Internet DRAFT - draft-bryant-mpls-rfc6374-over-udp
draft-bryant-mpls-rfc6374-over-udp
MPLS S. Bryant
Internet-Draft G. Swallow
Intended status: Standards Track S. Sivabalan
Expires: September 3, 2015 Cisco Systems
March 2, 2015
RFC6374 over UDP
draft-bryant-mpls-rfc6374-over-udp-00
Abstract
In draft-bryant-mpls-synonymous-flow-labels the concept of MPLS
synonymous flow labels (SFL) was introduced and it was shown how they
could be used to support RFC6374 loss measurements. In draft-bryant-
mpls-sfl-control the request, lifetime management and withdrawal of
SFLs was described. In this memo we show how these two protocols can
be run over UDP to support the operation of RFC6374 in systems that
do not support the Generic Associated Channel Label (GAL) (RFC5586).
Status of This Memo
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This Internet-Draft will expire on September 3, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Protocol Stack . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Querier to Responder . . . . . . . . . . . . . . . . . . 3
4. Manageability Considerations . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
In draft-bryant-mpls-synonymous-flow-labels the concept of MPLS
synonymous flow labels (SFL) was introduced and it was shown how they
could be used to support RFC6374 loss measurements. In draft-bryant-
mpls-sfl-control the request, lifetime management and withdrawal of
SFLs was described. In this memo we show how these two protocols can
be run over UDP to support the operation of RFC6374 in systems that
do not support the Generic Associated Channel Label (GAL) [RFC5586].
The approach is to run an Associated Channel Header directly over UDP
using the ACH UDP port supplemented by addressing information carried
in the ACH payload. This memo explains how the extension of RFC6374
as described in draft-bryant-mpls-synonymous-flow-labels and draft-
bryant-mpls-sfl-control provide the necessary information to provide
mapping between the RFC6374 packet carried over UDP and the MPLS
construct being monitored, even when the RFC6374 protocol exchange is
entirely out of band relative to the Label Switched Path (LSP),
Virtual Private Network (VPN) or Pseudowire (PW) being instrumented.
The key to this is the decoupling between the RFC6374 message and the
data plane provided through the use of synonymous flow labels (SFL)
as described in draft-bryant-mpls-synonymous-flow-labels.
Nothing in this memo prevents the use of the ACH UDP port for other
types of Associated Channels, but the precise method of doing so is
outside the scope of this text.
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2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
3. Protocol Stack
The protocol stack is shown in Figure 1. It consists of three
components, the UDP header, the ACH and either an RFC6374 message or
an SFL Control message.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | Destination Port | UDP
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Checksum | UDP
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version| Reserved | Channel Type | ACH
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| RFC6374 or SFL Control Payload with SFL TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: RFC6374 over UDP Protocol Stack
3.1. Querier to Responder
The following is rather laboured, but it is necessary to demonstrate
that all of the required mapping information is carried.
Consider the direction Querier to Responder for RFC6374 Messages.
The following explains the identifier mapping.
1. Destination IP address (carried in the outer IP header (not
shown)). This is used to identify the targeted RFC6374 Responder
to the IP network.
2. Source IP address (carried in the outer IP header (not shown)).
This is used to identify the originating RFC6374 Querier to the
RFC6374 Responder in order for it to construct the return IP
packet.
3. UDP Source Port used by the RFC6374 Responder to direct responses
to the correct Query process on the RFC6374 Querier.
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4. UDP Destination Port is used by RFC6374 Querier to direct the
message to the correct process on the RFC6374 Responder.
5. IP and UDP source and destination information are reversed in the
usual way in the ACH Response messages from Responder back to
Querier.
6. The RFC6374 Session Identifier used by both Querier and Responder
to discriminate between multiple RFC6374 sessions running
concurrently between the two nodes.
7. The SFL from the SFL TLV in the RFC6374 messages is used to
identify the MPLS label that is being instrumented.
8. The SFL Control Protocol Session identifier used by both Querier
and Responder to discriminate between multiple RFC6374 sessions
running concurrently between the two nodes and used to bind the
SFL control protocol session to the RFC6374 session.
Note that a node running the SFL control protocol allocates a unique
SFL in response to each SFL request, and thus there is no ambiguity
as to which session between which source-destination pair a
particular label belongs.
Also note that there is no restriction on the use of the same SFL by
many nodes since it always known which node allocated it by reference
to items 1..8 in the list above.
4. Manageability Considerations
This may be provided in a future version of this document.
5. Security Considerations
Great care needs to be taken to ensure that the UDP packets defined
in this document do not enter the network from unauthorised sources.
This can be achieved by careful address management and the use of
appropriate access control at the network's IP entry points.
6. IANA Considerations
IANA is requested to allocate a UDP port from the user port range:
Service Name: ACH over UDP
Port Number: TBD
Descriptiopn Transport of Associated Channel Headers over UDP
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Reference This memo
7. Acknowledgements
TBD
8. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5586] Bocci, M., Vigoureux, M., and S. Bryant, "MPLS Generic
Associated Channel", RFC 5586, June 2009.
Authors' Addresses
Stewart Bryant
Cisco Systems
Email: stbryant@cisco.com
George Swallow
Cisco Systems
Email: swallow@cisco.com
Siva Sivabalan
Cisco Systems
Email: msiva@cisco.com
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