A YANG Data Model for Fabric Topology in Data Center NetworkHuawei101 Software Avenue, Yuhua DistrictNanjingJiangsu210012Chinazhuangyan.zhuang@huawei.comHuawei101 Software Avenue, Yuhua DistrictNanjingJiangsu210012Chinashidanian@huawei.comChina Mobile32 Xuanwumen West Ave, Xicheng DistrictBeijingBeijing100053Chinagurong_cmcc@outlook.comPacket Designhari@packetdesign.com
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I2RS Working GroupRFCRequest for CommentsI-DInternet-DraftThis document defines a YANG data model for fabric topology in Data Center Network.Normally, a data center network is composed of single or multiple fabrics which are also known as PODs (a Point Of Delivery).
These fabrics may be heterogeneous due to implementation of different technologies while DC network upgrading or enrolling
new techniques and features. For example, Fabric A may use VXLAN while Fabric B may use VLAN within a DC network. Likewise, a
legacy Fabric may use VXLAN while a new Fabric B implemented technique discussed in NVO3 WG such as GPE[I-D. draft-ietf-nvo3-vxlan-gpe]
may be built due to DC expansion and upgrading. The configuration and management of such DC networks with heterogeneous fabrics
will be sophisticated and complex.Luckily, for a DC network, a fabric can be considered as an atomic structure to provide network services and management,
as well as expand network capacity. From this point of view, the miscellaneous DC network management can be decomposed to task
of managing each fabric respectively along with their connections, which can make the entire management much concentrated and
flexible, also easy to expand.With this purpose, this document defines a YANG data model for the Fabric-based Data center topology by using YANG [6020][7950].
To do so, it augments the generic network and network topology data models defined in [I-D.ietf-i2rs-yang-network-topo] with information
specific to Data Center fabric network. This model defines the generic configuration and operational state for a fabric-based network topology, which can be extended
by vendors with specific information. This model can then be used by a network controller
to represent its view of the fabric topology that it controls and expose it to network administrators or applications for DC network management. With the context of topology architecture defined in [I-D.ietf-i2rs-yang-network-topo] and [I.D. draft-ietf-i2rs-usecase-reqs-summary],
this model can also be treated as an application of I2RS network topology model [I-D.ietf-i2rs-yang-network-topo] in the scenario of Data
center network management. It can also act as a service topology when mapping network elements at fabric layer to elements
to other topologies, such as L3 topology defined in [I.D. draft-ietf-i2rs-yang-l3-topology-01.By using this fabric topology model, people can treat a fabric as an entity and focus on characteristics of fabrics (such as encapsulation type, gateway type, etc.) as well as their interconnections while putting the underlay topology aside. As such, clients can consume the topology information at fabric level, while no need to be aware of entire set of links and nodes in underlay networks. The configuration of a fabric topology can be made by a network administractor to the controller by adding physical devices and links of a fabric into a fabric network. Alternatively, the fabric topology can also learnt from the underlay network infrastructure.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
DC Fabric: also known as POD, is a module of network, compute,
storage, and application components that work together to deliver
networking services. It is a repeatable design pattern, and its
components maximize the modularity, scalability, and manageability of
data centers.The following notations are used within the data tree and carry the
meaning as below.In this document, these words will appear with that interpretation only
when in ALL CAPS. Lower case uses of these words are not to be interpreted
as carrying RFC-2119 significance.
This section provides an overview of the DC Fabric topology model and
its relationship with other topology models.The relationship of the DC fabric topology model and other topology
models is shown in the following figure (dotted lines in the figure
denote augmentations).From the perspective of resource management and service provisioning for a Data Center network, the fabric topology model augments the basic network topology model with definitions and features specific to a DC fabric, to provide common
configuration and operations for heterogeneous fabrics.The fabric topology model module is designed
to be generic and can be applied to data center fabrics built with
different technologies, such as VLAN, VXLAN etc. The main purpose
of this module is to configure and manage fabrics and their connections. provide a fabric-based topology view for data center network applications.
In the fabric topology module, a fabric is modeled as a node in the network, while the fabric-based
Data center network consists of a set of fabric nodes and their connections known as "fabric port".
The following is the snip of the definition to show the main structure of the model:The fabric topology module augments the generic ietf-network and ietf-network-topology modules as follows:A new topology type "ietf-fabric-topology" is introduced and added under the "network-types" container of the ietf-network module.Fabric is defined as a node under the network/node container. A new container of "fabric-attributes" is defined to carry attributes for a fabric network such as gateway mode, fabric types, involved device nodes and links etc.Termination points (in network topology module) are augmented with fabric port attributes defined in a container. The "termination-point" here can represent the "port" of a fabric that provides connections to other nodes, such as device internally, another fabric externally and also end hosts. Details of fabric node and fabric termination point extension will be explained in the following sections.As a network, a fabric itself is composed of set of network elements i.e. devices, and related links. As stated previously, the configuration of a fabric is contained under the "fabric-attributes" container depicted as follows:As in the module, additional data objects for nodes are introduced by augmenting the "node" list of the network module. New objects include fabric name, type of the fabric, descriptions of the fabric as well as a set of options defined in an "options" container. The options container includes type of the gateway-mode (centralized or distributed) and traffic-behavior (whether acl needed for the traffic).Also, it defines a list of device-nodes and related links as supporting-nodes to form a fabric network. These device nodes and links are leaf-ref of existing nodes and links in the underlay topology. For the device-node, the "role" object is defined to represents the role of the device within the fabric, such as "SPINE" or "LEAF", which should work together with gateway-mode.Since the fabric can be considered as a node, in this concept, "termination-points" can represent "ports" of a fabric that connects to other fabrics or end hosts, besides representing ports that connect devices inside the fabric itself.As such, the "termination-point" in the fabric topology has three roles, that are internal TP that connects to devices within a fabric, external TP that connects to outside network, and access TP to end hosts.The set of "termination-point" of a fabric indicates all connections of the fabric, including its internal connections, interconnections with other fabrics and also connections to end hosts for a DC network.The structure of fabric ports is as follows:It augments the termination points (in network topology module) with fabric port attributes defined in a container. New nodes are defined for fabric ports which include name, role of the port within the fabric (internal port, external port to outside network, access port to end hosts), port type (l2 interface, l3 interface etc). By defining the device-port as a tp-ref, a fabric port can be mapped to a device node in the underlay network.Also, a new container for tunnel-options is introduced to present the tunnel configuration on the port.The termination points information are all learnt from the underlay networks but not configured by the fabric topology layer.This document registers the following namespace URIs in the "IETF XML Registry" [RFC3688]: URI: urn:ietf:params:xml:ns:yang:ietf-dc-fabric-types
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology-state
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
This document registers the following YANG modules in the "YANG
Module Names" registry [RFC6020]:
NOTE TO THE RFC EDITOR: In the list below, please replace references
to "draft-ietf-i2rs-yang-dc-fabric-network-topology-03 (RFC form)" with RFC number
when published (i.e. RFC xxxx).
Name: ietf-dc-fabric-types
Namespace: urn:ietf:params:xml:ns:yang:ietf-dc-fabric-types
Prefix: fabrictypes
Reference: draft-ietf-i2rs-yang-dc-fabric-network-topology-03.txt (RFC form)
Name: ietf-dc-fabric-topology
Namespace: urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology
Prefix: fabric
Reference: draft-ietf-i2rs-yang-dc-fabric-network-topology-03.txt (RFC form)
Name: ietf-dc-fabric-topology-state
Namespace: urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology-state
Prefix: sfabric
Reference: draft-ietf-i2rs-yang-dc-fabric-network-topology-03.txt (RFC form)
The YANG module defined in this document 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 [RFC6536] 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.These are the subtrees and data nodes
and their sensitivity/vulnerability in the ietf-dc-fabric-topology module:fabric-attributes: A malicious client could attempt to sabotage the configuration of important fabric attributes, such as device-nodes, type.Some of the readable data nodes in this YANG module 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 in the ietf-dc-fabric-topology module: fport-attributes: A malicious client could attempt to read the connections of fabrics without permission, such as device-port, name.We wish to acknowledge the helpful contributions, comments, and
suggestions that were received from Alexander Clemm, Xufeng Liu, Susan Hares, Wei Song, Luis M. Contreras and Benoit Claise.Generic Protocol Extension for VXLANA YANG Data Model for Network TopologiesA YANG Data Model for Layer 3 TopologiesA Revised Conceptual Model for YANG DatastoresKey words for use in RFCs to Indicate Requirement LevelsTransport Layer Security (TLS) Protocol Version 1.2YANG - A Data Modeling Language for the Network Configuration
Protocol (NETCONF)Network Configuration Protocol (NETCONF)Using the NETCONF Protocol over Secure Shell (SSH)Network Configuration Protocol (NETCONF) Access Control ModelCommon YANG Data TypesThe YANG 1.1 Data Modeling LanguageRESTCONF ProtocolSummary of I2RS Use Case RequirementsThe YANG module ietf-fabric-toplogy defined in this document augments two modules, ietf-network and ietf-network-topology, that are designed to be used in conjunction with implementations that support the Network Management Datastore Architecture (NMDA) defined in [I-D.draft-ietf-netmod-revised-datastores]. In order to allow implementations to use the model even in case when NMDA is not supported, a set of companion modules have been defined that represent a state model of networks and network topologies, ietf-network-state and ietf-network-topology-state, respectively. In order to be able to use the model for fabric topologies defined
in this in this document in conjunction with non-NMDA compliant implementations, a corresponding companion module needs to be introduced as well. This companion module, ietf-fabric-topology-state, mirrors ietf-fabric-topology. However, the module augments ietf-network-state (instead of ietf-network and ietf-network-topology) and all of its data nodes are non-configurable.Like ietf-network-state and ietf-network-topology-state, ietf-fabric-topology-state SHOULD NOT be supported by implementations that support NMDA. It is for this reason that the module is defined in the Appendix.The definition of the module follows below. As the structure of the
module mirrors that of its underlying module, the YANG tree is not
depicted separately.