draft-ietf-mboned-driad-amt-discovery-07.txt		draft-ietf-mboned-driad-amt-discovery-08.txt
	Mboned J. Holland		Mboned J. Holland
	Internet-Draft Akamai Technologies, Inc.		Internet-Draft Akamai Technologies, Inc.
	Updates: 7450 (if approved) June 13, 2019		Updates: 7450 (if approved) June 14, 2019
	Intended status: Standards Track		Intended status: Standards Track
	Expires: December 15, 2019		Expires: December 16, 2019
	DNS Reverse IP AMT Discovery		DNS Reverse IP AMT Discovery
	draft-ietf-mboned-driad-amt-discovery-07		draft-ietf-mboned-driad-amt-discovery-08
	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.
	skipping to change at page 1, line 37 ¶		skipping to change at page 1, line 37 ¶
	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 December 15, 2019.		This Internet-Draft will expire on December 16, 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
	skipping to change at page 2, line 34 ¶		skipping to change at page 2, line 34 ¶
	2.4.3. Connecting to Multiple Relays . . . . . . . . . . . . 13		2.4.3. Connecting to Multiple Relays . . . . . . . . . . . . 13
	2.5. Guidelines for Restarting Discovery . . . . . . . . . . . 13		2.5. Guidelines for Restarting Discovery . . . . . . . . . . . 13
	2.5.1. Overview . . . . . . . . . . . . . . . . . . . . . . 13		2.5.1. Overview . . . . . . . . . . . . . . . . . . . . . . 13
	2.5.2. Updates to Restarting Events . . . . . . . . . . . . 14		2.5.2. Updates to Restarting Events . . . . . . . . . . . . 14
	2.5.3. Tunnel Stability . . . . . . . . . . . . . . . . . . 15		2.5.3. Tunnel Stability . . . . . . . . . . . . . . . . . . 15
	2.5.4. Traffic Health . . . . . . . . . . . . . . . . . . . 15		2.5.4. Traffic Health . . . . . . . . . . . . . . . . . . . 15
	2.5.5. Relay Loaded or Shutting Down . . . . . . . . . . . . 17		2.5.5. Relay Loaded or Shutting Down . . . . . . . . . . . . 17
	2.5.6. Relay Discovery Messages vs. Restarting Discovery . . 17		2.5.6. Relay Discovery Messages vs. Restarting Discovery . . 17
	2.5.7. Independent Discovery Per Traffic Source . . . . . . 18		2.5.7. Independent Discovery Per Traffic Source . . . . . . 18
	2.6. DNS Configuration . . . . . . . . . . . . . . . . . . . . 18		2.6. DNS Configuration . . . . . . . . . . . . . . . . . . . . 18
	2.7. Waiting for DNS resolution . . . . . . . . . . . . . . . 19		2.7. Waiting for DNS resolution . . . . . . . . . . . . . . . 18
	3. Example Deployments . . . . . . . . . . . . . . . . . . . . . 19		3. Example Deployments . . . . . . . . . . . . . . . . . . . . . 19
	3.1. Example Receiving Networks . . . . . . . . . . . . . . . 19		3.1. Example Receiving Networks . . . . . . . . . . . . . . . 19
	3.1.1. Tier 3 ISP . . . . . . . . . . . . . . . . . . . . . 19		3.1.1. Tier 3 ISP . . . . . . . . . . . . . . . . . . . . . 19
	3.1.2. Small Office . . . . . . . . . . . . . . . . . . . . 20		3.1.2. Small Office . . . . . . . . . . . . . . . . . . . . 20
	3.2. Example Sending Networks . . . . . . . . . . . . . . . . 22		3.2. Example Sending Networks . . . . . . . . . . . . . . . . 22
	3.2.1. Sender-controlled Relays . . . . . . . . . . . . . . 22		3.2.1. Sender-controlled Relays . . . . . . . . . . . . . . 22
	3.2.2. Provider-controlled Relays . . . . . . . . . . . . . 23		3.2.2. Provider-controlled Relays . . . . . . . . . . . . . 23
	4. AMTRELAY Resource Record Definition . . . . . . . . . . . . . 24		4. AMTRELAY Resource Record Definition . . . . . . . . . . . . . 24
	4.1. AMTRELAY RRType . . . . . . . . . . . . . . . . . . . . . 24		4.1. AMTRELAY RRType . . . . . . . . . . . . . . . . . . . . . 24
	4.2. AMTRELAY RData Format . . . . . . . . . . . . . . . . . . 24		4.2. AMTRELAY RData Format . . . . . . . . . . . . . . . . . . 24
	skipping to change at page 12, line 46 ¶		skipping to change at page 12, line 46 ¶
	The gateway MAY introduce a bias in the non-deterministic choice		The gateway MAY introduce a bias in the non-deterministic choice
	according to information obtained out of band or from a historical		according to information obtained out of band or from a historical
	record about network topology, timing information, or the response to		record about network topology, timing information, or the response to
	a probing mechanism, that indicates some expected benefits from		a probing mechanism, that indicates some expected benefits from
	selecting some relays in preference to others. Details about the		selecting some relays in preference to others. Details about the
	structure and collection of this information are out of scope for		structure and collection of this information are out of scope for
	this document, but a gateway in possession of such information MAY		this document, but a gateway in possession of such information MAY
	use it to prefer topologically closer relays.		use it to prefer topologically closer relays.
	Note also that certain relay addresses may be excluded from		Note also that certain relay addresses might 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
	of [RFC8305] for successively launched concurrent connection		of [RFC8305] for successively launched concurrent connection
	attempts.		attempts.
	skipping to change at page 17, line 26 ¶		skipping to change at page 17, line 26 ¶
	NOT be considered for the relay selection.		NOT be considered for the relay selection.
	It is also RECOMMENDED that gateways avoid choosing a relay that has		It is also RECOMMENDED that gateways avoid choosing a relay that has
	recently sent an L flag, with approximately a 10-minute hold-down.		recently sent an L flag, with approximately a 10-minute hold-down.
	Gateways SHOULD treat this hold-down timer in the same way as the		Gateways SHOULD treat this hold-down timer in the same way as the
	hold-down in Section 2.5.4.1, so that the relay is removed from		hold-down in Section 2.5.4.1, so that the relay is removed from
	consideration for short-term subsequent rounds of discovery.		consideration for short-term subsequent rounds of discovery.
	2.5.6. Relay Discovery Messages vs. Restarting Discovery		2.5.6. Relay Discovery Messages vs. Restarting Discovery
	A gateway should only send DNS queries with the AMTRELAY RRType or		All AMT relays are required by [RFC7450] to support handling of Relay
	the DNS-SD DNS queries for an AMT service as part of starting or
	restarting the discovery process.
	However, all AMT relays are required to support handling of Relay
	Discovery messages (e.g. in Section 5.3.3.2 of [RFC7450]).		Discovery messages (e.g. in Section 5.3.3.2 of [RFC7450]).
	So a gateway with an existing connection to a relay can send a Relay		So a gateway with an existing connection to a relay can send a Relay
	Discovery message to the unicast address of that AMT relay. Under		Discovery message to the unicast address of that AMT relay. Under
	stable conditions with an unloaded relay, it's expected that the		stable conditions with an unloaded relay, it's expected that the
	relay will return its own unicast address in the Relay Advertisement,		relay will return its own unicast address in the Relay Advertisement,
	in response to such a Relay Discovery message. Since this will not		in response to such a Relay Discovery message. Since this will not
	result in the gateway changing to another relay unless the relay		result in the gateway changing to another relay unless the relay
	directs the gateway away, this is a reasonable exception to the		directs the gateway away, this is a reasonable exception to the
	advice against handling event #3 described in Section 2.5.3.		advice against handling event #3 described in Section 2.5.3.
	skipping to change at page 18, line 8 ¶		skipping to change at page 18, line 4 ¶
	messages regularly. When a relay is under load or has started a		messages regularly. When a relay is under load or has started a
	graceful shutdown, it may respond with a different relay address,		graceful shutdown, it may respond with a different relay address,
	which the gateway can use to connect to a different relay. This kind		which the gateway can use to connect to a different relay. This kind
	of coordinated handoff will likely result in a smaller disruption to		of coordinated handoff will likely result in a smaller disruption to
	the traffic than if the relay simply stops responding to Request		the traffic than if the relay simply stops responding to Request
	messages, and stops forwarding traffic.		messages, and stops forwarding traffic.
	This style of Relay Discovery message (one sent to the unicast		This style of Relay Discovery message (one sent to the unicast
	address of a relay that's already forwarding traffic to this gateway)		address of a relay that's already forwarding traffic to this gateway)
	SHOULD NOT be considered a full restart of the relay discovery		SHOULD NOT be considered a full restart of the relay discovery
	process. It is recommended for gateways to support the L flag, but		process. It is RECOMMENDED for gateways to support the L flag, but
	for gateways that do not support the L flag, sending this message		for gateways that do not support the L flag, sending this message
	during event #3 may help mitigate service degradation when relays		during event #3 may help mitigate service degradation when relays
	become unstable.		become unstable.
	2.5.7. Independent Discovery Per Traffic Source		2.5.7. Independent Discovery Per Traffic Source
	Relays discovered via the AMTRELAY RR are source-specific relay		Relays discovered via the AMTRELAY RR are source-specific relay
	addresses, and may use different pseudo-interfaces from each other		addresses, and may use different pseudo-interfaces from each other
	and from relays discovered via DNS-SD or a non-source-specific		and from relays discovered via DNS-SD or a non-source-specific
	address, as described in Section 4.1.2.1 of [RFC7450].		address, as described in Section 4.1.2.1 of [RFC7450].
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