| MPLS Working Group | R. Li |
| Internet-Draft | Q. Zhao |
| Intended status: Standards Track | Huawei Technologies |
| Expires: January 06, 2013 | C. Jacquenet |
| France Telecom Orange | |
| July 07, 2012 |
Receiver-Driven Multicast Traffic-Engineered Label-Switched Paths
draft-lzj-mpls-receiver-driven-multicast-rsvp-te-01.txt
This document describes extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for the setup of Receiver-Driven Traffic-Engineered point-to-multipoint (P2MP) and multipoint-to-multipoint (MP2MP)Label Switched Paths (LSPs) in Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS)networks.
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Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/.
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This Internet-Draft will expire on January 06, 2013.
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Multiparty multimedia applications are getting greater attention in the telecom and datacom world. Such applications are QoS-demanding and can therefore benefit from the activation of MPLS traffic engineering capabilities that lead to the dynamic computation and establishment of MPLS LSPs whose characteristics comply with application-specific QoS requirements. P2MP-TE [RFC4875] defines a procedure to set up point-to-multipoint LSPs from sender to receivers. Sometimes multicast data streams are required to get transported over both IP networks and MPLS networks, which require PIM must interwork with RSVP-TE. On other times, PIM bootstraping messages need to transport over an intermediate MPLS domain. This document extends RSVP-TE for the dynamic computation of receiver-driven P2MP and MP2MP LSP tree structures.
IP multicast distribution trees are receiver-initiated and dynamic by nature. IP multicast-enabled applications are also bandwidth savvy, especially in the area of residential IPTV services, where the delivery of multicast contents to several hundreds of thousands of IPTV receivers assumes the appropriate level of quality.
Current source-driven P2MP LSP establishment, as defined as in [RFC4875], assumes a priori knowledge of receiver locations, and the LSP signalling is initiated and driven by the data sender(headend). The priori knowledge of receiver locations is obtained either through static configuration or by using another protocol to discover such receivers. On the other hand, there is no straightfoward way to support MP2MP applications by using P2MP LSP unless full-meshed P2MP LSPs are set up.
The receiver-driven extension to RSVP-TE defined in this document will support both P2MP LSPs and MP2MP LSPs. Moreover, it does not require the sender to know all the receivers' locations a priori. The protocols for discovery of receivers are not needed. It provides a natural mechanism to interwork with PIM dynamically.
The following terms are used in this document:
Although the receiver-driven extensions to RSVP-TE as defined in this document use the existing sender-driven syntax, there are important semantic differences that need to be defined for correct interpretation and interoperability. In the receiver-driven context, we inverted the semantics of RSVP-TE messages, while keeping the syntax unchanged as much as possible. We will use mRSVP-TE to represent the RSVP-TE with receiver-driven extensions described in this document.
The following are some key differences that are specific to the receiver-driven paradigm:
In what follows we describe two examples to show how P2MP and MP2MP are set up, respectively. In both of such examples, Path messages are initiated by data receivers.
For the P2MP example, a Path message carries a label for the use of sending data downstream. And for the MP2MP example, both Path message and Resv message carries a label for sending data downstream and upstream.
Sender/Source/Path Terminator/Ingress Router
+---------+
| R1 |
+-----+---+
_
\ \ /\
\ \ \ Path Message w/ Label OBJECT
Resv \ \ \ (msg2)
Message \ \ \
(msg3) \ \ \
_\/ \ \
+----------------+ Path Remerge
| R3 | Creates Branch Point
+----------------+
_ _
/ / /\ \ \ /\
/ / / \ \ \ Path Message (msg1)
Resv Message / / / msg4 \ \ \ w/ Label OBJECT
(msg6) / / / \ \ \
/ / /Path Msg \ \ \
/ / / (msg5) \ \ \
\/_ / / w/Label OBJ _\/ \ \
+----------+ +---+-----+
| R4 | | R5 |
+----------+ +---------+
Path Initiator Path Initiator
Originator ID = R4 Originator ID = R5
L2S Destination = R1 L2S Destination = R1
Session = S Session = S
In Figure 1, when R5 is added as the first leaf of a mulitcast distribution tree (multicast LSP), the message flow goes as follows: R5->msg1->R3->msg2->R1->msg3->R3->msg4->R5. When the leaf R4 is added, the message flow goes from R4->msg5->R3->msg6->R4. In this case, when R3 receives msg5, R3 finds out that a multicast LSP has already been set up for the same session and the same source. Therefore, R3 finds itself a branch node for leaf R4 and R5, so it will terminate the PATH message and build the corresponding RESV message and send it back to R4. The association of the LSP initiated by R4 to the existing multicast LSP is determined based on the processing of the SESSION object and L2S_SUB_LSP object from the mRSVP-TE message. The SESSION object and the L2S_SUB_LSP objects are documented later in this draft.
Root/Path Terminator/Ingress Router
+---------+
| R1 |
+-----+---+
_
\ \ /\
\ \ \ Path-mp2mp Message w/ Label OBJECT
Resv \ \ \ (msg2)
Message \ \ \
(msg3) \ \ \
w/ Label OBJECT _\/ \ \
+----------------+ Path-mp2mp
| R3 | (Branch Point)
+----------------+
_ _
/ / /\ \ \ /\
/ / / \ \ \ Path-mp2mp Message (msg1)
Resv Message / / / msg4 \ \ \ (msg1)
(msg6) / / / \ \ \ w/ Label OBJECT
w/ Label OBJECT/ / /Path-mp2mp \ \ \
/ / / Message \ \ \
/ / / (msg5) \ \ \
\/_ / / w/ Label OBJ _\/ \ \
+----------+ +---+-----+
| R4 | | R5 |
+----------+ +---------+
Path-mp2mp Initiator Path-mp2mp Initiator
Originator ID = R4 Originator ID = R5
L2S Destination = R1 L2S Destination = R1
Session = S Session = S
In Figure 2, when R5 is added as the first leaf (as both a sender and a receiver) of an MP2MP multicast LSP, the message flow goes from R5->msg1->R3->msg2->R1->msg3->R3->msg4->R5. When the leaf R4 ( as both a sender and a receiver)is added, the message flow goes from R4->msg5->R3->msg6->R4. In this case, when R3 receives msg5, R3 finds out that an MP2MP mulitcast LSP has already been set up for the same session and the same root and R3 will become the branch LSR for the leaf R4 and R5, so it will terminate the PATH message, build a RESV message and send the RESV message back to R4. The association of the LSP initiated by R4 to the existing MP2MP LSP is determined based on the processing of the SESSION object and the S2L_SUB_LSP from the mRSVP-TE message. The SESSION objects and the L2S_SUB_LSP objects are further documented later in this draft.
The RSVP-TE with receiver-driven extensions (mRSVP-TE) is similar to the RSVP-TE protocol as specified in [RFC4875], [RFC3473] and [RFC3209], but differs in that the data receivers of an LSP tunnel initiate the Path messages toward the data sender (or the root of a mulitcast LSP). Compared with [RFC4875], mRSVP-TE can also be used to set up MP2MP LSPs.
In the context of the receiver-driven RSVP-TE, the Receiver is the Path-Originator. The Path messages go from the Receivers towards the Sender. The Resv messages flow in the opposite direction as compared to the Path messages, i.e. Resv messages are generated by the Sender or a branch LSR. Path messages flow in opposite directions as cmpared with those of the multicast stream distributions, while Resv messages flow in the same directions as the multicast streams.
In the context of the receiver-driven RSVP-TE, a Path message will be terminated at the "root" of the multicast distribution tree (multicast LSP) or at an intermediate node if the intermediate node has received another Path message from another receiver for the same multicast distribution tree. When an intermediate node receives two or more Path messages for the same multicast distribution tree, the intermediate node will merge them together. Whether two Path messages should be merged depends on the information encoded in the SESSION and L2S-SUB-LSP objects. The SESSION object encodes multicast group information and the L2S-SUB-LSP (leaf-to-source sub-lsp) object encodes the multicast source or multicast root information.
The following sections describe the receiver-driven extensions to the RSVP-TE protocol. When there is no difference in the protocol, the usage of [RFC4875] is assumed.
As specified in [RFC2205], a session is a data flow with a particular destination and transport-layer protocol. In the context of multicast, the data flow is essentially a multicast distribution tree rooted at the P2MP source or MP2MP root.
For the sake of reliability, two or more sources/roots may be deployed to distribute the same multicast streams. A mulitcast stream is often represented by a mulitcast group address. In this document, we will encode the mulitcast group address in the SESSION object and the mulitcast source/root address in the leaf-to-source sub-LSP object. Note that the same session can have different sources/roots, and the same sources/roots can have different sessions.
In the context of the receiver-driven mRSVP-TE, the processing of SESSION objects is different from that of SESSION objects in sender-driven RSVP-TE [RFC4875]. In order to distinguish them, we will employ different C-Types of SESSIONs. In this document we will document SESSION objects for native IPv4/IPv6 multicast applications. For new and more applications, new types of SESSION objects will be added.
Following the method used by RSVP-TE and P2MP RSVP-TE, this draft documents the use of some new SESSION C-Type as follows:
Class Name = SESSION
C-Type
XX+0 mRSVP_TE_P2MP_LSP_TUNNEL_IPv4 C-Type
XX+1 mRSVP_TE_P2MP_LSP_TUNNEL_IPv6 C-Type
XX+2 mRSVP_TE_MP2MP_LSP_TUNNEL_IPv4 C-Type
XX+3 mRSVP_TE_MP2MP_LSP_TUNNEL_IPv6 C-Type
Where XX is a number to be allocated by IANA.
The new SESSION C-Type MUST be used in all receiver-driven P2MP RSVP-TE messages.
A multicast LSP is composed of one or more leaf-to-source sub-LSPs, which are merged together at the branch nodes. There are two ways to identify each such sub-LSP:
This document takes the approach from the Receiver's perspective. The approach from the Sender's perspective is documented in [RFC 4875].
Once an LSR receives a receiver-driven Path message with the SESSION object and L2S_SUB_LSP object, the LSR should be able to use the SESSION object and L2S_SUB_LSP object to determine whether the sub-LSP signaled by this Path message should be merged with existing multicast LSPs.
In the context of the receiver-driven RSVP-TE, a Path Originator is also a Data Receiver. This document will document a new type of SENDER_TEMPLATE object, which contains the Path-Originator's IP address and describes the identity of the Path Originator.
In [RFC 2205] and [RFC 4875], the "sender" is both a path originator and a data sender. In the receiver-driven context, path originators and data senders may be different. For P2MP, path originators are actually the data receivers. For MP2MP, path originators are also both the data senders and data receivers.
In this document, we will use the same Object Class SENDER_TEMPLATE with a different C-Type to represent and identify Path Originator. In the case of P2MP LSP, the SENDER_TEMPLATE describes the identify of a data receiver. In the case of MP2MP, the SENDER_TEMPLATE describes the identify of an LSR which work as both a data sender and a data receiver.
All of the SESSION object, L2S_SUB_LSP object and SENDER_TEMPLATE object together contained in a Path message will uniquely identify a leaf-to-source sub-LSP.
An EXPLICIT_ROUTE Object (ERO) is used to optionally specify the explicit route of an L2S sub-LSP. Each signaled ERO corresponds to a particular L2S_SUB_LSP object. Details of explicit route encoding are specified in section 4.5 of [RFC4875], but they are encoded in a reverse order in the receiver-driven context.
When a Path message signals a L2S sub-LSP, the EXPLICIT_ROUTE object encodes the path from the leaf to the root LSR. The Path message also includes the L2S_SUB_LSP object for the L2S sub-LSP being signaled. The < [<EXPLICIT_ROUTE>], <L2S_SUB_LSP>> tuple represents the L2S sub-LSP and is referred to as the sub-LSP descriptor.
The absence of the ERO should be interpreted as requiring hop-by-hop reverse-forwarding for the sub-LSP based on the root address field of the L2S_SUB_LSP object.
The mechanism specified in this document allows a multicast P2MP/MP2MP LSP to be signaled using one or more Path messages. Each Path message may signal one L2S sub-LSPs.
A receiver-driven P2MP MPLS-TE LSP uses the Path message to carry the LABEL object upstream from the Receiver towards the Sender. With a receiver-driven usage of the RSVP PATH messages, the LABEL_REQUEST object carried by the PATH message is no longer mandatory, it becomes optional for receiver-driven PATH messages, as specified in Figure 4:
<Path Message> ::= <Common Header> [ <INTEGRITY> ]
[ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ...]
[ <MESSAGE_ID> ]
<SESSION> <RSVP_HOP>
<TIME_VALUES>
[ <EXPLICIT_ROUTE> ]
[ <LABEL_REQUEST> ]
[ <PROTECTION> ]
[ <LABEL_SET> ... ]
[ <SESSION_ATTRIBUTE> ]
[ <NOTIFY_REQUEST> ]
[ <ADMIN_STATUS> ]
[ <POLICY_DATA> ... ]
<sender descriptor>
[<L2S_SUB_LSP>]
The SESSION object encodes information about the being-signalled multicast stream. The SESSION object together with L2S_SUB_LSP will be used as the key to associate different sub-LSPs to the same multicast LSP.
Using [RFC4875] as the base specification, the LABEL object is added to the <sender descriptor> as specified in Figure 5:
<sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC>
[ <ADSPEC> ]
[ <RECORD_ROUTE> ]
[ <SUGGESTED_LABEL> ]
[ <RECOVERY_LABEL> ]
<LABEL>
The LABEL object is defined in section 4.1 of [RFC3209]
Note that the receiver-driven Path messages convey the LABEL_REQUEST as an optional object. If the Path message signals a P2MP LSP, the LABEL_REQUEST in the Path message is not used. If the Path message signals an MP2MP, the LABEL_REQUEST is needed to ask for labels from its upstream LSR.
Receiver-driven P2MP RSVP-TE does not need any change to the basic RESV messages specified in section 6.1 of [RFC4875], as long as the receiver-driven SESSION objects of the new C-Types are used.
For receiver-driven P2MP LSPs, the Path message carries the LABEL object, and thus the Resv message doesn't have to carry the LABEL object anymore. But for MP2MP LSPs, both Path and Resv messages will carry LABEL objects for sending and receiving purposes, respectively. Within the context of MP2MP LSPs, one of the directions is established as per [RFC3209]. Thus, this document is changing the use of the LABEL object in the FF Flow Descriptor and SE Filter Spec from mandatory to optional, as specified in Figure 6:
<FF flow descriptor> ::= [ <FLOWSPEC> ] <FILTER_SPEC> [ <LABEL> ]
[ <RECORD_ROUTE> ]
[ <L2S_SUB_LSP> ]
<SE filter spec> ::= <FILTER_SPEC> [ <LABEL> ] [ <RECORD_ROUTE> ]
[ <L2S_SUB_LSP> ]
The receiver-driven PathErr messages have the same syntax and utilization as the PathErr message described in [RFC4875], with the difference in the <sender descriptor> carried by the PathErr message. The receiver-driven PathErr message will use the <sender descriptor> defined in this document, the same as that carried by the Path messages which the PathErr messages correspond to.
The receiver-driven ResvErr messages have the same syntax and utilization as the ResvErr message described in [RFC4875]. But the ResvErr messages will be processed as per this document, given that the <FF flow descriptor> and the <SE filter spec> can optionally contain the LABEL object instead of mandating the use of the LABEL object. The optional use of the LABEL object is conditioned by the nature of the multicast LSP, either uni-directional (P2MP) or bi-directional (MP2MP).
The receiver-driven PathTear messages have the same syntax and utilization as the PathTear messages described in [RFC4875] except for the <sender descriptor> carried by the PathTear messages. The receiver-driven PathTear messages will use <sender descriptor> defined in this document, the same as that carried by the Path messages which the PathTear messages correspond to.
An mRSVP-TE LSP SESSION object is used to represent a multicast stream whose traffic will be carried by the multicast LSP being set up by the mRSVP-TE. The object still uses the existing SESSION C-Num assigned for RSVP-TE, but new C-Types are defined for the new purposes. Different from the values in the existing point-to-point or point-to-multipoint RSVP-TE SESSION object, the new objects defined by the new C-Types will encode "multicasting" information. The new SESSION object will have enough information so that the Path-Receivers can use the SESSION objects together with L2S_SUB_LSP to determine whether or not to associate different Path messages from different leaves to the same P2MP/MP2MP LSP. The combination of the SESSION object, the SENDER_TEMPLATE object and the L2S_SUB_LSP object will uniquely identify a single L2S sub-LSP.
For native IPv4/IPv6 multicast, IPv4/IPv6 (S, G) or (*, G, RP) will be encoded in the SESSION object for P2MP or MP2MP LSPs. In what follows we specify such session objects for IPv4/IPv6 P2MP and MP2MP applications in the context of receiver-driven RSVP-TE. Other SESSION objects in the receiver-driven context are defined in other documents.
Class = SESSION, mRSVP_TE_P2MP_LSP_TUNNEL_IPv4 C-Type = TBD.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Multicast Group Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Class = SESSION, mRSVP_TE_MP2MP_LSP_TUNNEL_IPv4 C-Type = TBD.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Multicast Group Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The MP2MP LSP for IPv4 SESSION objects are of the same format as P2MP LSP for IPv4 SESSION objects, but their C-Types are different.
This is the same as the P2MP LSP for IPv4 SESSION object with the difference that the IPv6 multicast group addresses are 16-byte long.
Class = SESSION, mRSVP_TE_P2MP_LSP_TUNNEL_IPv6 C-Type = TBD.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Multicast Group Address (16 bytes) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Class = SESSION, mRSVP_TE_MP2MP_LSP_TUNNEL_IPv6 C-Type = TBD.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Multicast Group Address (16 bytes) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The SENDER_TEMPLATE object contains the Path-Initiator LSR address. In this document, the Path-Initiator is the same as the Leaf Router or Data Receiver. The LSP ID can be changed to allow a sender to do a certain level of resource sharing. Thus, multiple instances of the same mutlicast LSP can be created, each with a different LSP ID. The instances can share resources with each other. The L2S sub-LSPs corresponding to a particular instance use the same LSP ID.
Class = SENDER_TEMPLATE, mRSVP_TE_LSP_TUNNEL_IPv4 C-Type = TBD.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Leaf Router Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv4 Leaf Router Address: The IPv4 address of the Data Receiver.
LSP ID: A 2-byte identifier that can be changed to allow it to share resources with itself. Its usage is the same as that described in [RFC3209].
Class = SENDER_TEMPLATE, mRSVP-TE_LSP_TUNNEL_IPv6 C-Type = TBD.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| IPv6 Leaf Router address |
+ +
| (16 bytes) |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 Leaf Router Address: The IPv6 address of the Data Receiver.
LSP ID: A 2-byte identifier that can be changed to allow it to share resources with itself. Its usage is the same as that described in [RFC3209].
An L2S_SUB_LSP object identifies a particular L2S sub-LSP belonging to a multicast LSP, as explained earlier in this document.
L2S_SUB_LSP Class = TBD, L2S_SUB_LSP_IPv4 C-Type = TBD.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 L2S Sub-LSP Root Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv4 L2S Sub-LSP Root Address: IPv4 address of the L2S sub-LSP sender.
L2S_SUB_LSP Class = TBD, L2S_SUB_LSP_IPv6 C-Type = TBD
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 L2S Sub-LSP Root Address (16 bytes) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The FILTER_SPEC object is canonical to the SENDER_TEMPLATE object.
Class = FILTER_SPEC, P2MP LSP_IPv4 C-Type = TBD.
The format of the mRSVP-TE LSP_IPv4 FILTER_SPEC object is identical to the mRSVP_TE_LSP_TUNNEL_IPv4 SENDER_TEMPLATE object.
The format of the mRSVP-TE LSP_IPv6 FILTER_SPEC object is identical to the mRSVP_TE_LSP_TUNNEL_IPv6 SENDER_TEMPLATE object.
There are two basic applications for receiver-driven RSVP-TE: inter-work with PIM and Multicast VPN.
Some multicast applications may involve several domains, some of which are operated with PIM while others are enabled with RSVP-TE. This requires the multicast distribution trees to be computed and set up across different domains with PIM and MPLS configured in different domains. When a PIM Join message is received at the border of the MPLS domain, information encoded from the PIM Join message can be encoded as a receiver-driven RSVP-TE Path message which will set up a multicast distribution LSP across the MPLS domain. The root of such a multicast LSP can encode a PIM Join message by using the information encoded in the RSVP-TE Path message. The result of doing so will enable to build a mulitcast distribution tree across both IP and MPLS domains. The multicast tree will consist of a set of IP multicast sub-trees built by PIM and a set of MPLS multicast LSPs built by the receiver-driven RSVP-TE. In PIM, there is a bootstrapping mechanism about the RP. For bootstrap messages, an MP2MP LSP can be used.
The detailed protocol extensions and procedures for such in-band signaling applications are described in other documents.
A L3VPN service that supports multicast is known as a Multicast VPN, or MVPN for short. There have been different proposed messages, procedures and mechanisms to support MVPN. These methods differ in protocols used in the service provider's network, for example, the mGRE-based MVPN, BGP extensions to transport customer's PIM signaling and P2MP RSVP-TE extensions to transport multicast data streams, and mLDP-based MVPN.
The receiver-driven multicast extensions to RSVP-TE can be used to support multicast VPN. Such an approach will greatly reduce the number of trees and multicast states in the core compared with the P2MP RSVP-TE approach.
The detailed procedures and mechanisms are described in [I-D.hlj-l3vpn-mvpn-mrsvp-te].
The Fast Re-Route mechanisms and procedures specified in [RFC 4090] will not be applicable to the receiver-driven extension to RSVP-TE described in this document, since their Path/Resv messages are sent in different directions.
Extensions to mRSVP-TE to support Fast Re-Route are described in the document [I-D.zlj-mpls-mpls-mrsvp-te-frr].
A receiver-driven P2MP LSP mechanism uses different C-Types than those in the sender-driven P2MP RSVP-TE. If LSRs do not recognize the receiver-driven C-Types, they will not support the receiver-driven extensions described in this document. LSRs that do not support receiver-driven P2MP-TE LSP, send Path Error [TBD] back to the Path Originator.
The complete discussion on the backward compatibility will be provided in the Next version of the document.
We would like to thank Lin Han and Katherine Zhao for their comments on early drafts of this work. In particular we would like to thank Lou Berger and Eric Osborne for their very helpful questions, comments and suggestions on our presentation of this work in Paris.
This section is TBD.
How a receiver is authenticated is outside the scope of this document. But we will briefly summarize the requirements which are detailed in the requirements draft.
It is a requirement that any mRSVP-TE solution developed to meet some or all of the requirements expressed in this document MUST include mechanisms to enable the secure establishment and management of mRSVP-TE MPLS-TE LSPs. This includes, but is not limited to: