SAM Research Group J. Buford
Internet-Draft Avaya Labs Research
Intended status: Informational M. Kolberg, Ed.
Expires: May 17, 2013 University of Stirling
November 13, 2012
Application Layer Multicast Extensions to RELOAD
draft-irtf-samrg-sam-baseline-protocol-01
Abstract
We define a RELOAD Usage for Application Layer Multicast as well as a
mapping to the RELOAD experimental message type to support ALM. The
ALM Usage is intended to support a variety of ALM control algorithms
in an overlay-independent way. Two example algorithms are defined,
based on Scribe and P2PCast.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Overlay Network . . . . . . . . . . . . . . . . . . . . . 5
2.2. Overlay Multicast . . . . . . . . . . . . . . . . . . . . 5
2.3. Peer . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Overlay . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Overlay Multicast . . . . . . . . . . . . . . . . . . . . 6
3.3. RELOAD . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.4. NAT . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.5. Tree Topology . . . . . . . . . . . . . . . . . . . . . . 7
4. Architecture Extensions to RELOAD . . . . . . . . . . . . . . 7
5. RELOAD ALM Usage . . . . . . . . . . . . . . . . . . . . . . . 9
6. ALM Tree Control Signaling . . . . . . . . . . . . . . . . . . 9
7. ALM Messages Mapped to RELOAD . . . . . . . . . . . . . . . . 11
7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 11
7.2. Tree Lifecycle Messages . . . . . . . . . . . . . . . . . 12
7.2.1. Create Tree . . . . . . . . . . . . . . . . . . . . . 12
7.2.2. CreateTreeResponse . . . . . . . . . . . . . . . . . . 13
7.2.3. Join . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.2.4. Join Accept (Join Response) . . . . . . . . . . . . . 14
7.2.5. Join Reject (Join Response) . . . . . . . . . . . . . 15
7.2.6. Join Confirm . . . . . . . . . . . . . . . . . . . . . 15
7.2.7. Join Confirm Response . . . . . . . . . . . . . . . . 16
7.2.8. Join Decline . . . . . . . . . . . . . . . . . . . . . 16
7.2.9. Join Decline Response . . . . . . . . . . . . . . . . 16
7.2.10. Leave . . . . . . . . . . . . . . . . . . . . . . . . 16
7.2.11. Leave Response . . . . . . . . . . . . . . . . . . . . 17
7.2.12. Re-Form or Optimize Tree . . . . . . . . . . . . . . . 17
7.2.13. Reform Response . . . . . . . . . . . . . . . . . . . 17
7.2.14. Heartbeat . . . . . . . . . . . . . . . . . . . . . . 17
7.2.15. Heartbeat Response . . . . . . . . . . . . . . . . . . 18
7.2.16. NodeQuery . . . . . . . . . . . . . . . . . . . . . . 18
7.2.17. NodeQuery Response . . . . . . . . . . . . . . . . . . 18
7.2.18. Push . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.2.19. PushResponse . . . . . . . . . . . . . . . . . . . . . 21
8. Scribe Algorithm . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.2. Create . . . . . . . . . . . . . . . . . . . . . . . . . . 22
8.3. Join . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8.4. Leave . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8.5. JoinConfirm . . . . . . . . . . . . . . . . . . . . . . . 23
8.6. JoinDecline . . . . . . . . . . . . . . . . . . . . . . . 24
8.7. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 24
9. P2PCast Algorithm . . . . . . . . . . . . . . . . . . . . . . 24
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9.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 24
9.2. Create . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.3. Join . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.4. Leave . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9.5. JoinConfirm . . . . . . . . . . . . . . . . . . . . . . . 26
9.6. JoinDecline . . . . . . . . . . . . . . . . . . . . . . . 26
9.7. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 27
10. ALMTree Kind . . . . . . . . . . . . . . . . . . . . . . . . . 27
11. Message Codes . . . . . . . . . . . . . . . . . . . . . . . . 27
11.1. ALMHeader Definition . . . . . . . . . . . . . . . . . . . 29
11.2. ALMMessageContents Definition . . . . . . . . . . . . . . 29
11.3. Response Codes . . . . . . . . . . . . . . . . . . . . . . 30
11.4. Algorithm Codes . . . . . . . . . . . . . . . . . . . . . 31
12. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
12.1. Create Tree . . . . . . . . . . . . . . . . . . . . . . . 31
12.2. Join Tree . . . . . . . . . . . . . . . . . . . . . . . . 32
12.3. Leave Tree . . . . . . . . . . . . . . . . . . . . . . . . 34
12.4. Push Data . . . . . . . . . . . . . . . . . . . . . . . . 34
13. Kind Definitions . . . . . . . . . . . . . . . . . . . . . . . 35
13.1. ALMTree Kind Definition . . . . . . . . . . . . . . . . . 35
14. Configuration File Extensions . . . . . . . . . . . . . . . . 36
15. Change History . . . . . . . . . . . . . . . . . . . . . . . . 36
16. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 36
17. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36
18. Security Considerations . . . . . . . . . . . . . . . . . . . 36
19. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 37
20. References . . . . . . . . . . . . . . . . . . . . . . . . . . 37
20.1. Normative References . . . . . . . . . . . . . . . . . . . 37
20.2. Informative References . . . . . . . . . . . . . . . . . . 37
Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . 39
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39
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1. Introduction
The concept of scalable adaptive multicast includes both scaling
properties and adaptability properties. Scalability is intended to
cover:
o large group size
o large numbers of small groups
o rate of group membership change
o admission control for QoS
o use with network layer QoS mechanisms
o varying degrees of reliability
o trees connect nodes over global internet
Adaptability includes
o use of different control mechanisms for different multicast trees
depending on initial application parameters or application class
o changing multicast tree structure depending on changes in
application requirements, network conditions, and membership
Application Layer Multicast (ALM) has been demonstrated to be a
viable multicast technology where native multicast isn't available.
Many ALM designs have been proposed. This ALM Usage focuses on:
o ALM implemented in RELOAD-based overlays
o Support for a variety of ALM control algorithms
o Providing a basis for defining a separate hybrid-ALM RELOAD Usage
RELOAD [I-D.ietf-p2psip-base] has an application extension mechanism
in which a new type of application defines a Usage. A RELOAD Usage
defines a set of data types and rules for their use. In addition,
this document describes additional message types and a new ALM
algorithm plugin architectural component.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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document are to be interpreted as described in RFC 2119 [RFC2119].
2. Definitions
We adopt the terminology defined in section 2 of
[I-D.ietf-p2psip-base], specifically the distinction between Node,
Peer, and Client.
2.1. Overlay Network
P P P P P
..+....+....+...+.....+...
. +P
P+ .
. +P
..+....+....+...+.....+...
P P P P P
Figure 1
Overlay network - An application layer virtual or logical network in
which end points are addressable and that provides connectivity,
routing, and messaging between end points. Overlay networks are
frequently used as a substrate for deploying new network services, or
for providing a routing topology not available from the underlying
physical network. Many peer-to-peer systems are overlay networks
that run on top of the Internet. In the above figure, "P" indicates
overlay peers, and peers are connected in a logical address space.
The links shown in the figure represent predecessor/successor links.
Depending on the overlay routing model, additional or different links
may be present.
2.2. Overlay Multicast
Overlay Multicast (OM): Hosts participating in a multicast session
form an overlay network and utilize unicast connections among pairs
of hosts for data dissemination. The hosts in overlay multicast
exclusively handle group management, routing, and tree construction,
without any support from Internet routers. This is also commonly
known as Application Layer Multicast (ALM) or End System Multicast
(ESM). We call systems which use proxies connected in an overlay
multicast backbone "proxied overlay multicast" or POM.
2.3. Peer
Peer: an autonomous end system that is connected to the physical
network and participates in and contributes resources to overlay
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construction, routing and maintenance. Some peers may also perform
additional roles such as connection relays, super nodes, NAT
traversal, and data storage.
3. Assumptions
3.1. Overlay
Peers connect in a large-scale overlay, which may be used for a
variety of peer-to-peer applications in addition to multicast
sessions. Peers may assume additional roles in the overlay beyond
participation in the overlay and in multicast trees. We assume a
single structured overlay routing algorithm is used. Any of a
variety of multi-hop, one-hop, or variable-hop overlay algorithms
could be used.
Castro et al. [CASTRO2003]compared multi-hop overlays and found that
tree-based construction in a single overlay out-performed using
separate overlays for each multicast session. We use a single
overlay rather than separate overlays per multicast sessions.
An overlay multicast algorithm may leverage the overlay's mechanism
for maintaining overlay state in the face of churn. For example, a
peer may store a number of DHT (Distributed Hash Table) entries.
When the peer gracefully leaves the overlay, it transfers those
entries to the nearest peer. When another peer joins which is closer
to some of the entries than the current peer which holds those
entries, than those entries are migrated. Overlay churn affects
multicast trees as well; remedies include automatic migration of the
tree state and automatic re-join operations for dislocated children
nodes.
3.2. Overlay Multicast
The overlay supports concurrent multiple multicast trees. The limit
on number of concurrent trees depends on peer and network resources
and is not an intrinsic property of the overlay.
3.3. RELOAD
We use RELOAD [I-D.ietf-p2psip-base] as the distibuted hash table
(DHT) for data storage and overlay by which the peers interconnect
and route messages. RELOAD is a generic P2P overlay, and application
support is defined by profiles called Usages.
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3.4. NAT
Some nodes in the overlay may be in a private address space and
behind firewalls. We use the RELOAD mechanisms for NAT traversal.
We permit clients to be leaf nodes in an ALM tree.
3.5. Tree Topology
All tree control messages are routed in the overlay. Two types of
data or media topologies are envisioned: 1) tree edges are paths in
the overlay, 2) tree edges are direct connections between a parent
and child peer in the tree, formed using the RELOAD AppAttach method.
4. Architecture Extensions to RELOAD
There are two changes, shown in the figure below. New ALM messages
are mapped to RELOAD Message Transport using the RELOAD experimental
message type. A plug-in for ALM algorithms handles the ALM state and
control. The ALM Algorithm is under control of the application via
the Group API [I-D.irtf-samrg-common-api].
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+---------+
|Group API|
+---------+
|
------------------- Application ------------------------
+-------+ |
| ALM | |
| Usage | |
+-------+ |
-------------- Messaging Service Boundary --------------
|
+--------+ +-----------+---------+ +---------+
| Storage|<---> | RELOAD | ALM |<-->| ALM Alg |
+--------+ | Message | Messages| +---------+
^ | Transport | |
| +-----------+---------+
v | |
+-------------+ |
| Topology | |
| Plugin | |
+-------------+ |
^ |
v v
+-------------------+
| Forwarding& |
| Link Management |
+-------------------+
---------- Overlay Link Service Boundary --------------
Figure 2
The ALM components interact with RELOAD as follows:
o ALM uses the RELOAD data storage functionality to store a ALMTree
instance when a new ALM tree is created in the overlay, and to
retrieve ALMTree instance(s) for existing ALM trees.
o ALM applications and management tools may use the RELOAD data
storage functionality to store diagnostic information about the
operation of tree, including average number of tree, delay from
source to leaf nodes, bandwidth use, lost packet rate. In
addition, diagnostic information may include statistics specific
to the tree root, or to any node in the tree.
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5. RELOAD ALM Usage
Applications of RELOAD are restricted in the data types that can be
stored in the DHT. The profile of accepted data types for an
application is referred to as a Usage. RELOAD is designed so that
new applications can easily define new Usages. New RELOAD Usages are
needed for multicast applications since the data types in base RELOAD
and existing usages are not sufficient.
We define an ALM Usage in RELOAD. This ALM Usage is sufficient for
applications which require ALM functionality in the overlay. The
figure above shows the internal structure of the ALM Usage. This
contains the Group API ([I-D.irtf-samrg-common-api]) an ALM algorithm
plugin (e.g. Scribe) and the ALM messages which are then sent out to
the RELOAD network.
A RELOAD Usage is required [I-D.ietf-p2psip-base] to define the
following:
o Register Kind-Id points
o Define data structures for each kind
o Defines access control rules for each kind
o Defines the Resource Name used to hash to the Resource ID where
the kind is stored
o Addresses restoration of values after recovery from a network
partition
o Defines the types of connections that can be initiated using
AppConnect
A ALM GroupID is a RELOAD Node-ID. The owner of a ALM group creates
a RELOAD Node-ID as specified in [I-D.ietf-p2psip-base]. This means
that a GroupID is used as a RELOAD Destination for overlay routing
purposes.
6. ALM Tree Control Signaling
Peers use the overlay to support ALM operations such as:
o Create tree
o Join
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o Leave
o Re-Form or optimize tree
There are a variety of algorithms for peers to form multicast trees
in the overlay. We permit multiple such algorithms to be supported
in the overlay, since different algorithms may be more suitable for
certain application requirements, and since we wish to support
experimentation. Therefore, overlay messaging corresponding to the
set of overlay multicast operations must carry algorithm
identification information.
For example, for small groups, the join point might be directly
assigned by the rendezvous point, while for large trees the join
request might be propagated down the tree with candidate parents
forwarding their position directly to the new node.
Here is a simplistic algorithm for forming a multicast tree in the
overlay. Its main advantage is use of the overlay routing mechanism
for routing both control and data messages. The group creator
doesn't have to be the root of the tree or even in the tree. It
doesn't consider per node load, admission control, or alternative
paths.
As stated earlier, multiple algorithms will co-exist in the overlay.
1. Peer which initiates multicast group:
groupID = create(); // allocate a unique groupId
// the root is the nearest
// peer in the overlay
// out of band advertisement or
// distribution of groupID,
// perhaps by publishing in DHT
Figure 3
2. Any joining peer:
// out of band discovery of groupID, perhaps by lookup in DHT
joinTree(groupID); // sends "join groupID" message
Figure 4
The overlay routes the join request using the overlay routing
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mechanism toward the peer with the nearest id to the groupID.
This peer is the root. Peers on the path to the root join the
tree as forwarding points.
3. Leave Tree:
leaveTree(groupID) // removes this node from the tree
Propagates a leave message to each child node and to the parent
node. If the parent node is a forwarding node and this is its
last child, then it propagates a leave message to its parent. A
child node receiving a leave message from a parent sends a join
message to the groupID.
4. Message forwarding:
multicastMsg(groupID, msg);
5. For the message forwarding there are two approaches:
* SSM tree: The creator of the tree is the source. It sends
data messages to the tree root which are forwarded down the
tree.
* ASM tree: A node sending a data message sends the message to
its parent and its children. Each node receiving a data
message from one edge forwards it to remaining tree edges it
is connected to.
7. ALM Messages Mapped to RELOAD
7.1. Introduction
In this document we define messages for overlay multicast tree
creation, using an existing protocol (RELOAD) in the P2P-SIP WG
[I-D.ietf-p2psip-base] for a universal structured peer-to-peer
overlay protocol. RELOAD provides the mechanism to support a number
of overlay topologies. Hence the overlay multicast framework
[I-D.irtf-sam-hybrid-overlay-framework] (hereafter SAM framework) can
be used with P2P-SIP, and that the SAM framework is overlay agnostic.
As discussed in the SAM requirements draft, there are a variety of
ALM tree formation and tree maintenance algorithms. The intent of
this specification is to be algorithm agnostic, similar to how RELOAD
is overlay algorithm agnostic. We assume that all control messages
are propagated using overlay routed messages.
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The message types needed for ALM behavior are divided into the
following categories:
o Tree life-cycle (create, join, leave, re-form, heartbeat)
o Peer region and multicast properties
The message codes are defined in Section 11 of this documents.
Messages are mapped to the RELOAD experimental message type.
In the following descriptions we use two datatypes: DictionaryElement
and Dictionary. Definitions of these two types are as follows:
struct {
opaque name<0..2^16-1>;
opaque value<0..2^16-1>;
} DictionaryElement;
struct {
DictionaryElement elements<0..2^16-1>;
} Dictionary;
7.2. Tree Lifecycle Messages
Peers use the overlay to transmit ALM (application layer multicast)
operations defined in this section.
7.2.1. Create Tree
A new ALM tree is created in the overlay with the identity specified
by group_id. The usual interpretation in a DHT based overlay of
group_id is that the peer with peer id closest to and less than the
group_id is the root of the tree. However, other overlay types are
supported. The tree has no children at the time it is created.
The group_id is generated from a well-known session key to be used by
other Peers to address the multicast tree in the overlay. The
generation of the group_id from the session_key MUST be done using
the overlay's id generation mechanism.
A successful Create Tree causes an ALMTree structure to be stored in
the overlay at the node G responsible for node_id equal to the
group_id. This node G performs the RELOAD-defined StoreReq as a side
effect of performing the Create Tree. If the StoreReq fails, the
Create Tree fails. Since node G is the node which receives the
Create Tree, it is both the sender and receiver of the StoreReq to
store the ALMTree structure.
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After a successful Create Tree, peers can use the RELOAD Fetch method
to retrieve the ALMTree struct at address group_id. The ALMTree kind
is defined in Section 10.
struct {
node_id peer_id;
opaque session_key<0..2^32-1>;
node_id group_id;
Dictionary options;
} ALMTree;
peer_id: the overlay address of the peer that creates the multicast
tree.
session_key: a well-known string when hashed using the overlay's id
generation algorithm produces the group_id.
group_id: the overlay address of the root of the tree
options: name-value list of properties to be associated with the
tree, such as the maximum size of the tree, restrictions on peers
joining the tree, latency constraints, preference for distributed or
centralized tree formation and maintenance, heartbeat interval.
Tree creation is subject to access control since it involves a Store
operation. The NODE-MATCH access policy defined in section 7.3.2 of
RELOAD is used.
7.2.2. CreateTreeResponse
After receiving a CreateTree message from node S, the peer sends a
CreateTreeReponse to node S.
struct {
Dictionary options;
} CreateTreeResponse;
options: A node may provide algorithm-dependent parameters about the
created tree to the requesting node.
7.2.3. Join
Causes the distributed algorithm for peer join of a specific ALM
group to be invoked. If successful, the peer_id is notified of one
or more candidate parent peers in one or more JoinAccept messages.
The particular ALM join algorithm is not specified in this protocol.
RELOAD is a client server protocol. Consequently, the messages
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JoinAccept and JoinReject (defined below) are matching responses for
Join. If JoinReject is received, then no further action on this
request is carried out. If JoinAccept is received, then either a
JoinConfirm or a JoinDecline message (see below) is then sent. The
matching response for JoinConfirm is JoinConfirmResponse. The
matching response for JoinDecline is JoinDeclineResponse.
The following list shows the matching request-responses according to
the request-response mechanism defined in RELOAD.
Join -- JoinAccept: Node C sends a Join request to node P. If node
P accepts, it responds with JoinAccept.
Join -- JoinReject: Node C sends a Join request to node P. If node
P does not accept the join request, it responds with JoinReject.
JoinConfirm -- JoinConfirmResponse: If node P sent node C a
JoinAccept, then node C confirms with a JoinConfirm request. Node
P then responds with a JoinConfirmResponse.
JoinDecline -- JoinDeclineResponse: If node P sent node C a
JoinAccept, then node C declines with a JoinDecline request. Node
P then responds with a JoinDeclineResponse
Thus Join, JoinConfirm, and JoinDecline are treated as requests as
defined in RELOAD, are mapped to the RELOAD exp_a_req message, and
are therefore retransmitted until either retry limit is reached or a
matching response received. JoinAccept, JoinReject,
JoinConfirmResponse, and JoinDeclineResponse are treated as message
responses as defined above, and are mapped to the RELOAD exp_a_ans
message.
struct {
node_id peer_id;
node_id group_id;
Dictionary options;
} Join;
peer_id: overlay address of joining/leaving peer
group_id: the overlay address of the root of the tree
options: name-value list of options proposed by joining peer
7.2.4. Join Accept (Join Response)
Tells the requesting joining peer that the indicated peer is
available to act as its parent in the ALM tree specified by group_id,
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with the corresponding options specified. A peer MAY receive more
than one JoinAccept from different candidate parent peers in the
group_id tree. The peer accepts a peer as parent using a JoinConfirm
message. A JoinAccept which receives neither a JoinConfirm or
JoinDecline message MUST expire.
struct {
node_id parent_peer_id;
node_id child_peer_id;
node_id group_id;
Dictionary options;
} JoinAccept;
parent_peer_id: overlay address of a peer which accepts the joining
peer
child_peer_id: overlay address of joining peer
group_id: the overlay address of the root of the tree
options: name-value list of options accepted by parent peer
7.2.5. Join Reject (Join Response)
A peer receiving a Join message responds with a JoinReject response
to indicate the request is rejected.
7.2.6. Join Confirm
A peer receiving a JoinAccept message which it wishes to accept MUST
explicitly accept it before the expiration of the JoinAccept using a
JoinConfirm message. The joining peer MUST include only those
options from the JoinAccept which it also accepts, completing the
negotiation of options between the two peers.
struct {
node_id child_peer_id;
node_id parent_peer_id;
node_id group_id;
Dictionary options;
} JoinConfirm;
child_peer_id: overlay address of joining peer which is a child of
the parent peer
parent_peer_id: overlay address of the peer which is the parent of
the joining peer
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group_id: the overlay address of the root of the tree
options: name-value list of options accepted by both peers
7.2.7. Join Confirm Response
A peer receiving a JoinConfirm message responds with a
JoinConfirmResponse
7.2.8. Join Decline
A peer receiving a JoinAccept message which does not wish to accept
it MAY explicitly decline it using a JoinDecline message.
struct {
node_id peer_id;
node_id parent_peer_id;
node_id group_id;
} JoinDecline;
peer_id: overlay address of joining peer which declines the
JoinAccept
parent_peer_id: overlay address of the peer which issued a JoinAccept
to this peer
group_id: the overlay address of the root of the tree
7.2.9. Join Decline Response
A peer receiving a JoinConfirm message responds with a
JoinDeclineResponse
7.2.10. Leave
A peer which is part of an ALM tree identified by group_id which
intends to detach from either a child or parent peer SHOULD send a
Leave message to the peer it wishes to detach from. A peer receiving
a Leave message from a peer which is neither in its parent or child
lists SHOULD ignore the message.
struct {
node_id peer_id;
node_id group_id;
Dictionary options;
} Leave;
peer_id: overlay address of leaving peer
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group_id: the overlay address of the root of the tree
options: name-value list of options
7.2.11. Leave Response
A peer receiving a Leave message responds with a LeaveResponse
7.2.12. Re-Form or Optimize Tree
This triggers a reorganization of either the entire tree or only a
sub-tree. It MAY include hints to specific peers of recommended
parent or child peers to reconnect to. A peer receiving this message
MAY ignore it, MAY propagate it to other peers in its subtree, and
MAY invoke local algorithms for selecting preferred parent and/or
child peers.
struct {
node_id group_id;
node_id peer_id;
Dictionary options;
} Reform;
group_id: the overlay address of the root of the tree
peer_id: if omitted, then the tree is reorganized starting from the
root, otherwise it is reorganized only at the sub-tree identified by
peer_id.
options: name-value list of options
7.2.13. Reform Response
A peer receiving a Reform message responds with a ReformResponse
struct {
Dictionary options;
} ReformResponse;
options: algorithm dependent information about the results of the
reform operation
7.2.14. Heartbeat
A child node signals to its adjacent parent nodes in the tree that it
is alive. If a parent node does not receive a Heartbeat message
within N heartbeat time intervals, it MUST treat this as an explicit
Leave message from the unresponsive peer. N is configurable.
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struct {
node_id peer_id_1;
node_id peer_id_2;
node_id group_id;
Dictionary options;
} Heartbeat;
peer_id_1: source of heartbeat
peer_id_2: destination of heartbeat
group_id: overlay address of the root of the tree
options: an algorithm may use the heartbeat message to provide state
information to adjacent nodes in the tree
7.2.15. Heartbeat Response
A parent node responds to a Heartbeat message from a child node in a
tree that it has received the Heartbeat message.
7.2.16. NodeQuery
The NodeQuery message is used to obtain information about the state
and performance of the tree on a per node basis. A set of nodes
could be queried to construct a centralized view of the multicast
trees, similar to a web crawler.
struct {
node_id peer_id_1;
node_id peer_id_2;
} NodeQuery;
peer_id_1: source of query
peer_id_2: destination of query
7.2.17. NodeQuery Response
The response to a NodeQuery message contains a NodeStatistics
instance for this node.
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public struct {
uint32 node_lifetime;
uint32 total_number_trees;
uint16 number_algorithms_supported;
uint8 algorithms_supported[32];
TreeData max_tree_data;
uint16 active_number_trees;
TreeData tree_data<0..2^8-1>;
ImplementationInfo imp_info;
} NodeStatistics;
node_lifetime: time the node has been alive in seconds since last
restart
total_number_trees: total number of trees this node has been part
of during the node lifetime
number_algorithms_supported: value between 0..2^16-1 corresponding
to the number of algorithms supported
algorithms_supported: list of algorithms, each byte encoded using
the corresponding algorithm code
max_tree_data: data about tree with largest number of nodes that
this node was part of
active_number_trees: current number of trees that the node is part
of
tree_data: details of each active tree, the number of such is
specified by the number_active_trees.
impl_info: information about the implementation of this usage
public struct {
uint32 tree_id;
uint8 algorithm;
NodeId tree_root;
uint8 number_parents;
NodeId parent<0..2^8-1>;
Uint16 number_children_nodes;
NodeId children<0..2^16-1>;
Uint32 path_length_to_root;
Uint32 path_delay_to_root;
Uint32 path_delay_to_child;
} TreeData;
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tree_id: the id of the tree
algorithm: code identifying the multicast algorithm used by this
tree
tree_root: node_id of tree root, or 0 if unknown
number_parents: 0 .. 2^8-1 indicates number of parent nodes for
this node
parent: the RELOAD NodeId of each parent node
number_children_nodes: 0..2^16-1 indicates number of children
children: the RELOAD NodeId of each child node
path_length_to_root: number of overlay hops to the root of the
tree
path_delay_to_root: RTT in millisec. to root node
path_delay_to_child: last measured RTT in msec to child node with
largest RTT.
public struct {
uint32 join_confim_timeout;
uint32 heartbeat_interval;
uint32 heartbeat_reponse_timeout;
uint16 info_length;
uint8 info<0..2^16-1>;
} ImplementationInfo;
join_confirm_timeout: The default time for join confirm/decline,
intended to provide sufficient time for a join request to receive
all responses and confirm the best choice. Default value is 5000
msec. An implementation can change this value.
heartbeat interval: The heartbeat interval is 2000 msec.
heartbeat timeout interval: The heartbeat timeout is 5000 msec,
and is the max time between heartbeat reports from an adjacent
node in the tree at which point the heartbeat is missed.
info_length: length of the info field
info: implementation specific information, such as name of
implementation, build version, and implementation specific
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features
7.2.18. Push
A peer sends arbitrary multicast data to other peers in the tree.
Nodes in the tree forward this message to adjacent nodes in the tree
in an algorithm dependent way.
struct {
node_id group_id;
uint8 priority;
uint32 length;
uint8 data<0..2^32-1>;
} Push;
group_id: overlay address of root of the ALM tree
priority: the relative priority of the message, highest priority is
255. A node may ignore this field
length: length of the data field in bytes
data: the data
7.2.19. PushResponse
After receiving a Push message from node S, the peer sends a
PushReponse to node S.
struct {
Dictionary options;
} PushResponse;
options: A node may provide feedback to the sender about previous
push messages in some window, for example, the last N push messages.
The feedback could include, for each push message received, the
number of adjacent nodes which were forwarded the push message, and
the number of adjacent nodes from which a PushResponse was received.
8. Scribe Algorithm
8.1. Overview
The following table shows a mapping between RELOAD ALM messages (as
defined in Section 5 of this draft) and Scribe messages as defined in
[CASTRO2002].
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+------------------+-------------------+-----------------+
| Section in Draft |RELOAD ALM Message | Scribe Message |
+------------------+-------------------+-----------------+
| 7.2.1 | CreateALMTree | Create |
+------------------+-------------------+-----------------+
| 7.2.2 | Join | Join |
+------------------+-------------------+-----------------+
| 7.2.3 | JoinAccept | |
+------------------+-------------------+-----------------+
| 7.2.4 | JoinConfirm | |
+------------------+-------------------+-----------------+
| 7.2.5 | JoinDecline | |
+------------------+-------------------+-----------------+
| 7.2.6 | Leave | Leave |
+------------------+-------------------+-----------------+
| 7.2.7 | Reform | |
+------------------+-------------------+-----------------+
| 7.2.8 | Heartbeat | |
+------------------+-------------------+-----------------+
| 7.2.9 | NodeQuery | |
+------------------+-------------------+-----------------+
| 7.2.10 | Push | Multicast |
+------------------+-------------------+-----------------+
| | Note 1 | deliver |
+------------------+-------------------+-----------------+
| | Note 1 | forward |
+------------------+-------------------+-----------------+
| | Note 1 | route |
+------------------+-------------------+-----------------+
| | Note 1 | send |
+------------------+-------------------+-----------------+
Figure 5
Note 1: These Scribe messages are handled by RELOAD messages.
The following sections describe the Scribe algorithm in more detail.
8.2. Create
This message will create a group with group_id. This message will be
delivered to the node whose node_id is closest to the group_id. This
node becomes the rendezvous point and root for the new multicast
tree. Groups may have multiple sources of multicast messages.
CREATE : groups.add(msg.group_id)
group_id: the overlay address of the root of the tree
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8.3. Join
To join a multicast tree a node sends a JOIN request with the
group_id as the key. This message gets routed by the overlay to the
rendezvous point of the tree. If an intermediate node is already a
forwarder for this tree, it will add the joining node as a child.
Otherwise the node will create a child table for the group and adds
the joining node. It will then send the JOIN request towards the
rendevous point terminating the JOIN message from the child.
To adapt the Scribe algorithm into the ALM Usage proposed here, after
a JOIN request is accepted, a JOINAccept message is returned to the
joining node.
JOIN : if(checkAccept(msg)) {
recvJoins.add(msg.source, msg.group_id)
SEND(JOINAccept(node_id, msg.source, msg.group_id))
}
8.4. Leave
When leaving a multicast group a node will change its local state to
indicate that it left the group. If the node has no children in its
table it will send a LEAVE request to its parent, which will travel
up the multicast tree and will stop at a node which has still
children remaining after removing the leaving node.
LEAVE : groups[msg.group_id].children.remove(msg.source)
if (groups[msg.group].children = 0)
SEND(msg,groups[msg.group_id].parent)
8.5. JoinConfirm
This message is not part of the Scribe protocol, but required by the
basic protocol proposed in this draft. Thus the usage will send this
message to confirm a joining node accepting its parent node.
JOINConfirm: if(recvJoins.contains(msg.source,msg.group_id)){
if !(groups.contains(msg.group_id)) {
groups.add(msg.group_id)
SEND(msg,msg.group_id)
}
groups[msg.group_id].children.add(msg.source)
recvJoins.del(msg.source, msg.group_id)
}
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8.6. JoinDecline
JOINDecline: if(recvJoins.contains(msg.source,msg.group_id))
recvJoins.del(msg.source, msg.group_id)
8.7. Multicast
A message to be multicast to a group is sent to the rendevous node
from where it is forwarded down the tree. If a node is a member of
the tree rather than just a forwarder it will pass the multicast data
up to the application.
MULTICAST : foreach(groups[msg.group_id].children as node_id)
SEND(msg,node_id)
if memberOf(msg.group_id)
invokeMessageHandler(msg.group_id, msg)
9. P2PCast Algorithm
9.1. Overview
P2PCast [P2PCAST]creates a forest of related trees to increase load
balancing. P2PCast is independent on the underlying P2P substrate.
Its goals and approach are similar to Splitstream [SPLITSTREAM](which
assumes Pastry as the P2P overlay). In P2PCast the content provider
splits the stream of data into f stripes. Each tree in the forest of
multicast trees is an (almost) full tree of arity f. These trees are
conceptually separate: every node of the system appears once in each
tree, with the content provider being the source in all of them. To
ensure that each peer contributes as much bandwidth as it receives,
every node is a leaf in all the trees except for one, in which the
node will serve as an internal node (proper tree of this node). The
remainder of this section will assume f=2 for the discussion. This
is to keep the complexity for the description down. However, the
algorithm scales for any number f.
P2PCast distinguishes the following types of nodes:
o Incomplete Nodes: A node with less than f children in its proper
stripe;
o Only-Child Nodes: A node whose parent (in any multicast tree) is
an incomplete node;
o Complete Nodes: A node with exactly f children in its proper
stripe
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o Special Node: A single node which is a leaf in all multicast trees
of the forest
9.2. Create
This message will create a group with group_id. This message will be
delivered to the node whose node_id is closest to the group_id. This
node becomes the rendezvous point and root for the new multicast
tree. The rendezvous point will maintain f subtrees.
9.3. Join
To join a multicast tree a joining node N sends a JOIN request to a
random node A already part of the tree. Depending of the type of A
the joining algorithm continues as follows:
o Incomplete Nodes: Node A will arbitrarily select for which tree it
wants to serve as an internal node, and adopt N in that tree. In
the other tree node N will adopt node A as a child (taking node
A's place in the tree) thus becoming an internal node in the
stripe that node A didn't choose.
o Only-Child Nodes: As this node has a parent which is an incomplete
node, the joining node will be redirected to the parent node and
will handle the request as detailed above.
o Complete Nodes: The contacted node A must be a leaf in the other
tree. If node A is a leaf node in Stripe 1, node N will become an
internal node in Stripe 1, taking the place of node A, adopting it
at the same time. To find a place for itself in the other stripe,
node N starts a random walk down the subtree rooted at the sibling
of node A (if node A is the root and thus does not have siblings,
node N is sent directly to a leaf in that tree), which ends as
soon as node N finds an incomplete node or a leaf. In this case
node N is adopted by the incomplete node.
o Special Node: as this node is a leaf in all subtrees, the joining
node can adopt the node in one tree and become a child in the
other.
P2PCast uses defined messages for communication between nodes during
reorganisation. Here these messages are encapsulated by the message
type REFORM is used. The P2PCast message is included in the options
parameter of REFORM. The following messages are defined by P2PCast:
TAKEON: To take another peer as a child
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SUBSTITUTE: To take the place of a child of some peer
SEARCH: To obtain the child of a node in a particular stripe
REPLACE: Different from SUBSTITUTE in that the node which makes us
its child sheds off a random child
DIRECT: To direct a node to its would-be parent
UPDATE: A node sends its updated state to its children
To adapt the P2PCast algorithm into the ALM Usage proposed here,
after a JOIN request is accepted, a JOINAccept message is returned to
the joining node (one for every subtree).
9.4. Leave
When leaving a multicast group a node will change its local state to
indicate that it left the group. Distregarding the case where the
leaving node is the root of the tree, the leaving node must be
complete or incomplete in its proper tree. In the other trees the
node is a leaf and can just disappear by notifying its parent. For
the proper tree, if the node is incomplete, it is replaced by its
child. However, if the node is complete, a bubble is created which
is filled by a random child. If this child is incomplete, it can
simply fill the gap. However, if it is complete, it needs to shed a
random child. This child is directed to its sibling, which sheds a
random child. This process ripples down the tree until the next-to-
last level is reached. The shed node is then taken as a child by the
parent of the deleted node in the other stripe.
Again, for the reorganisation of the tree, the REFORM message type is
used as defined in the previous section.
9.5. JoinConfirm
This message is not part of the P2PCast protocol, but required by the
basic protocol defined in this draft. Thus the usage will send this
message to confirm a joining node accepting its parent node. As with
Join and JoinAccept, this will be carried out for every subtree.
9.6. JoinDecline
JOINDecline: if(recvJoins.contains(msg.source,msg.group_id))
recvJoins.del(msg.source, msg.group_id)
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9.7. Multicast
A message to be multicast to a group is sent to the rendezvous node
from where it is forwarded down the tree by being split into k
stripes. Each stripe is then sent via a subtree. If a receiving
node is a member of the tree rather than just a forwarder it will
pass the multicast data up to the application.
10. ALMTree Kind
A ALMTree Kind is defined per section 7.4.5 in RELOAD. An instance
of the ALMTree kind is stored in the overlay for each ALM tree
instance. It is stored at the address group_id.
Meaning: The meaning of the fields is given in Section 7.2.1.
Kind-Id: 0xf0000001 (This is a private-use code-point per section
14.6 of RELOAD.
Data model:
struct {
node_id peer_id;
opaque session_key<0..2^32-1>;
node_id group_id;
Dictionary options;
} ALMTree;
Access control model: The node performing the store operation is
required to have NODE-MATCH access.
11. Message Codes
All messages are mapped to the RELOAD experimental message type. The
mapping is given in the following table. The format of the body of a
message is given below.
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+-------------------------+------------------+------------------+
| Message |RELOAD Code Point | ALM Message Code |
+-------------------------+------------------+------------------+
| CreateALMTRee | exp_a_req | 00 |
+-------------------------+------------------+------------------+
| CreateALMTreeResponse | exp_a_ans | 01 |
+-------------------------+------------------+------------------+
| Join | exp_a_req | 02 |
+-------------------------+------------------+------------------+
| JoinAccept | exp_a_ans | 03 |
+-------------------------+------------------+------------------+
| JoinReject | exp_a_ans | 04 |
+-------------------------+------------------+------------------+
| JoinConfirm | exp_a_req | 05 |
+-------------------------+------------------+------------------+
| JoinConfirmResponse | exp_a_ans | 06 |
+-------------------------+------------------+------------------+
| JoinDecline | exp_a_req | 07 |
+-------------------------+------------------+------------------+
| JoinDeclineResponse | exp_a_ans | 08 |
+-------------------------+------------------+------------------+
| Leave | exp_a_req | 09 |
+-------------------------+------------------+------------------+
| LeaveResponse | exp_a_ans | x0A |
+-------------------------+------------------+------------------+
| Reform | exp_a_req | x0B |
+-------------------------+------------------+------------------+
| ReformResponse | exp_a_ans | x0C |
+-------------------------+------------------+------------------+
| Heartbeat | exp_a_req | x0D |
+-------------------------+------------------+------------------+
| HeartbeatResponse | exp_a_ans | x0E |
+-------------------------+------------------+------------------+
| NodeQuery | exp_a_req | x0F |
+-------------------------+------------------+------------------+
| NodeQueryResponse | exp_a_ans | x10 |
+-------------------------+------------------+------------------+
| Push | exp_a_req | x11 |
+-------------------------+------------------+------------------+
| PushResponse | exp_a_ans | x12 |
+-------------------------+------------------+------------------+
Figure 6
For Data Kind-IDs, the RELOAD specification states: "Code points in
the range 0xf0000001 to 0xfffffffe are reserved for private use".
ALM Usage Kind-IDs will be defined in the private use range.
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All ALM Usage messages support the RELOAD Message Extension
mechanism.
Code points for the kinds defined in this document MUST not conflict
with any defined code points for RELOAD. RELOAD defines exp_a_req,
exp_a_ans for experimental purposes. This specification uses only
these message types for all ALM messages. RELOAD defines the
MessageContents data structure. The ALM mapping uses the fields as
follows:
o message_code: exp_a_req for requests and exp_a_ans for responses
o message_body: contains one instance of ALMHeader followed by one
instance of ALMMessageContents
o extensions: unused
11.1. ALMHeader Definition
struct {
uint32 sam_token;
uint32 algorithm;
uint8 version;
} ALMHeader;
The fields in ALMHeader are used as follows:
sam_token: The first four bytes identify this message as an ALM
message. This field MUST contain the value 0xd3414d42 (the string
"SAMB" with the high bit of the first byte set.
algorithm: The code of the multicast algorithm being used. Each
multicast tree uses only one algorithm. Trees with different
multicast algorithm can co-exist, and can share the same nodes.
version: The version of the ALM protocol being used. This is a
fixed point integer between 0.1 and 25.4 This document describes
version 1.0 with a value of 0xa.
11.2. ALMMessageContents Definition
struct {
uint16 alm_message_code;
opaque alm_message_body;
} ALMMessageContents;
The fields in ALMMessageContents are used as follows:
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alm_message_code: This indicates the message being sent. The
message codes are listed in Section 11.
alm_message_body: The message body itself, represented as a
variable-length string of bytes. The bytes themselves are
dependent on the code value. See Section 8 and Section 9
describing the various ALM methods for the definitions of the
payload contents.
11.3. Response Codes
Response codes are defined in section 6.3.3.1 in RELOAD. This
experimental specification maps to RELOAD ErrorResponse as follows:
ErrorResponse.error_code = Error_Exp_A;
Error_info contains a ALMErrorResponse instance.
public struct {
uint16 alm_error_code;
opaque alm_error_info<0..2^16-1>;
} ALMErrorResponse;
alm_error_code: The following error code values are defined. Numeric
values for these are defined in section X.
Error_Unknown_Algorithm: The multicast algorithm is not known or
not supported.
Error_Child_Limit_Reached: The maximum number of children nodes
has been reached for this node
Error_Node_Bandwidth_Reached: The overall data bandwidth limit
through this node has been reached
Error_Node_Connection_Limit_Reached: The total number of
connections to this node has been reached
Error_Link_Capacity_Limit_Reached: The capacity of a link has been
reached
Error_Node_Memory_Capacity_Limit_Reached: An internal memory
capacity of the node has been reached
Error_Node_CPU_Capacity_Limit_Reached: An internal processing
capacity of the node has been reached
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Error_Path_Limit_Reached: The maximum path length in hopcount over
the multicast tree has been reached
Error _Path_Delay_Limit_Reached: The maximum path length in
message delay over the multicast tree has been reached
Error_Tree_Fanout_Limit_Reached: The maximum fanout of a multicast
tree has been reached
Error_Tree_Depth_Limit_Reached: The maximum height of a multicast
tree has been reached
Error_Other: A human-readable description is placed in the
alm_error_info field.
11.4. Algorithm Codes
ALM Algorithm Types: There are currently two types: SCRIBE and
P2PCAST.
0001 - SCRIBE
0002 - P2PCAST
0003 .. 0xFFFF undefined
12. Examples
All peers in the examples are assumed to have completed
bootstrapping. "Pn" refers to peer N. "GroupID" refers to a peer
responsible for storing the ALMTree instance with GroupID.
12.1. Create Tree
A node with "NODE-MATCH" rights sends a request CreateTree to the
group-id node, which also has NODE-MATCH rights for its own address.
The group-id node determines whether to create the new tree, and if
so, performs a local StoreReq. If the CreateTree succeeds, the
ALMTree instance can be retrieved using Fetch.
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P1 P2 P3 P4 GroupID
| | | | |
| | | | |
| | | | |
| CreateTree | | |
|------------------------------->|
| | | | |
| | | | | StoreReq
| | | | |--+
| | | | | |
| | | | | |
| | | | |<-+
| | | | | StoreResponse
| | | | |--+
| | | | | |
| | | | | |
| | | | |<-+
| | | | |
| | | | |
| | CreateTreeResponse |
|<-------------------------------|
| | | | |
| | | | |
| Fetch | | |
|------------------------------->|
| | | | |
| | | | |
| | FetchResponse |
|<-------------------------------|
| | | | |
Figure 7
12.2. Join Tree
P1 joins node GroupID as child node. P2 joins the tree as a child of
P1. P4 joins the tree as a child of P1.
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P1 P2 P3 P4 GroupID
| | | | |
| | | | |
| Join |
|------------------------------->|
| | | | |
| JoinAccept |
|<-------------------------------|
| | | | |
| | | | |
| |Join |
| |----------------------->|
| | | | |
| Join|
|<-------------------------------|
| | | | |
|JoinAccept | | |
|------>| | | |
| | | | |
|JoinConfirm | | |
|<------| | | |
| | | | |
| | | |Join |
| | | |------>|
| | | | Join |
|<-------------------------------|
| | | | |
| Join | | | |
|------>| | | |
| | | | |
| JoinAccept | | |
|----------------------->| |
| | | | |
| | JoinAccept | |
| |--------------->| |
| | | | |
| | | | |
| | Join Confirm | |
|<-----------------------| |
| | | | |
| | Join Decline | |
| |<---------------| |
| | | | |
| | | | |
Figure 8
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12.3. Leave Tree
P1 P2 P3 P4 GroupID
| | | | |
| | | | |
| | | Leave | |
|<-----------------------| |
| | | | |
| LeaveResponse | | |
|----------------------->| |
| | | | |
| | | | |
Figure 9
12.4. Push Data
The multicast data is pushed recursively P1 => GroupID => P1 => P2,
P4 following the tree topology created in the Join example above.
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P1 P2 P3 P4 GroupID
| | | | |
| Push | | | |
|------------------------------->|
| | | | |
| | | PushResponse|
|<-------------------------------|
| | | | |
| | | | Push|
|<-------------------------------|
| | | | |
| PushResponse | | |
|------------------------------->|
| | | | |
|Push | | | |
|------>| | | |
| | | | |
|PushResponse | | |
|<------| | | |
| | | | |
| Push | | | |
|----------------------->| |
| | | | |
| | PushResponse | |
|<-----------------------| |
| | | | |
| | | | |
| | | | |
Figure 10
13. Kind Definitions
13.1. ALMTree Kind Definition
This section defines the ALMTree kind.
Kind IDs The Resource Name for the ALMTree Kind-ID is the session_key
used to identify the ALM tree
Data Model The data model is the ALMTree structure.
Access Control NODE-MATCH
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14. Configuration File Extensions
In RELOAD, peers receive a configuration document at bootstrap time.
No ALM parameter definitions for the configuration file are currently
defined.
15. Change History
o Version 02: Remove Hybrid ALM material. Define ALMTree kind.
Define new RELOAD messages. Define RELOAD architecture
extensions. Add Scribe as base algorithm for ALM usage. Define
code points. Define preliminary ALM-specific security issues.
o Version 03: Add P2Pcast Algorithm.
o Version 04: Add mapping to RELOAD experimental message. Modified
IANA considerations setion. New algorithm identification coding.
New message coding. Added push message. Create Tree access
policy changed to use NODE-MATCH. Create Tree StoreReq clarified.
Updated the diagrams in the Examples section. Added a Push data
example. Defined the ALMTree kind.
16. Open Issues
o ALM parameter definitions for the RELOAD configuration file will
be implementation defined.
17. IANA Considerations
This memo includes no request to IANA.
18. Security Considerations
Overlays are vulnerable to DOS and collusion attacks. We are not
solving overlay security issues. We assume the node authentication
model as defined in [I-D.ietf-p2psip-base].
ALM Usage specific security issues:
o Right to create GroupID at some node_id
o Right to store Tree info at some Location in the DHT
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o Limit on # messages / sec and bandwidth use
o Right to join an ALM tree
19. Acknowledgement
Marc Petit-Huguenin provided important comments on earlier versions
of this draft.
20. References
20.1. Normative References
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, September 1981.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
Thyagarajan, "Internet Group Management Protocol, Version
3", RFC 3376, October 2002.
[RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery
Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.
[RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick,
"Internet Group Management Protocol (IGMP) / Multicast
Listener Discovery (MLD)-Based Multicast Forwarding
("IGMP/MLD Proxying")", RFC 4605, August 2006.
[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
IP", RFC 4607, August 2006.
[RFC5058] Boivie, R., Feldman, N., Imai, Y., Livens, W., and D.
Ooms, "Explicit Multicast (Xcast) Concepts and Options",
RFC 5058, November 2007.
20.2. Informative References
[AGU1984] Aguilar, L., "Datagram Routing for Internet Multicasting",
ACM Sigcomm 84 1984, March 1984,
<http://dl.acm.org/citation.cfm?id=802060>.
[CASTRO2002]
Castro, M., Druschel, P., Kermarrec, A., and A. Rowstron,
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"Scribe: A large-scale and decentralized application-level
multicast infrastructure", IEEE Journal on Selected Areas
in Communications vol.20, No.8, October 2002, <http://
research.microsoft.com/en-us/um/people/antr/past/
jsac.pdf>.
[CASTRO2003]
Castro, M., Jones, M., Kermarrec, A., Rowstron, A.,
Theimer, M., Wang, H., and A. Wolman, "An Evaluation of
Scalable Application-level Multicast Built Using Peer-to-
peer overlays", Proceedings of IEEE INFOCOM 2003,
April 2003, <http://research.microsoft.com/en-us/um/
people/mcastro/publications/infocom-compare.pdf>.
[HE2005] He, Q. and M. Ammar, "Dynamic Host-Group/Multi-Destination
Routing for Multicast Sessions", J. Telecommunication
Systems vol. 28, pp. 409-433, 2005, <http://
ieeexplore.ieee.org/xpl/
freeabs_all.jsp?arnumber=1284204&abstractAccess=no&
userType=inst>.
[I-D.ietf-mboned-auto-multicast]
Bumgardner, G., "Automatic Multicast Tunneling",
draft-ietf-mboned-auto-multicast-14 (work in progress),
June 2012.
[I-D.ietf-p2psip-base]
Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and
H. Schulzrinne, "REsource LOcation And Discovery (RELOAD)
Base Protocol", draft-ietf-p2psip-base-23 (work in
progress), November 2012.
[I-D.ietf-p2psip-sip]
Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and
H. Schulzrinne, "A SIP Usage for RELOAD",
draft-ietf-p2psip-sip-07 (work in progress), January 2012.
[I-D.irtf-p2prg-rtc-security]
Schulzrinne, H., Marocco, E., and E. Ivov, "Security
Issues and Solutions in Peer-to-peer Systems for Realtime
Communications", draft-irtf-p2prg-rtc-security-05 (work in
progress), September 2009.
[I-D.irtf-sam-hybrid-overlay-framework]
Buford, J., "Hybrid Overlay Multicast Framework",
draft-irtf-sam-hybrid-overlay-framework-02 (work in
progress), February 2008.
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[I-D.irtf-samrg-common-api]
Waehlisch, M., Schmidt, T., and S. Venaas, "A Common API
for Transparent Hybrid Multicast",
draft-irtf-samrg-common-api-06 (work in progress),
August 2012.
[I-D.matuszewski-p2psip-security-overview]
Yongchao, S., Matuszewski, M., and D. York, "P2PSIP
Security Overview and Risk Analysis",
draft-matuszewski-p2psip-security-overview-01 (work in
progress), October 2009.
[P2PCAST] Nicolosi, A. and S. Annapureddy, "P2PCast: A Peer-to-Peer
Multicast Scheme for Streaming Data", Stanford Secure
Computer Systems Group Report 2003, May 2003, <http://
www.scs.stanford.edu/~reddy/research/p2pcast/report.pdf>.
[RFC1112] Deering, S., "Host extensions for IP multicasting", STD 5,
RFC 1112, August 1989.
[RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation,
selection, and registration of an Autonomous System (AS)",
BCP 6, RFC 1930, March 1996.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
July 2003.
[RFC4286] Haberman, B. and J. Martin, "Multicast Router Discovery",
RFC 4286, December 2005.
[SPLITSTREAM]
Castro, M., Druschel, P., Nandi, A., Kermarrec, A.,
Rowstron, A., and A. Singh, "SplitStream: High-bandwidth
multicast in a cooperative environment", SOSP'03,Lake
Bolton, New York 2003, October 2003, <http://
research.microsoft.com/en-us/um/people/antr/PAST/
SplitStream-sosp.pdf>.
Appendix A. Additional Stuff
This becomes an Appendix.
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Authors' Addresses
John Buford
Avaya Labs Research
211 Mt. Airy Rd
Basking Ridge, New Jersey 07920
USA
Phone: +1 908 848 5675
Email: buford@avaya.com
Mario Kolberg (editor)
University of Stirling
Dept. Computing Science and Mathematics
Stirling, FK9 4LA
UK
Phone: +44 1786 46 7440
Email: mkolberg@ieee.org
URI: http://www.cs.stir.ac.uk/~mko
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