Internet DRAFT - draft-wang-lsr-igp-extensions-ifit
draft-wang-lsr-igp-extensions-ifit
Link State Routing Working Group Y. Wang
Internet-Draft T. Zhou
Intended status: Standards Track Huawei
Expires: January 29, 2021 F. Qin
China Mobile
H. Chen
China Telecom
R. Pang
China Unicom
July 28, 2020
IGP Extensions for In-situ Flow Information Telemetry (IFIT) Capability
Advertisement
draft-wang-lsr-igp-extensions-ifit-01
Abstract
This document extends Node and Link Attribute TLVs to Interior
Gateway Protocols (IGP) to advertise supported In-situ Flow
Information Telemetry (IFIT) capabilities at node and/or link
granularity. An ingress router cannot insert IFIT-Data-Fields for
packets going into a path unless an egress router has indicated via
signaling that it has the capability to process IFIT-Data-Fields. In
addition, such advertisements would be useful for ingress routers to
gather each router's IFIT capability for achieving the computation of
Traffic Engineering (TE) paths or loose TE paths that be able to
fulfill the visibility of on-path OAM data.
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].
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
Wang, et al. Expires January 29, 2021 [Page 1]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
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 January 29, 2021.
Copyright Notice
Copyright (c) 2020 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 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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IFIT Capability . . . . . . . . . . . . . . . . . . . . . . . 4
4. Signaling IFIT Capability Using IS-IS . . . . . . . . . . . . 6
4.1. IS-IS Node IFIT Sub-TLV . . . . . . . . . . . . . . . . . 6
4.2. IS-IS Link IFIT Sub-TLV . . . . . . . . . . . . . . . . . 6
5. Signaling IFIT Capability Using OSPF . . . . . . . . . . . . 7
5.1. OSPF Node IFIT TLV . . . . . . . . . . . . . . . . . . . 7
5.2. OSPFv2 Link IFIT sub-TLV . . . . . . . . . . . . . . . . 8
5.3. OSPFv3 Link IFIT Sub-TLV . . . . . . . . . . . . . . . . 9
6. Application . . . . . . . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
IFIT provides a high-level framework and a reflection-loop solution
for on-path telemetry [I-D.song-opsawg-ifit-framework]. At present,
there is a family of emerging on-path telemetry techniques, including
In-situ OAM (IOAM) [I-D.ietf-ippm-ioam-data], IOAM Direct Export
Wang, et al. Expires January 29, 2021 [Page 2]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
(DEX) [I-D.ietf-ippm-ioam-direct-export], Enhanced Alternate Marking
(EAM) [I-D.ietf-6man-ipv6-alt-mark], etc.
IFIT is a solution focusing on network domains. The "network domain"
consists of a set of network devices or entities within a single
Autonomous System (AS). The part of the network which employs IFIT
is referred to as the IFIT domain. One network domain may consist of
multiple IFIT domains. An IFIT domain may cross multiple network
domains. The family of emerging on-path telemetry techniques may be
partially enabled in different vendors' devices as an emerging
feature for various use cases of application-aware network
operations. So that in order to dynamically enable IFIT
functionality in a network domain, it is necessary to advertise the
information of IFIT option types supported in each device.
An ingress router cannot insert IFIT-Data-Fields for packets going
into a path unless an egress router has indicated via signaling that
it has the capability to process IFIT-Data-Fields. In addition, such
advertisements would be useful for ingress routers to gather each
router's IFIT capability for achieving the computation of TE paths or
loose TE paths that be able to fulfill the visibility of on-path OAM
data.
BGP-LS defines a way to advertise topology and associated attributes
and capabilities of the nodes in that topology to a centralized
controller [RFC7752]. Typically, BGP-LS is configured on a small
number of nodes that do not necessarily act as head-ends. In order
for BGP-LS to signal IFIT node capabilities for all the devices in
the network, IFIT node capabilities SHOULD be advertised by every IGP
router in the network.
This document defines a mechanism to signal the supported IFIT
capabilities at node and/or link granularity using IS-IS, OSPFv2 and
OSPFv3.
2. Terminology
Following are abbreviations used in this document:
o BGP-LS: Border Gateway Protocol - Link State
o IS-IS: Intermediate System to Intermediate System
o OSPF: Open Shortest Path First
o IFIT: In-situ Flow Information Telemetry
o TE: Traffic Engineering
Wang, et al. Expires January 29, 2021 [Page 3]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
o IOAM: In-situ OAM
o PBT: Postcard-Based Telemetry
o DEX: IOAM Direct Export
o EAM: Enhanced Alternate Marking
o IGP: Interior Gateway Protocols
o AS: Autonomous System
o E2E: Edge-to-Edge
o NLRI: Network Layer Reachability Information
3. IFIT Capability
Each IFIT-capable node is configured with a node-id which uniquely
identifies a node within the associated IFIT domain. To accommodate
the different use cases or requirements of in-situ flow information
telemetry, IFIT data fields updated by network nodes fall into
different categories which are referred as different IFIT option
types, including IOAM Trace Option-Types [I-D.ietf-ippm-ioam-data],
IOAM Edge-to-Edge (E2E) Option-Type [I-D.ietf-ippm-ioam-data], IOAM
DEX Option-Type [I-D.ietf-ippm-ioam-direct-export] and EAM Option-
Type [I-D.ietf-6man-ipv6-alt-mark]. A subset or all the IFIT-Option-
Types and their corresponding IFIT-Data-Fields can be associated to
an IFIT-Namespace. Namespace identifiers allow a device which is
IFIT-capable to determine whether IFIT-Option-Types need to be
processed. So that IFIT-Option-Types and Namespace-IDs SHOULD be
included in IFIT capability information.
This document defines the IFIT Capability information formed of one
or more pairs of a 2-octet Namespace-ID and 16-bit Option-Type Flag.
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
+---------------------------------------------------------------+
| Namespace-ID_1 | Option-Type enabled Flag_1 |
+---------------------------------------------------------------+
| Namespace-ID_2 | Option-Type enabled Flag_2 |
+---------------------------------------------------------------+
| ... | ... |
+---------------------------------------------------------------+
Fig. 1 IFIT Capability Format
Where:
Wang, et al. Expires January 29, 2021 [Page 4]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
o Namespace-ID: A 2-octet identifier, which must be present and
populated in all IFIT-Option-Types. The definition is the same as
described in [I-D.ietf-ippm-ioam-data].
o Option-Type Flag: A 16-bit bitmap, which is defined as:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-------------------------------+
|p|i|d|e|m| Reserved |
+-------------------------------+
Where:
o p-Flag: IOAM Pre-allocated Trace Option Type flag. When set, this
indicates that the router is capable of IOAM Pre-allocated Trace
[I-D.ietf-ippm-ioam-data].
o i-Flag: IOAM Incremental Trace Option Type flag. When set, this
indicates that the router is capable of IOAM Incremental Tracing
[I-D.ietf-ippm-ioam-data].
o d-Flag: IOAM DEX Option Type flag. When set, this indicates that
the router is capable of IOAM DEX
[I-D.ietf-ippm-ioam-direct-export].
o e-Flag: IOAM E2E Option Type flag. When set, this indicates that
the router is capable of IOAM E2E processing
[I-D.ietf-ippm-ioam-data].
o m-Flag: EAM flag. When set, this indicates that the router is
capable of processing Enhanced Alternative Marking packets
[I-D.ietf-6man-ipv6-alt-mark].
o Reserved: Must be set to zero upon transmission and ignored upon
receipt.
An IFIT node MAY be capable of more than one IFIT option types. In
this case, Option-Type Flag can has more than one bit being set.
In this document, Link IFIT Capability is defined as the supported
IFIT-Option-Types of the interface associated with the link. When
all interfaces associated with links support the same IFIT-Option-
Type, the Node IFIT Capability SHOULD represent the Link IFIT
Capability. Both of Node and Link IFIT Capability information are
formed of one or more pairs of Namespace-ID and Option-Type Flag.
When both of Node and Link IFIT Capability are advertised, the Link
IFIT Capability information MUST take precedence over the Node IFIT
Wang, et al. Expires January 29, 2021 [Page 5]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
Capability. Besides, when a Link IFIT Capability is not signaled,
then the Node IFIT Capability SHOULD be considered to be the IFIT
Capability for this link.
4. Signaling IFIT Capability Using IS-IS
The IS-IS Extensions for advertising Router Information TLV named IS-
IS Router CAPABILITY TLV [RFC7981], which allows a router to announce
its capabilities within an IS-IS level or the entire routing domain.
And [RFC5305] describes extensions to IS-IS to support Traffic
Engineering.
4.1. IS-IS Node IFIT Sub-TLV
According to the format of IS-IS Router CAPABILITY TLV [RFC7981], the
Node IFIT sub-TLV within the body of the IS-IS router CAPABILITY TLV
is composed of three fields, a one-octet Type field, a one-octet
Length field, and a multiple of 4-octet Value field. The following
format is used:
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
+---------------+---------------+
| Type | Length |
+---------------+---------------+-------------------------------+
| Node-IFIT-Capability |
~ ~
+---------------------------------------------------------------+
Fig. 2 IS-IS Node IFIT Sub-TLV Format
Where:
o Type: To be assigned by IANA
o Length: A one-octet field that indicates the length of the value
portion in octets.
o Node-IFIT-Capability: A multiple of 4-octet field, which is same
as defined in Section 3.
4.2. IS-IS Link IFIT Sub-TLV
The Link IFIT sub-TLV is defined to carry the IFIT-Capability
information of the interface associated with the link, which is
formed of three fields, a one-octet Type field, a one-octet Length
field, and a multiple of 4-octet Value field. The following format
is used:
Wang, et al. Expires January 29, 2021 [Page 6]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
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
+---------------+---------------+
| Type | Length |
+---------------+---------------+-------------------------------+
| Link-IFIT-Capability |
~ ~
+---------------------------------------------------------------+
Fig. 3 IS-IS Link IFIT Sub-TLV Format
Where:
o Type: To be assigned by IANA
o Length: A one-octet field that indicates the length of the value
portion in octets.
o Link-IFIT-Capability: A multiple of 4-octet field, which is same
as defined in Section 3.
5. Signaling IFIT Capability Using OSPF
Given that OSPF uses the options field in LSAs and hello packets to
advertise optional router capabilities [RFC7770], this document
defines a new IFIT Node TLV within the body of the OSPF RI Opaque LSA
[RFC7770] to carry the IFIT Capabilities of the router originating
the RI LSA.
This document defines the Link IFIT sub-TLV to carry the IFIT-
Capability information of the interface associated with the link.
For OSPFv2, the link-level IFIT capability information is advertised
as a sub-TLV of the OSPFv2 Extended Link TLV as defined in [RFC7684].
For OSPFv3, the link-level IFIT capability information is advertised
a sub-TLV of the E-Router-LSA TLV as defined in [RFC8362].
5.1. OSPF Node IFIT TLV
The Node IFIT TLV is composed of three fields, a 2-octet Type field,
a 2-octet Length field, and a multiple of 4-octet Value field. The
following format is used:
Wang, et al. Expires January 29, 2021 [Page 7]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
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
+-------------------------------+-------------------------------+
| Type | Length |
+---------------------------------------------------------------+
| Node-IFIT-Capability |
~ ~
+---------------------------------------------------------------+
Fig. 4 OSPF Node IFIT TLV
Where:
o Type: To be assigned by IANA
o Length: A 2-octet field that indicates the length of the value
field.
o Node-IFIT-Capability: A multiple of 4-octet field, which is as
defined in Section 3.
5.2. OSPFv2 Link IFIT sub-TLV
The Link IFIT sub-TLV encoded in the OSPFv2 Extended Link TLV is
constructed of three fields, a 2-octet Type field, a 2-octet Length
field, and a multiple of 4-octet Value field. The following format
is used:
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
+-------------------------------+-------------------------------+
| Type | Length |
+---------------------------------------------------------------+
| Link-IFIT-Capability |
~ ~
+---------------------------------------------------------------+
Fig. 5 OSPFv2 Link IFIT sub-TLV
Where:
o Type: To be assigned by IANA
o Length: A 2-octet field that indicates the length of the value
field.
Wang, et al. Expires January 29, 2021 [Page 8]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
o Link-IFIT-Capability: A multiple of 4-octet field, which is as
defined in Section 3.
5.3. OSPFv3 Link IFIT Sub-TLV
The Link IFIT sub-TLV encoded in the OSPFv3 E-Router-LSA TLV is
constructed of three fields, a 2-octet Type field, a 2-octet Length
field, and a multiple of 4-octet Value field. The following format
is used:
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
+-------------------------------+-------------------------------+
| Type | Length |
+---------------------------------------------------------------+
| Link-IFIT-Capability |
~ ~
+---------------------------------------------------------------+
Fig. 6 OSPFv3 Link IFIT sub-TLV
Where:
o Type: To be assigned by IANA
o Length: A 2-octet field that indicates the length of the value
field.
o Link-IFIT-Capability: A multiple of 4-octet field, which is as
defined in Section 3.
6. Application
As any packet with IFIT-Data-Fields must not leak out from the IFIT
domain, the IFIT decapsulating node must be able to capture packets
with IFIT-specific header and metadata and recover their format
before forwarding them out of the IFIT domain. Thus, an ingress
router cannot insert IFIT-Data-Fields for packets going into a path
unless an egress router has indicated via signaling that it has the
capability to process IFIT-Data-Fields. In this case, such
advertisements are helpful for avoiding the leak of IFIT-specific
header and metadata.
In addition, such advertisements would be useful for ingress routers
to gather each router's IFIT capability for achieving the computation
of TE paths or loose TE paths that be able to fulfill the visibility
of on-path OAM data. For example, for achieving the computation of
Wang, et al. Expires January 29, 2021 [Page 9]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
low-latency SR-TE path, latency is expected to be collected at every
node that a packet traverses to ensure performance visibility into
the entire path. IOAM Trace Option-Types is a desired option to have
a hop-by-hop latency measurement. If not all nodes on this path are
IOAM Trace Option-Type capable, an incomplete measurement can have
negative impacts on SR-TE path computation and adjustment for low-
latency assurance.
7. IANA Considerations
IANA is requested to allocate values for the following new TLV and
sub-TLVs.
+------+-------------------------+
| Type | Description |
+------+-------------------------+
| TBD | IS-IS Node IFIT Sub-TLV |
| TBD | IS-IS Link IFIT Sub-TLV |
+------+-------------------------+
+------+-------------------------------------+
| Type | Description |
+------+-------------------------------------+
| TBD | OSPF Node IFIT Capability TLV |
| TBD | OSPFv2 Link IFIT Capability sub-TLV |
| TBD | OSPFv3 Link IFIT Capability sub-TLV |
+------+-------------------------------------+
8. Security Considerations
This document introduces new IGP Node and Link Attribute TLVs and
sub-TLVs for the IFIT Capability advertisements at node and/or link
granularity. It does not introduce any new security risks to IS-IS,
OSPFv2 and OSPFv3.
9. Acknowledgements
The authors would like to thank Acee Lindem, Christian Hopps, Robert
Raszuk, Les Ginsberg, Jeff Tantsura, Rakesh Gandhi and Greg Mirsky
for the comments and advices.
10. References
10.1. Normative References
Wang, et al. Expires January 29, 2021 [Page 10]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
[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>.
[RFC5305] "IS-IS Extensions for Traffic Engineering",
<https://www.rfc-editor.org/info/rfc5305>.
[RFC7684] "OSPFv2 Prefix/Link Attribute Advertisement",
<https://www.rfc-editor.org/info/rfc7684>.
[RFC7752] "North-Bound Distribution of Link-State and Traffic
Engineering (TE) Information Using BGP",
<https://datatracker.ietf.org/doc/rfc7752/>.
[RFC7770] "Extensions to OSPF for Advertising Optional Router
Capabilities", <https://www.rfc-editor.org/info/rfc7770>.
[RFC7981] "IS-IS Extensions for Advertising Router Information",
<https://www.rfc-editor.org/info/rfc7981>.
[RFC8362] "OSPFv3 Link State Advertisement (LSA) Extensibility",
<https://www.rfc-editor.org/info/rfc8362>.
10.2. Informative References
[I-D.ietf-6man-ipv6-alt-mark]
"IPv6 Application of the Alternate Marking Method",
<https://datatracker.ietf.org/doc/draft-ietf-6man-ipv6-
alt-mark/>.
[I-D.ietf-ippm-ioam-data]
"Data Fields for In-situ OAM".
[I-D.ietf-ippm-ioam-direct-export]
"In-situ OAM Direct Exporting",
<https://datatracker.ietf.org/doc/draft-ietf-ippm-ioam-
direct-export/>.
[I-D.song-opsawg-ifit-framework]
"In-situ Flow Information Telemetry Framework",
<https://datatracker.ietf.org/doc/draft-song-opsawg-ifit-
framework/>.
Wang, et al. Expires January 29, 2021 [Page 11]
Internet-Draft draft-wang-lsr-igp-extensions-ifit-01 July 2020
Authors' Addresses
Yali Wang
Huawei
156 Beiqing Rd., Haidian District
Beijing
China
Email: wangyali11@huawei.com
Tianran Zhou
Huawei
156 Beiqing Rd., Haidian District
Beijing
China
Email: zhoutianran@huawei.com
Fengwei Qin
China Mobile
32 Xuanwumenxi Ave.
Beijing
China
Email: qinfengwei@chinamobile.com
Huanan Chen
China Telecom
109 West Zhongshan Ave.
Guangzhou, Guangdong
China
Email: chenhuan6@chinatelecom.cn
Ran Pang
China Unicom
9 Shouti South Rd., Haidian District
Beijing
China
Email: pangran@chinaunicom.cn
Wang, et al. Expires January 29, 2021 [Page 12]