DLEP Traffic Classification Data Item

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Table of Contents

1. Introduction

The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175]. It provides the exchange of link related control information between DLEP peers. DLEP peers are comprised of a modem and a router. DLEP defines a base set of mechanisms as well as support for possible extensions. DLEP defines Data Items which are sets of information that can be reused in DLEP messaging. The base DLEP specification does not include any flow identification beyond DLEP endpoints. This document defines DLEP Data Item formats which provide flow identification on a more granular basis. Specifically it enables a router to use traffic flow classification information provided by the modem to identify traffic flows. In this case, a flow is identified based on information found in a data plane header and one or more matches are associated with a single flow. (For general background on traffic classification see [RFC2475] Section 2.3.) The Data Item is structured to allow for use of the defined traffic classification information with applications such as credit window control as specified in [I-D.ietf-manet-dlep-da-credit-extension]¶

This document defines traffic classification based on a DLEP destination and flows identified by either DiffServ [RFC2475] DSCPs (differentiated services codepoints) or IEEE 802.1Q [IEEE.802.1Q_2014] Ethernet Priority Code Points (PCP). The defined mechanism allows for flows to be described in a flexible fashion and when combined with applications such as credit window control, allows credit windows to be shared across traffic sent to multiple DLEP destinations and as part of multiple flows, or used exclusively for traffic sent to a particular destination and/or belonging to a particular flow. The extension also supports the "wildcard" matching of any flow (DSCP or PCP). Traffic classification information is provided such that it can be readily extended to support other traffic classification techniques, or be used by non-credit window related extensions, such as [RFC8651] or even 5-tuple IP flows.¶

This document defines support for traffic classification using a single new Data Item in Section 2.1 for general support and two new Sub-Data Items are defined to support identification of flows based on DSCPs and PCPs.¶

2. Traffic Classification

The Traffic Classification Data Item is used to represent a list of flows that may be used at the same time for traffic sent from a router to a modem. The data plane information used to identify each flow is represented in a separate Sub-Data Item. The Data Item and Sub-Data Item structure is intended to be independent of any specific usage of the flow identification, e.g., flow control. The Sub-Data Item structure is also intended to allow for future traffic classification types, e.g., 5-tuple flows. While the structure of the Data Items is extensible, actual flow information is expected to be used in an extension dependent manner. Support for DSCP and PCP-based flows are defined via individual Sub-Data Items below. Other types of flow identification, e.g., based on IP protocol and ports, may be defined in the future via new Sub-Data Items. Note that when extensions supporting multiple Sub-Data Item types are negotiated, these types MAY be combined in a single Data Item.¶

Each list of flows is identified using a "Traffic Classification Identifier" or "TID" and is expected to represent a valid combination of data plane identifiers that may be used at the same time. Each flow is identified via a "Flow Identifier" or "FID". Each FID is defined in a Sub-Data Item which carries the data plane identifier or identifiers used to associate traffic with the flow. A DLEP destination address is also needed to complete traffic classification information used in extensions such as flow control. This information is expected to be provided in an extension specific manner. For example, this address can be provided by a modem when it identifies the traffic classification set in a Destination Up Message using the Credit Window Associate Data Item defined in [I-D.ietf-manet-dlep-credit-flow-control]. TID and FID values have modem-local scope.¶

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Data Item Type                | Length                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |Traffic Class. Identifier (TID)|   Num SDIs    |   Reserved    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |           Traffic Classification Sub-Data Item 1              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                                ...                            :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |           Traffic Classification Sub-Data Item n              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+