| 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
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.
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.
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 August 16, 2020.
Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved.
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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.
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
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.
Behavior of an uSID: the SRv6 function associated with a given ID. Section 3 defines them.
For human readability, the examples in this document follow this notation:
The SRv6 SRH encapsulation and its network programming model are extended with the following functions:
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.
If N is configured with a uN SID 2001:db8::/32 then the operator must ensure that N advertises 2001:db8::/32 in routing.
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.
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
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:
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.
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:
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:
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:
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.
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):
Software open-source implementations (in alphabetical order):
The security rules defined in Section 7 of [I-D.ietf-spring-srv6-network-programming], protect intra-domain deployments that includes SRv6 uSID.
Future version of this document will include other uSID behaviors related to TE, VPN and service programming.
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 Semco, Bertrand Duvivier, Frederic Trate, Kris Michielsen, Eyal Dagan, Eli Stein, Ofer Iny, Elad Naor, Aviad Behar, Joseph Chin.
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
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
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
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
| [I-D.ietf-6man-segment-routing-header] | Filsfils, C., Dukes, D., Previdi, S., Leddy, J., Matsushima, S. and D. Voyer, "IPv6 Segment Routing Header (SRH)", Internet-Draft draft-ietf-6man-segment-routing-header-26, 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", Internet-Draft draft-ietf-spring-srv6-network-programming-09, February 2020. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC8174] | Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017. |
| [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", Internet-Draft draft-filsfils-spring-srv6-net-pgm-illustration-01, August 2019. |