When OpenDaylight tries to open a NETCONF session with a Cisco router, OpenDaylight generates an error during the reception of the <hello> message coming from the router:

io.netty.handler.codec.DecoderException: java.lang.IllegalStateException: Hello message not received, instead received: <hello>
<capabilities>
<capability>urn:ietf:params:netconf:base:1.0</capability>
<capability>urn:ietf:params:netconf:capability:writeable-running:1.0</capability>
<capability>urn:ietf:params:netconf:capability:startup:1.0</capability>
<capability>urn:ietf:params:netconf:capability:url:1.0</capability>
<capability>urn:cisco:params:netconf:capability:pi-data-model:1.0</capability>
<capability>urn:cisco:params:netconf:capability:notification:1.0</capability>
</capabilities>
<session-id>1409770544</session-id>
</hello>

Consequently, the NETCONF session fails to open.

This has been observed with the follwoing Cisco equipments and IOS versions:

• CSR1000V (virtual routeur) with IOS 15.4(1)S
• ASR1001-X with IOS 15.4(2)S0a
• ISR2900 with IOS 15.1(4)M1

Attached is a test program that can be used to reproduce the problem with a Cisco router.

Some investigations in OpenDaylight NETCONF code show that the failure is due to the lack of xmlns attribute in the <hello> message sent by the router. OpenDaylight expects something like:

<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">

Whether the NETCONF RFC mandates the presence of the xmlns attribute is unclear to me. So I don't know if this is a bug in OpenDaylight or a bug in Cisco routers. Anyway, it can be fixed (or worked around depending on the point of view) in OpenDaylight, and I will propose a patch to do this.