Internet DRAFT - draft-duchene-spring-srv6-socket
draft-duchene-spring-srv6-socket
SPRING Working Group F. Duchene
Internet-Draft O. Bonaventure
Intended status: Informational UCLouvain
Expires: September 6, 2018 March 05, 2018
A socket API to control IPv6 Segment Routing
draft-duchene-spring-srv6-socket-00
Abstract
This document proposes a socket API to allow applications to control
the utilisation of IPv6 Segment Routing (SRv6).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 6, 2018.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. SRv6 Socket API . . . . . . . . . . . . . . . . . . . . . . . 2
2.1. Inserting an Segment Routing Header . . . . . . . . . . . 2
3. IANA considerations . . . . . . . . . . . . . . . . . . . . . 5
4. Security considerations . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Segment Routing [I-D.ietf-spring-segment-routing] was initially
defined as a technique to enable network operators to better control
the flow of packets inside their network. Most use cases
[I-D.ietf-spring-ipv6-use-cases]
[I-D.ietf-spring-resiliency-use-cases]
[I-D.filsfils-spring-srv6-network-programming]
[I-D.ietf-spring-oam-usecase] leverage Segment Routing on routers
only. In contrast with the MPLS data plane that is traditionally
only supported on routers, the IPv6 Segment Routing Header
[I-D.ietf-6man-segment-routing-header] is supported on both routers
[SR6Demo] and on endhosts [SR6Linux]. The ability of setting and
processing the IPv6 Segment Routing Header on endhosts opens new
"end-to-end" use cases for Segment Routing. We can envision networks
where clients set the IPv6 Segment Routing Header in all the packets
they send to reach a given server along a specific path that depends
on the client's or the network policies.
In this document, we propose a socket option that enables
applications to use the IPv6 Segment Routing Header on a per UDP
datagram basis or a per TCP connection basis.
2. SRv6 Socket API
From an application viewpoint, the interaction with the underlying
stack is performed using a socket option. The socket option is set
by using "setsockopt()".
2.1. Inserting an Segment Routing Header
A SRv6 routing header [I-D.ietf-6man-segment-routing-header] can be
attached to a socket by calling "setsockopt()" with the option
"IPV6_RTHDR". The structure of a SRH is presented in figure
Figure 1.
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struct ipv6_sr_hdr {
uint8_t nexthdr;
uint8_t hdrlen;
uint8_t type;
uint8_t segments_left;
uint8_t first_segment;
uint8_t flags;
uint16_t reserved;
struct in6_addr segments[0];
};
Figure 1: The SRv6 routing header structure
Once the SRH has been attached to the socket, the packets will use
the path described in the segments list of the SRH. An example using
a TCP connection from 2001:DB8:1111::1 to 2001:DB8:3333::1 and
passing through 2001:DB8:2222::1 is shown in figure Figure 2.
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int fd, err, srh_len, n;
struct ipv6_sr_hdr *srh;
struct sockaddr_in6 sin6, sin6_bind;
srh_len = sizeof(*srh) + 2 * sizeof(struct in6_addr);
srh = malloc(srh_len);
srh->nexthdr = 0;
srh->hdrlen = 4;
srh->type = 4;
srh->segments_left = 1;
srh->first_segment = 1;
srh->flags = 0;
srh->reserved = 0;
/* Space for the destination segment */
memset(&srh->segments[0], 0, sizeof(struct in6_addr));
/* Adding the segment 2001:DB8:2222::1 to the segments list of
the SRH */
inet_pton(AF_INET6, "2001:DB8:2222::1", &srh->segments[1]);
fd = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);
err = setsockopt(fd, IPPROTO_IPV6, IPV6_RTHDR, srh, srh_len);
memset(&sin6_bind, 0, sizeof(sin6_bind));
sin6_bind.sin6_family = AF_INET6;
inet_pton(AF_INET6, "2001:DB8:1111::1", &sin6_bind.sin6_addr);
err = bind(fd, (struct sockaddr *)&sin6_bind, sizeof(sin6_bind));
memset(&sin6, 0, sizeof(sin6));
sin6.sin6_family = AF_INET6;
sin6.sin6_port = htons(1234);
inet_pton(AF_INET6, "2001:DB8:3333::1", &sin6.sin6_addr);
err = connect(fd, (struct sockaddr *)&sin6, sizeof(sin6));
Figure 2: Sample code to establish a TCP connection
While figure Figure 2 shows a TCP connection, the same socket option
can be applied to UDP sockets.
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3. IANA considerations
There are no IANA considerations in this document.
4. Security considerations
There are no security considerations in this document.
5. Acknowledgements
The initial implementation of the socket option was written by David
Lebrun [LEBRUN17]
6. References
6.1. Normative References
[I-D.ietf-6man-segment-routing-header]
Previdi, S., Filsfils, C., Raza, K., Dukes, D., Leddy, J.,
Field, B., daniel.voyer@bell.ca, d.,
daniel.bernier@bell.ca, d., Matsushima, S., Leung, I.,
Linkova, J., Aries, E., Kosugi, T., Vyncke, E., Lebrun,
D., Steinberg, D., and R. Raszuk, "IPv6 Segment Routing
Header (SRH)", draft-ietf-6man-segment-routing-header-08
(work in progress), January 2018.
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing
Architecture", draft-ietf-spring-segment-routing-15 (work
in progress), January 2018.
[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>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, <https://www.rfc-
editor.org/info/rfc8200>.
6.2. Informative References
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[I-D.filsfils-spring-srv6-network-programming]
Filsfils, C., Li, Z., Leddy, J., daniel.voyer@bell.ca, d.,
daniel.bernier@bell.ca, d., Steinberg, D., Raszuk, R.,
Matsushima, S., Lebrun, D., Decraene, B., Peirens, B.,
Salsano, S., Naik, G., Elmalky, H., Jonnalagadda, P., and
M. Sharif, "SRv6 Network Programming", draft-filsfils-
spring-srv6-network-programming-04 (work in progress),
March 2018.
[I-D.ietf-spring-ipv6-use-cases]
Brzozowski, J., Leddy, J., Filsfils, C., Maglione, R., and
M. Townsley, "IPv6 SPRING Use Cases", draft-ietf-spring-
ipv6-use-cases-12 (work in progress), December 2017.
[I-D.ietf-spring-oam-usecase]
Geib, R., Filsfils, C., Pignataro, C., and N. Kumar, "A
Scalable and Topology-Aware MPLS Dataplane Monitoring
System", draft-ietf-spring-oam-usecase-10 (work in
progress), December 2017.
[I-D.ietf-spring-resiliency-use-cases]
Filsfils, C., Previdi, S., Decraene, B., and R. Shakir,
"Resiliency use cases in SPRING networks", draft-ietf-
spring-resiliency-use-cases-12 (work in progress),
December 2017.
[LEBRUN17]
Lebrun, D., "Reaping the Benefits of IPv6 Segment
Routing", 2017, <https://inl.info.ucl.ac.be/system/files/
phdthesis-lebrun.pdf>.
[SR6Demo] Filsfils, C., Clad, F., Camarillo, P., Liste, J.,
Jonnalagadda, P., Sharif, M., Salsano, S., and A.
AbdelSalam, "IPv6 Segment Routing", SIGCOMM'17, Industrial
demo , August 2017.
[SR6Linux]
Lebrun, D. and O. Bonaventure, "Implementing IPv6 Segment
Routing in the Linux Kernel.", Applied Networking Research
Workshop 2017 , July 2017,
<http://www.segment-routing.org>.
Authors' Addresses
Fabien Duchene
UCLouvain
Email: Fabien.Duchene@uclouvain.be
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Olivier Bonaventure
UCLouvain
Email: Olivier.Bonaventure@uclouvain.be
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