MPLS S. Bryant
Internet-Draft S. Sivabalan
Intended status: Standards Track S. Soni
Expires: October 9, 2014 Cisco Systems
April 7, 2014
MPLS Performance Measurement UDP Return Path
draft-bryant-mpls-oam-udp-return-00
Abstract
This document specifies an extension to the protocol for making
performance measurements of MPLS LSPs that is defined in RFC6374. It
specifies the procedure used for sending and processing MPLS
performance management out-of-band responses for delay and loss
measurements over an IP/UDP return path.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on October 9, 2014.
Copyright Notice
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document authors. All rights reserved.
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
1. Introduction
[RFC6374] does not define how an MPLS performance measurement (PM)
out-of-band response delivered over IP will be transmitted to the
Querier.
In a highly scaled system some PM sessions may be off-loaded to a
specific node within a the distributed system that comprises the LSR
as a whole. In such systems the response may arrive via any
interface in the LSR and need to internally forwarded to the
processor tasked with handling the particular PM measurement.
Currently the MPLS PM protocol does not have any mechanism to deliver
the PM Response message to particular node within a multi-CPU LSR.
The procedure described in this specification shows how to deliver
the response over a dynamic UDP port.
2. Requirements Language
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 [RFC2119].
3. Solution Overview
This document specifies that, unless configured otherwise, the
"Return Address TLV" defined in [RFC6374] SHALL be used to carry the
return address. It also defines "Return UDP Port" TLV which, unless
configured otherwise SHALL be used to carry the return UDP port. The
Return Address TLV and the Return UDP PORT TLV carried in the MPLS-PM
query message are used to specify to the Responder how to return the
response message.
The procedures defined in this document may be applied to both
unidirectional tunnels and Bidirectional LSPs. In this document, the
term bidirectional LSP includes the co-routed Bidirectional LSP
defined in [RFC3945] and the associated bidirectional LSP that is
constructed from a pair of unidirectional LSPs (one for each
direction) that are associated with one another at the LSP's ingress/
egress points [RFC5654]. The mechanisms defined in this document can
apply to both IP/MPLS and the MPLS Transport Profile (MPLS-TP).
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3.1. Return UDP Port TLV
The format of the Return UDP TLV is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP TLV Type | Length | UDP Dest Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The UDP TLV Type has a value of <TBD>.
4. Theory of Operation
This document defines the "Return UDP Port TLV" and uses "Return
Address TLV" that enables the MPLS-PM Querier to specify the return
path for the MPLS-PM reply using IP/UDP encapsulation.
When the MPLS-PM Response is requested out-of-band by setting Control
Code of the MPLS-PM Query to "Out-of-band Response Requested", the
responder SHOULD send the response back to Querier on the specified
destination UDP port at the specified destination IP address as
received in the "Return UDP Port TLV and "Return Address TLV"
respectively.
If either the "Return Address TLV" or "Return UDP port TLV" is not
present in Query Packet and MPLS PM Response is requested out-of-
band, the Query message MUST NOT be processed further. If received
over a bidirectional LSP, the control code of the Response packet
MUST be set to "Invalid Message" and a Response SHOULD be sent over
the reverse LSP. The receipt of such a mal-formed request SHOULD be
notified to the operator through the management system, taking the
normal precautions with respect to the prevention of overload of the
error reporting system.
4.1. Sending an MPLS-PM Query
When sending an MPLS PM Query packet, in addition to the rules and
procedures defined in [RFC6374]; the Control Code of the MPLS-PM
Query MUST be set to "Out-of-band Response Requested", and a "Return
UDP Port TLV" along with "Return Address TLV" MUST be carried in the
MPLS-PM Query message.
Since the Querier uses the UDP port to de-multiplex response for
different measurement type, there SHOULD be a different UDP port for
each measurement type (Delay, loss and delay-loss combined).
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Implementation MAY use multiple UDP ports for same measurement type
to direct the response to the correct management process in the LSR.
4.2. Receiving an MPLS PM Query Request
The processing of MPLS-PM query messages as defined in [RFC6374]
applies in this document. In addition, when an MPLS PM Query request
is received, with the Control Code of the MPLS-PM Query set to "Out-
of-band Response Requested" with a Return address TLV and Return UDP
TLV is present, then the Responder SHOULD use that IP address and UDP
port to send MPLS-PM response back to Querier.
If an Out-of-band response is requested and either the Return Address
TLV or the Return UDP port TLV is missing, the Query SHOULD be
dropped in the case of unidirectional LSP. If either of these TLVs
is missing on a bidirectional LSP, the control code of Response
packet should set to "Invalid Message" and the response SHOULD be
sent over the reverse LSP. In either case the receipt of such a mal-
formed request SHOULD be notified to the operator through the
management system, taking the normal precautions with respect to the
prevention of overload of the error reporting system.
4.3. Sending an MPLS-PM Response
As specified in [RFC6374] the MPLS PM Response packet can be sent
over either the reverse MPLS LSP for a bidirectional LSP or over an
IP path. It MUST NOT be sent other than in response to an MPLS PM
Query Packet.
When the requested return path is an IP forwarding path and this
method is in use, the destination IP address and UDP port SHOULD be
copied from the Return Address TLV and the Return UDP TLV
respectively. The source IP address and the source UDP port of
Response packet is left to discretion of the Responder subject to the
normal management and security considerations. The packet format for
the PM response after the UDP header is as specified in [RFC6374].
As shown in Figure 1 the Associate Channel Header (ACH) [RFC5586] is
not incuded. The information provided by the ACH is not needed since
the correct binding between the Querry and Response messages is
achived though the UDP Port and the Session Indentifier contained in
the RFC6374 message.
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+----------------------------------------------------------+
| IP Header |
. Source Address = Responders IP Address |
. Destination Addess = Return Address TLV.Address |
. Protocol = UDP .
. .
+----------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Responder .
. Destination Port = Return UDP Port TLV.UDP Dest Port .
. .
+----------------------------------------------------------+
| Message as specified in RFC6374 |
. .
+----------------------------------------------------------+
Figure 1: Response packet Format
If the return path is IP path, only one-way delay or one-way loss
measurement can be carried out. In this case timestamps 3 and 4 MUST
be zero as specified in [RFC6374].
4.4. Receiving an MPLS-PM Response
If the response was received over UDP/IP and an out-of-band response
was expected, the Response message SHOULD be directed to the
appropriate measurement process as determined by the destination UDP
Port, and processed using the corresponding measurement type
procedure specified in [RFC6374].
If the Response was received over UDP/IP and an out-of-band response
was not requested, that response should be dropped and the event
SHOULD be notified to the operator through the management system,
taking the normal precautions with respect to the prevention of
overload of the error reporting system.
5. Manageability Considerations
The manageability considerations described in Section 7 of [RFC6374]
are applicable to this specification. Additional manageability
considerations are noted within the elements of procedure of this
document.
Nothing in this document precludes the use of a configured UDP/IP
return path in a deployment in which configuration is preferred to
signalling. In these circumstances the address and UDP port TLVs MAY
be omitted from the MPLS PM messages.
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6. Security Considerations
The MPLS PM system is not intended to be deployed on the public
Internet. It is intended for deployment in well manages private and
service provider networks. The security considerations described in
Section 8 of [RFC6374] are applicable to this specification and the
reader's attention is drawn to the last two paragraphs.
Cryptographic measures may be enhanced by the correct configuration
of access control lists and firewalls.
There is no additional exposure of information to pervasive
monitoring systems observing LSPs that are being monitored.
7. IANA Considerations
IANA is requested to assign a new Optional TLV type from MPLS Loss/
Delay Measurement TLV Object Registry contained within the g-ach-
parameters parameters registry set.
Code Description Reference
TBD Return UDP Port [This]
The TLV 131 is recommended
8. Acknowledgements
We acknowledge the contribution of Joseph Chin and Rakesh Gandhi,
both with Cisco Systems.
We thank all who have reviewed this text and provided feedback.
9. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
(GMPLS) Architecture", RFC 3945, October 2004.
[RFC5586] Bocci, M., Vigoureux, M., and S. Bryant, "MPLS Generic
Associated Channel", RFC 5586, June 2009.
[RFC5654] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N.,
and S. Ueno, "Requirements of an MPLS Transport Profile",
RFC 5654, September 2009.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374, September 2011.
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Authors' Addresses
Stewart Bryant
Cisco Systems
Email: stbryant@cisco.com
Siva Sivabalan
Cisco Systems
Email: msiva@cisco.com
Sagar Soni
Cisco Systems
Email: sagsoni@cisco.com
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