Hello messages exchange

After establishing a secure transport connection, both the NETCONF server and client send a <hello> element simultaneously to announce their capabilities and session identifier.

The NETCONF server must include the <session-id> element in the <hello> element. The <session-id> element contains the unique session value for the NETCONF session. If the client receives the <hello> element without the <session-id>, the client aborts the NETCONF session by closing the underlying SSH session.

The NETCONF client must not include the <session-id> element in the <hello> element. If the server receives the <hello> element with the <session-id>, the server aborts the NETCONF session by closing the underlying SSH session.

The NETCONF client must include a valid xmlns attribute in the <hello> element. If the server receives the <hello> element without a valid xmlns attribute, the server aborts the NETCONF session by closing the underlying SSH session.

The NETCONF client must include a base capability. The server receiving the <hello> element without a NETCONF base capability aborts the NETCONF session by closing the underlying SSH session.

The server receiving an <rpc> element without first receiving a <hello> element aborts the NETCONF session by closing the underlying SSH session.

The following example shows a <hello> element from the NETCONF server.

<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
	<capabilities>
		<capability>urn:ietf:params:netconf:base:1.0</capability>
		<capability>urn:ietf:params:netconf:capability:writable-running:1.0	</capability>
		<capability>urn:ietf:params:netconf:capability:startup:1.0</capability>	
		<capability>urn:ietf:params:netconf:capability:xpath:1.0</capability>
		<capability>urn:ietf:params:netconf:capability:validate:1.0</capability>
		<capability>http://tail-f.com/ns/netconf/actions/1.0</capability>
		<capability>http://tail-f.com/ns/aaa/1.1?revision=2010-06-17&module=tailfaaa</capability>
		<capability>urn:brocade.com:mgmt:brocade-aaa?revision=2010-10-21&module=brocade-aaa</capability>
		<capability>urn:brocade.com:mgmt:brocade-aaa-ext?revision=2010-09-21&module=brocade-aaa-ext</capability>
		<capability>urn:brocade.com:mgmt:brocade-cdp?revision=2010-08-17&module=brocade-cdp</capability>
		<capability>urn:brocade.com:mgmt:brocade-cee-map?revision=2011-04-18&module=brocade-cee-map</capability>
		<capability>urn:brocade.com:mgmt:brocade-chassis?revision=2011-04-11&module=brocade-chassis</capability>
	</capabilities>
	(output truncated)
	<session-id>4</session-id>
</hello>