Network Working Group                                            E. Lear
Internet-Draft                                                  J. Henry
Intended status: Experimental                              Cisco Systems
Expires: January 9, 2020                                   July 08, 2019

                 Bandwidth Profiling Extensions for MUD


   Manufacturer Usage Descriptions (MUD) are a means by which devices
   can establish expectations about how they are intended to behave, and
   how the network should treat them.  Earlier work focused on access
   control.  This draft specifies a means by which manufacturers can
   express to deployments what form of bandwidth profile devices are
   expected to have with respect to specific services.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 9, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Envisioned Uses . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Limitations . . . . . . . . . . . . . . . . . . . . . . .   3
     1.3.  What devices would use this extension?  . . . . . . . . .   3
   2.  The ietf-mud-bw-profile model extension . . . . . . . . . . .   4
     2.1.  The mud-qos YANG model  . . . . . . . . . . . . . . . . .   4
   3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
     4.1.  Manufacturer Attempts to Exhaust Available Bandwidth  . .   7
     4.2.  Device lies about what it is to get more bandwidth  . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Changes from Earlier Versions  . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Devices connecting to networks will often exhibit certain nominal
   behaviors that can be described.  In addition, sometimes device
   require particular network behaviors such as appropriate quality-of-
   service treatment.  Manufacturer Usage Descriptions [RFC8520] discuss
   how to characterize access control requirements, for instance.  As
   just mentioned, access control requirements are not the only
   requirements device manufacturers may wish to specify.  This memo
   defines an extension to the MUD YANG model by which manufacturers can
   characterize the traffic exchanged with a Thing, and specify how much
   bandwidth is required by a device or may be expected of a device over
   some period of time for each given service it uses.

   Network deployments may use this information in two ways:

   o  Provisioning of bandwidth based on device requirements;

   o  Facilitating proper traffic characterization and marking by the
      network infrastructure

   o  Policing of devices to not permit them to exceed design
      requirements.  In particular, a device that is transmitting a DSCP
      value that exceeds the expected value, or that manifests unusual
      transmission patterns, should be viewed with great suspicion.

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   The basis of the model is that services may be identified by access-
   lists, and that each service can then be assigned an attendant
   bandwidth expectation in terms of either bits-per-second or packets-
   per-second.  In addition, a DSCP marking can be specified.

   When a service is identified by access lists, each access list is
   appended to the existing access list entries.  N.B., as a reminder,
   acl names in MUD files are scoped solely to those files, and may
   conflict with acl names in _other_ MUD files.

1.1.  Envisioned Uses

   A luminaire may require a few packets per minute of a predictable
   payload size (e.g. keepalives), and may expect that traffic to be
   sent in the background, as one or more keepalive packet loss would
   not impede the luminaire functions.  Additionally, when a virtual
   'light switch' changes its state, a burst of 3 to 4 packets over a
   well-defined port are expected, with a QoS marking of OAM.  Last,
   occasional firmware updates may bring an exchange of a few kilobytes
   marked as best effort.

   A smoke detector may require at most 1 packet per second at best
   effort (keepalive), except when there is a problem, at which point it
   may send a frame upstream to a specific port and of a specified
   payload size, with a DSCP marking of EF.

   A coffee maker may be designed never set DSCP to anything other than
   AF13 (even when it's empty, perish the thought), nor may it ever use
   more than 5 packets of 120 bytes payload per minute, even if it has a

   A different coffee maker may be designed to set DSCP to EF if the it
   has caught fire.

1.2.  Limitations

   Not every device can be easily profiled.  Not every service on every
   device may be easily profiled.  A manufacturer may use this extension
   to describe those services that _are_ easily profile, and omit
   services that the device offers or uses that are not easily profiled.
   The local deployment is cautioned not to assume that a service not
   profiled is in some way anomalous, even when other services are.

1.3.  What devices would use this extension?

   The MUD manager remains a key component of this system.  To begin
   with, it is the component that retrieves the MUD file, and would
   identify the extension.  From that point, different implementation

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   decisions can be made.  For instance, the MUD manager or associated
   infrastructure can retain the mapping between devices and MUD-URLs.
   A dispatch function could be implemented wherever that mapping is
   housed, such that either enforcement or monitoring functions can be
   invoked.  Enforcement functions would almost certainly begin with
   some form of telemetry on access switches, routers or firewalls.
   That same telemetry might be exported to an IPFIX analyzer [RFC7011]
   that might report anomalies.

2.  The ietf-mud-bw-profile model extension

   To extend MUD the "qos" extension is added as an element to the
   "extensions" node when a MUD file is generated.

   The model augmentation appears as follows:

   module: ietf-mud-bw-profile
     augment /mud:mud/mud:to-device-policy:
       +--rw bw-params
          +--rw service* [name]
             +--rw name         string
             +--rw timeframe    uint32
             +--rw pps?         uint32
             +--rw bps?         uint64
             +--rw dscp?        inet:dscp
             +--rw aclname?     -> /acl:acls/acl/name
     augment /mud:mud/mud:from-device-policy:
       +--rw bw-params
          +--rw service* [name]
             +--rw name         string
             +--rw timeframe    uint32
             +--rw pps?         uint32
             +--rw bps?         uint64
             +--rw dscp?        inet:dscp
             +--rw aclname?     -> /acl:acls/acl/name

2.1.  The mud-qos YANG model

 <CODE BEGINS>file "ietf-mud-bw-profile@2019-07-08.yang"
 module ietf-mud-bw-profile {
   yang-version 1.1;
   namespace "urn:ietf:params:xml:ns:yang:ietf-mud-bw-profile";
   prefix mud-qos;

   import ietf-access-control-list {
     prefix acl;
   import ietf-inet-types {

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     prefix inet;
   import ietf-mud {
     prefix mud;

     "IETF OPSAWG (Ops Area) Working Group";
     "WG Web:
      WG List:
      Author: Eliot Lear
      Author: Jerome Henry

     "This YANG module augments the ietf-mud model to provide the
      network with some understanding as to the QoS requirements and
      anticipated behavior of a device.

      The to-device-policy and from-device-policy containers are
      augmented with one additional container, which expresses how many
      packets per second a device is expected to transmit, how much
      bandwidth it is expected to use, and what QoS is required, and
      how much bandwidth is to be expected to be prioritized.  An
      access-list is further specified to indicate how QoS should be
      marked on ingress and egress.

      Copyright (c) 2016,2017,2018 IETF Trust and the persons
      identified as the document authors.  All rights reserved.
      Redistribution and use in source and binary forms, with or
      without modification, is permitted pursuant to, and subject
      to the license terms contained in, the Simplified BSD
      License set forth in Section 4.c of the IETF Trust's Legal
      Provisions Relating to IETF Documents
      This version of this YANG module is part of RFC XXXX; see
      the RFC itself for full legal notices.";

   revision 2019-07-08 {
       "Initial proposed standard.";
     reference "RFC XXXX: Bandwidth Descriptions for MUD Specification";

   grouping mud-bw-params {

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       "QoS and Bandwidth additions for MUD";
     container bw-params {
         "Expected Bandwidth to/from device";
       list service {
         key "name";
           "a list of services that are being described.";
         leaf name {
           type string;
             "Service Name";
         leaf timeframe {
           type uint32;
           mandatory true;
             "the period of time in seconds one
              expects a service to burst at described rates";
         leaf pps {
           type uint32;
             "number of packets per second to be expected.";
         leaf bps {
           type uint64;
             "number of bits per second to be expected.";
         leaf dscp {
           type inet:dscp;
             "The DSCP that packets for this service should
              treated with.  N.B., just because the manufacturer
              wants this, doesn't mean it will get it.  However,
              manufacturers who do set the DSCP value in their
              packets SHOULD indicate that in this description.

              This field differs from the dscp field in the matches
              portion of the access-list in that here the field is
              populated when the manufacturer states what the nominal
              value of the DSCP field MAY be, and how much bandwidth
              can be used when it is set.  Note that it is possible
              that the same service may use multiple DSCP values,
              depending on the circumstances.  In this case, service
              entry MUST be made.";

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         leaf aclname {
           type leafref {
             path "/acl:acls/acl:acl/acl:name";
             "The name of the ACL that will match packets
              for a given service.";

   augment "/mud:mud/mud:to-device-policy" {
       "add inbound QoS parameters";
     uses mud-bw-params;
   augment "/mud:mud/mud:from-device-policy" {
       "add outbound QoS parameters";
     uses mud-bw-params;

3.  Examples


4.  Security Considerations

4.1.  Manufacturer Attempts to Exhaust Available Bandwidth

   An attacking manufacturer claims a device would require substantial
   bandwidth or QoS for use.  This attack would be effected when a
   device is installed into a local deployment and its MUD file
   interpreted.  The impact of a device demanding excessive bandwidth
   could be overprovisioning of the network or denial of service to
   other uses.

   This attack is remediated by a human being reviewing the bandwidth
   consumption projections suggested by the MUD file when they are in
   some way beyond the norm for any device being installed.

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4.2.  Device lies about what it is to get more bandwidth

   If the device is emitting a MUD-URL via insecure, it is possible for
   an attacker to modify it.  Devices emitting such URLs should already
   receive additional scrutiny from administrators as they are
   onboarded.  This mechanism SHOULD NOT be used to admit devices into
   privileged queues without them having been securely admitted to the
   network, through means such as IEEE 802.1X.

5.  IANA Considerations

   The IANA is requested to add "qos" to the MUD extensions registry as

     Extension Name: MUD
     Standard reference: This document

6.  References

6.1.  Normative References

   [RFC8520]  Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
              Description Specification", RFC 8520,
              DOI 10.17487/RFC8520, March 2019,

6.2.  Informative References

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,

Appendix A.  Changes from Earlier Versions

   Draft -01:

   o  Very modest changes.

   Draft -00:

   o  Initial revision

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Authors' Addresses

   Eliot Lear
   Cisco Systems
   Richtistrasse 7
   Wallisellen  CH-8304

   Phone: +41 44 878 9200

   Jerome Henry
   Cisco Systems
   170 W. Tasman Dr.
   San Jose, CA  95134
   United States


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