Internet DRAFT - draft-filsfils-spring-srv6-stateless-slice-id
draft-filsfils-spring-srv6-stateless-slice-id
SPRING C. Filsfils, Ed.
Internet-Draft F. Clad, Ed.
Intended status: Standards Track P. Camarillo
Expires: 1 August 2024 K. Raza
Cisco Systems, Inc.
D. Voyer
Bell Canada
R. Rokui
Ciena
29 January 2024
Stateless and Scalable Network Slice Identification for SRv6
draft-filsfils-spring-srv6-stateless-slice-id-09
Abstract
This document defines a stateless and scalable solution to achieve
network slicing with SRv6.
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 1 August 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
Filsfils, et al. Expires 1 August 2024 [Page 1]
Internet-Draft SRv6 Stateless Slice Identification January 2024
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 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. Slice Identifier . . . . . . . . . . . . . . . . . . . . . . 3
3. SLID Presence Indicator . . . . . . . . . . . . . . . . . . . 3
4. Ingress PE SLID Assignment . . . . . . . . . . . . . . . . . 3
5. Per-Slice Forwarding . . . . . . . . . . . . . . . . . . . . 4
6. Bandwidth-Allocation Slice . . . . . . . . . . . . . . . . . 4
7. Backward Compatibility . . . . . . . . . . . . . . . . . . . 4
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
SRv6 Network Programming[RFC8986] enables the creation of overlays
with underlay optimization to be deployed in an SR domain[RFC8402].
As defined in [RFC8754], all inter-domain packets are encapsulated
for the part of the packet journey that is within the SR domain. The
outer IPv6 header is originated by a node of the SR domain and is
destined to a node of the SR domain.
This document describes a stateless encoding of slice identification
in the outer IPv6 header of an SR domain. The slice identification
is independent of topology and the QoS/DiffServ policy of the
network, thus enabling scalable network slicing for SRv6 overlays.
Filsfils, et al. Expires 1 August 2024 [Page 2]
Internet-Draft SRv6 Stateless Slice Identification January 2024
The definition of network slicing in the context of networks built
from IETF technologies is specified in
[I-D.ietf-teas-ietf-network-slices]. It defines the term "IETF
Network Slice" and establishes the general principles of network
slicing in the IETF context. It also discusses the general framework
for requesting and operating IETF Network Slices, the characteristics
of an IETF Network Slice, the necessary system components and
interfaces, and how abstract requests can be mapped to more specific
technologies. The document also discusses related considerations
with monitoring and security.
2. Slice Identifier
The Slice Identifier (SLID) is a value encoded within the IPv6 packet
that allows transit routers to process the packet according to
network slice-based policy. An example of slice-based policy that
can be enforced using the SLID is described in Section 6.
The SLID may identify a unique IETF network slice or a group of
slices that share the same policy. For example, a SLID may identify
a slice aggregate [I-D.bestbar-teas-ns-packet].
This document proposes to encode the SLID in a portion of the IPv6
Flow Label.
The precise SLID location within the IPv6 Flow Label and the number
of bits used to encode it are governed by local policy and uniform
within the SR domain.
3. SLID Presence Indicator
The SLID Presence Indicator (SPI) is set by a SLID-capable IPv6
source node to inform transit routers that a SLID is encoded in the
packet.
The SPI is encoded as a specific bit or range of values in the
Traffic Class field of the IPv6 header.
The encoding of the SPI in the IPv6 header is governed by local
policy and uniform within the SR domain.
4. Ingress PE SLID Assignment
When an ingress PE receives a packet that traverses the SR domain, it
encapsulates the packet in an outer IPv6 header and optional SRH as
defined in [RFC8754]. The ingress PE MAY also classify the packet
into a slice and set the slice identifier as follows:
Filsfils, et al. Expires 1 August 2024 [Page 3]
Internet-Draft SRv6 Stateless Slice Identification January 2024
* Set the SPI in the outer IPv6 header.
* Write the SLID in the outer IPv6 header.
The slice classification method is outside the scope of this
document.
5. Per-Slice Forwarding
Any router within the SR domain that forwards a packet with SPI bit
set uses the SLID to select a slice and apply per-slice policies.
There are many different policies that could define a slice for a
particular application or service. The most basic of these is
bandwidth-allocation, an implementation complying with this
specification SHOULD support the bandwidth-allocation slice as
defined in the next section.
6. Bandwidth-Allocation Slice
A per-slice policy is configured at each interface of each router in
the SR domain, with one traffic shaper per SLID. The bitrate of each
shaper is configured to reflect the bandwidth allocation of the per-
slice policy.
If shapers are not available, or desirable, an implementation MAY
configure one scheduling queue per SLID with a guaranteed bandwidth
equal to the bandwidth-allocation for the slice. This option allows
a slice to consume more bandwidth than its allocation when available.
Per-slice shapers or queues effectively provides a virtual port per
slice. This solution MAY be complemented with a per-virtual-port
hierarchical DiffServ policy. Within the context of one specific
slice, packets are further classified into children DiffServ queues
which hang from the virtual port. The DSCP value in the IPv6 header
SHOULD be used for queue selection.
7. Backward Compatibility
The Flow Label usage described in this document is consistent with
[RFC6437] and [RFC6438].
PE routers that do not set the SPI do not enable the SLID semantic of
the Flow Label bits. Hence, SLID-aware routers would not attempt to
classify these packets into a slice.
Any router that does not process the SPI nor the SLID forwards
packets as usual.
Filsfils, et al. Expires 1 August 2024 [Page 4]
Internet-Draft SRv6 Stateless Slice Identification January 2024
8. Acknowledgements
The authors would like to thank Darren Dukes, Ketan Talaulikar, Jisu
Bhattacharya, John Bettink, Aman Manot, and David Melman for their
insightful feedback on this document.
9. References
9.1. Normative References
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/info/rfc8986>.
9.2. Informative References
[I-D.bestbar-teas-ns-packet]
Saad, T., Beeram, V. P., Dong, J., Wen, B., Ceccarelli,
D., Halpern, J. M., Peng, S., Chen, R., Liu, X.,
Contreras, L. M., Rokui, R., and L. Jalil, "Realizing
Network Slices in IP/MPLS Networks", Work in Progress,
Internet-Draft, draft-bestbar-teas-ns-packet-10, 5 May
2022, <https://datatracker.ietf.org/doc/html/draft-
bestbar-teas-ns-packet-10>.
[I-D.ietf-teas-ietf-network-slices]
Farrel, A., Drake, J., Rokui, R., Homma, S., Makhijani,
K., Contreras, L. M., and J. Tantsura, "A Framework for
Network Slices in Networks Built from IETF Technologies",
Work in Progress, Internet-Draft, draft-ietf-teas-ietf-
network-slices-25, 14 September 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
ietf-network-slices-25>.
Filsfils, et al. Expires 1 August 2024 [Page 5]
Internet-Draft SRv6 Stateless Slice Identification January 2024
[RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
"IPv6 Flow Label Specification", RFC 6437,
DOI 10.17487/RFC6437, November 2011,
<https://www.rfc-editor.org/info/rfc6437>.
[RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label
for Equal Cost Multipath Routing and Link Aggregation in
Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011,
<https://www.rfc-editor.org/info/rfc6438>.
Authors' Addresses
Clarence Filsfils (editor)
Cisco Systems, Inc.
Belgium
Email: cf@cisco.com
Francois Clad (editor)
Cisco Systems, Inc.
France
Email: fclad.ietf@gmail.com
Pablo Camarillo
Cisco Systems, Inc.
Spain
Email: pcamaril@cisco.com
Kamran Raza
Cisco Systems, Inc.
Canada
Email: skraza@cisco.com
Daniel Voyer
Bell Canada
Canada
Email: daniel.voyer@bell.ca
Reza Rokui
Ciena
Canada
Email: rrokui@ciena.com
Filsfils, et al. Expires 1 August 2024 [Page 6]
