8. IANA Considerations
This document defines the initial version of the IANA-maintained "iana-hardware" YANG module. The "iana-hardware" YANG module is intended to reflect the "IANA-ENTITY-MIB" MIB module so that if a new enumeration is added to the "IANAPhysicalClass" textual convention, the same class is added as an identity derived from "ianahw:hardware-class". When the "iana-hardware" YANG module is updated, a new "revision" statement must be added in front of the existing revision statements.8.1. URI Registrations
This document registers three URIs in the "IETF XML Registry" [RFC3688]. Per the format in RFC 3688, the following registrations have been made. URI: urn:ietf:params:xml:ns:yang:iana-hardware Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-hardware Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-hardware-state Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace.
8.2. YANG Module Registrations
This document registers three YANG modules in the "YANG Module Names" registry [RFC6020]. name: iana-hardware namespace: urn:ietf:params:xml:ns:yang:iana-hardware prefix: ianahw reference: RFC 8348 name: ietf-hardware namespace: urn:ietf:params:xml:ns:yang:ietf-hardware prefix: hw reference: RFC 8348 name: ietf-hardware-state namespace: urn:ietf:params:xml:ns:yang:ietf-hardware-state prefix: hw-state reference: RFC 83489. Security Considerations
The YANG modules specified in this document define a schema for data that is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC5246]. The NETCONF access control model [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. There are a number of data nodes defined in the YANG module "ietf-hardware" that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability: /hardware/component/admin-state: Setting this node to 'locked' or 'shutting-down' can cause disruption of services ranging from those running on a port to those on an entire device, depending on the type of component.
Some of the readable data nodes in these YANG modules may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability: /hardware/component: The leafs in this list expose information about the physical components in a device, which may be used to identify the vendor, model, version, and specific device-identification information of each system component. /hardware/component/sensor-data/value: This node may expose the values of particular physical sensors in a device. /hardware/component/state: Access to this node allows one to figure out what the active and standby resources in a device are.10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC3433] Bierman, A., Romascanu, D., and K. Norseth, "Entity Sensor Management Information Base", RFC 3433, DOI 10.17487/RFC3433, December 2002, <https://www.rfc-editor.org/info/rfc3433>. [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, <https://www.rfc-editor.org/info/rfc3688>. [RFC4268] Chisholm, S. and D. Perkins, "Entity State MIB", RFC 4268, DOI 10.17487/RFC4268, November 2005, <https://www.rfc-editor.org/info/rfc4268>. [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, <https://www.rfc-editor.org/info/rfc5246>. [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, <https://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, <https://www.rfc-editor.org/info/rfc6241>. [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, <https://www.rfc-editor.org/info/rfc6242>. [RFC6933] Bierman, A., Romascanu, D., Quittek, J., and M. Chandramouli, "Entity MIB (Version 4)", RFC 6933, DOI 10.17487/RFC6933, May 2013, <https://www.rfc-editor.org/info/rfc6933>. [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, <https://www.rfc-editor.org/info/rfc6991>. [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, <https://www.rfc-editor.org/info/rfc7950>. [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, <https://www.rfc-editor.org/info/rfc8040>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>. [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, <https://www.rfc-editor.org/info/rfc8341>. [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, <https://www.rfc-editor.org/info/rfc8342>.10.2. Informative References
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, <https://www.rfc-editor.org/info/rfc8340>.
Appendix A. Hardware State Data Model
This non-normative appendix contains a data model designed as a temporary solution for implementations that do not yet support the Network Management Datastore Architecture (NMDA) defined in [RFC8342]. It has the following structure: module: ietf-hardware-state x--ro hardware x--ro last-change? yang:date-and-time x--ro component* [name] x--ro name string x--ro class identityref x--ro physical-index? int32 {entity-mib}? x--ro description? string x--ro parent? -> ../../component/name x--ro parent-rel-pos? int32 x--ro contains-child* -> ../../component/name x--ro hardware-rev? string x--ro firmware-rev? string x--ro software-rev? string x--ro serial-num? string x--ro mfg-name? string x--ro model-name? string x--ro alias? string x--ro asset-id? string x--ro is-fru? boolean x--ro mfg-date? yang:date-and-time x--ro uri* inet:uri x--ro uuid? yang:uuid x--ro state {hardware-state}? | x--ro state-last-changed? yang:date-and-time | x--ro admin-state? hw:admin-state | x--ro oper-state? hw:oper-state | x--ro usage-state? hw:usage-state | x--ro alarm-state? hw:alarm-state | x--ro standby-state? hw:standby-state x--ro sensor-data {hardware-sensor}? x--ro value? hw:sensor-value x--ro value-type? hw:sensor-value-type x--ro value-scale? hw:sensor-value-scale x--ro value-precision? hw:sensor-value-precision x--ro oper-status? hw:sensor-status x--ro units-display? string x--ro value-timestamp? yang:date-and-time x--ro value-update-rate? uint32
notifications: x---n hardware-state-change x---n hardware-state-oper-enabled {hardware-state}? | x--ro name? -> /hardware/component/name | x--ro admin-state? -> /hardware/component/state/admin-state | x--ro alarm-state? -> /hardware/component/state/alarm-state x---n hardware-state-oper-disabled {hardware-state}? x--ro name? -> /hardware/component/name x--ro admin-state? -> /hardware/component/state/admin-state x--ro alarm-state? -> /hardware/component/state/alarm-stateA.1. Hardware State YANG Module
<CODE BEGINS> file "ietf-hardware-state@2018-03-13.yang" module ietf-hardware-state { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-hardware-state"; prefix hw-state; import ietf-inet-types { prefix inet; } import ietf-yang-types { prefix yang; } import iana-hardware { prefix ianahw; } import ietf-hardware { prefix hw; } organization "IETF NETMOD (Network Modeling) Working Group"; contact "WG Web: <https://datatracker.ietf.org/wg/netmod/> WG List: <mailto:netmod@ietf.org> Editor: Andy Bierman <mailto:andy@yumaworks.com> Editor: Martin Bjorklund <mailto:mbj@tail-f.com> Editor: Jie Dong <mailto:jie.dong@huawei.com>
Editor: Dan Romascanu <mailto:dromasca@gmail.com>"; description "This module contains a collection of YANG definitions for monitoring hardware. This data model is designed as a temporary solution for implementations that do not yet support the Network Management Datastore Architecture (NMDA) defined in RFC 8342. Such an implementation cannot implement the module 'ietf-hardware' properly, since without NMDA support, it is not possible to distinguish between instances of nodes in the running configuration and operational states. The data model in this module is the same as the data model in 'ietf-hardware', except all nodes are marked as 'config false'. If a server that implements this module but doesn't support NMDA also supports configuration of hardware components, it SHOULD also implement the module 'ietf-hardware' in the configuration datastores. The corresponding state data is found in the '/hw-state:hardware' subtree. Copyright (c) 2018 IETF Trust and the persons identified as authors of the code. 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 (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC 8348; see the RFC itself for full legal notices."; revision 2018-03-13 { description "Initial revision."; reference "RFC 8348: A YANG Data Model for Hardware Management"; } /* * Features */
feature entity-mib { status deprecated; description "This feature indicates that the device implements the ENTITY-MIB."; reference "RFC 6933: Entity MIB (Version 4)"; } feature hardware-state { status deprecated; description "Indicates that ENTITY-STATE-MIB objects are supported"; reference "RFC 4268: Entity State MIB"; } feature hardware-sensor { status deprecated; description "Indicates that ENTITY-SENSOR-MIB objects are supported"; reference "RFC 3433: Entity Sensor Management Information Base"; } /* * Data nodes */ container hardware { config false; status deprecated; description "Data nodes representing components."; leaf last-change { type yang:date-and-time; status deprecated; description "The time the '/hardware/component' list changed in the operational state."; } list component { key name; status deprecated; description "List of components.
When the server detects a new hardware component, it initializes a list entry in the operational state. If the server does not support configuration of hardware components, list entries in the operational state are initialized with values for all nodes as detected by the implementation. Otherwise, this procedure is followed: 1. If there is an entry in the '/hardware/component' list in the intended configuration with values for the nodes 'class', 'parent', and 'parent-rel-pos' that are equal to the detected values, then: 1a. If the configured entry has a value for 'mfg-name' that is equal to the detected value or if the 'mfg-name' value cannot be detected, then the list entry in the operational state is initialized with the configured values for all configured nodes, including the 'name'. Otherwise, the list entry in the operational state is initialized with values for all nodes as detected by the implementation. The implementation may raise an alarm that informs about the 'mfg-name' mismatch condition. How this is done is outside the scope of this document. 1b. Otherwise (i.e., there is no matching configuration entry), the list entry in the operational state is initialized with values for all nodes as detected by the implementation. If the '/hardware/component' list in the intended configuration is modified, then the system MUST behave as if it re-initializes itself and follow the procedure in (1)."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalEntry"; leaf name { type string; status deprecated; description "The name assigned to this component. This name is not required to be the same as entPhysicalName.";
} leaf class { type identityref { base ianahw:hardware-class; } mandatory true; status deprecated; description "An indication of the general hardware type of the component."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalClass"; } leaf physical-index { if-feature entity-mib; type int32 { range "1..2147483647"; } status deprecated; description "The entPhysicalIndex for the entPhysicalEntry represented by this list entry."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalIndex"; } leaf description { type string; status deprecated; description "A textual description of the component. This node should contain a string that identifies the manufacturer's name for the component and should be set to a distinct value for each version or model of the component."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalDescr"; } leaf parent { type leafref { path "../../component/name"; require-instance false; } status deprecated;
description "The name of the component that physically contains this component. If this leaf is not instantiated, it indicates that this component is not contained in any other component. In the event that a physical component is contained by more than one physical component (e.g., double-wide modules), this node contains the name of one of these components. An implementation MUST use the same name every time this node is instantiated."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalContainedIn"; } leaf parent-rel-pos { type int32 { range "0 .. 2147483647"; } status deprecated; description "An indication of the relative position of this child component among all its sibling components. Sibling components are defined as components that: o share the same value of the 'parent' node and o share a common base identity for the 'class' node. Note that the last rule gives implementations flexibility in how components are numbered. For example, some implementations might have a single number series for all components derived from 'ianahw:port', while some others might have different number series for different components with identities derived from 'ianahw:port' (for example, one for RJ45 and one for SFP)."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalParentRelPos"; } leaf-list contains-child { type leafref { path "../../component/name"; }
status deprecated; description "The name of the contained component."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalChildIndex"; } leaf hardware-rev { type string; status deprecated; description "The vendor-specific hardware revision string for the component. The preferred value is the hardware revision identifier actually printed on the component itself (if present)."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalHardwareRev"; } leaf firmware-rev { type string; status deprecated; description "The vendor-specific firmware revision string for the component."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalFirmwareRev"; } leaf software-rev { type string; status deprecated; description "The vendor-specific software revision string for the component."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalSoftwareRev"; } leaf serial-num { type string; status deprecated;
description "The vendor-specific serial number string for the component. The preferred value is the serial number string actually printed on the component itself (if present)."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalSerialNum"; } leaf mfg-name { type string; status deprecated; description "The name of the manufacturer of this physical component. The preferred value is the manufacturer name string actually printed on the component itself (if present). Note that comparisons between instances of the 'model-name', 'firmware-rev', 'software-rev', and 'serial-num' nodes are only meaningful amongst components with the same value of 'mfg-name'. If the manufacturer name string associated with the physical component is unknown to the server, then this node is not instantiated."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalMfgName"; } leaf model-name { type string; status deprecated; description "The vendor-specific model name identifier string associated with this physical component. The preferred value is the customer-visible part number, which may be printed on the component itself. If the model name string associated with the physical component is unknown to the server, then this node is not instantiated."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalModelName"; } leaf alias { type string; status deprecated;
description "An 'alias' name for the component, as specified by a network manager, that provides a non-volatile 'handle' for the component. If no configured value exists, the server MAY set the value of this node to a locally unique value in the operational state. A server implementation MAY map this leaf to the entPhysicalAlias MIB object. Such an implementation needs to use some mechanism to handle the differences in size and characters allowed between this leaf and entPhysicalAlias. The definition of such a mechanism is outside the scope of this document."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalAlias"; } leaf asset-id { type string; status deprecated; description "This node is a user-assigned asset tracking identifier for the component. A server implementation MAY map this leaf to the entPhysicalAssetID MIB object. Such an implementation needs to use some mechanism to handle the differences in size and characters allowed between this leaf and entPhysicalAssetID. The definition of such a mechanism is outside the scope of this document."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalAssetID"; } leaf is-fru { type boolean; status deprecated; description "This node indicates whether or not this component is considered a 'field-replaceable unit' by the vendor. If this node contains the value 'true', then this component identifies a field-replaceable unit. For all components that are permanently contained within a field-replaceable unit, the value 'false' should be returned for this node.";
reference "RFC 6933: Entity MIB (Version 4) - entPhysicalIsFRU"; } leaf mfg-date { type yang:date-and-time; status deprecated; description "The date of manufacturing of the managed component."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalMfgDate"; } leaf-list uri { type inet:uri; status deprecated; description "This node contains identification information about the component."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalUris"; } leaf uuid { type yang:uuid; status deprecated; description "A Universally Unique Identifier of the component."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalUUID"; } container state { if-feature hardware-state; status deprecated; description "State-related nodes"; reference "RFC 4268: Entity State MIB"; leaf state-last-changed { type yang:date-and-time; status deprecated; description "The date and time when the value of any of the admin-state, oper-state, usage-state, alarm-state, or standby-state changed for this component.
If there has been no change since the last re-initialization of the local system, this node contains the date and time of local system initialization. If there has been no change since the component was added to the local system, this node contains the date and time of the insertion."; reference "RFC 4268: Entity State MIB - entStateLastChanged"; } leaf admin-state { type hw:admin-state; status deprecated; description "The administrative state for this component. This node refers to a component's administrative permission to service both other components within its containment hierarchy as well as other users of its services defined by means outside the scope of this module. Some components exhibit only a subset of the remaining administrative state values. Some components cannot be locked; hence, this node exhibits only the 'unlocked' state. Other components cannot be shut down gracefully; hence, this node does not exhibit the 'shutting-down' state."; reference "RFC 4268: Entity State MIB - entStateAdmin"; } leaf oper-state { type hw:oper-state; status deprecated; description "The operational state for this component. Note that this node does not follow the administrative state. An administrative state of 'down' does not predict an operational state of 'disabled'. Note that some implementations may not be able to accurately report oper-state while the admin-state node has a value other than 'unlocked'. In these cases, this node MUST have a value of 'unknown'."; reference "RFC 4268: Entity State MIB - entStateOper";
} leaf usage-state { type hw:usage-state; status deprecated; description "The usage state for this component. This node refers to a component's ability to service more components in a containment hierarchy. Some components will exhibit only a subset of the usage state values. Components that are unable to ever service any components within a containment hierarchy will always have a usage state of 'busy'. In some cases, a component will be able to support only one other component within its containment hierarchy and will therefore only exhibit values of 'idle' and 'busy'."; reference "RFC 4268: Entity State MIB - entStateUsage"; } leaf alarm-state { type hw:alarm-state; status deprecated; description "The alarm state for this component. It does not include the alarms raised on child components within its containment hierarchy."; reference "RFC 4268: Entity State MIB - entStateAlarm"; } leaf standby-state { type hw:standby-state; status deprecated; description "The standby state for this component. Some components will exhibit only a subset of the remaining standby state values. If this component cannot operate in a standby role, the value of this node will always be 'providing-service'."; reference "RFC 4268: Entity State MIB - entStateStandby"; } }
container sensor-data { when 'derived-from-or-self(../class, "ianahw:sensor")' { description "Sensor data nodes present for any component of type 'sensor'"; } if-feature hardware-sensor; status deprecated; description "Sensor-related nodes."; reference "RFC 3433: Entity Sensor Management Information Base"; leaf value { type hw:sensor-value; status deprecated; description "The most recent measurement obtained by the server for this sensor. A client that periodically fetches this node should also fetch the nodes 'value-type', 'value-scale', and 'value-precision', since they may change when the value is changed."; reference "RFC 3433: Entity Sensor Management Information Base - entPhySensorValue"; } leaf value-type { type hw:sensor-value-type; status deprecated; description "The type of data units associated with the sensor value"; reference "RFC 3433: Entity Sensor Management Information Base - entPhySensorType"; } leaf value-scale { type hw:sensor-value-scale; status deprecated; description "The (power of 10) scaling factor associated with the sensor value";
reference "RFC 3433: Entity Sensor Management Information Base - entPhySensorScale"; } leaf value-precision { type hw:sensor-value-precision; status deprecated; description "The number of decimal places of precision associated with the sensor value"; reference "RFC 3433: Entity Sensor Management Information Base - entPhySensorPrecision"; } leaf oper-status { type hw:sensor-status; status deprecated; description "The operational status of the sensor."; reference "RFC 3433: Entity Sensor Management Information Base - entPhySensorOperStatus"; } leaf units-display { type string; status deprecated; description "A textual description of the data units that should be used in the display of the sensor value."; reference "RFC 3433: Entity Sensor Management Information Base - entPhySensorUnitsDisplay"; } leaf value-timestamp { type yang:date-and-time; status deprecated; description "The time the status and/or value of this sensor was last obtained by the server."; reference "RFC 3433: Entity Sensor Management Information Base - entPhySensorValueTimeStamp"; }
leaf value-update-rate { type uint32; units "milliseconds"; status deprecated; description "An indication of the frequency that the server updates the associated 'value' node, represented in milliseconds. The value zero indicates: - the sensor value is updated on demand (e.g., when polled by the server for a get-request), - the sensor value is updated when the sensor value changes (event-driven), or - the server does not know the update rate."; reference "RFC 3433: Entity Sensor Management Information Base - entPhySensorValueUpdateRate"; } } } } /* * Notifications */ notification hardware-state-change { status deprecated; description "A hardware-state-change notification is generated when the value of /hardware/last-change changes in the operational state."; reference "RFC 6933: Entity MIB (Version 4) - entConfigChange"; } notification hardware-state-oper-enabled { if-feature hardware-state; status deprecated; description "A hardware-state-oper-enabled notification signifies that a component has transitioned into the 'enabled' state."; leaf name { type leafref { path "/hardware/component/name";
} status deprecated; description "The name of the component that has transitioned into the 'enabled' state."; } leaf admin-state { type leafref { path "/hardware/component/state/admin-state"; } status deprecated; description "The administrative state for the component."; } leaf alarm-state { type leafref { path "/hardware/component/state/alarm-state"; } status deprecated; description "The alarm state for the component."; } reference "RFC 4268: Entity State MIB - entStateOperEnabled"; } notification hardware-state-oper-disabled { if-feature hardware-state; status deprecated; description "A hardware-state-oper-disabled notification signifies that a component has transitioned into the 'disabled' state."; leaf name { type leafref { path "/hardware/component/name"; } status deprecated; description "The name of the component that has transitioned into the 'disabled' state."; } leaf admin-state { type leafref { path "/hardware/component/state/admin-state"; } status deprecated;
description "The administrative state for the component."; } leaf alarm-state { type leafref { path "/hardware/component/state/alarm-state"; } status deprecated; description "The alarm state for the component."; } reference "RFC 4268: Entity State MIB - entStateOperDisabled"; } } <CODE ENDS>
Acknowledgments
The authors wish to thank the following individuals, who all provided helpful comments on various draft versions of this document: Bart Bogaert, Timothy Carey, William Lupton, and Juergen Schoenwaelder.Authors' Addresses
Andy Bierman YumaWorks Email: andy@yumaworks.com Martin Bjorklund Tail-f Systems Email: mbj@tail-f.com Jie Dong Huawei Technologies Email: jie.dong@huawei.com Dan Romascanu Email: dromasca@gmail.com