IS-IS, OSPF, and BGP-LS Extensions for Advertising Bit Error Rate Metric for Traffic Engineering
draft-gandhi-lsr-ber-02
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | Rakesh Gandhi | ||
| Last updated | 2026-07-18 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
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draft-gandhi-lsr-ber-02
LSR Working Group R. Gandhi, Ed.
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track 18 July 2026
Expires: 19 January 2027
IS-IS, OSPF, and BGP-LS Extensions for Advertising Bit Error Rate Metric
for Traffic Engineering
draft-gandhi-lsr-ber-02
Abstract
Networks may experience transmission bit errors due to various
factors, such as poor fiber quality. This document describes
extensions to IS-IS, OSPF, and BGP-LS to advertise the Bit Error Rate
(BER) and Packet Error Rate (PER) metrics for the links that can be
used for Traffic Engineering.
Note that mechanisms for measuring bit errors or acting on that
information, once advertised, are outside the scope of this document.
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 https://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 19 January 2027.
Copyright Notice
Copyright (c) 2026 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 (https://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
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extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 3
4.1. IS-IS Extensions . . . . . . . . . . . . . . . . . . . . 4
4.2. OSPF Extensions . . . . . . . . . . . . . . . . . . . . . 5
4.3. BGP-LS Extensions . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. IS-IS Link Sub-TLVs . . . . . . . . . . . . . . . . . . . 7
6.2. OSPF Link Sub-TLVs . . . . . . . . . . . . . . . . . . . 7
6.3. BGP-LS Link Attribute TLVs . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Networks may experience transmission bit errors due to various
factors, such as poor fiber quality. The bit error can be a single
bit error or a burst of bit errors at a time. Bit errors include
layer-2 bit errors (e.g., causing CRC errors) or layer-3 and layer-4
bit errors (e.g., causing checksum failures). It is feasible to
measure the Bit Error Rate (BER) and Packet Error Rate (PER) of the
links using measurement packets.
[RFC8570] for IS-IS, [RFC7471] for OSPF, and [RFC8571] for BGP-LS,
define Traffic Engineering (TE) metrics extensions for advertising
latency, loss, and bandwidth metrics.
In this document, IS-IS, OSPF, and BGP-LS extensions are defined to
advertise the BER and PER metrics for the links in the network that
can be used for TE. Additionally, IS-IS, OSPF and BGP-LS extensions
are defined to advertise anomaly state that can be used to avoid the
links with anomaly state in path computation.
Note that the mechanisms for measuring bit errors or acting on that
information, once advertised, are outside the scope of this document.
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2. Conventions Used in This Document
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2.2. Abbreviations
BER: Bit Error Rate
EMA: Exponential Moving Average
PER: Rate of Packets with Bit Errors
TLV: Type-Length-Value
3. Overview
In this document, IS-IS, OSPF, and BGP-LS extensions are defined to
advertise the BER and PER metrics for the links in the network that
can be used for TE. Additionally, IS-IS, OSPF, and BGP-LS extensions
are defined to advertise anomaly state that can be used to avoid the
links with anomaly state in path computation.
The PER metric can be added in the existing packet loss metric
(instead of using it as a separate metric). However, the PER metric
can provide different characteristics of the network, since,
depending on the BER pattern (bursty or single), there can be high
BER but low packet loss, and vice versa.
Editor's note: The BER and PER metrics of the links can be used as
generic metrics in IS-IS, OSPF and BGP-LS. However, this does not
support anomaly state advertisement.
4. Protocol Extensions
IS-IS, OSPF, and BGP-LS extensions are defined to advertise BER and
PER metrics as well as anomaly state as follows.
A bit:
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This field represents the Anomalous (A) bit. The A bit is set when
the measured value of this parameter exceeds its configured maximum
threshold. The A bit is cleared when the measured value falls below
its configured reuse threshold. If the A bit is cleared, the sub-TLV
represents steady-state link performance.
Unit for BER and PER Metrics:
This 24-bit field carries BER or PER as a percentage over a
configurable interval. The basic unit is 0.000003%, where (2^24 - 2)
is 50.331642%. This value is the highest percentage that can be
expressed (the assumption that high-speed links with over 50% BER/PER
are unusable). Measured values that are larger than the field
maximum MUST be advertised as 0xFFFF FF.
EMA:
The BER metric advertised is the exponential moving average (EMA) of
the BER in order to suppress the frequent advertisements. Similarly,
the PER metric advertised is the exponential moving average (EMA) of
the PER.
Threshold:
The BER metric is only advertised when user-configured threshold is
crossed. Similarly, the PER metric is only advertised when user-
configured threshold is crossed.
4.1. IS-IS Extensions
IS-IS extensions for TE are defined in [RFC8570]. This document
extends the sub-TLV structure defined in [RFC8570]. These new sub-
TLVs provide ways to advertise network-performance information
related to BER and PER. The extensions in this document build on the
extensions provided in IS-IS TE [RFC5305] and GMPLS [RFC4203].
This document defines several additional sub-TLVs for the links.
Value Description
----- ----------------------------
TBA1 Unidirectional Link BER
TBA2 Unidirectional Link PER
Example Sub-TLV for advertising BER metric in IS-IS is shown in
Figure 1.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| RESERVED | BER |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: IS-IS Unidirectional BER Metric Sub-TLV
The format of the PER metric sub-TLV is the same as the BER metric
sub-TLV.
The Extended IS Reachability TLV (type 22) (defined in [RFC5305]),
Inter-AS Reachability TLV (also called "inter-AS reachability
information TLV") (type 141) (defined in [RFC9346]), and MT-ISN TLV
(type 222) (defined in [RFC5120]) have nested sub-TLVs that permit
the TLVs to be readily extended for BER and PER. This document
registers new IS-IS TE sub-TLVs in the Sub-TLVs for TLVs 22, 23, 25,
141, 222, and 223.
4.2. OSPF Extensions
OSPF extensions for TE are defined in [RFC7471]. This document
extends the sub-TLV structure defined in [RFC7471]. These new sub-
TLVs provide ways to advertise network-performance information
related to BER and PER.
This document defines several additional sub-TLVs for the links.
Value Description
----- ----------------------------
TBA11 Unidirectional Link BER
TBA12 Unidirectional Link PER
Example Sub-TLV for advertising BER metric in OSPF is shown in
Figure 2.
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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| RESERVED | BER |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 2: OSPF Unidirectional BER Metric Sub-TLV
The format of the PER metric sub-TLV is the same as the BER metric
sub-TLV.
The BER metric advertisement is carried in Application-Specific Link
Attributes Sub-TLV [RFC9492], which is advertised in Extended Link
Opaque LSAs [RFC7684] for OSPFv2 and E-Router-LSAs [RFC8362] for
OSPFv3.
4.3. BGP-LS Extensions
The IGP TE metric extensions in BGP - Link State (BGP-LS)
advertisement are defined in [RFC8571]. New BGP-LS Link Attribute
TLVs are defined for BER and PER. New TLV formats follow the rules
defined in [RFC9552].
Value Description
----- ----------------------------
TBA21 Unidirectional Link BER
TBA22 Unidirectional Link PER
Example TLV for advertising BER metric in BGP-LS is shown in Figure 3
below.
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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| RESERVED | BER |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: BGP-LS Unidirectional BER Metric TLV
The format of the PER metric TLV is the same as the BER metric TLV.
5. Security Considerations
The security considerations specified in [RFC7471], [RFC8570], and
[RFC8571] apply to the procedure and extensions defined in this
document.
6. IANA Considerations
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6.1. IS-IS Link Sub-TLVs
IANA maintains the registry for "IS-IS Sub-TLVs for TLVs Advertising
Neighbor Information". IANA is requested to allocate the following
sub-TLVs for types 22, 23, 25, 141, 222, and 223 from this registry.
+=======+=========================+===============+
| Value | Description | Reference |
+=======+=========================+===============+
| TBA1 | Unidirectional Link BER | This document |
+-------+-------------------------+---------------+
| TBA2 | Unidirectional Link PER | This document |
+-------+-------------------------+---------------+
Table 1: IS-IS Sub-TLV Types
The new sub-TLVs are also added in the registry "IS-IS Sub-Sub-TLV
Codepoints for Application-Specific Link Attributes".
6.2. OSPF Link Sub-TLVs
IANA maintains the registry for "Types for sub-TLVs of TE Link TLV"
for OSPF. IANA is requested to allocate the following sub-TLVs from
this registry.
+=======+=========================+===============+
| Value | Description | Reference |
+=======+=========================+===============+
| TBA11 | Unidirectional Link BER | This document |
+-------+-------------------------+---------------+
| TBA12 | Unidirectional Link PER | This document |
+-------+-------------------------+---------------+
Table 2: Types for sub-TLVs of TE Link TLV in OSPF
6.3. BGP-LS Link Attribute TLVs
IANA maintains the registry for "BGP-LS NLRI and Attribute TLVs".
IANA is requested to allocate the following TLVs from this registry.
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+=======+=========================+===============+
| Value | Description | Reference |
+=======+=========================+===============+
| TBA21 | Unidirectional Link BER | This document |
+-------+-------------------------+---------------+
| TBA22 | Unidirectional Link PER | This document |
+-------+-------------------------+---------------+
Table 3: BGP-LS Attribute TLV Types
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7471] Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
Previdi, "OSPF Traffic Engineering (TE) Metric
Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015,
<https://www.rfc-editor.org/info/rfc7471>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>.
[RFC8570] Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward,
D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE)
Metric Extensions", RFC 8570, DOI 10.17487/RFC8570, March
2019, <https://www.rfc-editor.org/info/rfc8570>.
[RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and
C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of
IGP Traffic Engineering Performance Metric Extensions",
RFC 8571, DOI 10.17487/RFC8571, March 2019,
<https://www.rfc-editor.org/info/rfc8571>.
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[RFC9492] Psenak, P., Ed., Ginsberg, L., Henderickx, W., Tantsura,
J., and J. Drake, "OSPF Application-Specific Link
Attributes", RFC 9492, DOI 10.17487/RFC9492, October 2023,
<https://www.rfc-editor.org/info/rfc9492>.
7.2. Informative References
[RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
<https://www.rfc-editor.org/info/rfc4203>.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008,
<https://www.rfc-editor.org/info/rfc5120>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
[RFC9346] Chen, M., Ginsberg, L., Previdi, S., and D. Xiaodong, "IS-
IS Extensions in Support of Inter-Autonomous System (AS)
MPLS and GMPLS Traffic Engineering", RFC 9346,
DOI 10.17487/RFC9346, February 2023,
<https://www.rfc-editor.org/info/rfc9346>.
[RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and
Traffic Engineering Information Using BGP", RFC 9552,
DOI 10.17487/RFC9552, December 2023,
<https://www.rfc-editor.org/info/rfc9552>.
Acknowledgments
TBA.
Author's Address
Rakesh Gandhi (editor)
Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
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