draft-ietf-6man-resilient-rs-00.txt   draft-ietf-6man-resilient-rs-01.txt 
6man Working Group S. Krishnan 6man Working Group S. Krishnan
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track D. Anipko Intended status: Standards Track D. Anipko
Expires: May 9, 2013 D. Thaler Expires: November 7, 2013 D. Thaler
Microsoft Microsoft
November 5, 2012 May 6, 2013
Packet loss resiliency for Router Solicitations Packet loss resiliency for Router Solicitations
draft-ietf-6man-resilient-rs-00 draft-ietf-6man-resilient-rs-01
Abstract Abstract
When an interface on a host is initialized, the host transmits Router When an interface on a host is initialized, the host transmits Router
Solicitations in order to minimize the amount of time it needs to Solicitations in order to minimize the amount of time it needs to
wait until the next unsolicited multicast Router Advertisement is wait until the next unsolicited multicast Router Advertisement is
received. In certain scenarios, these router solicitations received. In certain scenarios, these router solicitations
transmitted by the host might be lost. This document specifies a transmitted by the host might be lost. This document specifies a
mechanism for hosts to cope with the loss of the initial Router mechanism for hosts to cope with the loss of the initial Router
Solicitations. Furthermore, on some links, unsolicited multicast Solicitations. Furthermore, on some links, unsolicited multicast
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on May 9, 2013. This Internet-Draft will expire on November 7, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions used in this document . . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . . 3
2. Proposed algorithm . . . . . . . . . . . . . . . . . . . . . . 4 2. Proposed algorithm . . . . . . . . . . . . . . . . . . . . . . 4
3. Open Issue . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Stopping the retransmissions . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 3. Configuring the use of retransmissions . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 4. Known Limitations . . . . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
As specified in [RFC4861], when an interface on a host is As specified in [RFC4861], when an interface on a host is
initialized, in order to obtain Router Advertisements quickly, a host initialized, in order to obtain Router Advertisements quickly, a host
transmits up to MAX_RTR_SOLICITATIONS (3) Router Solicitation transmits up to MAX_RTR_SOLICITATIONS (3) Router Solicitation
messages, each separated by at least RTR_SOLICITATION_INTERVAL (4) messages, each separated by at least RTR_SOLICITATION_INTERVAL (4)
seconds. In certain scenarios, these router solicitations seconds. In certain scenarios, these router solicitations
transmitted by the host might be lost. transmitted by the host might be lost.
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The initial value IRT was chosen to be in line with the current The initial value IRT was chosen to be in line with the current
retransmission interval (RTR_SOLICITATION_INTERVAL) that is specified retransmission interval (RTR_SOLICITATION_INTERVAL) that is specified
by [RFC4861] and the maximum retransmission time MRT was chosen to be by [RFC4861] and the maximum retransmission time MRT was chosen to be
in line with the new value of SOL_MAX_RT as specified by [SOLMAXRT]. in line with the new value of SOL_MAX_RT as specified by [SOLMAXRT].
This is to ensure that the short term behavior of the RSs is similar This is to ensure that the short term behavior of the RSs is similar
to what is experienced in current networks, and longer term to what is experienced in current networks, and longer term
persistent retransmission behavior trends towards being similar to persistent retransmission behavior trends towards being similar to
that of DHCPv6 [RFC3315] [SOLMAXRT]. that of DHCPv6 [RFC3315] [SOLMAXRT].
3. Open Issue 2.1. Stopping the retransmissions
On multicast-capable links, the hosts following this specification
MUST stop retransmitting the RSs when an RA that results in a default
route is received. If an RA is recieved from a router and it does
not result in a default route the host MUST continue retransmitting
the RSs.
On non-multicast links, the hosts following this specification MUST
continue retransmitting the RSs even after an RA that results in a
default route is received. This is required because, in such links,
sending an RA can only be triggered by an RS.
3. Configuring the use of retransmissions
Implementations of this specification MAY provide a configuration
option to enable or disable the use of such potentially infinite
retransmissions. If the implementation provides such a configuration
option, it MUST be able to enable/disable retransmissions on a per-
interface basis.
4. Known Limitations
When an IPv6-capable host attaches to a network that does not have When an IPv6-capable host attaches to a network that does not have
IPv6 enabled, it transmits 3 (MAX_RTR_SOLICITATIONS) Router IPv6 enabled, it transmits 3 (MAX_RTR_SOLICITATIONS) Router
Solicitations as specified in [RFC4861]. If it receives no Router Solicitations as specified in [RFC4861]. If it receives no Router
Advertisements, it assumes that there are no routers present on the Advertisements, it assumes that there are no routers present on the
link and it ceases to send further RSs. With the mechanism specified link and it ceases to send further RSs. With the mechanism specified
in this document, the host will continue to retransmit RSs in this document, the host will continue to retransmit RSs
indefinitely at the rate of approximately 1 RS per hour. It is indefinitely at the rate of approximately 1 RS per hour. It is
unclear how to differentiate between such a network with no IPv6 unclear how to differentiate between such a network with no IPv6
routers and a link where an IPv6 router is temporarily unreachable routers and a link where an IPv6 router is temporarily unreachable
but could become reachable in the future. but could become reachable in the future.
4. IANA Considerations 5. IANA Considerations
This document does not require any IANA actions. This document does not require any IANA actions.
5. Security Considerations 6. Security Considerations
This document does not present any additional security issues beyond This document does not present any additional security issues beyond
those discussed in [RFC4861]. those discussed in [RFC4861].
6. Acknowledgements 7. Acknowledgements
The author would like to thank Steve Baillargeon, and Erik Kline for The author would like to thank Steve Baillargeon, and Erik Kline for
their reviews and suggestions that made this document better. their reviews and suggestions that made this document better.
7. References 8. References
7.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007. September 2007.
[SOLMAXRT] [SOLMAXRT]
Droms, R., "Modification to Default Value of SOL_MAX_RT", Droms, R., "Modification to Default Value of SOL_MAX_RT",
draft-droms-dhc-dhcpv6-solmaxrt-update-02 (work in draft-droms-dhc-dhcpv6-solmaxrt-update-02 (work in
progress), January 2012. progress), January 2012.
7.2. Informative References 8.2. Informative References
[RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site
Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214,
March 2008. March 2008.
Authors' Addresses Authors' Addresses
Suresh Krishnan Suresh Krishnan
Ericsson Ericsson
8400 Decarie Blvd. 8400 Decarie Blvd.
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