draft-ietf-teas-network-assigned-upstream-label-06.txt   draft-ietf-teas-network-assigned-upstream-label-07.txt 
TEAS Working Group X. Zhang, Ed. TEAS Working Group X. Zhang, Ed.
Internet-Draft Huawei Technologies Internet-Draft Huawei Technologies
Updates: 3473 (if approved) V. Beeram, Ed. Updates: 3473 (if approved) V. Beeram, Ed.
Intended status: Standards Track Juniper Networks Intended status: Standards Track Juniper Networks
Expires: December 24, 2017 I. Bryskin Expires: February 12, 2018 I. Bryskin
Huawei Technologies Huawei Technologies
D. Ceccarelli D. Ceccarelli
Ericsson Ericsson
O. Gonzalez de Dios O. Gonzalez de Dios
Telefonica Telefonica
June 22, 2017 August 11, 2017
Network Assigned Upstream-Label Network Assigned Upstream-Label
draft-ietf-teas-network-assigned-upstream-label-06 draft-ietf-teas-network-assigned-upstream-label-07
Abstract Abstract
This document discusses a Generalized Multi-Protocol Label Switching This document discusses a Generalized Multi-Protocol Label Switching
(GMPLS) Resource reSerVation Protocol with Traffic Engineering (RSVP- (GMPLS) Resource reSerVation Protocol with Traffic Engineering (RSVP-
TE) mechanism that enables the network to assign an upstream label TE) mechanism that enables the network to assign an upstream label
for a bidirectional LSP. This is useful in scenarios where a given for a bidirectional label-switched path (LSP). This is useful in
node does not have sufficient information to assign the correct scenarios where a given node does not have sufficient information to
upstream label on its own and needs to rely on the downstream node to assign the correct upstream label on its own and needs to rely on the
pick an appropriate label. This document updates RFC3473 as it downstream node to pick an appropriate label. This document updates
defines processing for a special label value. RFC3473.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 24, 2017. This Internet-Draft will expire on February 12, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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UPSTREAM_LABEL Object in the PATH message. As per the existing setup UPSTREAM_LABEL Object in the PATH message. As per the existing setup
procedure outlined for a bidirectional LSP, each upstream node must procedure outlined for a bidirectional LSP, each upstream node must
allocate a valid upstream label on the outgoing interface before allocate a valid upstream label on the outgoing interface before
sending the initial PATH message downstream. However, there are sending the initial PATH message downstream. However, there are
certain scenarios where it is not desirable or possible for a given certain scenarios where it is not desirable or possible for a given
node to pick the upstream label on its own. This document defines node to pick the upstream label on its own. This document defines
the protocol mechanism to be used in such scenarios. This mechanism the protocol mechanism to be used in such scenarios. This mechanism
enables a given node to offload the task of assigning the upstream enables a given node to offload the task of assigning the upstream
label for a given bidirectional LSP to nodes downstream in the label for a given bidirectional LSP to nodes downstream in the
network. It is meant to be used only for bidirectional LSPs that network. It is meant to be used only for bidirectional LSPs that
assign symmetric labels at each hop along the path of the LSP. assign symmetric labels at each hop along the path of the LSP. This
document updates [RFC3473] as it defines processing for a special
label value.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Unassigned Upstream Label 2. Unassigned Upstream Label
This document proposes the use of a special label value - This document proposes the use of a special label value -
"0xFFFFFFFF" (for a 4-byte label) - to indicate an Unassigned "0xFFFFFFFF" (for a 4-octet label) - to indicate an Unassigned
Upstream Label. Similar "all-ones" patterns are expected to be used Upstream Label. Similar "all-ones" patterns are expected to be used
for labels of other sizes. The presence of this value in the for labels of other sizes. The presence of this value in the
UPSTREAM_LABEL object of a PATH message indicates that the upstream UPSTREAM_LABEL object of a PATH message indicates that the upstream
node has not assigned an upstream label on its own and has requested node has not assigned an upstream label on its own and has requested
the downstream node to provide a label that it can use in both the downstream node to provide a label that it can use in both the
forward and reverse directions. The presence of this value in the forward and reverse directions. The presence of this value in the
UPSTREAM_LABEL object of a PATH message MUST also be interpreted by UPSTREAM_LABEL object of a PATH message MUST also be interpreted by
the receiving node as a request to mandate symmetric labels for the the receiving node as a request to mandate symmetric labels for the
LSP. LSP.
2.1. Processing Rules 2.1. Processing Rules
The Unassigned Upstream Label is used by an upstream node when it is The Unassigned Upstream Label is used by an upstream node when it is
not in a position to pick the upstream label on its own. In such a not in a position to pick the upstream label on its own. In such a
scenario, the upstream node sends a PATH message downstream with an scenario, the upstream node sends a PATH message downstream with an
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and sends it via the LABEL object in the RESV message. The upstream and sends it via the LABEL object in the RESV message. The upstream
node would then start using this symmetric label for both directions node would then start using this symmetric label for both directions
of the LSP. If the downstream node cannot pick the symmetric label, of the LSP. If the downstream node cannot pick the symmetric label,
it MUST issue a PATH-ERR message with a "Routing Problem/Unacceptable it MUST issue a PATH-ERR message with a "Routing Problem/Unacceptable
Label Value" indication. Label Value" indication.
The upstream node will continue to signal the Unassigned Upstream The upstream node will continue to signal the Unassigned Upstream
Label in the PATH message even after it receives an appropriate Label in the PATH message even after it receives an appropriate
symmetric label in the RESV message. This is done to make sure that symmetric label in the RESV message. This is done to make sure that
the downstream node would pick a different symmetric label if and the downstream node would pick a different symmetric label if and
when it needs to change the label at a later point in time. If the when it needs to change the label at a later time. If the upstream
upstream node receives an unacceptable changed label, then the error node receives an unacceptable changed label, then the error procedure
procedure defined in [RFC3473] MUST be followed. defined in [RFC3473] MUST be followed.
+----------+ +------------+ +----------+ +------------+
---| Upstream |--------------------| Downstream |--- ---| Upstream |--------------------| Downstream |---
+----------+ +------------+ +----------+ +------------+
PATH PATH
Upstream Label (Unassigned) Upstream Label (Unassigned)
Label-Set (L1, L2 ... Ln) Label-Set (L1, L2 ... Ln)
-------------------> ------------------->
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backwards compatibility concerns. If there is some existing backwards compatibility concerns. If there is some existing
implementation that exhibits the behavior in (b), then there could be implementation that exhibits the behavior in (b), then there could be
some potential issues. However, at the time of publication, there is some potential issues. However, at the time of publication, there is
no documented evidence of any existing implementation that uses the no documented evidence of any existing implementation that uses the
"all-ones" bit pattern as a valid label. Thus, it is safe to assume "all-ones" bit pattern as a valid label. Thus, it is safe to assume
that the behavior in (b) will never be exhibited. that the behavior in (b) will never be exhibited.
3. Use-Case: Wavelength Setup for IP over Optical Networks 3. Use-Case: Wavelength Setup for IP over Optical Networks
Consider the network topology depicted in Figure 2. Nodes A and B Consider the network topology depicted in Figure 2. Nodes A and B
are client IP routers that are connected to an optical WDM transport are client IP routers that are connected to an optical wavelength
network. F and I represent WDM nodes. The transponder sits on the division multiplexing (WDM) transport network. F and I represent WDM
router and is directly connected to the add-drop port on a WDM node. nodes. The transponder sits on the router and is directly connected
to the add-drop port on a WDM node.
The optical signal originating on "Router A" is tuned to a particular The optical signal originating on "Router A" is tuned to a particular
wavelength. On "WDM-Node F", it gets multiplexed with optical wavelength. On "WDM-Node F", it gets multiplexed with optical
signals at other wavelengths. Depending on the implementation of signals at other wavelengths. Depending on the implementation of
this multiplexing function, it may not be acceptable to have the this multiplexing function, it may not be acceptable to have the
router send signal into the optical network unless it is at the router send the signal into the optical network unless it is at the
appropriate wavelength. In other words, having the router send appropriate wavelength. In other words, having the router send
signal with a wrong wavelength may adversely impact existing optical signals with a wrong wavelength may adversely impact existing optical
trails. If the clients do not have full visibility into the optical trails. If the clients do not have full visibility into the optical
network, they are not in a position to pick the correct wavelength network, they are not in a position to pick the correct wavelength in
up-front. advance.
The rest of this section examines how the protocol mechanism proposed The rest of this section examines how the protocol mechanism proposed
in this document allows the optical network to select and communicate in this document allows the optical network to select and communicate
the correct wavelength to its clients. the correct wavelength to its clients.
3.1. Initial Setup 3.1. Initial Setup
+---+ /-\ /-\ +---+ +---+ /-\ /-\ +---+
| A |----------------( F ) ~~~~~~~~~ ( I )----------------| B | | A |----------------( F ) ~~~~~~~~~ ( I )----------------| B |
+---+ \-/ \-/ +---+ +---+ \-/ \-/ +---+
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Steps: Steps:
o "Router A" does not have enough information to pick an appropriate o "Router A" does not have enough information to pick an appropriate
client wavelength. It sends a PATH message downstream requesting client wavelength. It sends a PATH message downstream requesting
the network to assign an appropriate symmetric label for its use. the network to assign an appropriate symmetric label for its use.
Since the client wavelength is unknown, the laser is off at the Since the client wavelength is unknown, the laser is off at the
ingress client. ingress client.
o The downstream node (Node F) receives the PATH message, chooses o The downstream node (Node F) receives the PATH message, chooses
the appropriate wavelength values and forwards them in appropriate the appropriate wavelength values and forwards them in appropriate
label fields to the egress client ("Router B") label fields to the egress client ("Router B").
o "Router B" receives the PATH message, turns the laser ON and tunes o "Router B" receives the PATH message, turns the laser ON and tunes
it to the appropriate wavelength (received in the UPSTREAM_LABEL/ it to the appropriate wavelength (received in the UPSTREAM_LABEL/
LABEL_SET of the PATH) and sends out a RESV message upstream. LABEL_SET of the PATH) and sends a RESV message upstream.
o The RESV message received by the ingress client carries a valid o The RESV message received by the ingress client carries a valid
symmetric label in the LABEL object. "Router A" turns on the symmetric label in the LABEL object. "Router A" turns on the
laser and tunes it to the wavelength specified in the network laser and tunes it to the wavelength specified in the network
assigned symmetric LABEL. assigned symmetric LABEL.
For cases where the egress-node relies on RSVP signaling to determine For cases where the egress-node relies on RSVP signaling to determine
exactly when to start using the LSP, implementations may choose to exactly when to start using the LSP, implementations may choose to
integrate the above sequence with any of the existing graceful setup integrate the above sequence with any of the existing graceful setup
procedures: procedures:
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o "RESV-CONF" setup procedure ([RFC2205]) o "RESV-CONF" setup procedure ([RFC2205])
o 2-step "ADMIN STATUS" based setup procedure ("A" bit set in the o 2-step "ADMIN STATUS" based setup procedure ("A" bit set in the
first step; "A" bit cleared when the LSP is ready for use). first step; "A" bit cleared when the LSP is ready for use).
([RFC3473]) ([RFC3473])
3.2. Wavelength Change 3.2. Wavelength Change
After the LSP is set up, the network may decide to change the After the LSP is set up, the network may decide to change the
wavelength for the given LSP. This could be for a variety of reasons wavelength for the given LSP. This could be for a variety of reasons
- policy reasons, restoration within the core, preemption etc. including policy reasons, restoration within the core, preemption
etc.
In such a scenario, if the ingress client receives a changed label In such a scenario, if the ingress client receives a changed label
via the LABEL object in a RESV modify, it retunes the laser at the via the LABEL object in a modified RESV message, it retunes the laser
ingress to the new wavelength. Similarly, if the egress client at the ingress to the new wavelength. Similarly, if the egress
receives a changed label via UPSTREAM_LABEL/LABEL_SET in a PATH client receives a changed label via UPSTREAM_LABEL/LABEL_SET in a
modify, it retunes the laser at the egress to the new wavelength. modified PATH message, it retunes the laser at the egress to the new
wavelength.
4. Acknowledgements 4. Acknowledgements
The authors would like to thank Adrian Farrel and Chris Bowers for The authors would like to thank Adrian Farrel and Chris Bowers for
their inputs. their inputs.
5. Contributors 5. Contributors
John Drake John Drake
Juniper Networks Juniper Networks
skipping to change at page 7, line 24 skipping to change at page 7, line 29
7. Security Considerations 7. Security Considerations
This document defines a special label value to be carried in the This document defines a special label value to be carried in the
UPSTREAM_LABEL object of a PATH message. This special label value is UPSTREAM_LABEL object of a PATH message. This special label value is
used to enable the function of requesting network assignment of an used to enable the function of requesting network assignment of an
upstream label. The changes proposed in this document pertain to the upstream label. The changes proposed in this document pertain to the
semantics of a specific field in an existing RSVP object and the semantics of a specific field in an existing RSVP object and the
corresponding procedures. Thus, there are no new security corresponding procedures. Thus, there are no new security
implications raised by this document and the security considerations implications raised by this document and the security considerations
put together by [RFC3473] still applies. discussed by [RFC3473] still apply.
For a general discussion on MPLS and GMPLS related security issues, For a general discussion on MPLS and GMPLS related security issues,
see the MPLS/GMPLS security framework [RFC5920]. see the MPLS/GMPLS security framework [RFC5920].
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
 End of changes. 18 change blocks. 
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