BGP-4 [RFC4271].
BGP-LS attribute defined in [I.D-ietf-idr-ls-distribution] has nested
TLVs which allow the BGP-LS attribute to be readily extended. This
document proposes seven additional TLVs as its attributes:
Type Value
TBD1 Unidirectional Link Delay
TBD2 Min/Max Unidirectional Link Delay
TBD3 Unidirectional Delay Variation
TBD4 Unidirectional Packet Loss
TBD5 Unidirectional Residual Bandwidth
TBD6 Unidirectional Available Bandwidth
TBD7 Unidirectional Utilized Bandwidth
As can be seen in the list above, the TLVs described in this document
carry different types of network performance information. These TLVs
include a bit called the Anomalous (or "A") bit at the left-most bit
after length field of each TLV. The other bits in the first octets
after length field of each TLV is reserved for future use. When the
A bit is clear (or when the TLV does not include an A bit), the TLV
describes steady state link performance. This information could
conceivably be used to construct a steady state performance topology
for initial tunnel path computation, or to verify alternative
failover paths.
When network performance downgrades and exceeds configurable maximum
thresholds, a TLV with the A bit set is advertised. These TLVs could
be used by the receiving BGP peer to determine whether to redirect
failing traffic to a backup path, or whether to calculate an entirely
new path. If link performance improves later and falls below a
configurable value, that TLV can be re- advertised with the Anomalous
bit cleared. In this case, a receiving BGP peer can conceivably do
whatever re-optimization (or failback) it wishes to do (including
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nothing).
Note that when a TLV does not include the A bit, that TLV cannot be
used for failover purposes. The A bit was intentionally omitted from
some TLVs to help mitigate oscillations.
Consistent with existing ISIS TE specifications [ISIS-TE-METRIC], the
bandwidth advertisements,the delay and delay variation
advertisements, packetloss defined in this document MUST be encoded
in the same unit as one defined in IS-IS Extended IS Reachability
sub-TLVs [ISIS-TE-METRIC]. All values (except residual bandwidth)
MUST be calculated as rolling averages where the averaging period
MUST be a configurable period of time.
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5. Attribute TLV Details
Link attribute TLVs defined in section 3.2.2 of [I-D.ietf-idr-ls-
distribution]are TLVs that may be encoded in the BGP-LS attribute
with a link NLRI. Each 'Link Attribute' is a Type/Length/ Value
(TLV) triplet formatted as defined in Section 3.1 of [I-D.ietf-id r-
ls-distribution]. The format and semantics of the 'value' fields in
some 'Link Attribute' TLVs correspond to the format and semantics of
value fields in IS-IS Extended IS Reachability sub-TLVs, defined in
[RFC5305]. 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.
The following 'Link Attribute' TLVs are valid in the LINK_STATE
attribute:
+------------+---------------------+--------------+-----------------+
| TLV Code | Description | IS-IS | Defined in: |
| Point | | TLV/Sub-TLV | |
+------------+---------------------+--------------+-----------------+
| xxxx | Unidirectional | 22/xx | [ISIS-TE]/4.1 |
| | Link Delay | | |
| | | | |
| xxxx | Min/Max Unidirection| 22/xx | [ISIS-TE]/4.2 |
| | Link Delay | | |
| | | | |
| xxxx | Unidirectional | 22/xx | [ISIS-TE]/4.3 |
| | Delay Variation | | |
| | | | |
| xxxx | Unidirectional | 22/xx | [ISIS-TE]/4.4 |
| | Link Loss | | |
| | | | |
| xxxx | Unidirectional | 22/xx | [ISIS-TE]/4.5 |
| |Residual Bandwidth | | |
| | | | |
| xxxx | Unidirectional | 22/xx | [ISIS-TE]/4.6 |
| |Available Bandwidth | | |
| | | | |
| xxxx | Unidirectional | 22/xx | [ISIS-TE]/4.7 |
| |Utilized Bandwidth | | |
+------------+---------------------+--------------+-----------------+
Table 1: Link Attribute TLVs
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6. Security Considerations
This document does not introduce security issues beyond those
discussed in [I.D-ietf-idr-ls-distribution] and [RFC4271].
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7. IANA Considerations
IANA maintains the registry for the TLVs. BGP TE Performance TLV
will require one new type code per TLV defined in this document.
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8. References
8.1. Normative References
[I-D.ietf-idr-ls-distribution]
Gredler, H., "North-Bound Distribution of Link-State and
TE Information using BGP",
ID draft-ietf-idr-ls-distribution-03, May 2013.
[I-D.ietf-pce-pcep-service-aware]
Dhruv, D., "Extensions to the Path Computation Element
Communication Protocol (PCEP) to compute service aware
Label Switched Path (LSP)",
ID draft-ietf-pce-pcep-service-aware-01, July 2013.
[ISIS-TE-METRIC]
Giacalone, S., "ISIS Traffic Engineering (TE) Metric
Extensions", ID draft-ietf-isis-te-metric-extensions-00,
June 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC4271] Rekhter, Y., "A Border Gateway Protocol 4 (BGP-4)",
RFC 4271, January 2006.
[RFC5305] Li, T., "IS-IS Extensions for Traffic Engineering",
RFC 5305, October 2008.
8.2. Informative References
[ALTO] Yang, Y., "ALTO Protocol",
ID http://tools.ietf.org/html/draft-ietf-alto-protocol-16,
May 2013.
[RFC4655] Farrel, A., "A Path Computation Element (PCE)-Based
Architecture", RFC 4655, August 2006.
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Appendix A. Change Log
Note to the RFC-Editor: please remove this section prior to
publication as an RFC.
A.1. draft-wu-idr-te-pm-bgp-03
The following are the major changes compared to previous version 02:
o Add unidirectional utilized bandwidth metric as the seventh metric
Carried in a new BGP attribute.
A.2. draft-wu-idr-te-pm-bgp-02
The following are the major changes compared to previous version 01:
o Taking out link utilization metric and channel throughput metric
from this version and will add link utilization metric back to the
update when there was agreement on what measurement unit is used
for link utilization.
o Some additional texts in BGP extension section 4 to explain how to
position 'A' bit in the BGP TE performance TLV.
o Add two editor notes to explain the status of this draft and open
issue that need be resolved.
o Some additional text in the use case sections to clarify how to
use these TE performance metrics.
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Authors' Addresses
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: sunseawq@huawei.com
Danhua Wang
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: wangdanhua@huawei.com
Stefano Previdi
Cisco Systems, Inc.
Via Del Serafico 200
Rome 00191
Italy
Email: sprevidi@cisco.com
Hannes Gredler
Juniper Networks, Inc.
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: hannes@juniper.net
Saikat Ray
Cisco Systems, Inc.
170, West Tasman Drive
San Jose, CA 95134
US
Email: sairay@cisco.com
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