Internet DRAFT - draft-ali-ccamp-gmpls-uni-error-notification
draft-ali-ccamp-gmpls-uni-error-notification
CCAMP Working Group Zafar Ali
Internet Draft George Swallow
Intended status: Standard Track Matt Hartley
Expires: January 11, 2014 Clarence Filsfils
Cisco Systems
Kenji Kumaki
KDDI Corporation
July 12, 2013
Extensions to Resource ReserVation Protocol-Traffic Engineering
(RSVP-TE) for Error Notication in Generalized Multiprotocol Label
Switching (GMPLS) User-Network Interface (UNI)
draft-ali-ccamp-gmpls-uni-error-notification-00.txt
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Abstract
There are many scenarios in which extensions to Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) are required for error
notication in Generalized Multiprotocol Label Switching (GMPLS)
User-Network Interface (UNI). This document outlines these scenarios
and specifies the required extensions to RSVP-TE. Although the
GMPLS-UNI reference model is used to describe requirements and
solutions in the document, the proposed extensions are equally
applicable to other deployment scenarios such as inter-domain RSVP-
TE.
Conventions used in this document
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].
Table of Contents
1. Introduction...............................................3
2. Requirements...............................................4
2.1. Error Node Address in ERROR_SPEC object
...............4
2.2. Restoration Notification..............................4
3. RSVP-TE extensions for Error Notication....................5
3.1. Error Node Address Modification in ERROR_SPEC object
..5
3.1.1. Error Node Address Modification Flag
................ 5
3.1.2. Processing rules................................ 5
3.1.3. Example......................................... 6
3.2. Restoration Notification..............................6
3.2.1. Error sub-code.................................. 6
3.2.2. Processing rules................................ 6
4. Security Considerations....................................6
5. IANA Considerations........................................6
5.1. New ERROR_SPEC.Flags..................................6
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5.2. New RSVP error sub-codes..............................7
6. Acknowledgements...........................................7
7. References.................................................7
7.1. Normative References..................................7
7.2. Informative References................................8
1. Introduction
[RFC4208] provides mechanisms for GMPLS UNI signaling. Figure 1
borrows the reference network model of [RFC4208].
Overlay Overlay
Network +----------------------------------+ Network
+---------+ | | +---------+
| +----+ | | +-----+ +-----+ +-----+ | | +----+ |
| | | | UNI | | | | | | | | UNI | | | |
| -+ EN1+-+-----+--+ CN1 +----+ CN2 +----+ CN3 +---+-----+-+ EN3+- |
| | | | +--+--+ | | | | | | | | | |
| +----+ | | | +--+--+ +--+--+ +--+--+ | | +----+ |
+---------+ | | | | | | +---------+
| | | | | |
+---------+ | | +--+--+ | +--+--+ | +---------+
| +----+ | | | | | +-------+ | | | +----+ |
| | +-+--+ | | CN4 +---------------+ CN5 | | | | | |
| -+ EN2+-+-----+--+ | | +---+-----+-+ EN4+- |
| | | | UNI | +-----+ +-----+ | UNI | | | |
| +----+ | | | | +----+ |
+---------+ +----------------------------------+ +---------+
Overlay Core Network Overlay
Network Network
Legend: EN - Edge Node
CN - Core Node
Figure 1: GMPLS UNI Reference Model
For convenience, some terms used in [RFC4208] are re-stated below:
- "source EN": the edge node which initiates the connection
(e.g., EN1);
- "destination EN": the edge node where the connection is
terminated (e.g., EN3);
- "ingress CN": the core node to which the source EN is attached
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(e.g., CN1);
- "egress CN": the core node to which the destination EN is
attached (e.g., CN3).
[RFC4208] provides mechanisms for UNI signaling whereby a single
end-to-end RSVP session between source EN and destination EN is used
for the user connection, just as it would be for connection creation
between two core nodes. However, when considering policy
considerations such as a requirement to preserve the confidentiality
of topological information of the core network, additional
requirements for UNI signaling exist that are not addressed by
[RFC4208]. This document focuses on error notification aspects of
these additional requirements.
2. Requirements
This sections outlines addition requirements related to error
notification in GMPLS UNI. For the purpose of illustration, an end-
to-end UNI connection that passes through EN1-CN1-CN2-CN3-EN3 is
used as an example.
2.1. Error Node Address in ERROR_SPEC object
The IPv4 and IPv6 ERROR_SPEC objects are defined in [RFC2205]; both
objects contain an Error Node Address of the appropriate type,
defined as the IP address of the error originating node [RFC2205].
However, for confidentiality reasons, service provider of the core
network may not wish to expose addresses used in the core network
(other than the UNI link addresses) to edge nodes. To meet this
requirement, a core node should be allowed to change the Error Node
Address in the ERROR_SPEC. When such an address modification is made
by a core node, the edge node should be informed that Error Node
Address field in the ERROR_SPEC has been modified.
2.2. Restoration Notification
The ability to dynamically restore a Label Switched Path (LSP) is
one of the fundamental features of GMPLS, including GMPLS UNI. In
the context of GMPLS UNI, restoration of an LSP after a failure may
be performed by the core network alone, or may be triggered by the
edge nodes. There is a requirement that the two methods of
restoration co-exist.
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When the core network restores an LSP, in many cases there is no
need to re-signal the LSP. However, in order to avoid a concurrent
restoration process triggered by an edge node, it is required that
the core network notify the edge network that the LSP has been
restored.
3. RSVP-TE extensions for Error Notication
3.1. Error Node Address Modification in ERROR_SPEC object
3.1.1. Error Node Address Modification Flag
To allow a core node to change the Error Node Address in the
ERROR_SPEC object, the following new flag value is defined for the
Flags field of the IPv4 and IPv6 ERROR_SPEC objects [RFC2205], and
for the IPv4 IF_ID and IPv6 IF_ID objects [RFC3477].
ERROR_SPEC.Flags = 0x08 (value to be assigned by IANA): Error Node
Address Modified.
The "Error Node Address Modified" flag is applicable to all RSVP-TE
messages that use the ERROR_SPEC object.
3.1.2. Processing rules
When processing an ERROR_SPEC object received in a message from
another node, the processing node MAY replace the IPv4 or IPv6
address in the ERROR_SPEC object with another address relating to
itself if its local policy requires it to do so.
When making an address substitution in this manner, the
processing node SHOULD set the Error Node Address Modified flag
in the Flags field of the ERROR_SPEC object to indicate that a
change has been made.
When processing a received ERROR_SPEC object, a node SHOULD
examine the ERROR_SPEC.Flags field and check for the "Error Node
Address Modified" flag before processing the
ERROR_SPEC.Error_Node_Address field. The processing node MAY
alter its handling of the ERROR_SPEC object if this flag is set,
but any such variation in handling is implementation-dependent
and beyond the scope of this document.
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3.1.3. Example
To illustrate usage of this flag, consider an example connection
EN1-CN1-CN2-CN3-EN3 in the network specified by figure 1. In this
example, the CN2 detects a failure and sends a PathErr message
towards EN1, using a local address associated with the failed
resource in the ERROR_SPEC.
However, CN1's local policy is to conceal the topology of the core
network from edge nodes. When CN1 processes the PathErr message, it
changes the address in the ERROR_SPEC to CN1's address of the EN1-
CN1 UNI link. It also sets the Error Node Address Modified flag in
the Flags field of the ERROR_SPEC to indicate that a change has been
made. The PathErr message is then sent to EN1.
3.2. Restoration Notification
3.2.1. Error sub-code
In order to satisfy restoration notification requirement mentioned
above, a new path error sub-code "LSP restored" (value to be
assigned by IANA; suggested value: 16) for the error code "Notify
Error" (25) is defined.
3.2.2. Processing rules
When a core node restores an existing LSP after a failure, it SHOULD
send a PathErr message with the error code "Notify Error" (25) and
error sub-code "LSP restored" (suggested: 16) for the LSP.
When an edge node receives a PathErr message with the error code
"Notify Error" (25) and error sub-code "LSP restored" (suggested:
16), it MAY avoid triggering any other restoration process.
4. Security Considerations
This document does not introduce any additional security issues
above those identified in [RFC5920], [RFC2205], [RFC3209],
[RFC3473] and [RFC4874].
5. IANA Considerations
5.1. New ERROR_SPEC.Flags
This document defines the following new flag value for the Flags
field of the IPv4 and IPv6 ERROR_SPEC object defined in
[RFC2205].
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ERROR_SPEC.Flags: Error Node Address Modified. Value is to be
assigned by IANA (suggested value: 0x08).
5.2. New RSVP error sub-codes
IANA registry: RSVP PARAMETERS
Subsection: Error Codes and Globally-Defined Error Value Sub-
Codes
For Error Code "Notify Error" (25) (see [RFC3209]) the following
sub-code is defined.
Sub-code Value
-------- -----
LSP Restored To be assigned by IANA.
Suggested value: 16
6. Acknowledgements
TBD.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
V., and G. Swallow, "RSVP-TE: Extensions to RSVP for
LSP Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January
2003.
[RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude
Routes - Extension to Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE)", RFC 4874, April 2007.
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7.2. Informative References
[RFC4208] Swallow, G., Drake, J., Ishimatsu, H., and Y. Rekhter,
"Generalized Multiprotocol Label Switching (GMPLS)
User-Network Interface (UNI): Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Support for the
Overlay Model", RFC 4208, October 2005.
[RFC2209] Braden, R. and L. Zhang, "Resource ReSerVation Protocol
(RSVP) -- Version 1 Message Processing Rules", RFC
2209, September 1997.
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
Authors' Addresses
Zafar Ali
Cisco Systems.
Email: zali@cisco.com
George Swallow
Cisco Systems
swallow@cisco.com
Matt Hartley
Cisco Systems
Email: mhartley@cisco.com
Clarence Filsfils
Cisco Systems, Inc.
cfilsfil@cisco.com
Kenji Kumaki
KDDI Corporation
Email: ke-kumaki@kddi.com
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