Hi Patrice,
Please find attached the draft updated, please let me know if this address your comments.
Thanks,
Sami
On 5/18/17, 12:44 PM, "Patrice Brissette (pbrisset)" <pbrisset@xxxxxxxxx> wrote:
>Thank Sami
>
>Regards,
>Patrice Brissette
>
>On 2017-05-18, 12:25 PM, "Sami Boutros" <sboutros@xxxxxxxxxx> wrote:
>
> Hi Patrice,
>
>
>
>
> Please see comments inline.
>
> > >
> > >Here are my “detailed” comments:
> > >
> > >Abstract — What is the plus value on that draft? No clear
> > >
> > >Many Long sentences in the text. very hard to understand and follow.
> > >Syntax to be improved.
> >
> ><Patrice> This comment is regarding the draft in general. It doesn’t flow well. You need to read it more than once to see the overall picture. It might just be to reshuffle some sections.
> >
>
> Sure will look into that.
>
> >
> > I went over the abstract, I didn’t see any long sentences. Not sure
> > What to improve? Can you be specific?
> >
> >
> > >
> > >Introduction
> > >Typo : “A reference model or a P2MP PW is depicted in Figure 1 below”
> > >
> > >“In this document, we specify a method of signaling P2MP
> > > PW using LDP.” —> suggest to move it from intro to abstract
> >
> > Not sure if we can reference a figure in the abstract. The abstract
> > Already mention that the second sentence.
> >
> ><Patrice> This is NOT a figure but rather the explanation. That line makes the document very clear. It just need to be spelled out. “specify a method of signaling P2MP PW using LDP”.
>
> This is exactly what we have in the abstract first sentence “This document specifies a mechanism to signal Point-to-Multipoint
> (P2MP) Pseudowires (PW) tree using LDP.”
>
> >
> > >
> > >
> > >Also, make sure the 3rd person is used. Try to a void “we” usage
> >
> > Agreed, I will remove all usage of “we” in the document.
> >
> > >
> > >May I suggest to have a requirement section. Requirements are all over
> > >the document.
> >
> > There is already an RFC for that. [RFC7338] F. Jounay, et. al,
> > "Requirements for Point to Multipoint Pseudowire", RFC7338, September 2014.
> >
> > This solution document addresses the requirements.
> >
> ><Patrice> Your document enhances that based RFC by providing more “MUST”, “SHOULD”, etc.
> >They are all over the doc. To make it clear, grouping them in a section may help. Another idea is to have Requirement sub-sections per topic.
>
> It seems that this is the same as your document flow comment above, I will look into that.
>
> >
> >
> > >
> > >“ In case of mLDP, a Leaf-PE can decide to join the P2MP LSP at any
> > > time; whereas in the case of RSVP-TE, the P2MP LSP is set up by
> > >the
> > > R-PE, generally at the initial service provisioning time. It
> > >should
> > > be noted that local policy can override any decision to join, add
> > >or
> > > prune existing or new L-PE(s) from the tree. In any case, the PW
> > > setup can ignore these differences, and simply assume that the
> > >P2MP
> > > PSN LSP is available when needed
> > >“
> > >Quite complex to follow. Missing to “why” / explanation.
> >
> > Sure I can clarify this a little more, will remove some sentences
> > That make it confusing, we are simply here differentiating mLDP LSP from
> > p2mp LSP w/ RSVP-TE and saying that PW setup is agnostic of the transport
> > p2mp LSP setup.
> >
> > >
> > >“The LDP liberal label retention mode is used“
> > >Another requirement… is that a MAY, SHOULD, MUST?
> >
> > I will change it to a MUST.
> >
> > >
> > >“In this case, a PW status message with status
> > > code of 0x00000008 (Local PSN-facing PW (ingress) Receive Fault)
> > >MUST
> > > also be sent to the R-PE“
> > >
> > >How? The L-PE fails to join the P2MP PSN LSP.
> >
> > Correct the L-PE have to signal this failure to the root PE.
> >
> ><Patrice> question remains, how? If L-PE fails to join the LSP, PW will be down. How can it signals the failure to root PE?
> >
>
> L-PE will use the PW status message, to signal to root PE this is what the text is saying.
>
> > >
> > >Section 2.2
> > >“ Note that since the LDP label mapping message is only sent by the
> > >R-
> > > PE to all the L-PEs, it is not possible to negotiate any interface
> > > parameters.“
> > >Why is that note there? Is that already been mentioned previously.
> >
> > This is the only reference in the document.
> >
> ><Patrice> Forgot my thoughts on that one.
> >
> > >Fig.4 must be moved to proper in the text OR create 2 subsection in
> > >2.2
> >
> > Sorry didn’t get what you mean here? Can you elaborate?
> >
> ><Patrice> Sorry …Let me try again. “P2P PW Downstream FEC Element”. I think you should have a section just on that topic. Actually, maybe you can create a subsection for each different FEC explained in the document.
> >
>
> Ok, I will add subsections for Downstream and Upstream.
>
> Thanks,
>
> Sami
> > >
> > >“As such, PW status negotiation procedure
> > > described in [RFC4447bis] is not applicable to P2MP PW. A node
> > >MUST
> > > NOT claim to be P2MP PW capable by sending a LDP P2MP PW
> > >Capability
> > > TLV if it is not also capable of handling PW status“
> > >
> > >Should a node send LDP P2MP PW Capability TLV or not? Not well explain
> >
> > What is said here, that you can’t be P2MP PW capable without being PW status capable.
> > Not sure how to make it clearer.
> >
> ><Patrice> right… I must have been tired. Too many NOT
> >
> > >
> > >
> > >There is some reference to LSR in the text where the major part use
> > >the wording “node”.
> >
> > I will make all consistent, and use LSR instead of node.
> >
> > Thanks,
> >
> > Sami
> > >
> > >Nits:
> > >N/A
> > >
> > >Regards,
> > >Patrice Brissette
> > >
> > >
> > >
> > >
> >
> >
>
>
INTERNET-DRAFT Sami Boutros(Ed.)
Intended Status: Standard Track VMware
Updates: RFC7385 Siva Sivabalan(Ed.)
Cisco Systems
Expires: December 12, 2017 June 10, 2017
Signaling Root-Initiated Point-to-Multipoint Pseudowire using LDP
draft-ietf-pals-p2mp-pw-03.txt
Abstract
This document specifies a mechanism to signal Point-to-Multipoint
(P2MP) Pseudowires (PW) tree using LDP. Such a mechanism is suitable
for any Layer 2 VPN service requiring P2MP connectivity over an IP or
MPLS enabled PSN. A P2MP PW established via the proposed mechanism is
root initiated. This document updates RFC7385 by re-assigning
reserved value 0xFF to be the wildcard transport tunnel type.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
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and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
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http://www.ietf.org/shadow.html
Copyright and License Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Signaling P2MP PW . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 PW ingress to egress incompatibility issues . . . . . . . . 6
2.2 P2MP PW FEC . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.1 P2MP PW Upstream FEC Element . . . . . . . . . . . . . . 6
2.2.2 P2P PW Downstream FEC Element . . . . . . . . . . . . . 10
2.3 Typed Wildcard FEC Format for new FEC . . . . . . . . . . . 10
2.4 Group ID usage . . . . . . . . . . . . . . . . . . . . . . . 11
2.5 Generic Label TLV . . . . . . . . . . . . . . . . . . . . . 11
3. LDP Capability Negotiation . . . . . . . . . . . . . . . . . . 11
4. P2MP PW Status . . . . . . . . . . . . . . . . . . . . . . . . 13
5 Security Considerations . . . . . . . . . . . . . . . . . . . . 13
6 Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . 13
7 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 13
7.1. FEC Type Name Space . . . . . . . . . . . . . . . . . . . . 13
7.2. LDP TLV Type . . . . . . . . . . . . . . . . . . . . . . . 14
7.3. mLDP Opaque Value Element TLV Type . . . . . . . . . . . . 14
7.4. Selective Tree Interface Parameter sub-TLV Type . . . . . . 14
7.5. WildCard PMSI tunnel type . . . . . . . . . . . . . . . . . 14
8 References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1. Normative References . . . . . . . . . . . . . . . . . . . 15
8.2. Informative References . . . . . . . . . . . . . . . . . . 16
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1 Introduction
A Point-to-Multipoint (P2MP) Pseudowire (PW) emulates the essential
attributes of a unidirectional P2MP Telecommunications service such
as P2MP ATM over PSN. A major difference between a Point-to-Point
(P2P) PW outlined in [RFC3985] and a P2MP PW is that the former is
intended for bidirectional service whereas the latter is intended for
both unidirectional, and optionally bidirectional service.
Requirements for P2MP PW are described in [RFC7338]. P2MP PW can be
constructed as either Single Segment (P2MP SS-PW) or Multi Segment
(P2MP MS-PW) Pseudowires as mentioned in [RFC7338]. P2MP MS-PW is
outside the scope of this document. A reference model or a P2MP PW is
depicted in Figure 1 below. A transport LSP associated with a P2MP
SS-PW SHOULD be a P2MP MPLS LSP (i.e., P2MP TE tunnel established via
RSVP-TE [RFC4875] or P2MP LSP established via mLDP [RFC6388])
spanning from the Root-PE to the Leaf-PE(s) of the P2MP SS-PW tree.
For example, in Figure 1, PW1 can be associated with a P2MP TE tunnel
or P2MP LSP setup using mLDP originating from PE1 and terminating at
PE2, PE3 and PE4.
|<--------------P2MP PW---------------->|
Native | | Native
Service | |<--PSN1->| |<--PSN2->| | Service
(AC) V V V V V V (AC)
| +-----+ +------+ +------+ |
| | | | P1 |=========|T-PE2 |AC3 | +---+
| | | | .......PW1.........>|-------->|CE3|
| |T-PE1|=========| . |=========| | | +---+
| | .......PW1........ | +------+ |
| | . |=========| . | +------+ |
| | . | | . |=========|T-PE3 |AC4 | +---+
+---+ |AC1 | . | | .......PW1.........>|-------->|CE4|
|CE1|------->|... | | |=========| | | +---+
+---+ | | . | +------+ +------+ |
| | . | +------+ +------+ |
| | . |=========| P2 |=========|T-PE4 |AC5 | +---+
| | .......PW1..............PW1.........>|-------->|CE5|
| | |=========| |=========| | | +---+
| +-----+ +------+ +------+ |
Figure 1: P2MP PW
Mechanisms for establishing P2P SS-PW using LDP are described in
[RFC4447bis]. This document specify a method of signaling P2MP PW
using LDP. In particular, this document defines new FEC, TLVs,
parameters, and status codes to facilitate LDP to signal and maintain
P2MP PWs.
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As outlined in [RFC7338], even though the traffic flow from a Root-PE
(R-PE) to Leaf-PE(s) (L-PEs) is P2MP in nature, it may be desirable
for any L-PE to send unidirectional P2P traffic destined only to the
R-PE. The proposed mechanism takes such option into consideration.
The P2MP PW requires an MPLS LSP to carry the PW traffic, and the
MPLS packets carrying the PW upstream label will be encapsulated
according to the methods described in [RFC5332].
1.1 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
FEC: Forwarding Equivalence Class
LDP: Label Distribution Protocol
mLDP: Label Distribution Protocol for P2MP/MP2MP LSP
LSP: Label Switching Path
MS-PW: Multi-Segment Pseudowire
P2P: Point to Point
P2MP: Point to Multipoint
PE: Provider Edge
PSN: Packet Switched Network
PW: Pseudowire
SS-PW: Single-Segment Pseudowire
S-PE: Switching Provider Edge of MS-PW
TE: Traffic Engineering
R-PE: Root-PE - ingress PE, PE initiating P2MP PW setup.
L-PE: Leaf-PE - egress PE.
2. Signaling P2MP PW
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In order to advertise labels as well as exchange PW related LDP
messages, PEs must establish LDP sessions among themselves. A PE
discovers other PEs that are to be connected via P2MP PWs either via
manual configuration or autodiscovery [RFC6074].
R-PE and each L-PE MUST be configured with the same FEC as defined in
the following section.
P2MP PW requires that there is an active P2MP PSN LSP set up between
R-PE and L-PE(s). Note that the procedure to set up the P2MP PSN LSP
is different depending on the signaling protocol used (RSVP-TE or
mLDP).
In case of mLDP, a Leaf-PE can decide to join the P2MP LSP at any
time. In the case of RSVP-TE, the P2MP LSP is set up by the R-PE,
generally at the initial service provisioning time. It should be
noted that local policy can override any decision to join, add or
prune existing or new L-PE(s) from the tree. In any case, the PW
setup can ignore these differences, and simply assume that the P2MP
PSN LSP is available when needed.
P2MP PW signaling is initiated by the R-PE which sends a separate
P2MP-PW LDP label mapping message to each of the the L-PE(s)
belonging to that P2MP PW. This label mapping message will contain
the following:
1. A FEC TLV containing P2MP PW Upstream FEC element that
includes Transport LSP sub TLV.
2. An Interface Parameters TLV, as described in [RFC4447bis].
3. A PW Grouping TLV, as described in [RFC4447bis].
4. A label TLV for the upstream-assigned label used by R-PE
for the traffic going from R-PE to L-PE(s).
The R-PE imposes the upstream-assigned PW label on the outbound
packets sent over the P2MP-PW, and using this label an L-PE
identifies the inbound packets arriving over the P2MP PW.
Additionally, the R-PE MAY send label mapping message(s) to one or
more L-PE(s) to signal unidirectional P2P PW(s). The L-PE(s) can use
such PW(s) to send traffic to the R-PE. This optional label mapping
message will contain the following:
1. P2P PW Downstream FEC element.
2. A label TLV for the down-stream assigned label used by the
corresponding L-PE to send traffic to the R-PE.
The LDP liberal label retention mode MUST be used, and per
requirements specified in [RFC5036], the Label Request message MUST
also be supported.
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The upstream-assigned label is allocated according to the rules in
[RFC5331].
When an L-PE receives a PW Label Mapping Message, it MUST verify the
associated P2MP PSN LSP is in place. If the associated P2MP PSN LSP
is not in place, and its type is LDP P2MP LSP, the L-PE MUST attempt
to join the P2MP LSP associated with the P2MP PW. If the associated
P2MP PSN LSP is not in place, and its type is RSVP-TE P2MP LSP, the
L-PE SHOULD wait till the P2MP transport LSP is signaled. If an L-PE
fails to join the P2MP PSN LSP, that L-PE MUST not enable the PW, and
MUST notify the user. In this case, a PW status message with status
code of 0x00000008 (Local PSN-facing PW (ingress) Receive Fault) MUST
also be sent to the R-PE.
2.1 PW ingress to egress incompatibility issues
If an R-PE signals a PW with a pw type, CW mode, or interface
parameters that a particular L-PE cannot accept, then the L-PE MUST
not enable the PW, and notify the user. In this case, a PW status
message with status code of 0x00000001 (Pseudowire Not Forwarding)
MUST also be sent to the R-PE.
Note that this procedure does not apply if the L-PE had not been
provisioned with this particular P2MP PW. In this case according to
the LDP liberal label retention rules, no action is taken.
2.2 P2MP PW FEC
[RFC4447bis] specifies two types of LDP FEC elements called "PWid FEC
Element" and "Generalized PWid FEC Element" used to signal P2P PWs.
This document defines two new types of FEC elements called "P2MP PW
Upstream FEC Element" and "P2P PW Downstream FEC Element". These FEC
elements are associated with a mandatory upstream assigned label and
an optional downstream assigned label respectively.
2.2.1 P2MP PW Upstream FEC Element
A new FEC type for the P2MP PW Upstream FEC Element is encoded as
follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P2MP PW Up=0x82|C| PW Type | PW Info Length|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AGI Type | Length | AGI Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ AGI Value (contd.) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII Type | Length | SAII Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ SAII Value (contd.) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|PMSI Tunnel typ| Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+ +
~ Transport LSP ID ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Optional Parameters |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: P2MP PW Upstream FEC Element
* P2MP PW Up:
8 bits representation for the P2MP PW Upstream FEC type.
* PW Type:
15 bits representation of PW type as specified in [RFC4447].
* C bit:
A value of 1 or 0 indicates whether control word is present or absent
for the P2MP PW.
* PW Info Length:
Sum of the lengths of AGI, SAII, PMSI Tunnel info, and Optional
Parameters field in octets. If this value is 0, then it references
all PWs using the specified grouping ID. In this case, there are
neither other FEC element fields (AGI, SAII, etc.) present, nor any
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interface parameters TLVs. Alternatively, typed wildcard FEC
described in section 3.3, can be used to achieve the same or to have
better filtering.
* AGI:
Attachment Group Identifier can be used to uniquely identify VPN or
VPLS instance associated with the P2MP PW. This has the same format
as the Generalized PWid FEC element [RFC4447bis].
* SAII:
Source Attachment Individual Identifier is used to identify the root
of the P2MP PW. The root is represented using AII type 2 format
specified in [RFC5003]. Note that the SAII can be omitted by simply
setting the length and type to zero.
P2MP PW is identified by the Source Attachment Identifier (SAI). If
the AGI is non-null, the SAI is the combination of the SAII and the
AGI, if the AGI is null, the SAI is the SAII.
* PMSI Tunnel Type and Transport LSP ID:
A P2MP PW MUST be associated with a transport LSP which can be
established using RSVP-TE or mLDP.
* PMSI Tunnel Type:
The PMSI tunnel type is defined in [RFC6514].
When the type is set to mLDP P2MP LSP, the Tunnel Identifier is a
P2MP FEC Element as defined in [RFC6388]. A new mLDP Opaque Value
Element type for L2VPN-MCAST application as specified in the IANA
considerations MUST be used.
* Transport LSP ID: This is the Tunnel Identifier which is defined in
[RFC6514].
An R-PE sends Label Mapping Message as soon as the transport LSP ID
associated with the P2MP PW is known (e.g., via configuration)
regardless of the operational state of that transport LSP. Similarly,
an R-PE does not withdraw the labels when the corresponding transport
LSP goes down. Furthermore, an L-PE retains the P2MP PW labels
regardless of the operational status of the transport LSP.
Note that a given transport LSP can be associated with more than one
P2MP PWs in which case P2MP PWs will be sharing the same R-PE and L-
PE(s). An R-PE may also have many P2MP PWs with disjoint L-PE sets.
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In the case of LDP P2MP LSP, when an L-PE receives the Label Mapping
Message, it can initiate the process of joining the P2MP LSP tree
associated with the P2MP PW.
In the case of RSVP-TE P2MP LSP, only the R-PE initiates the
signaling of P2MP LSP.
* Optional Parameters:
The Optional Parameter field can contain some TLVs that are not part
of the FEC, but are necessary for the operation of the PW. This
proposed mechanism uses two such TLVs: Interface Parameters TLV, and
Group ID TLV.
The Interface Parameters TLV and Group ID TLV specified in
[RFC4447bis] can also be used in conjunction with P2MP PW FEC in a
label message. For Group ID TLV, the sender and receiver of these
TLVs should follow the same rules and procedures specified in
[RFC4447bis]. For Interface Parameters TLV, the procedure differs
from the one specified in [RFC4447bis] due to specifics of P2MP
connectivity. When the interface parameters are signaled by a R-PE,
each L-PE must check if its configured value(s) is less than or equal
to the threshold value provided by the R-PE (e.g. MTU size
(Ethernet), max number of concatenated ATM cells, etc)). For other
interface parameters like CEP/TDM Payload bytes (TDM), the value MUST
exactly match the values signaled by the R-PE.
Multicast traffic stream associated with a P2MP PW can be selective
or inclusive. To support the former, this document defines a new
optional Selective Tree Interface Parameter sub-TLV, as described in
the IANA considerations and according to the format described in
[RFC4447bis]. The value of the sub-TLV contains the source and the
group for a given multicast tree as shown in Figure 3. Also, if a
P2MP PW is associated with multiple selective trees, the
corresponding label mapping message will carry more than one instance
of this Sub-TLV. Furthermore, in the absence of this sub-TLV, the
P2MP PW is associated with all multicast traffic stream originating
from the root.
+----------------------------------------- +
| Sub-TLV Type (1 Octet) |
+----------------------------------------- +
| Length (1 Octet) |
+----------------------------------------- +
| Multicast Source Length (1 Octet) |
+----------------------------------------- +
| Multicast Source (variable length) |
+----------------------------------------- +
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| Multicast Group Length (1 Octet) |
+----------------------------------------- +
| Multicast Group (variable length) |
+----------------------------------------- +
Figure 3: Selective Tree Interface Parameter Sub-TLV Value
Note that since the LDP label mapping message is only sent by the R-
PE to all the L-PEs, it is not possible to negotiate any interface
parameters.
2.2.2 P2P PW Downstream FEC Element
The optional P2P PW Downstream FEC Element is encoded as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P2P PWDown=0x83|C| PW Type | PW Info Length|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AGI Type | Length | AGI Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ AGI Value (contd.) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII Type | Length | SAII Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ SAII Value (contd.) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: P2P PW Downstream FEC Element
The definition of the fields in the P2P PW Downstream FEC Element is
the same as those of P2MP PW Upstream FEC Element shown in Figure 2.
2.3 Typed Wildcard FEC Format for new FEC
[RFC5918] defines the general notion of a "Typed Wildcard" FEC
Element, and requires FEC designer to specify a typed wildcard FEC
element for newly defined FEC element types. This document defines
two new FEC elements, "P2MP PW Upstream" and "P2P PW Downstream" FEC
element, and hence requires us to define their Typed Wildcard format.
[RFC6667] defines Typed Wildcard FEC element format for other PW FEC
Element types (PWid and Gen. PWid FEC Element) in section 2 as
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follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Typed Wcard=0x5|Type=PW FEC | Len = 3 |R| PW type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . . . | PMSI Tun Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Typed Wildcard Format for P2MP PW FEC Elements
[RFC6667] specifies that "Type" field can be either "PWid" (0x80) or
"Generalized PWid" (0x81) FEC element type. This document reuses the
existing typed wildcard format as specified in [RFC6667] and
illustrated in Figure 5 and extends the definition of "Type" field to
also include "P2MP PW Upstream" and "P2P PW Downstream" FEC element
types. This document adds an additional field "PMSI Tun Type". This
document reserves PMSI tunnel Type 0xFF to mean "wildcard" transport
tunnel type. The PMSI tunnel Type field only applies to Typed
wildcard P2MP PW Upstream FEC and MUST be set to "wildcard" for "P2P
PW Downstream FEC" typed wildcard element.
2.4 Group ID usage
The Grouping TLV as defined in [RFC4447bis] contains a group ID
capable of indicating an arbitrary group membership of a P2MP-PW.
This group ID can be used in LDP "wild card" status, and withdraw
label messages, as described in [RFC4447bis].
2.5 Generic Label TLV
As in the case of P2P PW signaling, P2MP PW labels are carried within
Generic Label TLV contained in LDP Label Mapping Message. A Generic
Label TLV is formatted and processed as per the rules and procedures
specified in [RFC4447bis]. For a given P2MP PW, a single upstream-
assigned label is allocated by the R-PE, and is advertised to all L-
PEs using the Generic Label TLV in label mapping message containing
the P2MP PW Upstream FEC element.
The R-PE can also allocate a unique label for each L-PE from which it
intends to receive P2P traffic. Such a label is advertised to the L-
PE using Generic Label TLV and P2P PW Downstream FEC in label mapping
message.
3. LDP Capability Negotiation
The capability of supporting P2MP PW MUST be advertised to all LDP
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peers. This is achieved by using the methods in [RFC5561] to
advertise the LDP "P2MP PW Capability" TLV. If an LDP peer supports
the dynamic capability advertisement, this can be done by sending a
new Capability message with the S bit set for the P2MP PW capability
TLV. If the peer does not supports dynamic capability advertisement,
then the P2MP PW Capability TLV MUST be included in the LDP
Initialization message during the session establishment. An LSR
having P2MP PW capability MUST recognize both P2MP PW Upstream FEC
Element and P2P PW Downstream FEC Element in LDP label messages.
In line with requirements listed in [RFC5561], the following TLV is
defined to indicate the P2MP PW capability:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| P2MP PW Capability TLV | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S| Reserved | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: LDP P2MP PW Capability TLV
* U-bit:
SHOULD be 1 (ignore if not understood).
* F-bit:
SHOULD be 0 (don't forward if not understood).
* P2MP PW Capability TLV Code Point:
The TLV type, which identifies a specific capability. The P2MP PW
capability code point is requested in the IANA allocation section
below.
* S-bit:
The State Bit indicates whether the sender is advertising or
withdrawing the P2MP PW capability. The State bit is used as
follows:
1 - The TLV is advertising the capability specified by the
TLV Code Point.
0 - The TLV is withdrawing the capability specified by the
TLV Code Point.
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* Length:
MUST be set to 2 (octet).
4. P2MP PW Status
In order to support the proposed mechanism, an LSR MUST be capable of
handling PW status. As such, PW status negotiation procedure
described in [RFC4447bis] is not applicable to P2MP PW. An LSR MUST
NOT claim to be P2MP PW capable by sending a LDP P2MP PW Capability
TLV if it is not also capable of handling PW status.
Once an L-PE successfully processes a Label Mapping Message for a
P2MP PW, it MUST send appropriate PW status according to the
procedure specified [RFC4447bis] to report the PW status. If no PW
status notification is required, then no PW status notification is
sent (for example if the P2MP PW is established and operational with
a status code of Success (0x00000000), a PW status message is not
necessary). A PW status message sent from an L-PE to R-PE MUST
contain the P2P PW Downstream FEC to identify the PW.
An R-PE also sends PW status to L-PE(s) to reflect its view of a P2MP
PW state. Such PW status message contains P2MP PW Upstream FEC to
identify the PW.
Connectivity status of the underlying P2MP LSP that P2MP PW is
associated with, can be verified using LSP Ping and Traceroute
procedures described in [RFC6425].
5 Security Considerations
The security measures described in [RFC4447bis] are adequate for the
proposed mechanism.
6 Acknowledgment
Authors would like thank Andre Pelletier and Parag Jain for their
valuable suggestions.
7 IANA Considerations
7.1. FEC Type Name Space
This document uses two new FEC element types, number 0x82 and 0x83
are suggested for assignment from the registry "FEC Type Name Space"
for the Label Distribution Protocol (LDP RFC5036):
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Value Hex Name Reference
------- ----- ----------------------------- ---------
130 0x82 P2MP PW Upstream FEC Element RFCxxxx
131 0x83 P2P PW Downstream FEC Element RFCxxxx
7.2. LDP TLV Type
This document uses a new LDP TLV types, IANA already maintains a
registry of name "TLV TYPE NAME SPACE" defined by RFC5036. The
following values are suggested for assignment:
TLV type Description:
0x0703 P2MP PW Capability TLV
7.3. mLDP Opaque Value Element TLV Type
This document requires allocation of a new mLDP Opaque Value Element
Type from "LDP MP Opaque Value Element basic type" name space defined
in [RFC6388].
The following value is suggested for assignment:
TLV type Description
0x3 L2VPN-MCAST application TLV
7.4. Selective Tree Interface Parameter sub-TLV Type
This document requires allocation of a sub-TLV from the registry
"Pseudowire Interface Parameters Sub-TLV Type" defined in [RFC4446].
The following value is suggested for assignment:
TLV type Description
0x1b Selective Tree Interface Parameter.
7.5. WildCard PMSI tunnel type
This document requests that IANA modify the following entry in the
"P-Multicast Service Interface Tunnel (PMSI Tunnel) Tunnel Types"
registry within the "Border Gateway Protocol (BGP) Parameters"
namespace previously assigned by RFC7385 as "reserved".
Value Meaning Reference
0xFF wildcard transport tunnel type [This document]
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8 References
8.1. Normative References
[RFC2119] Bradner. S, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March, 1997.
[RFC4447bis] "Pseudowire Setup and Maintenance using the Label
Distribution Protocol", Martini, L., et al., draft-ietf-pals-
rfc4447bis-05.txt, July 2016.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC5003] C. Metz, L. Martini, F. Balus, J. Sugimoto, "Attachment
Individual Identifier (AII) Types for Aggregation", RFC5003,
September 2007.
[RFC5331] R. Aggarwal, Y. Rekhter, E. Rosen, "MPLS Upstream Label
Assignment and Context-Specific Label Space", RFC 5331, August 2008.
[RFC5332] T. Eckert, E. Rosen, Ed.,R. Aggarwal, Y. Rekhter, "MPLS
Multicast Encapsulations", RFC 5332, August 2008.
[RFC6388] I. Minei, K. Kompella, I. Wijnands, B. Thomas, "Label
Distribution Protocol Extensions for Point-to-Multipoint and
Multipoint-to-Multipoint Label Switched Paths", RFC 6388, November
2011.
[RFC4875] R. Aggarwal, Ed., D. Papadimitriou, Ed., S. Yasukawa, Ed.,
"Extensions to Resource Reservation Protocol - Traffic Engineering
(RSVP-TE) for Point-to-Multipoint TE Label Switched Paths (LSPs).",
RFC 4875, May 2007.
[RFC6514] R. Aggarwal, E. Rosen, T. Morin, Y. Rekhter, "BGP Encodings
and Procedures for Multicast in MPLS/BGP IP VPNs", RFC6514, February
2012.
[RFC5561] B.Thomas, K.Raza, S.Aggarwal, R.Agarwal, JL. Le Roux, "LDP
Capabilities", RFC 5561, July 2009.
[RFC5918] R. Asati, I. Minei, and B. Thomas, "LDP Typed Wildcard
Forwarding Equivalence Class", RFC 5918, August 2010.
[RFC6667] K. Raza, S. Boutros, and C. Pignataro, "LDP Typed Wildcard
FEC for PWid and Generalized PWid FEC Elements", RFC 6667, July 2012.
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8.2. Informative References
[RFC3985] Stewart Bryant, et al., "PWE3 Architecture", RFC3985
[RFC6074] E. Rosen,W. Luo,B. Davie,V. Radoaca "Provisioning, Auto-
Discovery, and Signaling in Layer 2 Virtual Private Networks
(L2VPNs)", RFC6074, January 2011.
[RFC7338] F. Jounay, et. al, "Requirements for Point to Multipoint
Pseudowire", RFC7338, September 2014.
[RFC6425] A. Farrel, S. Yasukawa, "Detecting Data Plane Failures in
Point-to-Multipoint Multiprotocol Label Switching (MPLS)- Extensions
to LSP Ping", RFC6425, November 2011.
Contributors
The following co-authors have also contributed to this document:
Luca Martini
Cisco Systems, Inc.
Email: lmartini@xxxxxxxxx
Maciek Konstantynowicz
Cisco Systems, Inc.
e-mail: maciek@xxxxxxxxx
Gianni Del Vecchio
Swisscom
Email: Gianni.DelVecchio@xxxxxxxxxxxx
Thomas D. Nadeau
Brocade
Email: tnadeau@xxxxxxxxxxxxxxx
Frederic Jounay
Orange CH
Email: Frederic.Jounay@xxxxxxx
Philippe Niger
Orange CH
Email: philippe.niger@xxxxxxxxxx
Yuji Kamite
NTT Communications Corporation
Email: y.kamite@xxxxxxx
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Lizhong Jin
Email: lizho.jin@xxxxxxxxx
Martin Vigoureux
Nokia
Email: martin.vigoureux@xxxxxxxxx
Laurent Ciavaglia
Nokia
Email: laurent.ciavaglia@xxxxxxxxx
Simon Delord
Telstra
E-mail: simon.delord@xxxxxxxxx
Kamran Raza
Cisco Systems
Email: skraza@xxxxxxxxx
Authors' Addresses
Sami Boutros
VMware Inc.
Email: sboutros@xxxxxxxxxx
Siva Sivabalan
Cisco Systems, Inc.
Email: msiva@xxxxxxxxx
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