SPRING C. Filsfils, Ed.
Internet-Draft P. Camarillo, Ed.
Intended status: Standards Track Cisco Systems, Inc.
Expires: August 16, 2020 D. Cai
Alibaba
D. Voyer
Bell Canada
I. Meilik
Broadcom
K. Patel
Arrcus, Inc.
W. Henderickx
Nokia
P. Jonnalagadda
Barefoot Networks
D. Melman
Marvell
February 13, 2020
Network Programming extension: SRv6 uSID instruction
draft-filsfils-spring-net-pgm-extension-srv6-usid-03
Abstract
The SRv6 "micro segment" (SRv6 uSID or uSID for short) instruction is
defined and illustrated.
It is a straightforward extension to the SRv6 Network Programming
model and its SRH encapsulation.
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.
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/.
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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 August 16, 2020.
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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Notation for human readability . . . . . . . . . . . . . 4
3. SRv6 behaviors associated with a uSID . . . . . . . . . . . . 4
3.1. uN . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Illustration . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Reference diagram . . . . . . . . . . . . . . . . . . . . 5
5.2. SRv6 overlay with underlay optimization . . . . . . . . . 5
6. Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Running code . . . . . . . . . . . . . . . . . . . . . . . . 8
8. Security . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9. Work in progress . . . . . . . . . . . . . . . . . . . . . . 8
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
12.1. Normative References . . . . . . . . . . . . . . . . . . 12
12.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
SRv6 Network Programming [I-D.ietf-spring-srv6-network-programming]
defines a mechanism to build a network program with topological and
service segments. It leverages the SRH
[I-D.ietf-6man-segment-routing-header] to encode a network program
together with optional metadata shared among the different SIDs.
This draft extends SRv6 Network Programming with a new type of SRv6
SID behavior: SRv6 uN. This is combined with the rest of
instructions of the network program and the SRH encapsulation to
build programs in a scalable and efficient way.
2. Terminology
The SRv6 Network Programming
[I-D.ietf-spring-srv6-network-programming] and SRH
[I-D.ietf-6man-segment-routing-header] terminology is leveraged and
extended with the following terms:
uSID carrier: a 128bit SRv6 SID of format <uSID-Block><Active-
uSID><Next-uSID>...<Last-uSID><End-of-Carrier>...<End-of-Carrier>. A
uSID carrier can be encoded in the Destination Address of an IPv6
header or at any position in the Segment List of an SRH.
uSID block: A block of uSID's
It can be any IPv6 prefix allocated to the provider (e.g. /40 or
/48), or it can be any block generally available for private use
(e.g. /16 or /32). An SR domain may have multiple uSID blocks.
uSID: in this document a 16-bit ID. A different uSID length may be
used.
Active uSID: first uSID after the uSID block
Next uSID: next uSID after the Active uSID
Last uSID: from left to right, the last uSID before the first End-of-
Carrier uSID
End-of-Carrier: reserved ID used to mark the end of a uSID carrier.
The value 0000 is selected as End-of-Carrier. All of the empty uSID
carrier positions must be filled with the End-of-Carrier ID. Hence,
the End-of-Carrier can be present more than once in a uSID carrier.
Parent (node): the node at which an uSID is instantiated. The uSIDs
are instantiated on a per-parent node basis.
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Behavior of an uSID: the SRv6 function associated with a given ID.
Section 3 defines them.
2.1. Notation for human readability
For human readability, the examples in this document follow this
notation:
2001:db8::/32 is the uSID block used in the SR domain
0N00: uN behavior bound to node N
3. SRv6 behaviors associated with a uSID
The SRv6 SRH encapsulation and its network programming model are
extended with the following functions:
3.1. uN
The uN behavior is a variant of the endpoint behavior.
This behavior takes a 80b argument, "Arg", which contains the next
uSIDs in the uSID carrier.
When N receives a packet whose IPv6 DA is S and S is a local uN SID,
N does:
1. IF DA[48..63] != 0 ;; Ref1
2. Copy DA[48..127] into DA[32..111]
3. Set DA[112..127] to 0x0000
4. Forward the packet to the new DA
5. ELSE
6. Execute the End pseudocode ;; Ref2
Ref 1: DA[X..Y] refers to the bits from position X to Y (included) in
the IPv6 Destination Address of the received packet. The bit 0 is
the MSB, while the bit 127 is the LSB.
Ref 2: This refers to the End behavior as defined in Section 4.1 of
[I-D.ietf-spring-srv6-network-programming]. The End behavior may be
combined with the PSP, USP and USD flavours.
4. Routing
If N is configured with a uN SID 2001:db8::/32 then the operator must
ensure that N advertises 2001:db8::/32 in routing.
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5. Illustration
This section extends the illustrations for SRv6 Network Programming
[I-D.filsfils-spring-srv6-net-pgm-illustration] to cover uSID. The
reference topology is the same with the addition of link 6-8.
5.1. Reference diagram
Nodes 1 to 8 are considered within the network domain.
Nodes X and Y are outside the domain.
Nodes 1 and 8 act as PE respectively to nodes X and Y.
All the links within the domain have the same IGP metric. The IGP-
metric shortest-path from 1 to 8 is 1-2-7-8 while the latency-metric
shortest-path from 1 to 8 is 1-2-3-4-5-6-7-8.
3------4---5
| \ /
| 6
| / \
1--- 2------7---8
/ \
X Y
Tenant100 Tenant100 with
IPv4 20/8
Figure 1: Reference topology
5.2. SRv6 overlay with underlay optimization
Let us illustrate a low-latency SR-L3VPN service delivered to a
packet (X,Y).
PE 1 encapsulates (X, Y) in an outer IPv6 header with DA =
2001:db8:0300:0500:0700:: and SRH (B:8:D0::; SL=1; NH=4). Leveraging
the illustration conventions from SRv6 network programming, the
following resulting packet leaves node 1 in the direction of node 3:
(A1::, 2001:db8:0300:0500:0700::)(B:8:D0::; SL=1; NH=4)(X, Y)
2001:db8:0300:0500:0700:: is a uSID carrier encoding a source routed
stateless path via node 3 then 5 then 7.
B:8:D0:: is an End.DT4 SID instantiated at node 8.
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1 sends this packet to 2, as 2 is on the shortest-path to
2001:db8:0300::/48 advertised by 3.
When 2 receives the packet, 2 performs a regular IPv6 FIB lookup. It
finds a FIB entry for 2001:db8:0300::/48 and forwards along the
shortest path to 3.
When 3 receives the packet, 3 matches 2001:db8:0300::/48 in its "My
SID Table" and executes the uN behavior. The updated DA becomes
2001:db8:0500:0700::. Node 3 then performs a lookup on the updated DA
and forwards the packet to 5 along the shortest path to
2001:db8:0500::/48.
The following packet leaves node 3:
(A1::, 2001:db8:0500:0700::)(B:8:D0::; SL=1; NH=4)(X, Y)
4 forwards along the shortest path to 2001:db8:0500::/48.
When 5 receives the packet, 5 matches 2001:db8:0500::/48 in its "My
SID Table" and executes the uN behavior. The updated DA becomes
2001:db8:0700::. 5 performs a lookup on the updated DA and forwards
the packet to 7 along the shortest path to 2001:db8:0700::/48.
The following packet leaves node 5:
(A1::, 2001:db8:0700::)(B:8:D0::; SL=1; NH=4)(X, Y)
6 forwards along the shortest path to 2001:db8:0700::/48.
When 7 receives the packet, 7 matches 2001:db8:0700::/48 in its "My
SID Table" and finds the bound function uN. As a result, Node 7
executes the "End with PSP and USD support" pseudocode, decrementing
the SL value in the SRH, and updating the DA with the next SID
B:8:D0::. Since the SL value is zero the SRH is removed. Node 7
performs a lookup on the updated DA and forwards along the shortest
path.
The following packet leaves node 7:
(A1::, B:8:D0::)(X, Y)
8 receives it, performs the End.DT4 function and sends the IP packet
(X, Y) towards its VPN destination.
This example illustrates the benefits highlighted in the next
section.
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6. Benefits
Perfect integration with SRv6 Network Programming
SRv6 uSID is an instruction of the SRv6 network programming
model
Perfect integration with SRH
Any SID in DA or SRH can be an SRv6 uSID carrier
Scalable SR Policy
6 uSID' per uSID carrier
18 source routing waypoints in solely 40bytes of overhead
T.Encaps.Red with an SRH of 40 bytes (8 fixed + 2 * 16
bytes)
6 uSID's in DA and 12 in SRH
Efficient MTU overhead
In apple to apple comparison, the SRv6 solution outperforms any
alternative (VxLAN with SR-MPLS, CRH).
Scalable number of globally unique nodes in the domain
16-bit uSID: 65k uSIDs per domain block
32-bit uSID: 4.3M uSIDs per domain block
Hardware-friendly:
Leverages mature hardware capabilities (shift)
Avoids any extra lookup in indexed mapping table
Demonstrated by Cisco linerate implementation on Jericho1
Control-Plane friendly
No indexed mapping table is required
No routing extension is required: a simple prefix advertisement
suffices
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7. Running code
The hardware and software platforms listed below have demonstrated
support for the uN instruction defined in this document.
Further on, all these implementations have participated in a joint
interoperability testing.
Hardware implementations (in alphabetical order):
Arrcus ArcOS (based on Broadcom Jericho2)
Barefoot Tofino NPU
Cisco 8000 Series Routers (based on Cisco Silicon One Q100)
Cisco ASR9000 platform (with 3rd gen Tomahawk and 4th gen
Lightspeed line-cards)
Cisco NCS5500 platform (based on Broadcom Jericho/Jericho+)
Marvell Prestera Falcon CX 8500
Software open-source implementations (in alphabetical order):
FD.io VPP
Linux Kernel
8. Security
The security rules defined in Section 7 of
[I-D.ietf-spring-srv6-network-programming], protect intra-domain
deployments that includes SRv6 uSID.
9. Work in progress
Future version of this document will include other uSID behaviors
related to TE, VPN and service programming.
10. Acknowledgements
The authors would like to acknowledge Francois Clad, Peter Psenak,
Ketan Talaulikar, Jakub Horn, Swadesh Agrawal, Zafar Ali, Darren
Dukes, Kiran Sadshiran, Junaid Israr, Lakshmanan Srikanth, Asif
Islam, Saleem Hafeez, Michael MacKenzie, Sushek Shekar, YuanChao Su,
Alexander Preusche, Alberto Donzelli, Miya Kohno, David Smith, Ianik
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Semco, Bertrand Duvivier, Frederic Trate, Kris Michielsen, Eyal
Dagan, Eli Stein, Ofer Iny, Elad Naor, Aviad Behar, Joseph Chin.
11. Contributors
Jisu Bhattacharyaa
Cisco Systems, Inc.
United States of America
Email: jisu@cisco.com
Kamran Raza
Cisco Systems, Inc.
Canada
Email: skraza@cisco.com
John Bettink
Cisco Systems, Inc.
United States of America
Email: jbettink@cisco.com
Tomonobu Niwa
KDDI
Japan
Email: to-niwa@kddi.com
Luay Jalil
Verizon
United States of America
Email: luay.jalil@one.verizon.com
Zhichun Jiang
Tencent
China
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Email: zcjiang@tencent.com
Ahmed Shawky
Saudi Telecom Company
Saudi Arabia
Email: ashawky@stc.com.sa
Nic Leymann
Deutsche Telekom
Germany
Email: N.Leymann@telekom.de
Dirk Steinberg
Lapishills Consulting Limited
Cyprus
Email: dirk@lapishills.com
Shawn Zandi
LinkedIn
United States of America
Email: szandi@linkedin.com
Gaurav Dawra
LinkedIn
United States of America
Email: gdawra@linkedin.com
Jim Uttaro
AT&T
United States of America
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Email: ju1738@att.com
Ning So
Reliance
United States of America
Email: Ning.So@ril.com
Michael Fiumano
Sprint
United States of America
Email: michael.f.fiumano@sprint.com
Mazen Khaddam
Cox
United States of America
Email: Mazen.Khaddam@cox.com
Jichun Ma
China Unicom
China
Email: majc16@chinaunicom.cn
Satoru Matsushima
Softbank
Japan
Email: satoru.matsushima@g.softbank.co.jp
Francis Ferguson
CenturyLink
United States of America
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Email: Francis.Ferguson@centurylink.com
Takuya Miyasaka
KDDI
Japan
Email: ta-miyasaka@kddi.com
Kentaro Ebisawa
Toyota Motor Corporation
Japan
Email: ebisawa@toyota-tokyo.tech
Yukito Ueno
NTT Communications Corporation
Japan
Email: yukito.ueno@ntt.com
12. References
12.1. Normative References
[]
Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", draft-ietf-6man-segment-routing-header-26 (work in
progress), October 2019.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-08 (work in
progress), January 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>.
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[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>.
12.2. Informative References
[I-D.filsfils-spring-srv6-net-pgm-illustration]
Filsfils, C., Camarillo, P., Li, Z., Matsushima, S.,
Decraene, B., Steinberg, D., Lebrun, D., Raszuk, R., and
J. Leddy, "Illustrations for SRv6 Network Programming",
draft-filsfils-spring-srv6-net-pgm-illustration-01 (work
in progress), August 2019.
Authors' Addresses
Clarence Filsfils (editor)
Cisco Systems, Inc.
Belgium
Email: cf@cisco.com
Pablo Camarillo Garvia (editor)
Cisco Systems, Inc.
Spain
Email: pcamaril@cisco.com
Dennis Cai
Alibaba
China
Email: d.cai@alibaba-inc.com
Daniel Voyer
Bell Canada
Canada
Email: daniel.voyer@bell.ca
Israel Meilik
Broadcom
Israel
Email: israel.meilik@broadcom.com
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Keyur Patel
Arrcus, Inc.
United States of America
Email: keyur@arrcus.com
Wim Henderickx
Nokia
Belgium
Email: wim.henderickx@nokia.com
Prem Jonnalagadda
Barefoot Networks
United States of America
Email: prem@barefootnetworks.com
David Melman
Marvell
Israel
Email: davidme@marvell.com
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