| Internet-Draft | MNA Flow ID | July 2024 |
| Zhou & Song | Expires 9 January 2025 | [Page] |
This document specifies a general flow ID as an in-stack data item for MPLS network action. The flow ID can be used by multiple network actions which require to identify flows.¶
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Many MNAs affiliate to specific flows or exhibit different behavior to different flows. For example, the network operator may apply certain OAM on a number of selected flows and collect per flow data. However, in MPLS networks, the labels are used to identify paths but not flows. If multiple flows sharing the same path require the same MNA, the LSR may need to differentiate the flows and execute the action on a per-flow basis.¶
The flow information can be extracted from the L3/L4 header in the MPLS payload by deep packet inspection, which incurs significant processing overhead. Alternatively, each flow-based MNA may carry its own unique identifier to differentiate the flows. However, this approach has several issues.¶
First, one packet may have multiple MNAs that require a flow identification. There will be obvious data redundancy if each MNA carries its own flow identifier. Second, limited by the MNA ISD encoding and size, the flow identifier may have to be tailored to a sub-optimal size, resulting in poor scalability. Third, A customized flow identifier per MNA may cause network management difficulties and waste network resources.¶
Therefore, it is desired to have a General Flow Identifier (GFI) which can be shared by all the MNAs relying on it. In this draft, we propose a new ISD item for GFI using the encoding format described in [I-D.ietf-mpls-mna-hdr]. We also list the possible use cases which can use the GFI.¶
The following terminology and acronyms are used in this document.¶
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 BCP 14 [RFC2119][RFC8174] when, and only when, they appear in all capitals, as shown here.¶
As shown in Figure 1, an Opcode is assigned for GFI and the encoding of GFI takes the LSE Format C as specified in [I-D.ietf-mpls-mna-hdr], in which the GFI uses the 20-bit data field.¶
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OC(TBD) | GFI |S| GFI | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The GFI can have multiple possible use cases:¶
This document requires a new option code assigned to indicate GFI.¶
The comments and suggestions of the following are gratefully acknowledged:¶
TBD¶