< draft-previdi-isis-te-metric-extensions-00.txt   draft-previdi-isis-te-metric-extensions-01.txt >
Network Working Group S. Previdi
Internet Draft Cisco Systems
Intended status: Proposed Standard
Expires: April 2012 S. Giacalone
Thomson Reuters
D. Ward
Juniper Networks
J. Drake
Juniper Networks
A. Atlas
Juniper Networks
C.Filsfils Networking Working Group S. Previdi, Ed.
Cisco Systems Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track S. Giacalone
October 10, 2011 Expires: September 9, 2012 Thomson Reuters
D. Ward
Cisco Systems, Inc.
J. Drake
A. Atlas
Juniper Networks
C. Filsfils
Cisco Systems, Inc.
March 08, 2012
IS-IS Traffic Engineering (TE) Metric Extensions IS-IS Traffic Engineering (TE) Metric Extensions
draft-previdi-isis-te-metric-extensions-00.txt draft-previdi-isis-te-metric-extensions-01
Abstract Abstract
In certain networks, such as, but not limited to, financial In certain networks, such as, but not limited to, financial
information networks (e.g. stock market data providers), network information networks (e.g. stock market data providers), network
performance criteria (e.g. latency) are becoming as critical to data performance criteria (e.g. latency) are becoming as critical to data
path selection as other metrics. path selection as other metrics.
This document describes extensions to IS-IS TE [RFC5305] such that This document describes extensions to IS-IS TE [RFC5305] such that
network performance information can be distributed and collected in a network performance information can be distributed and collected in a
scalable fashion. The information distributed using ISIS TE Express scalable fashion. The information distributed using ISIS TE Express
Path can then be used to make path selection decisions based on Path can then be used to make path selection decisions based on
network performance. network performance.
Note that this document only covers the mechanisms with which network Note that this document only covers the mechanisms with which network
performance information is distributed. The mechanisms for measuring performance information is distributed. The mechanisms for measuring
network performance or acting on that information, once distributed, network performance or acting on that information, once distributed,
are outside the scope of this document. are outside the scope of this document.
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 RFC 2119 [RFC2119].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF). Note that other groups may also distribute
other groups may also distribute working documents as Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts. Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
The list of current Internet-Drafts can be accessed at This Internet-Draft will expire on September 9, 2012.
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
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This Internet-Draft will expire on April 10, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2011 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction...................................................3
2. Conventions used in this document..............................4
3. Express Path Extensions to IS-IS TE............................4
4. Sub TLV Details................................................6
4.1. Unidirectional Link Delay Sub-TLV.........................6
4.2. Unidirectional Delay Variation Sub-TLV....................6
4.3. Unidirectional Link Loss Sub-TLV..........................7
4.4. Unidirectional Residual Bandwidth Sub-TLV.................8
4.5. Unidirectional Available Bandwidth Sub-TLV................9
5. Announcement Thresholds and Filters...........................10
6. Announcement Suppression......................................11
7. Network Stability and Announcement Periodicity................11
8. Compatibility.................................................11
9. Security Considerations.......................................11
10. IANA Considerations..........................................11
11. References...................................................12
11.1. Normative References....................................12
11.2. Informative References..................................12
12. Acknowledgments..............................................12
13. Author's Addresses...........................................12
1. Introduction 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Express Path Extensions to IS-IS TE . . . . . . . . . . . . . 4
3. Sub TLV Details . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Unidirectional Link Delay Sub-TLV . . . . . . . . . . . . 6
3.2. Unidirectional Delay Variation Sub-TLV . . . . . . . . . . 7
3.3. Unidirectional Link Loss Sub-TLV . . . . . . . . . . . . . 7
3.4. Unidirectional Residual Bandwidth Sub-TLV . . . . . . . . 8
3.5. Unidirectional Available Bandwidth Sub-TLV . . . . . . . . 9
4. Announcement Thresholds and Filters . . . . . . . . . . . . . 10
5. Announcement Suppression . . . . . . . . . . . . . . . . . . . 11
6. Network Stability and Announcement Periodicity . . . . . . . . 11
7. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
In certain networks, such as, but not limited to, financial In certain networks, such as, but not limited to, financial
information networks (e.g. stock market data providers), network information networks (e.g. stock market data providers), network
performance information (e.g. latency) is becoming as critical to performance information (e.g. latency) is becoming as critical to
data path selection as other metrics. data path selection as other metrics.
In these networks, extremely large amounts of money rest on the In these networks, extremely large amounts of money rest on the
ability to access market data in "real time" and to predictably make ability to access market data in "real time" and to predictably make
trades faster than the competition. Because of this, using metrics trades faster than the competition. Because of this, using metrics
such as hop count or cost as routing metrics is becoming only such as hop count or cost as routing metrics is becoming only
tangentially important. Rather, it would be beneficial to be able to tangentially important. Rather, it would be beneficial to be able to
make path selection decisions based on performance data (such as make path selection decisions based on performance data (such as
latency) in a cost-effective and scalable way. latency) in a cost-effective and scalable way.
This document describes extensions to IS-IS Extended Reachability TLV This document describes extensions to IS-IS Extended Reachability TLV
[RFC5305](hereafter called "IS-IS TE Express Path"), that can be used defined in [RFC5305] (hereafter called "IS-IS TE Express Path"), that
to distribute network performance information (such as link delay, can be used to distribute network performance information (such as
delay variation, packet loss, residual bandwidth, and available link delay, delay variation, packet loss, residual bandwidth, and
bandwidth). available bandwidth).
The data distributed by IS-IS TE Express Path is meant to be used as The data distributed by IS-IS TE Express Path is meant to be used as
part of the operation of the routing protocol (e.g. by replacing cost part of the operation of the routing protocol (e.g. by replacing cost
with latency or considering bandwidth as well as cost), by enhancing with latency or considering bandwidth as well as cost), by enhancing
CSPF, or for other uses such as supplementing the data used by an CSPF, or for other uses such as supplementing the data used by an
Alto server [Alto]. With respect to CSPF, the data distributed by IS- Alto server [I-D.ietf-alto-protocol]. With respect to CSPF, the data
IS TE Express Path can be used to setup, fail over, and fail back distributed by IS- IS TE Express Path can be used to setup, fail
data paths using protocols such as RSVP-TE [RFC3209]. over, and fail back data paths using protocols such as RSVP-TE
[RFC3209].
Note that the mechanisms described in this document only disseminate Note that the mechanisms described in this document only disseminate
performance information. The methods for initially gathering that performance information. The methods for initially gathering that
performance information, such as [Frost], or acting on it once it is performance information, such as [RFC6375], or acting on it once it
distributed are outside the scope of this document. is distributed are outside the scope of this document.
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 RFC-2119 [RFC2119].
In this document, these words will appear with that interpretation 2. Express Path Extensions to IS-IS TE
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
3. Express Path Extensions to IS-IS TE This document proposes new IS-IS TE sub-TLVs that can be announced in
ISIS Extended Reachability TLV (TLV-22) to distribute network
performance information. The extensions in this document build on
the ones provided in IS-IS TE [RFC5305] and GMPLS [RFC4203].
This document proposes new IS-IS TE sub-TLVs that can be announced IS-IS Extended Reachability TLV 22 (defined in [RFC5305]), Inter-AS
in ISIS Extended Reachability TLV (TLV-22) to distribute network reachability information TLV 141 (defined in [RFC5316]) and MT-ISN
performance information. The extensions in this document build on the TLV 222 (defined in [RFC5120]) have nested sub-TLVs which permit the
ones provided in IS-IS TE [RFC5305] and GMPLS [RFC4203]. TLVs to be readily extended. This document proposes several
additional sub-TLVs:
IS-IS Extended Reachability TLV (TLV-22) defined in [RFC5305] has Type Value
nested sub-TLVs which permit the ISIS Reachability TLV to be readily
extended. This document proposes several additional sub-TLVs:
Type Length Value TBD1 Unidirectional Link Delay
TBD1 6 Unidirectional Link Delay TBD2 Unidirectional Delay Variation
TBD2 6 Unidirectional Delay Variation TBD3 Unidirectional Packet Loss
TBD3 6 Unidirectional Packet Loss TBD4 Unidirectional Residual Bandwidth Sub TLV
TBD4 6 Unidirectional Residual Bandwidth Sub TLV TBD5 Unidirectional Available Bandwidth Sub TLV
TBD5 6 Unidirectional Available Bandwidth Sub TLV
As can be seen in the list above, the sub-TLVs described in this As can be seen in the list above, the sub-TLVs described in this
document carry different types of network performance information. document carry different types of network performance information.
Many (but not all) of the sub-TLVs include a bit called the Anomalous Many (but not all) of the sub-TLVs include a bit called the Anomalous
(or "A") bit. When the A bit is clear (or when the sub-TLV does not (or "A") bit. When the A bit is clear (or when the sub-TLV does not
include an A bit), the sub-TLV describes steady state link include an A bit), the sub-TLV describes steady state link
performance. This information could conceivably be used to construct performance. This information could conceivably be used to construct
a steady state performance topology for initial tunnel path a steady state performance topology for initial tunnel path
computation, or to verify alternative failover paths. computation, or to verify alternative failover paths.
When network performance violates configurable link-local thresholds When network performance violates configurable link-local thresholds
a sub-TLV with the A bit set is advertised. These sub-TLVs could be a sub-TLV with the A bit set is advertised. These sub-TLVs could be
used by the receiving node to determine whether to fail traffic to a used by the receiving node to determine whether to fail traffic to a
backup path, or whether to calculate an entirely new path. From an backup path, or whether to calculate an entirely new path. From an
MPLS perspective, the intent of the A bit is to permit LSP ingress MPLS perspective, the intent of the A bit is to permit LSP ingress
nodes to: nodes to:
A) Determine whether the link referenced in the sub-TLV affects any A) Determine whether the link referenced in the sub-TLV affects any
of the LSPs for which it is ingress. If there are, then: of the LSPs for which it is ingress. If there are, then:
B) Determine whether those LSPs still meet end-to-end performance B) Determine whether those LSPs still meet end-to-end performance
objectives. If not, then: objectives. If not, then:
C) The node could then conceivably move affected traffic to a pre- C) The node could then conceivably move affected traffic to a pre-
established protection LSP or establish a new LSP and place the established protection LSP or establish a new LSP and place the
traffic in it. traffic in it.
If link performance then improves beyond a configurable minimum If link performance then improves beyond a configurable minimum value
value (reuse threshold), that sub-TLV can be re-advertised with the (reuse threshold), that sub-TLV can be re-advertised with the
Anomalous bit cleared. In this case, a receiving node can Anomalous bit cleared. In this case, a receiving node can
conceivably do whatever re-optimization (or failback) it wishes to conceivably do whatever re-optimization (or failback) it wishes to do
do (including nothing). (including nothing).
Note that when a sub-TLV does not include the A bit, that sub-TLV Note that when a sub-TLV does not include the A bit, that sub-TLV
cannot be used for failover purposes. The A bit was intentionally cannot be used for failover purposes. The A bit was intentionally
omitted from some sub-TLVs to help mitigate oscillations. See section omitted from some sub-TLVs to help mitigate oscillations. See
5. for more information. Section 4 for more information.
Consistent with existing IS-IS TE specifications [RFC5305], the Consistent with existing IS-IS TE specifications [RFC5305], the
bandwidth advertisements defined in this draft MUST be encoded as bandwidth advertisements defined in this draft MUST be encoded as
IEEE floating point values. The delay and delay variation IEEE floating point values. The delay and delay variation
advertisements defined in this draft MUST be encoded as integer advertisements defined in this draft MUST be encoded as integer
values. Delay values MUST be quantified in units of microseconds, values. Delay values MUST be quantified in units of microseconds,
packet loss MUST be quantified as a percentage of packets sent, and packet loss MUST be quantified as a percentage of packets sent, and
bandwidth MUST be sent as bytes per second. All values (except bandwidth MUST be sent as bytes per second. All values (except
residual bandwidth) MUST be calculated as rolling averages where the residual bandwidth) MUST be calculated as rolling averages where the
averaging period MUST be a configurable period of time. See section averaging period MUST be a configurable period of time. See
5. for more information. Section 4 for more information.
4. Sub TLV Details 3. Sub TLV Details
4.1. Unidirectional Link Delay Sub-TLV 3.1. Unidirectional Link Delay Sub-TLV
This sub-TLV advertises the average link delay between two directly This sub-TLV advertises the average link delay between two directly
connected IS-IS neighbors. The delay advertised by this sub-TLV MUST connected IS-IS neighbors. The delay advertised by this sub-TLV MUST
be the delay from the local neighbor to the remote one (i.e. the be the delay from the local neighbor to the remote one (i.e. the
forward path latency). The format of this sub-TLV is shown in the forward path latency). The format of this sub-TLV is shown in the
following diagram: following diagram:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | A | RESERVED | | Type | Length |A| RESERVED | Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED | Delay | | Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This sub-TLV has a type of TBD1.
The length is 4.
This sub-TLV has a type of TBD1.
The length is 6.
Where: Where:
"A" represents the Anomalous (A) bit. The A bit is set when the "A" represents the Anomalous (A) bit. The A bit is set when the
measured value of this parameter exceeds its configured maximum measured value of this parameter exceeds its configured maximum
threshold. The A bit is cleared when the measured value falls below threshold. The A bit is cleared when the measured value falls below
its configured reuse threshold. If the A bit is clear, the sub-TLV its configured reuse threshold. If the A bit is clear, the sub-TLV
represents steady state link performance. represents steady state link performance.
The "Reserved" field is reserved for future use. It MUST be set to 0 The "Reserved" field is reserved for future use. It MUST be set to 0
when sent and MUST be ignored when received. when sent and MUST be ignored when received.
"Delay Value" is a 24-bit field carries the average link delay over a "Delay Value" is a 24-bit field carries the average link delay over a
configurable interval in micro-seconds, encoded as an integer value. configurable interval in micro-seconds, encoded as an integer value.
When set to 0, it has not been measured. When set to the maximum When set to 0, it has not been measured. When set to the maximum
value 16,777,215 (16.777215 sec), then the delay is at least that value 16,777,215 (16.777215 sec), then the delay is at least that
value and may be larger. value and may be larger.
4.2. Unidirectional Delay Variation Sub-TLV 3.2. Unidirectional Delay Variation Sub-TLV
This sub-TLV advertises the average link delay variation between two This sub-TLV advertises the average link delay variation between two
directly connected IS-IS neighbors. The delay variation advertised by directly connected IS-IS neighbors. The delay variation advertised
this sub-TLV MUST be the delay from the local neighbor to the remote by this sub-TLV MUST be the delay from the local neighbor to the
one (i.e. the forward path latency). The format of this sub-TLV is remote one (i.e. the forward path latency). The format of this sub-
shown in the following diagram: TLV is shown in the following diagram:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | A | RESERVED | | Type | Length |A| RESERVED |Delay Variation|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED | Delay Variation | | Delay Variation |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This sub-TLV has a type of TBD2. This sub-TLV has a type of TBD2.
The length is 6. The length is 4.
Where: Where:
"A" represents the Anomalous (A) bit. The A bit is set when the "A" represents the Anomalous (A) bit. The A bit is set when the
measured value of this parameter exceeds its configured maximum measured value of this parameter exceeds its configured maximum
threshold. The A bit is cleared when the measured value falls below threshold. The A bit is cleared when the measured value falls below
its configured reuse threshold. If the A bit is clear, the sub-TLV its configured reuse threshold. If the A bit is clear, the sub-TLV
represents steady state link performance The "Reserved" field is represents steady state link performance.
reserved for future use. It MUST be set to 0 when sent and MUST be
ignored when received. The "Reserved" field is reserved for future use. It MUST be set to 0
when sent and MUST be ignored when received.
"Delay Variation" is a 24-bit field carries the average link delay "Delay Variation" is a 24-bit field carries the average link delay
variation over a configurable interval in micro-seconds, encoded as variation over a configurable interval in micro-seconds, encoded as
an integer value. When set to 0, it has not been measured. When set an integer value. When set to 0, it has not been measured. When set
to the maximum value 16,777,215 (16.777215 sec), then the delay is at to the maximum value 16,777,215 (16.777215 sec), then the delay is at
least that value and may be larger. least that value and may be larger.
4.3. Unidirectional Link Loss Sub-TLV 3.3. Unidirectional Link Loss Sub-TLV
This sub-TLV advertises the loss (as a packet percentage) between two This sub-TLV advertises the loss (as a packet percentage) between two
directly connected IS-IS neighbors. The link loss advertised by this directly connected IS-IS neighbors. The link loss advertised by this
sub-TLV MUST be the packet loss from the local neighbor to the remote sub-TLV MUST be the packet loss from the local neighbor to the remote
one (i.e. the forward path loss). The format of this sub-TLV is shown one (i.e. the forward path loss). The format of this sub-TLV is
in the following diagram: shown in the following diagram:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | A | RESERVED | | Type | Length |A| RESERVED | Link Loss |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED | Link Loss | | Link Loss |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This sub-TLV has a type of TBD3. This sub-TLV has a type of TBD3.
The length is 6. The length is 4.
Where: Where:
The "A" bit represents the Anomalous (A) bit. The A bit is set when The "A" bit represents the Anomalous (A) bit. The A bit is set when
the measured value of this parameter exceeds its configured maximum the measured value of this parameter exceeds its configured maximum
threshold. The A bit is cleared when the measured value falls below threshold. The A bit is cleared when the measured value falls below
its configured reuse threshold. If the A bit is clear, the sub-TLV its configured reuse threshold. If the A bit is clear, the sub-TLV
represents steady state link performance. represents steady state link performance.
"Reserved" field is reserved for future use. It MUST be set to 0 when "Reserved" field is reserved for future use. It MUST be set to 0
sent and MUST be ignored when received. when sent and MUST be ignored when received.
"Link Loss" is a 24-bit field carries link packet loss as a "Link Loss" is a 24-bit field carries link packet loss as a
percentage of the total traffic sent over a configurable interval. percentage of the total traffic sent over a configurable interval.
The basic unit is 0.000003%, where (2^24 - 2) is 50.331642%. This The basic unit is 0.000003%, where (2^24 - 2) is 50.331642%. This
value is the highest packet loss percentage that can be expressed value is the highest packet loss percentage that can be expressed
(the assumption being that precision is more important on high speed (the assumption being that precision is more important on high speed
links than the ability to advertise loss rates greater than this, and links than the ability to advertise loss rates greater than this, and
that high speed links with over 50% loss are unusable). Therefore, that high speed links with over 50% loss are unusable). Therefore,
measured values that are larger than the field maximum SHOULD be measured values that are larger than the field maximum SHOULD be
encoded as the maximum value. When set to a value of all 1s (2^24 - encoded as the maximum value. When set to a value of all 1s (2^24 -
1), the link packet loss has not been measured. 1), the link packet loss has not been measured.
4.4. Unidirectional Residual Bandwidth Sub-TLV 3.4. Unidirectional Residual Bandwidth Sub-TLV
This TLV advertises the residual bandwidth (defined in section Error!
Reference source not found.between two directly connected IS-IS
neighbors. The residual bandwidth advertised by this sub-TLV MUST be
the residual bandwidth from the system originating the sub-TLV to its
neighbor.
The format of this sub-TLV is shown in the following diagram: This TLV advertises the residual bandwidth between two directly
connected IS-IS neighbors. The residual bandwidth advertised by this
sub-TLV MUST be the residual bandwidth from the system originating
the sub-TLV to its neighbor. The format of this sub-TLV is shown in
the following diagram:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | RESERVED | | Type | Length | Residual Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Residual Bandwidth | | Residual Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This sub-TLV has a type of TBD4. This sub-TLV has a type of TBD4.
The length is 6. The length is 4.
"Reserved" field is reserved for future use. It MUST be set to 0 when Where:
sent and MUST be ignored when received.
"Residual Bandwidth" is a field carries the residual bandwidth on a "Residual Bandwidth" is the residual bandwidth in IEEE floating point
link, forwarding adjacency [RFC4206], or bundled link in IEEE format in units of bytes per second. The link may be a single link,
floating point format with units of bytes per second. For a link or forwarding adjacency [RFC4206], or bundled link. For a link or
forwarding adjacency, residual bandwidth is defined to be Maximum forwarding adjacency, residual bandwidth is defined to be Maximum
Link Bandwidth [RFC5305] minus the bandwidth currently allocated to Link Bandwidth [RFC5305] minus the bandwidth currently allocated to
RSVP-TE LSPs. For a bundled link, residual bandwidth is defined to RSVP-TE LSPs. For a bundled link, residual bandwidth is defined to
be the sum of the component link residual bandwidths. be the sum of the component link residual bandwidths.
Note that although it may seem possible to calculate Residual Note that although it may seem possible to calculate Residual
Bandwidth using the existing sub-TLVs in RFC 5305, this is not a Bandwidth using the existing sub-TLVs in [RFC5305], this is not a
consistently reliable approach and hence the Residual Bandwidth sub- consistently reliable approach and hence the Residual Bandwidth sub-
TLV has been added here. For example, because the Maximum Reservable TLV has been added here. For example, because the Maximum Reservable
Bandwidth [RFC5305] can be larger than the capacity of the link, Bandwidth [RFC5305] can be larger than the capacity of the link,
using it as part of an algorithm to determine the value of the using it as part of an algorithm to determine the value of the
Maximum Link Bandwidth [RFC5305] minus the bandwidth currently Maximum Link Bandwidth [RFC5305]minus the bandwidth currently
allocated to RSVP-TE Label Switched Paths cannot be considered allocated to RSVP-TE Label Switched Paths cannot be considered
reliably accurate. reliably accurate.
4.5. Unidirectional Available Bandwidth Sub-TLV 3.5. Unidirectional Available Bandwidth Sub-TLV
This TLV advertises the available bandwidth (defined in section This TLV advertises the available bandwidth between two directly
Error! Reference source not found.between two directly connected IS- connected IS-IS neighbors. The available bandwidth advertised in
IS neighbors. The available bandwidth advertised by this sub-TLV MUST this sub-TLV MUST be the available bandwidth from the originating
be the available bandwidth from the system originating the Sub-TLV to system to its neighbor. The format of this sub-TLV is shown in the
its neighbor. The format of this sub-TLV is shown in the following following diagram:
diagram:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | RESERVED | | Type | Length | Available Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Available Bandwidth | | Available Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This sub-TLV has a type of TBD5. This sub-TLV has a type of TBD5.
The length is 6. The length is 4.
Where: Where:
"Reserved" field is reserved for future use. It MUST be set to 0 when
sent and MUST be ignored when received.
"Available Bandwidth" is a field that carries the available bandwidth "Available Bandwidth" is a field that carries the available bandwidth
on a link, forwarding adjacency, or bundled link in IEEE floating on a link, forwarding adjacency, or bundled link in IEEE floating
point format with units of bytes per second. For a link or point format with units of bytes per second. For a link or
forwarding adjacency, available bandwidth is defined to be residual forwarding adjacency, available bandwidth is defined to be residual
bandwidth (see section 4.4. minus the measured bandwidth used for the bandwidth (see Section 3.4) minus the measured bandwidth used for the
actual forwarding of non-RSVP-TE Label Switched Paths packets. For a actual forwarding of non-RSVP-TE Label Switched Paths packets. For a
bundled link, available bandwidth is defined to be the sum of the bundled link, available bandwidth is defined to be the sum of the
component link available bandwidths. component link available bandwidths.
5. Announcement Thresholds and Filters 4. Announcement Thresholds and Filters
The values advertised in all sub-TLVs MUST be controlled using an The values advertised in all sub-TLVs MUST be controlled using an
exponential filter (i.e. a rolling average) with a configurable exponential filter (i.e. a rolling average) with a configurable
measurement interval and filter coefficient. measurement interval and filter coefficient.
Implementations are expected to provide separately configurable Implementations are expected to provide separately configurable
advertisement thresholds. All thresholds MUST be configurable on a advertisement thresholds. All thresholds MUST be configurable on a
per sub-TLV basis. per sub-TLV basis.
The announcement of all sub-TLVs that do not include the A bit SHOULD The announcement of all sub-TLVs that do not include the A bit SHOULD
be controlled by variation thresholds that govern when they are sent. be controlled by variation thresholds that govern when they are sent.
Sub-TLV that include the A bit are governed by several thresholds. Sub-TLVs that include the A bit are governed by several thresholds.
Firstly, a threshold SHOULD be implemented to govern the announcement Firstly, a threshold SHOULD be implemented to govern the announcement
of sub-TLVs that advertise a change in performance, but not an SLA of sub-TLVs that advertise a change in performance, but not an SLA
violation (i.e. when the A bit is not set). Secondly, implementations violation (i.e. when the A bit is not set). Secondly,
MUST provide configurable thresholds that govern the announcement of implementations MUST provide configurable thresholds that govern the
sub-TLVs with the A bit set (for the indication of a performance announcement of sub-TLVs with the A bit set (for the indication of a
violation). Thirdly, implementations SHOULD provide reuse performance violation). Thirdly, implementations SHOULD provide
thresholds. These thresholds govern sub-TLV re-announcement with the reuse thresholds. These thresholds govern sub-TLV re-announcement
A bit cleared to permit fail back. with the A bit cleared to permit fail back.
6. Announcement Suppression 5. Announcement Suppression
When link performance average values change, but fall under the When link performance average values change, but fall under the
threshold that would cause the announcement of a sub-TLV with the A threshold that would cause the announcement of a sub-TLV with the A
bit set, implementations MAY suppress or throttle sub-TLV bit set, implementations MAY suppress or throttle sub-TLV
announcements. All suppression features and thresholds SHOULD be announcements. All suppression features and thresholds SHOULD be
configurable. configurable.
7. Network Stability and Announcement Periodicity 6. Network Stability and Announcement Periodicity
To mitigate concerns about stability, all values (except residual To mitigate concerns about stability, all values (except residual
bandwidth) MUST be calculated as rolling averages where the averaging bandwidth) MUST be calculated as rolling averages where the averaging
period MUST be a configurable period of time, rather than period MUST be a configurable period of time, rather than
instantaneous measurements. instantaneous measurements.
Announcements MUST also be able to be throttled using configurable Announcements MUST also be able to be throttled using configurable
inter-update throttle timers. The minimum announcement periodicity is inter-update throttle timers. The minimum announcement periodicity
1 announcement per second. is 1 announcement per second.
8. Compatibility 7. Compatibility
As per (RFC5305), unrecognized TLVs should be silently ignored As per [RFC5305], unrecognized Sub-TLVs should be silently ignored
9. Security Considerations 8. Security Considerations
This document does not introduce security issues beyond those This document does not introduce security issues beyond those
discussed in [RFC3630] and [RFC5329]. discussed in [RFC3630] and [RFC5329].
10. IANA Considerations 9. IANA Considerations
IANA maintains the registry for the sub-TLVs. IS-IS TE Express Path IANA maintains the registry for the sub-TLVs. IS-IS TE Express Path
will require one new type code per sub-TLV defined in this document. will require one new type code per sub-TLV defined in this document.
11. References 10. Acknowledgements
11.1. Normative References The authors would like to recognize Ayman Soliman and Les Ginsberg
for their contributions.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 11. References
Requirement Levels", BCP 14, RFC 2119, March 1997. 11.1. Normative References
[RFC5305] Li, T., Smit, H., "IS-IS Extensions for Traffic [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Engineering", RFC 3630, September 2003. Requirement Levels", BCP 14, RFC 2119, March 1997.
11.2. Informative References [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3031] Rosen, E., Viswanathan, A., Callon, R., "Multiprotocol [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
Label Switching Architecture", January 2001 (TE) Extensions to OSPF Version 2", RFC 3630,
September 2003.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,V., [RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP of Generalized Multi-Protocol Label Switching (GMPLS)",
Tunnels", RFC 3209, December 2001. RFC 4203, October 2005.
[Frost] D. Frost, S. Bryant"A Packet Loss and Delay Measurement [RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP)
Profile for MPLS-based Transport Networks" Hierarchy with Generalized Multi-Protocol Label Switching
(GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.
[Alto] R. Alimi R. Penno Y. Yang, "ALTO Protocol" [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120, February 2008.
12. Acknowledgments [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
The authors would like to recognize Ayman Soliman and Les Ginsberg [RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
for their contributions. Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5316, December 2008.
This document was prepared using 2-Word-v2.0.template.dot. [RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem,
"Traffic Engineering Extensions to OSPF Version 3",
RFC 5329, September 2008.
13. Author's Addresses [RFC6375] Frost, D. and S. Bryant, "A Packet Loss and Delay
Measurement Profile for MPLS-Based Transport Networks",
RFC 6375, September 2011.
Stefano Previdi 11.2. Informative References
Cisco Systems
[I-D.ietf-alto-protocol]
Penno, R., Alimi, R., and Y. Yang, "ALTO Protocol",
draft-ietf-alto-protocol-10 (work in progress),
October 2011.
Authors' Addresses
Stefano Previdi (editor)
Cisco Systems, Inc.
Via Del Serafico 200 Via Del Serafico 200
00142 Rome Rome 00191
Italy IT
Email: sprevidi@cisco.com Email: sprevidi@cisco.com
Spencer Giacalone Spencer Giacalone
Thomson Reuters Thomson Reuters
195 Broadway 195 Broadway
New York NY 10007, USA New York, NY 10007
USA
Email: Spencer.giacalone@thomsonreuters.com Email: Spencer.giacalone@thomsonreuters.com
Dave Ward Dave Ward
Juniper Networks Cisco Systems, Inc.
1194 N. Mathilda Ave. 3700 Cisco Way
Sunnyvale, CA 94089, USA SAN JOSE, CA 95134
US
Email: dward@juniper.net Email: wardd@cisco.com
John Drake John Drake
Juniper Networks Juniper Networks
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, CA 94089, USA Sunnyvale, CA 94089
USA
Email: jdrake@juniper.net Email: jdrake@juniper.net
Alia Atlas Alia Atlas
Juniper Networks Juniper Networks
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, CA 94089, USA Sunnyvale, CA 94089
USA
Email: akatlas@juniper.net Email: akatlas@juniper.net
Clarence Filsfils Clarence Filsfils
Cisco Systems Cisco Systems, Inc.
Brussels, Belgium Brussels
Belgium
Email: cfilsfil@cisco.com Email: cfilsfil@cisco.com
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