PlAwAnSaI
Administrator
Introduction to YANG Data Modeling:
- It's written in YANG.
- That's YANG Data.
- We use YANG Data Models.
- When first getting started with YANG, may find yourself confused because of the word "YANG" is used to refer to different things. All are related, but they are different enough to cause confusion if think there is "One YANG".
- module ietf-interfaces {
import ietf-yang-types {
prefix yang;
}
container interfaces {
list interface {
key "name";
leaf name {
type string;
}
leaf enabled {
type boolean;
default "true";
}
}
Example edited for simplicity and brevity
- YANG is first a language for describing data models. The YANG language could be used to describe ANY data model, but it was designed to describe networking data models.
- As a language, it is highly structured and typed, something that should be appreciated in a data modelling language. Some aspects of the language to note:
- Every data model is a module that is a self-contained top-level hierarchy of nodes
- Leverages data types that can be imported from another YANG module, or defined within a module
- Uses containers to group related nodes
- Leverages lists to identify nodes that are stored in sequence
- Each individual attribute of a node is represented by a leaf
- Every leaf must have an associated type
- Event Preparation for DevNet Express for DNA v2.1:
learninglabs.cisco.com/modules/00-pre-event-preparation
- To retrieve (or send) YANG data, we will leverage "NETCONF" (Transport Protocol) to communicate from a "Manager" (Client) on our workstation to an "Agent" (Server) running on a network element using "XML" (Data Format).
- This means that when we send or receive data using NETCONF, we will be working with YANG Modeled data represented in XML.
- NETCONF is just one of the Standard Transport Protocols available for leveraging YANG Data Models. Though NETCONF is the only fully standardized option so far, even in the draft from RESTCONF is becoming popular because of its REST-based foundation.
- When using RESTCONF, the developer has the option of leveraging either XML or JSON for sending and receiving data.
- It is less expensive is the main benefit of having an out-of-band management network for an infrastructure controller.
A Reliable In-band Control In A Software-defined Network:
www.jatit.org/volumes/Vol95No17/25Vol95No17.pdf
- NETCONF and SNMP network configuration protocols use XML as a data representation format.
Data modelling language for the definition of data sent over the NETCONF network configuration protocol.
Many network management protocols have associated data modelling languages. The first widely deployed Internet standard for network management was the Simple Network Management Protocol (SNMP).
en.wikipedia.org/wiki/YANG
wh.cs.vsb.cz/sps/images/2/23/SoftwareOrientedManagement.pdf
- VXLAN feature enables service function chaining to steer traffic to virtual network functions.
networkop.co.uk/blog/2017/09/15/os-sfc-skydive
www.sciencedirect.com/science/article/pii/S0920548916302458
tools.ietf.org/id/draft-ietf-sfc-nsh-17.html
- Service deployments will be driven by applications/application policy
- Service will be built using flexible service graphs rather than linear service chains
- These services will adhere to application-centric business policies/requirements
- The service elements used to build service chains will be both physical and virtualized
- Flexible placement of service elements will require that the coupling of services to the underlying network topology be broken allowing transport agnostic service deployment
- Policy distribution through metadata exchange between service functions and the network
- Flexible service creation through service graphs rather than linear service chains
- The collection of service functions in a network form a graph
- The graph is composed of possible service function options:
- Directed graph
- Weighted graph if required
- Vertices: Service Functions
- Edges: Overlay connectivity
- A service is rendered based on a business policy like ...
- All traffic between the Internet & web front-end servers apply:
- De/Encryption with highest throughput / low latency and least $$ cost
- Copy all "mobile" only transactions to a Big Data analytics system
- Perform the copy at most optimal point ($$ cost & least latency impact)
- Send all traffic through a SLB+WAF & and IDS
- Additionally, deploy this policy with other caveats like:
- Service functions are both virtual and physical and vendor neutral
- Compute & service elasticity; compute mobility
- As an initial and transitional step, service chaining may be achieved through overlays that provide topological independence
- Tunnel encapsulation choices; VXLAN, GRE, MPLS, etc
- Application Centricity
- Programmability of:
- Infrastructure
- Controllers
- Services
- Virtualization of:
- vAF: Application Functions
- vMF: Management Functions
- vNF: Network Functions
- Network Expenses:
- 33% CAPEX
- 67% OPEX
- Deployment Speed:
- Computing 5 Seconds
- Networking 1,000 Seconds
- 80% Time IT spends on operations
- 55% CMOs think IT is not responding fast enough to time-sensitive projects
- 57% CEOs are worried about IT strategy not supporting business growth
