Internet DRAFT - draft-rtgyangdt-rtgwg-lne-model
draft-rtgyangdt-rtgwg-lne-model
Network Working Group L. Berger
Internet-Draft LabN Consulting, L.L.C.
Intended status: Standards Track C. Hopps
Expires: November 18, 2016 Deutsche Telekom
A. Lindem
Cisco Systems
D. Bogdanovic
May 17, 2016
Logical Network Element Model
draft-rtgyangdt-rtgwg-lne-model-00
Abstract
This document defines a logical network element module. This module
along with the network instance module can be used to manage the
logical and virtual resource representations that may be present on a
network device. Examples of common industry terms for logical
resource representations are Logical Systems or Logical Routers.
Examples of of common industry terms for virtual resource
representations are Virtual Routing and Forwarding (VRF) instances
and Virtual Switch Instances (VSIs).
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
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This Internet-Draft will expire on November 18, 2016.
Copyright Notice
Copyright (c) 2016 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Status of Work and Open Issues . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Logical Network Elements . . . . . . . . . . . . . . . . . . 6
3.1. LNE Management - Host Network Device View . . . . . . . . 6
3.2. LNE Management - LNE View . . . . . . . . . . . . . . . . 8
3.3. LNE Instantiation . . . . . . . . . . . . . . . . . . . . 8
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Logical Network Element Model . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . 11
7.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 12
Appendix B. Contributors . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
This document defines a YANG [RFC6020] module to support the creation
of logical network elements on a network device. A logical network
element (LNE) is an independently managed virtual device made up of
resources allocated to it from the host, or parent, network device.
(An LNE running on a host network device conceptually parallels a
virtual machine running on a host system.) This document also
defines the necessary augmentations for allocating host resources to
a given LNE. As the interface management model [RFC7223] is the only
a module that currently defines host resources, this document
currently defines only a single augmentation to cover the assignment
of interfaces to an LNE.
As each LNE is an independently managed device, each will have its
own set of YANG modeled data that is independent of the host device
and other LNEs. For example, multiple LNEs may all have their own
"Tunnel0" interface defined which will not conflict with each other
and will not exist in the host's interface model. An LNE will have
it's own management interfaces possibly including independent
instances of netconf/restconf/etc servers to support configuration of
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their YANG models. As an example of this independence, an
implementation may choose to completely rename assigned interfaces,
so on the host the assigned interface might be called "Ethernet0/1"
while within the LNE it might be called "eth1".
In addition to standard management interfaces, a host device
implementation may support accessing LNE configuration and
operational YANG models directly from the host system. When
supported, such access is accomplished through a schema-mount mount
point [I-D.ietf-netmod-schema-mount] under which the root level LNE
YANG models may be accessed.
Examples of vendor terminology for an LNE include logical system or
logical router, and virtual switch, chassis, or fabric.
This document was motivated by, and derived from, [RTG-DEVICE-MODEL].
1.1. Status of Work and Open Issues
The top open issues are:
1. This document will need to match the evolution and
standardization of [I-D.openconfig-netmod-opstate] or
[I-D.ietf-netmod-opstate-reqs] by the Netmod WG.
It will also make use of emerging YANG functionality supported by
YANG Schema Mount This document is expected to use whatever Schema
Mount solution is agreed upon by the Netmod Working Group.
2. Overview
In this document, we consider network devices that support protocols
and functions defined within the IETF Routing Area, e.g, routers,
firewalls and hosts. Such devices may be physical or virtual, e.g.,
a classic router with custom hardware or one residing within a
server-based virtual machine implementing a virtual network function
(VNF). Each device may sub-divide their resources into logical
network elements (LNEs) each of which provides a managed logical
device. Examples of vendor terminology for an LNE include logical
system or logical router, and virtual switch, chassis, or fabric.
Each LNE may also support virtual routing and forwarding (VRF) and
virtual switching instance (VSI) functions, which are referred to
below as a network instances (NIs). This breakdown is represented in
Figure 1.
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,''''''''''''''''''''''''''''''''''''''''''''''`.
| Network Device (Physical or Virtual) |
| ..................... ..................... |
| : Logical Network : : Logical Network : |
| : Element : : Element : |
| :+-----+-----+-----+: :+-----+-----+-----+: |
| :| Net | Net | Net |: :| Net | Net | Net |: |
| :|Inst.|Inst.|Inst.|: :|Inst.|Inst.|Inst.|: |
| :+-----+-----+-----+: :+-----+-----+-----+: |
| : | | | | | | : : | | | | | | : |
| :..|.|...|.|...|.|..: :..|.|...|.|...|.|..: |
| | | | | | | | | | | | | |
`'''|'|'''|'|'''|'|'''''''''|'|'''|'|'''|'|'''''
| | | | | | | | | | | |
Interfaces Interfaces
Figure 1: Module Element Relationships
A model for LNEs is described in Section 3 and the model for network
instances is covered in [NI-MODEL]. For more information on how
these models may be used within an overall device model structure,
see [RTG-DEVICE-MODEL].
The interface management model [RFC7223] is and existing model that
is impacted by the definition of LNEs and network instances. This
document and [NI-MODEL] define augmentations to the interface module
to support LNEs and NIs. Similar elements, although perhaps only for
LNEs, may also need to be included as part of the definition of the
future hardware and QoS modules.
Interfaces are a crucial part of any network device's configuration
and operational state. They generally include a combination of raw
physical interfaces, link-layer interfaces, addressing configuration,
and logical interfaces that may not be tied to any physical
interface. Several system services, and layer 2 and layer 3
protocols may also associate configuration or operational state data
with different types of interfaces (these relationships are not shown
for simplicity). The interface management model is defined by
[RFC7223].
The logical-network-element and network-instance modules augment the
existing interface management model in two ways: The first, by the
logical-network-element module, adds an identifier which is used on
physical interface types to identify an associated LNE. The second,
by the network-instance module, adds a name which is used on
interface or sub-interface types to identify an associated network
instance. Similarly, this name is also added for IPv4 and IPv6
types, as defined in [RFC7277].
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The interface related augmentations are as follows:
module: ietf-logical-network-element
augment /if:interfaces/if:interface:
+--rw bind-lne-name? string
augment /if:interfaces/if:interface:
+--rw bind-network-instance-name? string
augment /if:interfaces/if:interface/ip:ipv4:
+--rw bind-network-instance-name? string
augment /if:interfaces/if:interface/ip:ipv6:
+--rw bind-network-instance-name? string
The following is an example of envisioned combined usage. The
interfaces container includes a number of commonly used components as
examples:
+--rw interfaces
| +--rw interface* [name]
| +--rw name string
| +--rw lne:bind-lne-name? string
| +--rw ethernet
| | +--rw ni:bind-network-instance-name? string
| | +--rw aggregates
| | +--rw rstp
| | +--rw lldp
| | +--rw ptp
| +--rw vlans
| +--rw tunnels
| +--rw ipv4
| | +--rw ni:bind-network-instance-name? string
| | +--rw arp
| | +--rw icmp
| | +--rw vrrp
| | +--rw dhcp-client
| +--rw ipv6
| +--rw ni:bind-network-instance-name? string
| +--rw vrrp
| +--rw icmpv6
| +--rw nd
| +--rw dhcpv6-client
The [RFC7223] defined interface model is structured to include all
interfaces in a flat list, without regard to logical or virtual
instances (e.g., VRFs) supported on the device. The bind-lne-name
and bind-network-instance-name leaves provide the association between
an interface and its associated LNE and NI (e.g., VRF or VSI).
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3. Logical Network Elements
A logical network element is a network-device which is contained
within another network-device. Using host-virtualization terminology
one could refer to an LNE as a "Guest", and the containing network-
device as the "Host". While LNEs may be implemented via host-
virtualization technologies this is not a requirement.
Logical network elements represent the capability of some devices to
partition resources into independent logical routers and/or switches.
Device support for multiple logical network elements is
implementation specific. Systems without such capabilities need not
include support for the logical-network-element module. In physical
devices, some hardware features are shared across partitions, but
control plane (e.g., routing) protocol instances, tables, and
configuration are managed separately. For example, in virtual
routers or VNFs, this may correspond to establishing multiple logical
instances using a single software installation. The model supports
configuration of multiple instances on a single device by creating a
list of logical network elements, each with their own configuration
and operational state related to routing and switching protocols, as
shown below:
module: ietf-logical-network-element
+--rw logical-network-inventory
+--rw logical-network-element* [name]
+--rw name? string
+--rw description? string
+--rw managed? boolean
+--rw root? schema-mount
augment /if:interfaces/if:interface:
+--rw bind-lne-name? string
`name` identifies the logical network element. `managed` indicates
if the host network device is able to manage the LNE via the `root`
structure.
3.1. LNE Management - Host Network Device View
There are multiple implementation approaches possible to enable a
network device to support the logical-network-element module and
multiple LNEs. Some approaches will allow the management functions
operating at network device level to access LNE configuration and
operation information, while others will not. Similarly, even when
LNE management from the network device is supported by the
implementation, it may be prohibited by user policy.
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The `managed` boolean mentioned above is used to indicate when LNE
management from the network device context is possible. When the
`managed` boolean is `false`, the LNE cannot be managed by the host
system and can only be managed from within the context of the LNE as
described in the next section, Section 3.2.
When the `managed` boolean is `true`, the LNE can be managed from
both the context of the LNE and the host network device. In this
case, the same information that is available from within the LNE
context is made available via the `root` element, with paths modified
as described in [I-D.ietf-netmod-schema-mount].
As an example, consider the case where an LNE with a `name` of "one"
is defined on a network device. In this case the following structure
might be made available:
.......................................................................
(network-device state)
+--rw yanglib:modules-state [I-D.ietf-netconf-yang-library]
+--rw lne:logical-network-elements [I-D.rtgyangdt-rtgwg-lne-model]
+--rw logical-network-element* [name]
+--rw name="one" string
+--rw manged=true boolean
+--rw root schema-mount
|
.......................................................................
| (exposed LNE state if managed=true)
|
+--rw yanglib:modules-state [I-D.ietf-netconf-yang-library]
+--rw if:intefaces [RFC7223]
+--rw hardware
+--rw qos
+--rw system-management
+--rw network-services
+--rw oam-protocols
+--rw rt:routing [I-D.ietf-netmod-routing-cfg]
+--rw mpls
+--rw ieee-dot1Q
+--rw ni:network-instances [I-D.rtgyangdt-rtgwg-ni-model]
As an LNE is a network device itself, all modules that may be present
at the top level network device may also be present for the LNE, be
made available under `root`, and be accessible via paths modified per
[I-D.ietf-netmod-schema-mount]. The list of available modules is
expected to be implementation dependent. As is the method used by an
implementation to support LNEs.
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Resources assigned to the LNE will be represented in that LNE's
resource modules. e.g., an LNE's interfaces module will contain the
interfaces assigned to that LNE from the containing network-device.
3.2. LNE Management - LNE View
Management functions operating with the context of an LNE are
accessed through standard LNE's management interfaces, e.g., NETCONF
and SNMP. When accessing an LNE via an LNE's management interface, a
network-device representation will be presented, but its scope will
be limited to the specific LNE. Normal YANG/NETCONF mechanisms,
together with yang library [I-D.ietf-netconf-yang-library], can be
used to identify the available modules. Each supported module will
be presented as a top level module. Only LNE associated resources
will be reflected in resource related modules, e.g., interfaces,
hardware and perhaps QoS. From the management perspective, there
will be no difference between the available LNE view (information)
and an a physical network device.
Multiple implementation approaches are possible to provide LNE views,
and these are outside the scope of this document.
3.3. LNE Instantiation
TBD -- need to resolve if instantiation is based on new list entry
creation per the pending Schema Mount solution definition.
4. Security Considerations
LNE portion is TBD
NI portion is TBD
5. IANA Considerations
This YANG model currently uses a temporary ad-hoc namespace. If it
is placed or redirected for the standards track, an appropriate
namespace URI will be registered in the "IETF XML Registry"
[RFC3688]. The YANG structure modules will be registered in the
"YANG Module Names" registry [RFC6020].
6. Logical Network Element Model
The structure of the model defined in this document is described by
the YANG module below.
<CODE BEGINS> file "ietf-logical-network-element@2016-05-01.yang"
module ietf-logical-network-element {
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yang-version "1";
// namespace
namespace "urn:ietf:params:xml:ns:yang:ietf-logical-network-element";
prefix "lne";
// import some basic types
import ietf-interfaces {
prefix if;
}
// meta
organization "IETF RTG YANG Design Team Collaboration
with OpenConfig";
contact
"Routing Area YANG Architecture Design Team -
<rtg-dt-yang-arch@ietf.org>";
description
"This module is used to support multiple logical network
elements on a single physical or virtual system.";
revision "2016-05-01" {
description
"IETF Routing YANG Design Team Meta-Model";
reference "TBD";
}
// feature statements
feature bind-lne-name {
description
"Logical network element to which an interface is bound";
}
// top level device definition statements
container logical-network-elements {
description "Allows a network device to support multiple logical
network element (device) instances";
list logical-network-element {
key name;
description "List of logical network elements";
leaf name {
type string;
description "Device-wide unique identifier for the
logical network element";
}
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leaf managed {
type boolean;
description
"True if the host can manage the LNE using the root mount
point";
}
leaf description {
type string;
description
"Description of the logical network element";
}
leaf root {
type schema-mount;
description "Root for models supported per logical
network element";
}
}
}
// augment statements
augment "/if:interfaces/if:interface" {
description
"Add a node for the identification of the logical network
element associated with an interface. Applies to interfaces
that can be assigned on a per logical network element basis.
A <TBD> error is returned when the interface type cannot be
assigned.";
leaf bind-lne-name {
type string;
description
"Logical network element ID to which interface is bound";
}
}
// rpc statements
// notification statements
}
<CODE ENDS>
7. References
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7.1. Normative References
[I-D.ietf-netmod-schema-mount]
Bjorklund, M. and L. Lhotka, "YANG Schema Mount", draft-
ietf-netmod-schema-mount-01 (work in progress), April
2016.
[NI-MODEL]
Berger, L., Hopps, C., Lindem, A., and D. Bogdanovic,
"Network Instance Model", draft-rtgyangdt-rtgwg-ni-model-
00.txt (work in progress), May 2016.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<http://www.rfc-editor.org/info/rfc3688>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<http://www.rfc-editor.org/info/rfc6020>.
[RFC7223] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
<http://www.rfc-editor.org/info/rfc7223>.
[RFC7277] Bjorklund, M., "A YANG Data Model for IP Management",
RFC 7277, DOI 10.17487/RFC7277, June 2014,
<http://www.rfc-editor.org/info/rfc7277>.
[RTG-DEVICE-MODEL]
Lindem, A., Ed., Berger, L., Ed., Bogdanovic, D., and C.
Hopps, "Network Device YANG Organizational Models", draft-
rtgyangdt-rtgwg-device-model-04.txt (work in progress),
May 2016.
7.2. Informative References
[I-D.ietf-netconf-yang-library]
Bierman, A., Bjorklund, M., and K. Watsen, "YANG Module
Library", draft-ietf-netconf-yang-library-05 (work in
progress), April 2016.
[I-D.ietf-netmod-opstate-reqs]
Watsen, K. and T. Nadeau, "Terminology and Requirements
for Enhanced Handling of Operational State", draft-ietf-
netmod-opstate-reqs-03 (work in progress), January 2016.
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[I-D.openconfig-netmod-opstate]
Shakir, R., Shaikh, A., and M. Hines, "Consistent Modeling
of Operational State Data in YANG", draft-openconfig-
netmod-opstate-01 (work in progress), July 2015.
Appendix A. Acknowledgments
The Routing Area Yang Architecture design team members included Acee
Lindem, Anees Shaikh, Christian Hopps, Dean Bogdanovic, Lou Berger,
Qin Wu, Rob Shakir, Stephane Litkowski, and Yan Gang.
The RFC text was produced using Marshall Rose's xml2rfc tool.
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Appendix B. Contributors
Contributors' Addresses
TBD
Authors' Addresses
Lou Berger
LabN Consulting, L.L.C.
Email: lberger@labn.net
Christan Hopps
Deutsche Telekom
Email: chopps@chopps.org
Acee Lindem
Cisco Systems
301 Midenhall Way
Cary, NC 27513
USA
Email: acee@cisco.com
Dean Bogdanovic
Email: ivandean@gmail.com
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