Internet DRAFT - draft-ietf-mpls-app-aware-tldp
draft-ietf-mpls-app-aware-tldp
MPLS Working Group Santosh Esale
INTERNET-DRAFT Raveendra Torvi
Updates: 7473 (if approved) Juniper Networks
Intended Status: Proposed Standard Luay Jalil
Expires: December 29, 2017 Verizon
Uma Chunduri
Huawei
Kamran Raza
Cisco Systems, Inc.
June 27, 2017
Application-aware Targeted LDP
draft-ietf-mpls-app-aware-tldp-09
Abstract
Recent targeted Label Distribution Protocol (tLDP) applications such
as remote loop-free alternate (LFA) and BGP auto discovered
pseudowire may automatically establish a tLDP session to any Label
Switching Router (LSR) in a network. The initiating LSR has
information about the targeted applications to administratively
control initiation of the session. However, the responding LSR has no
such information to control acceptance of this session. This document
defines a mechanism to advertise and negotiate Targeted Applications
Capability (TAC) during LDP session initialization. As the
responding LSR becomes aware of targeted applications, it may
establish a limited number of tLDP sessions for certain applications.
In addition, each targeted application is mapped to LDP Forwarding
Equivalence Class (FEC) Elements to advertise only necessary LDP FEC-
label bindings over the session. This document updates RFC 7473 for
enabling advertisement of LDP FEC-label bindings over the session.
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
Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
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."
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The list of current Internet-Drafts can be accessed at
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Copyright and License Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Conventions Used in This Document . . . . . . . . . . . . . 4
1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Targeted Application Capability . . . . . . . . . . . . . . . . 5
2.1 Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 LDP message procedures . . . . . . . . . . . . . . . . . . . 8
2.3.1 Initialization message . . . . . . . . . . . . . . . . . 8
2.3.2 Capability message . . . . . . . . . . . . . . . . . . . 9
3. Targeted Application FEC Advertisement Procedures . . . . . . . 9
4. Interaction of Targeted Application Capabilities and State
Advertisement Control Capabilities . . . . . . . . . . . . . . 10
5. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1 Remote LFA Automatic Targeted session . . . . . . . . . . . 12
5.2 FEC 129 Auto Discovery Targeted session . . . . . . . . . . 13
5.3 LDP over RSVP and Remote LFA targeted session . . . . . . . 13
5.4 mLDP node protection targeted session . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 15
9. Contributing Authors . . . . . . . . . . . . . . . . . . . . . 15
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
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10.1 Normative References . . . . . . . . . . . . . . . . . . . 16
10.2 Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1 Introduction
LDP uses the extended discovery mechanism to establish the tLDP
adjacency and subsequent session as described in [RFC5036]. A LSR
initiates extended discovery by sending tLDP Hello to specific
address. The remote LSR decides to either accept or ignore the tLDP
Hello based on local configuration only. Targeted LDP application is
an application that uses tLDP session to exchange information such as
FEC-Label bindings with a peer LSR in the network. For an application
such as FEC 128 pseudowire, the remote LSR is configured with the
source LSR address so that it can use that information to accept or
ignore given tLDP Hello.
However, applications such as Remote LFA and BGP auto discovered
pseudowire automatically initiate asymmetric extended discovery to
any LSR in a network based on local state only. With these
applications, the remote LSR is not explicitly configured with the
source LSR address. So the remote LSR either responds or ignores all
tLDP Hellos.
In addition, since the session is initiated and established after
adjacency formation, the responding LSR has no targeted applications
information available to choose a session with targeted application
that it is configured to support. Also, the initiating LSR may employ
a limit per application on locally initiated automatic tLDP sessions,
however the responding LSR has no such information to employ a
similar limit on the incoming tLDP sessions. Further, the responding
LSR does not know whether the source LSR is establishing a tLDP
session for configured, automatic or both applications.
This document proposes and describes a solution to advertise Targeted
Application Capability (TAC), consisting of a targeted application
list, during initialization of a tLDP session. It also defines a
mechanism to enable an new application and disable an old application
after session establishment. This capability advertisement provides
the responding LSR with the necessary information to control the
acceptance of tLDP sessions per application. For instance, an LSR may
accept all BGP auto discovered tLDP sessions as defined in [RFC6074]
but may only accept limited number of Remote LFA tLDP sessions as
defined in [RFC7490]
Also, the targeted LDP application is mapped to LDP FEC element type
to advertise specific application FECs only, avoiding the
advertisement of other unnecessary FECs over a tLDP session.
1.1 Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119] and RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here.
1.2 Terminology
In addition to the terminology defined in [RFC7473], this document
uses the following terms:
tLDP : Targeted LDP
TAC : Targeted Application Capability
TAE : Targeted Application Element
TA-Id : Targeted Application Identifier
SAC : State Advertisement Control Capability
LSR : Label Switching Router
mLDP : Multipoint LDP
PQ : Remote-LFA nexthops
RSVP-TE : RSVP Traffic Engineering
P2MP : Point-to-Multipoint
PW : Pseudowire
P2P-PW : Point-to-point Psuedowire
MP2MP : Multipoint-to-Multipoint
HSMP LSP: Hub and Spoke Multipoint Label Switched Path
LSP : Label Switched Path
MP2P : Multipoint-to-point
MPT : Merge Point
2. Targeted Application Capability
2.1 Encoding
An LSR MAY advertise that it is capable of negotiating a targeted LDP
application list over a tLDP session by using the Capability
Advertisement as defined in [RFC5561] and 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| TLV Code Point | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S| Reserved | |
+-+-+-+-+-+-+-+-+ Capability Data |
| +-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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This document defines a new optional capability TLV of type TBD1
called 'Targeted Application Capability (TAC)'. Flag "U" MUST be
set to 1 to indicate that this capability must be silently ignored
if unknown. The TAC's Capability Data contains the Targeted
Application Element (TAE) information encoded as follows:
Targeted Application Element(TAE)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Targ. Appl. Id |E| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Targeted Application Identifier (TA-Id):
a 16 bit Targeted Application Identifier value.
E-bit: The enable bit indicates whether the sender is
advertising or withdrawing the TAE. The E-bit value is used as
follows:
1 - The TAE is advertising the targeted application.
0 - The TAE is withdrawing the targeted application.
2.2 Procedures
At tLDP session establishment time, a LSR MAY include a new
capability TLV, TAC TLV, as an optional TLV in the LDP Initialization
message. The TAC TLV's Capability data MAY consist of zero or more
TAEs each pertaining to a unique TA-Id that a LSR supports over the
session. If the receiver LSR receives the same TA-Id in more than one
TAE, it MUST process the first element and ignore the duplicate
elements. If the receiver LSR receives an unknown TA-Id in the TAE,
it MUST silently ignore such a TAE and continue processing the rest
of the TLV.
If the receiver LSR does not receive the TAC TLV in the
Initialization message or it does not understand the TAC TLV, the TAC
negotiation is considered unsuccessful and the session establishment
proceeds as per [RFC5036]. On the receipt of a valid TAC TLV, an LSR
MUST generate its own TAC TLV with TAEs consisting of unique TA-Ids
that it supports over the tLDP session. If there is at least one TAE
common between the TAC TLV it has received and its own, the session
MUST proceed to establishment as per [RFC5036]. If not, A LSR MUST
send a 'Session Rejected/Targeted Application Capability Mis-Match'
Notification message to the peer and close the session. The
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initiating LSR SHOULD tear down the corresponding tLDP adjacency
after sent or receipt of a 'Session Rejected/Targeted Application
Capability Mis-Match' Notification message to or from the responding
LSR respectively.
If both the peers support TAC TLV, an LSR decides to establish or
close a tLDP session based on the negotiated targeted application
list. For example, an initiating LSR advertises A, B and C as TA-Ids,
and the responding LSR advertises C, D and E as TA-Ids. Then the
negotiated TA-Id as per both the LSRs is C. Another example, an
initiating LSR advertises A, B and C as TA-Ids, and the responding
LSR, which acts as a passive LSR, advertises all the applications -
A, B, C, D and E - as TA-Ids that it supports over this session. Then
the negotiated targeted applications as per both the LSRs are A, B
and C. Finally, If the initiating LSR advertises A, B and C as a TA-
Ids and the responding LSR advertises D and E as TA-Ids, then the
negotiated targeted applications as per both the LSRs are none.
Therefore, if the intersection of the sets of received and sent TA-Id
is null, then LSR sends 'Session Rejected/Targeted Application
Capability Mis-Match' Notification message to the peer LSR and closes
the session.
When the responding LSR playing the active role [RFC5036] in LDP
session establishment receives a 'Session Rejected/Targeted
Application Capability Mis-Match' Notification message, it MUST set
its session setup retry interval to a maximum value, as such 0xffff.
The session MAY stay in NON EXISTENT state. When it detects a change
in the initiating LSR or local LSR configuration pertaining to TAC
TLV, it MUST clear the session setup back off delay associated with
the session to re-attempt the session establishment. A LSR detects
configuration change on the other LSR with the receipt of tLDP Hello
message that has a higher configuration sequence number than the
earlier tLDP Hello message.
When the initiating LSR playing the active role in LDP session
establishment receives a 'Session Rejected/Targeted Application
Capability Mis-Match' Notification message, either it MUST close the
session and tear down the corresponding tLDP adjacency or it MUST set
its session setup retry interval to a maximum value, as such 0xffff.
If the initiating LSR decides to tear down the associated tLDP
adjacency, the session is closed on the initiating as well as the
responding LSR. It MAY also take appropriate actions. For instance,
if an automatic session intended to support the Remote LFA
application is rejected by the responding LSR, the initiating LSR may
inform the IGP to calculate another PQ node [RFC7490] for the route
or set of routes. More specific actions are a local matter and
outside the scope of this document.
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If the initiating LSR sets the session setup retry interval to
maximum, the session MAY stay in a non-existent state. When this LSR
detects a change in the responding LSR configuration or its own
configuration pertaining to TAC TLV, it MUST clear the session setup
back off delay associated with the session in order to re-attempt the
session establishment.
After a tLDP session has been established with TAC capability, the
initiating and responding LSR MUST distribute FEC-label bindings for
the negotiated applications only. For instance, if the tLDP session
is established for BGP auto discovered pseudowire, only FEC 129 label
bindings MUST be distributed over the session. Similarly, a LSR
operating in downstream on demand mode MUST request FEC-label
bindings for the negotiated applications only.
If the Targeted Application Capability and Dynamic Capability,
described in [RFC5561], are negotiated during session initialization,
TAC MAY be re-negotiated after session establishment by sending an
updated TAC TLV in LDP Capability message. The updated TAC TLV
carries TA-Ids with incremental update only. The updated TLV MUST
consist of one or more TAEs with E-bit set or E-bit off to advertise
or withdraw the new and old application respectively. This may lead
to advertisements or withdrawals of certain types of FEC-Label
bindings over the session or tear down of the tLDP adjacency and
subsequently the session.
The Targeted Application Capability is advertised on tLDP session
only. If the tLDP session changes to link session, a LSR SHOULD
withdraw it with S bit set to 0. Similarly, if the link session
changes to tLDP, a LSR SHOULD advertise it via the Capability
message. If the capability negotiation fails, this may lead to
destruction of the tLDP session.
By default, LSR SHOULD accept tLDP hellos in order to then accept or
reject the tLDP session based on the application information.
In addition, LSR SHOULD allow the configuration of any TA-Id in order
to facilitate private TA-Id's usage by a network operator.
2.3 LDP message procedures
2.3.1 Initialization message
1. The S-bit of the Targeted Application Capability TLV MUST be
set to 1 to advertise Targeted Application Capability and
SHOULD be ignored on the receipt as defined in [RFC5561]
2. The E-bit of the Targeted Application Element MUST be set to 1 to
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enable Targeted application and SHOULD be ignored on the receipt.
3. An LSR MAY add State Control Capability by mapping Targeted
Application Element to State Advertisement Control (SAC) Elements
as defined in Section 4.
2.3.2 Capability message
The initiating or responding LSR may re-negotiate the TAC after local
configuration change with the Capability message.
1. The S-bit of TAC is set to 1 or 0 to advertise or withdraw it.
2. After configuration change, If there is no common TAE between
its new TAE list and peers TAE list, the LSR MUST send a
'Session Rejected/Targeted Application Capability Mis-Match'
Notification message and close the session.
3. If there is a common TAE, a LSR MAY also update SAC Capability
based on updated TAC as described in section 4 and send the
updated TAC and SAC capabilities in a Capability message to
the peer.
4. A receiving LSR processes the Capability message with TAC TLV.
If the S-bit is set to 0, the TAC is disabled for the session.
5. If the S-bit is set to 1, a LSR process a list of TAEs from
TACs capability data with E-bit set to 1 or 0 to update the
peer's TAE.
3. Targeted Application FEC Advertisement Procedures
The targeted LDP application MUST be mapped to LDP FEC element types
as follows to advertise only necessary LDP FEC-Label bindings over
the tLDP session.
Targeted Application Description FEC mappings
+----------------------+------------------------+------------------+
|LDPv4 Tunneling | LDP IPv4 over RSVP-TE | IPv4 prefix |
| | or other MPLS tunnel | |
+----------------------+------------------------+------------------+
| | | |
|LDPv6 Tunneling | LDP IPv6 over RSVP-TE | IPv6 prefix |
| | or other MPLS tunnel | |
+----------------------+------------------------+------------------+
|mLDP Tunneling | mLDP over RSVP-TE or | P2MP |
| | or other MPLS tunnel | MP2MP-up |
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| | | MP2MP-down |
| | | HSMP-downstream |
| | | HSMP-upstream |
+----------------------+------------------------+------------------+
| | | |
|LDPv4 Remote LFA | LDPv4 over LDPv4 or | IPv4 prefix |
| | other MPLS tunnel | |
+----------------------+------------------------+------------------+
|LDPv6 Remote LFA | LDPv6 over LDPv6 or | IPv6 prefix |
| | other MPLS tunnel | |
+----------------------+------------------------+------------------+
| | | |
|LDP FEC 128 PW | LDP FEC 128 Pseudowire | PWid FEC Element |
+----------------------+------------------------+------------------+
| | | |
|LDP FEC 129 PW | LDP FEC 129 Pseudowire | Generalized PWid |
| | | FEC Element |
+----------------------+------------------------+------------------+
| | | FEC types as |
|LDP Session Protection| LDP session protection | per protected |
| | | session |
+----------------------+------------------------+------------------+
|LDP ICCP | LDP Inter-chasis | |
| | control protocol | None |
+----------------------+------------------------+------------------+
| | | |
|LDP P2MP PW | LDP P2MP Pseudowire | P2MP PW Upstream |
| | | FEC Element |
+----------------------+------------------------+------------------+
| | | P2MP |
|mLDP Node Protection | mLDP node protection | MP2MP-up |
| | | MP2MP-down |
| | | HSMP-downstream |
| | | HSMP-upstream |
+----------------------+------------------------+------------------+
| | | |
|IPv4 intra-area FECs | IPv4 intra-area FECs | IPv4 prefix |
+----------------------+------------------------+------------------+
| | | |
|IPv6 intra-area FECs | IPv6 intra-area FECs | IPv6 prefix |
+----------------------+------------------------+------------------+
Intra-area FECs : FECs that are on the shortest path tree and not
leafs of the shortest path tree.
4. Interaction of Targeted Application Capabilities and State
Advertisement Control Capabilities
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As described in this document, the set of TAEs negotiated between two
LDP peers advertising TAC represents the willingness of both peers to
advertise state information for a set of applications. The set of
applications negotiated by the TAC mechanism is symmetric between the
two LDP peers. In the absence of further mechanisms, two LDP peers
will both advertise state information for the same set of
applications.
As described in [RFC7473], State Advertisement Control(SAC) TLV can
be used by an LDP speaker to communicate its interest or disinterest
in receiving state information from a given peer for a particular
application. Two LDP peers can use the SAC mechanism to create
asymmetric advertisement of state information between the two peers.
The TAC negotiation facilitates the awareness of targeted
applications to both the peers. It enables them to advertise only
necessary LDP FEC-label bindings corresponding to negotiated
applications. With the SAC, the responding LSR is not aware of
targeted applications. Thus it may be unable to communicate its
interest or disinterest to receive state information from the peer.
Therefore, when the responding LSR is not aware of targeted
applications such a remote LFA and BGP auto discovered pseudowires,
TAC mechanism should be used and when the responding LSR is aware
(with appropriate configuration) of targeted applications such as FEC
128 pseudowire, SAC mechanism should be used. Also after TAC
mechanism makes the responding LSR aware of targeted application, the
SAC mechanism may be used to communicate its disinterest in receiving
state information from the peer for a particular negotiated
application, creating asymmetric advertisements.
Thus, the TAC mechanism enables two LDP peers to symmetrically
advertise state information for negotiated targeted applications.
Further, the SAC mechanism enables both of them to asymmetrically
disable receipt of state information for some of the already
negotiated targeted applications. Collectively, both TAC and SAC
mechanisms can be used to control the FEC-label bindings that are
advertised over the tLDP session. For instance, suppose the
initiating LSR establishes a tLDP session to the responding LSR for
Remote LFA and FEC 129 PW targeted applications with TAC. So each LSR
advertises the corresponding FEC-Label bindings. Further, suppose
the initiating LSR is not the PQ node for responding LSRs Remote LFA
IGP calculations. In such a case, the responding LSR may use the SAC
mechanism to convey its disinterest in receiving state information
for Remote LFA targeted LDP application.
For a given tLDP session, the TAC mechanism can be used without the
SAC mechanism, and the SAC mechanism can be used without the TAC
mechanism. It is useful to discuss the behavior when TAC and SAC
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mechanisms are used on the same tLDP session. The TAC mechanism MUST
take precedence over the SAC mechanism with respect to enabling
applications for which state information will be advertised. For a
tLDP session using the TAC mechanism, the LDP peers MUST NOT
advertise state information for an application that has not been
negotiated in the most recent TAE list (referred to as an un-
negotiated application). This is true even if one of the peers
announces its interest in receiving state information that
corresponds to the un-negotiated application by sending a SAC TLV.
In other words, when TAC is being used, SAC cannot and should not
enable state information advertisement for applications that have not
been enabled by TAC.
On the other hand, the SAC mechanism MUST take precedence over the
TAC mechanism with respect to disabling state information
advertisements. If an LDP speaker has announced its disinterest in
receiving state information for a given application to a given peer
using the SAC mechanism, its peer MUST NOT send state information for
that application, even if the two peers have negotiated that the
corresponding application via the TAC mechanism.
For the purposes of determining the correspondence between targeted
applications defined in this document and application state as
defined in [RFC7473] an LSR MUST use the following mappings:
LDPv4 Tunneling - IPv4 Prefix-LSPs
LDPv6 Tunneling - IPv6 Prefix-LSPs
LDPv4 Remote LFA - IPv4 Prefix-LSPs
LDPv6 Remote LFA - IPv6 Prefix-LSPs
LDP FEC 128 PW - FEC128 P2P-PW
LDP FEC 129 PW - FEC129 P2P-PW
An LSR MUST map Targeted Application to LDP capability as follows:
mLDP Tunneling - P2MP Capability, MP2MP Capability
and HSMP LSP Capability TLV
mLDP node protection - P2MP Capability, MP2MP Capability
and HSMP LSP Capability TLV
5. Use cases
5.1 Remote LFA Automatic Targeted session
The LSR determines that it needs to form an automatic tLDP session to
remote LSR based on IGP calculation as described in [RFC7490] or some
other mechanism, which is outside the scope of this document. The LSR
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forms the tLDP adjacency and constructs an Initialization message
with TAC TLV with TAE as Remote LFA during session establishment. The
receiver LSR processes the LDP Initialization message and verifies
whether it is configured to accept a Remote LFA tLDP session. If it
is, it may further verify that establishing such a session does not
exceed the configured limit for Remote LFA sessions. If all these
conditions are met, the receiver LSR may respond back with an
Initialization message with TAC corresponding to Remote LFA, and
subsequently the session may be established.
After the session has been established with TAC capability, the
sender and receiver LSR distribute IPv4 or IPv6 FEC label bindings
over the session. Further, the receiver LSR may determine that it
does not need these FEC label bindings. So it may disable the receipt
of these FEC label bindings by mapping targeted application element
to state control capability as described in section 4.
5.2 FEC 129 Auto Discovery Targeted session
BGP auto discovery may determine whether the LSR needs to initiate an
auto-discovery tLDP session with a border LSR. Multiple LSRs may try
to form an auto discovered tLDP session with a border LSR. So, a
service provider may want to limit the number of auto discovered tLDP
sessions a border LSR can accept. As described in Section 2, LDP may
convey targeted applications with TAC TLV to border LSR. A border LSR
may establish or reject the tLDP session based on local
administrative policy. Also, as the receiver LSR becomes aware of
targeted applications, it can also employ an administrative policy
for security. For instance, it can employ a policy to accept all
auto-discovered session from source-list.
Moreover, the sender and receiver LSR must exchange FEC 129 label
bindings only over the tLDP session.
5.3 LDP over RSVP and Remote LFA targeted session
A LSR may want to establish a tLDP session to a remote LSR for LDP
over RSVP tunneling and Remote LFA applications. The sender LSR may
add both these applications as a unique Targeted Application Element
in the Targeted Application Capability data of a TAC TLV. The
receiver LSR may have reached a configured limit for accepting Remote
LFA automatic tLDP sessions, but it may have been configured to
accept LDP over RSVP tunneling. In such a case, the tLDP session is
formed for both LDP over RSVP and Remote LFA applications as both
need same FECs - IPv4 or IPv6 or both.
5.4 mLDP node protection targeted session
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A merge point LSR may determine that it needs to form automatic tLDP
session to the upstream point of local repair (PLR) LSR for MP2P and
MP2MP LSP [RFC6388] node protection as described in the [RFC7715].
The MPT LSR may add a new targeted LDP application - mLDP protection
- as a unique TAE in the Targeted Application Capability Data of a
TAC TLV and send it in the Initialization message to the PLR. If the
PLR is configured for mLDP node protection and establishing this
session does not exceed the limit of either mLDP node protection
sessions or automatic tLDP sessions, the PLR may decide to accept
this session. Also, the PLR may respond back with the initialization
message with a TAC TLV that has one of the TAEs as - mLDP protection,
and the session proceeds to establishment as per [RFC5036].
6. Security Considerations
The Capability procedure described in this document does not
introduce any change to LDP Security Considerations section described
in [RFC5036].
As described in [RFC5036], DoS attacks via Extended Hellos, which are
required to establish a tLDP session, can be addressed by filtering
Extended Hellos using access lists that define addresses with which
Extended Discovery is permitted. Further, as described in section
5.2 of this document, a LSR can employ a policy to accept all auto-
discovered Extended Hellos from the configured source addresses
list.
Also for the two LSRs supporting TAC, the tLDP session is only
established after successful negotiation of the TAC. The initiating
and receiving LSR MUST only advertise TA-Ids that they support. In
other words, what they are configured for over the tLDP session.
7. IANA Considerations
This document requires the assignment of a new code point for a
Capability Parameter TLVs from the IANA managed LDP registry "TLV
Type Name Space", corresponding to the advertisement of the Targeted
Applications capability. IANA is requested to assign the lowest
available value after 0x050B.
Value Description Reference
----- -------------------------------- ---------
TBD1 Targeted Applications capability [this document]
This document requires the assignment of a new code point for a
status code from the IANA managed registry "STATUS CODE NAME SPACE"
on the Label Distribution Protocol (LDP) Parameters page,
corresponding to the notification of session Rejected/Targeted
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Application Capability Mis-Match. IANA is requested to assign the
lowest available value after 0x0000004B.
Value E Description Reference
----- - -------------------------------- ---------
TBD2 1 Session Rejected/Targeted
Application Capability Mis-Match [this document]
This document also creates a new name space 'the LDP Targeted
Application Identifier' on the Label Distribution Protocol (LDP)
Parameters page, that is to be managed by IANA. The range is 0x0001-
0xFFFE, with the following values requested in this document.
Value Description Reference
-------- ------------------------- ---------------
0x0000 Reserved [this document]
0x0001 LDPv4 Tunneling [this document]
0x0002 LDPv6 Tunneling [this document]
0x0003 mLDP Tunneling [this document]
0x0004 LDPv4 Remote LFA [this document]
0x0005 LDPv6 Remote LFA [this document]
0x0006 LDP FEC 128 PW [this document]
0x0007 LDP FEC 129 PW [this document]
0x0008 LDP Session Protection [this document]
0x0009 LDP ICCP [this document]
0x000A LDP P2MP PW [this document]
0x000B mLDP Node Protection [this document]
0x000C LDPv4 Intra-area FECs [this document]
0x000D LDPv6 Intra-area FECs [this document]
0x0001 - 0x1FFF Available for assignment
by IETF Review
0x2000 - 0F7FF Available for assignment
as first come first served
0xF800 - 0xFBFF Available for private use
0xFC00 - 0xFFFE Available for experimental use
0xFFFF Reserved [this document]
8. Acknowledgments
The authors wish to thank Nischal Sheth, Hassan Hosseini, Kishore
Tiruveedhul, Loa Andersson, Eric Rosen, Yakov Rekhter, Thomas
Beckhaus, Tarek Saad, Lizhong Jin and Bruno Decraene for doing the
detailed review. Thanks to Manish Gupta and Martin Ehlers for their
input to this work and many helpful suggestions.
9. Contributing Authors
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Chris Bowers
Juniper Networks
1133 Innovation Way
Sunnyvale, CA 94089
USA
EMail: cbowers@juniper.net
Zhenbin Li
Huawei
Bld No.156 Beiqing Rd
Beijing 100095
China
Email: lizhenbin@huawei.com
10. References
10.1 Normative References
[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
"LDP Specification", RFC 5036, October 2007,
<http://www.rfc-editor.org/info/rfc5036>.
[RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL.
Le Roux, "LDP Capabilities", RFC 5561, July 2009,
<http://www.rfc-editor.org/info/rfc5561>.
[RFC7473] Kamran Raza, Sami Boutros, "Controlling State
Advertisements of Non-negotiated LDP Applications", RFC
7473, March 2015, <http://www.rfc-
editor.org/info/rfc7473>.
[RFC7715] IJ. Wijnands, E. Rosen, K. Raza, J. Tantsura, A. Atlas, Q.
Zhao, "mLDP Node Protection", RFC 7715, January 2016,
<http://www.rfc-editor.org/info/rfc7715>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC8174] B. Leiba, "Ambiguity of Uppercase vs Lowercase in RFC 2119
Key Words", BCP 14, RFC8174, May 2017, <http://www.rfc-
editor.org/info/rfc8174>.
10.2 Informative References
[RFC7490] S. Bryant, C. Filsfils, S. Previdi, M. Shand, N. So,
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"Remote Loop-Free Alternate (LFA) Fast Reroute (FRR)",
April 2015.
[RFC6074] E. Rosen, B. Davie, V. Radoaca, and W. Luo, "Provisioning,
Auto-Discovery, and Signaling in Layer 2 Virtual Private
Networks (L2VPNs)", January 2011.
[RFC6388] IJ. Wijnands, I. Minei, K. Kompella, B. Thomas, "Label
Distribution Protocol Extensions for Point-to-Multipoint
and Multipoint-to-Multipoint Label Switched Paths",
November 2011.
Authors' Addresses
Santosh Esale
Juniper Networks
1133 Innovation Way
Sunnyvale, CA 94089
USA
EMail: sesale@juniper.net
Raveendra Torvi
Juniper Networks
10 Technology Park Drive
Westford, MA 01886
USA
EMail: rtorvi@juniper.net
Luay Jalil
Verizon
1201 E Arapaho Rd
Richardson, TX 75081
USA
Email: luay.jalil@verizon.com
Uma Chunduri
Huawei
2330 Central Expy
Santa Clara, CA 95050
USA
Email: uma.chunduri@huawei.com
Kamran Raza
Cisco Systems, Inc.
2000 Innovation Drive
Ottawa, ON K2K-3E8
Canada
E-mail: skraza@cisco.com
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