| 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
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).
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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.
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].
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
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.
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.
This may be provided in a future version of this document.
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.
IANA is requested to allocate a UDP port from the user port range:
TBD
| [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. |