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Balazs Lengyel, Ericsson Andy Bierman draft-ietf-netconf-with-defaults-03 IETF-76 Hiroshima, 2009 November. “with-defaults” capability in NETCONF. Problem. Different network elements handle defaults differently We want flexible and predictable behavior
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Balazs Lengyel, Ericsson Andy Bierman draft-ietf-netconf-with-defaults-03 IETF-76 Hiroshima, 2009 November “with-defaults”capabilityin NETCONF
Problem • Different network elements handle defaults differently • We want flexible and predictable behavior • We must leave optionality as we can’t force the world to converge • Default data may or may not be stored in the datastore
Define Default • Default data: Data that is • Defined as default in YANG • Set or used by the network element • Not set by the manager • Explicit default: data set by the manager with a real management operation to its YANG default value • e.g. using <edit-config>, CLI, SNMP, GUI
Examples of a Server Provided Data • DEFAULT data CAN be: • - documented as yang default and stored in datastore • - documented as yang default and not stored in datastore • Server created REAL data CAN be • - documented as yang description and stored in datastore, • may or may not be essential for the workings of the system • - factory default setting used after initial load or delete-config • Server provided data CAN NOT be: • - documented as yang description and not stored in datastore
Effects of a default Is it part of the datastore? • How the node really works • What is returned in <get-config>/<get>? • With-defaults report-all/trim/explicit • Does <edit-config> create/delete succeed or fail? • Intentionally left undefined to accommodate differing existing nodes • Are non-presence containers present? • Intentionally left undefined to accommodate differing existing nodes • Must/When/Reference constraints? • Defaults always considered
Default Handling in the Real World • Report all: All default data is always reported. • Trim: Values are not reported if they match the default. • Explicit: Report values if they are explicitly set. • One of the above based on user choice • Etc.
Thank you for your response • Receive 439 emails on 10 pages of content • More then 20 times the amount of the original text
Changes • Changed definition of default data !!!!!!! • XSD and YAM marked <CODE BEGINS>…<CODE ENDS>
Open Issues • Shall we make this mandatory as report-all is important? • No • Shall the basic mode be configurable? • Yes, add it to Netconf-Monitoring data model?
Open Issues • Shall we make explicit mandatory • No, it requires a change in the underlying database • 1 bit of extra storage is cheap, BUT adapting an existing database and handling logic is EXPENSIVE • Makes adapting existing device to Netconf much more costly • Ericsson would hate you for it
Open Issues • Shall we make 3 features/capabilities instead of using parameters • No this is more simple • Shall we speak of operations/operation replies instead of rpcs/rpc-replies? • No, other drafts/rfcs also speak about rpc-replies, why introduce new terminology • Yes, it is more correct
Open Issues • Shall we wait for YANG and 4741bis to make YANG mandatory? • Yes: Andy, Juergen, Phil, Martin, Lada • No it might take a long time especially 4741bis