draft-ietf-mboned-driad-amt-discovery-04.txt   draft-ietf-mboned-driad-amt-discovery-05.txt 
Mboned J. Holland Mboned J. Holland
Internet-Draft Akamai Technologies, Inc. Internet-Draft Akamai Technologies, Inc.
Updates: 7450 (if approved) April 22, 2019 Updates: 7450 (if approved) April 25, 2019
Intended status: Standards Track Intended status: Standards Track
Expires: October 24, 2019 Expires: October 27, 2019
DNS Reverse IP AMT Discovery DNS Reverse IP AMT Discovery
draft-ietf-mboned-driad-amt-discovery-04 draft-ietf-mboned-driad-amt-discovery-05
Abstract Abstract
This document updates RFC 7450 (Automatic Multicast Tunneling, or This document updates RFC 7450 (Automatic Multicast Tunneling, or
AMT) by extending the relay discovery process to use a new DNS AMT) by extending the relay discovery process to use a new DNS
resource record named AMTRELAY when discovering AMT relays for resource record named AMTRELAY when discovering AMT relays for
source-specific multicast channels. The reverse IP DNS zone for a source-specific multicast channels. The reverse IP DNS zone for a
multicast sender's IP address is configured to use AMTRELAY resource multicast sender's IP address is configured to use AMTRELAY resource
records to advertise a set of AMT relays that can receive and forward records to advertise a set of AMT relays that can receive and forward
multicast traffic from that sender over an AMT tunnel. multicast traffic from that sender over an AMT tunnel.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 24, 2019. This Internet-Draft will expire on October 27, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Eyeballs algorithm is a useful one, and so this section provides the Eyeballs algorithm is a useful one, and so this section provides the
following normative definition: following normative definition:
o An AMT connection is completed successfully when the gateway o An AMT connection is completed successfully when the gateway
receives from a newly discovered relay a valid Membership Query receives from a newly discovered relay a valid Membership Query
message (Section 5.1.4 of [RFC7450]) that does not have the L flag message (Section 5.1.4 of [RFC7450]) that does not have the L flag
set. set.
See Section 2.5.5 of this document for further information about the See Section 2.5.5 of this document for further information about the
relevance of the L flag to the establishment of a Happy Eyeballs relevance of the L flag to the establishment of a Happy Eyeballs
connection. connection. See Section 2.5.4 for an overview of how to respond if
the connection does not provide multicast connectivity to the source.
2.4. Optimal Relay Selection 2.4. Optimal Relay Selection
2.4.1. Overview 2.4.1. Overview
The reverse source IP DNS query of an AMTRELAY RR is a good way for a The reverse source IP DNS query of an AMTRELAY RR is a good way for a
gateway to discover a relay that is known to the sender. gateway to discover a relay that is known to the sender.
However, it is NOT necessarily a good way to discover the best relay However, it is NOT necessarily a good way to discover the best relay
for that gateway to use, because the RR will only provide information for that gateway to use, because the RR will only provide information
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above, a Happy Eyeballs algorithm for AMT MUST use the Destination above, a Happy Eyeballs algorithm for AMT MUST use the Destination
Address Selection defined in Section 6 of [RFC6724], as required by Address Selection defined in Section 6 of [RFC6724], as required by
[RFC8305]. [RFC8305].
Among relay addresses that still have an equivalent preference after Among relay addresses that still have an equivalent preference after
the above orderings, a gateway MUST make a non-deterministic choice the above orderings, a gateway MUST make a non-deterministic choice
for relay preference ordering, in order to support load balancing by for relay preference ordering, in order to support load balancing by
DNS configurations that provide many relay options. DNS configurations that provide many relay options.
The gateway MAY introduce a bias in the non-deterministic choice The gateway MAY introduce a bias in the non-deterministic choice
according to network topology or timing information obtained out of according to information obtained out of band or from a historical
band or from a historical record. The collection of this information record about network topology, timing information, or the response to
is out of scope for this document, but a gateway in possession of a probing mechanism, that indicates some expected benefits from
such information MAY use it to prefer topologically closer relays. selecting some relays in preference to others. Details about the
structure and collection of this information is out of scope for this
document, but a gateway in possession of such information MAY use it
to prefer topologically closer relays.
Note also that certain relay addresses may be excluded from Note also that certain relay addresses may be excluded from
consideration by the hold-down timers described in Section 2.5.4.1 or consideration by the hold-down timers described in Section 2.5.4.1 or
Section 2.5.5. These relays constitute "unusable destinations" under Section 2.5.5. These relays constitute "unusable destinations" under
Rule 1 of the Destination Address Selection, and are also not part of Rule 1 of the Destination Address Selection, and are also not part of
the superseding considerations described above. the superseding considerations described above.
The discovery and connection process for the relay addresses in the The discovery and connection process for the relay addresses in the
above described ordering MAY operate in parallel, subject to delays above described ordering MAY operate in parallel, subject to delays
prescribed by the Happy Eyeballs requirements described in Section 5 prescribed by the Happy Eyeballs requirements described in Section 5
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