Some concept used in SDN


The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs).


YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications.


describes a REST-like protocol that provides a programmatic interface over HTTP for accessing data defined in YANG, using the datastores defined in NETCONF.


Copied from internet

“BGP-LS is an extension to Border Gateway Protocol (BGP) for distributing the network’s link-state (LS) topology model to external entities, such as the SDN controller. It has received a lot of attention because many SDN apps need this model.

The network’s link-state topology model consists of nodes (typically, but not limited to, routers) and links that connect these routers together. For each link, a set of attributes is also contained. These may include interface addresses, various metrics, and each link’s total and available bandwidth. This topology model is distributed among routers using one of the two prominent Interior Gateway Protocols (IGPs): ISIS (Intermediate System to Intermediate System) and OSPF (Open Shortest Path First) protocols.

The detailed link-state models of these two protocols are not identical. As a result, BGP-LS defines its own more abstract topology model and defines how to map these IGP models to its own model. As the network topology is discovered by the IGPs, the changes are reflected in the BGP-LS model as well and are also distributed using BGP-LS messages to any interested party, such as SDN controllers and apps. Note that the network devices themselves are not interested in learning the network topology this way, as they already participate in IGP and learn it firsthand.”


The Cisco Application Policy Infrastructure Controller (Cisco APIC) is the unifying point of automation and management for the Application Centric Infrastructure (ACI) fabric.

It use policy agent to translate polices into instructions.


The EEM(Embedded Event manager is a software component of cisco IOS, XR, and NX-OS makes life easier for administrators by tracking and classifying events that take place on a router and providing notification options for those events. EEM allows you to automate tasks, perform minor enhancements and create workarounds.
There are two independent pieces: Applets and Scripting
-> Applets are a collection of CLI commands
-> Scripts are actions coded up in TCL(interpreter language)

EEM uses event detectors and actions to provide notifications of those events:

EEM detectors can be:
1) SNMP:-Monitoring SNMP objects.
2) Syslog:-Responds to various syslog messages, allowing for matching on regular expressions.
3) Counter: Monitoring and responding to interface counter when cross threshold settings.
4) CLI events: Screening CLI input for a regular expression match.
5) None: This event detector is use to test EEM script/applet using “event manager run” command.
6) Timers :(Countdown, watchdog and CRON)
7) IP SLA and Netflows events.


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