draft-ietf-mpls-targeted-mldp-02.txt   draft-ietf-mpls-targeted-mldp-03.txt 
MPLS Working Group Maria Napierala MPLS Working Group Maria Napierala
Internet Draft AT&T Internet Draft AT&T
Intended Status: Standards Track Intended Status: Standards Track
Expires: December 24, 2013 Eric C. Rosen Expires: February 5, 2014 Eric C. Rosen
IJsbrands Wijnands IJsbrands Wijnands
Cisco Systems, Inc. Cisco Systems, Inc.
June 24, 2013 August 5, 2013
Using LDP Multipoint Extensions on Targeted LDP Sessions Using LDP Multipoint Extensions on Targeted LDP Sessions
draft-ietf-mpls-targeted-mldp-02.txt draft-ietf-mpls-targeted-mldp-03.txt
Abstract Abstract
As specified in RFC 6388, Label Distribution Protocol (LDP) can be As specified in RFC 6388, Label Distribution Protocol (LDP) can be
used to set up Point-to-Multipoint (P2MP) and Multipoint-to- used to set up Point-to-Multipoint (P2MP) and Multipoint-to-
Multipoint (MP2MP) Label Switched Paths. However, RFC 6388 Multipoint (MP2MP) Label Switched Paths. However, RFC 6388
presupposes that the two endpoints of an LDP session are directly presupposes that the two endpoints of an LDP session are directly
connected. The LDP base specification (RFC 5036) allows for the case connected. The LDP base specification (RFC 5036) allows for the case
where the two endpoints of an LDP session are not directly connected; where the two endpoints of an LDP session are not directly connected;
such a session is known as a "Targeted LDP" session. This document such a session is known as a "Targeted LDP" session. This document
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Table of Contents Table of Contents
1 Introduction .......................................... 3 1 Introduction .......................................... 3
1.1 Targeted mLDP ......................................... 3 1.1 Targeted mLDP ......................................... 3
1.2 Targeted mLDP and the Upstream LSR .................... 3 1.2 Targeted mLDP and the Upstream LSR .................... 3
1.2.1 Selecting the Upstream LSR ............................ 3 1.2.1 Selecting the Upstream LSR ............................ 3
1.2.2 Sending data from U to D .............................. 4 1.2.2 Sending data from U to D .............................. 4
1.3 Applicability of Targeted mLDP ........................ 5 1.3 Applicability of Targeted mLDP ........................ 5
1.4 LDP Capabilities ...................................... 5 1.4 LDP Capabilities ...................................... 5
2 Targeted mLDP with Unicast Replication ................ 5 2 Targeted mLDP with Unicast Replication ................ 6
3 Targeted mLDP with Multicast Tunneling ................ 6 3 Targeted mLDP with Multicast Tunneling ................ 7
4 IANA Considerations ................................... 8 4 IANA Considerations ................................... 8
5 Security Considerations ............................... 8 5 Security Considerations ............................... 8
6 Acknowledgments ....................................... 8 6 Acknowledgments ....................................... 8
7 Authors' Addresses .................................... 8 7 Authors' Addresses .................................... 9
8 Normative References .................................. 9 8 Normative References .................................. 9
1. Introduction 1. Introduction
1.1. Targeted mLDP 1.1. Targeted mLDP
The Label Distribution Protocol (LDP) extensions for setting up The Label Distribution Protocol (LDP) extensions for setting up
Point-to-MultiPoint (P2MP) Label Switched Paths (LSPs) and Point-to-MultiPoint (P2MP) Label Switched Paths (LSPs) and
Multipoint-to-Multipoint (MP2MP) LSPs are specified in [mLDP]. This Multipoint-to-Multipoint (MP2MP) LSPs are specified in [mLDP]. This
set of extensions is generally known as "Multipoint LDP" (mLDP). set of extensions is generally known as "Multipoint LDP" (mLDP).
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LSR" for <R,X>. LSR" for <R,X>.
- If the "next hop interface" on D's path to R is an RSVP-TE P2P - If the "next hop interface" on D's path to R is an RSVP-TE P2P
tunnel whose remote endpoint is U, and if there is known to be an tunnel whose remote endpoint is U, and if there is known to be an
RSVP-TE P2P tunnel from U to D, and if there is a Targeted LDP RSVP-TE P2P tunnel from U to D, and if there is a Targeted LDP
session between U and D, then we allow D to select U as the session between U and D, then we allow D to select U as the
"upstream LSR" for <R,X>. This is useful when D and U are part "upstream LSR" for <R,X>. This is useful when D and U are part
of a network area that is fully meshed via RSVP-TE P2P tunnels. of a network area that is fully meshed via RSVP-TE P2P tunnels.
The particular method used to select an "upstream LSR" is determined The particular method used to select an "upstream LSR" is determined
by the SP. Other methods than the ones above MAY be used. by the Service Provider (SP). The method to use is determined by
provisioning; whichever method is used, must be known a priori to all
the LSRs involved.
Other methods than the two specified above MAY be used; however the
specification of other methods is outside the scope of this document.
1.2.2. Sending data from U to D 1.2.2. Sending data from U to D
By using Targeted mLDP, we can construct an MP-LSP <R,X> containing By using Targeted mLDP, we can construct an MP-LSP <R,X> containing
an LSR U, where U has one or more downstream LSR neighbors (D1, ..., an LSR U, where U has one or more downstream LSR neighbors (D1, ...,
Dn) to which it is not directly connected. In order for a data Dn) to which it is not directly connected. In order for a data
packet to travel along this MP-LSP, U must have some way of packet to travel along this MP-LSP, U must have some way of
transmitting the packet to D1, ..., Dn. We will cover two methods of transmitting the packet to D1, ..., Dn. We will cover two methods of
transmission: transmission:
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with downstream LSRs D2 and D3. Suppose also that there is a with downstream LSRs D2 and D3. Suppose also that there is a
multicast tunnel with U as root and with D1, D2, and D3 as leaf multicast tunnel with U as root and with D1, D2, and D3 as leaf
nodes. U can aggregate both MP-LSPs in this one tunnel. nodes. U can aggregate both MP-LSPs in this one tunnel.
However, D1 will have to discard packets that are traveling on However, D1 will have to discard packets that are traveling on
<R2,X1>, while D3 will have to discard packets that are traveling <R2,X1>, while D3 will have to discard packets that are traveling
on <R1,X2>. on <R1,X2>.
1.3. Applicability of Targeted mLDP 1.3. Applicability of Targeted mLDP
When LSR D is setting up MP-LSP <R,X>, it MUST NOT use targeted mLDP When LSR D is setting up MP-LSP <R,X>, it MUST NOT use targeted mLDP
unless D can select the "upstream LSR" for <R,X> using one of the unless D implements a procedure that can select, as the "upstream
procedures discussed in section 1.3.1. LSR" for <R,X>, an LSR U that is a Targeted mLDP peer of D. See
section 1.2.1.
Whether D uses Targeted mLDP when this condition holds is determined Whether D uses Targeted mLDP when this condition holds is determined
by provisioning, or by other methods that are outside the scope of by provisioning, or by other methods that are outside the scope of
this specification. this specification.
When Targeted mLDP is used, the choice between unicast replication When Targeted mLDP is used, the choice between unicast replication
and multicast tunneling is determined by provisioning, or by other and multicast tunneling is determined by provisioning, or by other
methods that are outside the scope of this specification. methods that are outside the scope of this specification. It is
presupposed that all nodes will have a priori knowledge of whether to
use unicast replication or to use multicast tunneling. If the
latter, it is presupposed that all nodes will have a priori knowledge
of the type of multicast tunneling to use.
1.4. LDP Capabilities 1.4. LDP Capabilities
Per [mLDP], any LSR that needs to set up an MP-LSP must support the Per [mLDP], any LSR that needs to set up an MP-LSP must support the
procedures of [LDP-CAP], and in particular must send and receive the procedures of [LDP-CAP], and in particular must send and receive the
P2MP Capability and/or the MP2MP Capability. This specification does P2MP Capability and/or the MP2MP Capability. This specification does
not define any new capabilities; the advertisement of the P2MP and/or not define any new capabilities; the advertisement of the P2MP and/or
MP2MP Capabilities on a Targeted LDP session means that the MP2MP Capabilities on a Targeted LDP session means that the
advertising LSR is capable of following the procedures of this advertising LSR is capable of following the procedures of this
document. document.
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Some of the procedures of this document require the use of upstream- Some of the procedures of this document require the use of upstream-
assigned labels [LDP-UP]. In order to use upstream-assigned labels assigned labels [LDP-UP]. In order to use upstream-assigned labels
as part of Targeted mLDP, an LSR must advertise the LDP Upstream- as part of Targeted mLDP, an LSR must advertise the LDP Upstream-
Assigned Label Capability [LDP-UP] on the Targeted LDP session. Assigned Label Capability [LDP-UP] on the Targeted LDP session.
2. Targeted mLDP with Unicast Replication 2. Targeted mLDP with Unicast Replication
When unicast replication is used, the mLDP procedures are exactly the When unicast replication is used, the mLDP procedures are exactly the
same as described in [mLDP], with the following exception. If LSR D same as described in [mLDP], with the following exception. If LSR D
is setting up MP-LSP <R,X>, its "upstream LSR" is selected according is setting up MP-LSP <R,X>, its "upstream LSR" is selected according
to the procedures of section 1.3.1, and is not necessarily the "IGP to the procedures of section 1.2.1, and is not necessarily the "IGP
next hop" on D's path to R. next hop" on D's path to R.
Suppose that LSRs D1 and D2 are both setting up the P2MP MP-LSP Suppose that LSRs D1 and D2 are both setting up the P2MP MP-LSP
<R,X>, and that LSR U is the upstream LSR on each of their paths to <R,X>, and that LSR U is the upstream LSR on each of their paths to
R. D1 and D2 each binds a label to <R,X>, and each uses a label R. D1 and D2 each binds a label to <R,X>, and each uses a label
mapping message to inform U of the label binding. Suppose D1 has mapping message to inform U of the label binding. Suppose D1 has
assigned label L1 to <R,X> and D2 has assigned label L2 to <R,X>. assigned label L1 to <R,X> and D2 has assigned label L2 to <R,X>.
(Note that L1 and L2 could have the same value or different values; (Note that L1 and L2 could have the same value or different values;
D1 and D2 do not coordinate their label assignments.) When U has a D1 and D2 do not coordinate their label assignments.) When U has a
packet to transmit on the MP-LSP <R,X>, it makes a copy of the packet to transmit on the MP-LSP <R,X>, it makes a copy of the
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This document has no considerations for IANA. This document has no considerations for IANA.
5. Security Considerations 5. Security Considerations
This document raises no new security considerations beyond those This document raises no new security considerations beyond those
discussed in [LDP], [LDP-UP], and [RFC5331]. discussed in [LDP], [LDP-UP], and [RFC5331].
6. Acknowledgments 6. Acknowledgments
The authors wish to think Lizhong Jin for his comments. The authors wish to think Lizhong Jin and Lizhen Bin for their
comments.
7. Authors' Addresses 7. Authors' Addresses
Maria Napierala Maria Napierala
AT&T Labs AT&T Labs
200 Laurel Avenue, Middletown, NJ 07748 200 Laurel Avenue, Middletown, NJ 07748
E-mail: mnapierala@att.com E-mail: mnapierala@att.com
Eric C. Rosen Eric C. Rosen
Cisco Systems, Inc. Cisco Systems, Inc.
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