Internet DRAFT - draft-ietf-mpls-pm-udp-return
draft-ietf-mpls-pm-udp-return
MPLS S. Bryant
Internet-Draft S. Sivabalan
Intended status: Standards Track S. Soni
Expires: January 30, 2015 Cisco Systems
July 29, 2014
MPLS Performance Measurement UDP Return Path
draft-ietf-mpls-pm-udp-return-00
Abstract
This document specifies the proceedure to be used by the Packet Loss
and Delay Measurement for MPLS Networks protocol defined in RFC6374
when 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 January 30, 2015.
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1. Introduction
This document describes how Packet Loss and Delay Measurement for
MPLS Networks protocol (MPLS-PLDM) [RFC6374] out-of-band responses
can be delivered to the Querier using UDP/IP.
The use of UDP may be required to support data path management such
as passage through firewalls, or to provide the necessary
multiplexing needed in bistatic operation where the querier and the
collector are not co-located and the collector is gathering the
response information for a number of responders. In a highly scaled
system some MPLS-PLDM 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 MPLS-PLDM measurement. Currently the MPLS-
PLDM protocol does not have any mechanism to deliver the PLDM
Response message to particular node within a multi-CPU LSR.
The procedure described in this specification describes how the
queryer requests delivery of the MPLS-PLDM response over IP to a
dynamic UDP port. It makes no other changes to the protocol and thus
does not affect the case where the reponse is delivered over a MPLS
Associated Channel [RFC5586].
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, if a UDP
Return Object (URO) is present in a MPLS-PLDM Query, the responder
MUST use the IP address and UDP port in the URO to reply back to the
querier. Multiple UROs MAY be present in a MPLS-PLDM Query
indicating that an identical responses SHOULD be sent to each addess-
port pair. A responder MAY be designed or configured to only
transmit a single response, in which case the response MUST be sent
using the parameters specified in the first URO in the querry packet.
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
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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).
3.1. UDP Return Object
[Note to reviewers - to be deleted before publication - We considered
a number of approaches to the design. The first was to use the
existing address object and a separate UDP object, but concern in the
WG was that there may be more than one collector that required this
information, and the combined size of the two objects. The next
approach considered by the authors was to create a new object by
appending a UDP port to the existing generalized address object.
However by noting that UDP is only likely to be sent over IP and that
it will be a long time before we design a third major version of IP
we can compress the object either by having separate IPv4 and an IPv4
objects, or using the address length as the discriminator. The
object design below uses the latter approach. The resultant combined
UDP port + address object is thus the same size as the original
address object.]
The format of the UDP Return Object (URO) 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| URO TLV Type | Length={6,18} | UDP-Destination-Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Type and Length fields are each 8 bits long, and the Length field
indicates the size in bytes of the remainder of the object (i.e. is
the size of the address in bytes plus 2). When the address is IPv4
the length field is thus 6 and when the address is IPv6 the length
field is thus 18. The length field therefore acts as both the TLV
parsing parameter and the address family type indicator.
The UDP Return Object Type (URO TLV Type) has a value of <TBD>.
The UDP Destination Port is a UDP Destination port as specified in
[RFC0768].
The Address is either an IPv4 or an IPv6 address.
The URO MUST NOT appear in a response.
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4. Theory of Operation
This document defines the UDP Return Object to enable the MPLS-PLDM
Querier to specify the return path for the MPLS-PLDM reply using IP/
UDP encapsulation.
When the MPLS-PLDM Response is requested out-of-band by setting
Control Code of the MPLS-PLDM Query to "Out-of-band Response
Requested", and the URO is present, 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 URO.
If the URO is expected but is not present in Query message and an
MPLS-PLDM 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 message MUST be set to "Error - Missing
TLV" 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. Missing TLV
The control code "Missing TLV", which is classified as an Error
response code, indicates that the operation failed because one or
more required TLV Objects was not sent in the query message.
4.2. Sending an MPLS-PM Query
When sending an MPLS-PLDM Query message, in addition to the rules and
procedures defined in [RFC6374]; the Control Code of the MPLS-PLDM
Query MUST be set to "Out-of-band Response Requested", and a URO MUST
be carried in the MPLS-PLDM Query message.
If the Querier uses the UDP port to de-multiplexing of the response
for different measurement type, there MUST be a different UDP port
for each measurement type (Delay, loss and delay-loss combined).
An implementation MAY use multiple UDP ports for same measurement
type to direct the response to the correct management process in the
LSR.
4.3. Receiving an MPLS PM Query Request
The processing of MPLS-PLDM query messages as defined in [RFC6374]
applies in this document. In addition, when an MPLS-PLDM Query
request is received, with the Control Code of the MPLS-PLDM Query set
to "Out-of-band Response Requested" with a URO present, then the
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Responder SHOULD use that IP address and UDP port to send MPLS-PLDM
response back to Querier.
If an Out-of-band response is requested and the Address object or the
URO is missing, the Query SHOULD be dropped in the case of a
unidirectional LSP. If both these TLVs are missing on a
bidirectional LSP, the control code of Response message should set to
"Invalid Message" and the 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.
4.4. Sending an MPLS-PM Response
As specified in [RFC6374] the MPLS-PLDM Response 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-PLDM
Query message.
When the requested return path is an IP forwarding path and this
method is in use, the destination IP address and UDP port MUST be
copied from the URO. 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 MPLS-PLDM 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 achieved 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 = URO.Address |
. Protocol = UDP .
. .
+----------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Responder .
. Destination Port = URO.UDP-Destination-Port .
. .
+----------------------------------------------------------+
| Message as specified in RFC6374 |
. .
+----------------------------------------------------------+
Figure 1: Response packet Format
If the return path is an 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].
4.5. 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 URO MAY be omitted from the
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MPLS-PLDM messages.
6. Security Considerations
The MPLS-PLDM 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 registry set.
Code Description Reference
TBD Return UDP Port [This]
The TLV 131 is recommended.
IANA is requested to assign a new response code in the MPLS Loss/
Delay Measurement Control Code Registry contained within the g-ach-
parameters registry set.
Code Description Reference
TBD Missing TLV [This]
The response code 0x1E is recommended.
8. Acknowledgements
We acknowledge the contribution of Joseph Chin and Rakesh Gandhi,
both with Cisco Systems. We thank Loa Andersson, Eric Osborne,
Mustapha Aissaoui, and Jeffrey Zhang for their review comments.
We thank all who have reviewed this text and provided feedback.
9. Normative References
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
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August 1980.
[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.
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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